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Sample records for attitude control

  1. Optimal magnetic attitude control

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Markley, F.L.

    1999-01-01

    because control torques can only be generated perpendicular to the local geomagnetic field vector. This has been a serious obstacle for using magnetorquer based control for three-axis stabilization of a low earth orbit satellite. The problem of controlling the spacecraft attitude using only magnetic...

  2. Satellite Attitude Control System Simulator

    Directory of Open Access Journals (Sweden)

    G.T. Conti

    2008-01-01

    Full Text Available Future space missions will involve satellites with great autonomy and stringent pointing precision, requiring of the Attitude Control Systems (ACS with better performance than before, which is function of the control algorithms implemented on board computers. The difficulties for developing experimental ACS test is to obtain zero gravity and torque free conditions similar to the SCA operate in space. However, prototypes for control algorithms experimental verification are fundamental for space mission success. This paper presents the parameters estimation such as inertia matrix and position of mass centre of a Satellite Attitude Control System Simulator (SACSS, using algorithms based on least square regression and least square recursive methods. Simulations have shown that both methods have estimated the system parameters with small error. However, the least square recursive methods have performance more adequate for the SACSS objectives. The SACSS platform model will be used to do experimental verification of fundamental aspects of the satellite attitude dynamics and design of different attitude control algorithm.

  3. Nonlinear Robust Control for Spacecraft Attitude

    Directory of Open Access Journals (Sweden)

    Wang Lina

    2013-07-01

    Full Text Available Nonlinear robust control of the spacecraft attitude with the existence of external disturbances is considered. A robust attitude controller is designed based on the passivity approach the quaternion representation, which introduces the suppression vector of external disturbance into the control law and does not need angular velocity measurement. Stability conditions of the robust attitude controller are given. And the numerical simulation results show the effectiveness of the attitude controller.

  4. Directional and Attitude Stability Control Kit

    Science.gov (United States)

    2014-07-01

    and Attitude Stability Control Kit Final Progress Report This report outlines progress on the DARPA M3 Program, project “Directional and Attitude ...2 ABSTRACT Number of Papers published in peer-reviewed journals: Number of Papers published in non peer-reviewed journals: Directional and Attitude ...Stability Control Kit Final Progress Report Report Title This report outlines progress on the DARPA M3 Program, project “Directional and Attitude

  5. Spacecraft attitude dynamics and control

    Science.gov (United States)

    Chobotov, Vladimir A.

    This overview of spacecraft dynamics encompasses the fundamentals of kinematics, rigid-body dynamics, linear control theory, orbital environmental effects, and the stability of motion. The theoretical treatment of each issue is complemented by specific references to spacecraft control systems based on spin, dual-spin, three-axis-active, and reaction-wheel methodologies. Also examined are control-moment-gyro, gravity-gradient, and magnetic control systems with attention given to key issues such as nutation damping, separation dynamics of spinning bodies, and tethers. Environmental effects that impinge on the application of spacecraft-attitude dynamics are shown to be important, and consideration is given to gravitation, solar radiation, aerodynamics, and geomagnetics. The publication gives analytical methods for examining the practical implementation of the control techniques as they apply to spacecraft.

  6. Design of a Control Moment Gyroscope Attitude Actuation System for the Attitude Control Subsystem Proving Ground

    Science.gov (United States)

    2013-03-01

    AAS Astrodynamice Specialist Conference, 2006. 33. Katsuhiko Ogata . Modern Control Engineering. Prentice-Hall, New Jersey, 4th edition, 2002. 109 34...DESIGN OF A CONTROL MOMENT GYROSCOPE ATTITUDE ACTUATION SYSTEM FOR THE ATTITUDE CONTROL SUBSYSTEM PROVING GROUND THESIS Samuel C. Johnson, 2Lt, USAF...the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENY-13-M-19 DESIGN OF A CONTROL MOMENT GYROSCOPE ATTITUDE

  7. Adaptive Fuzzy Attitude Control of Flexible Satellite

    Institute of Scientific and Technical Information of China (English)

    GUAN Ping; LIU Xiang-dong; CHEN Jia-bin

    2005-01-01

    The adaptive fuzzy control is applied in the attitude stabilization of flexible satellite. The detailed design procedure of the adaptive fuzzy control system is presented. Two T-S models are used as both controller and identifier. The parameters of the controller could be modified according to the information of the identifier. Simulation results show that the method can effectively cope with the uncertainty of flexible satellite by on-line learning and thus posses the good robustness. With the proposed method, the precise attitude control is accomplished.

  8. Fundamentals of spacecraft attitude determination and control

    CERN Document Server

    Markley, F Landis

    2014-01-01

    This book explores topics that are central to the field of spacecraft attitude determination and control. The authors provide rigorous theoretical derivations of significant algorithms accompanied by a generous amount of qualitative discussions of the subject matter. The book documents the development of the important concepts and methods in a manner accessible to practicing engineers, graduate-level engineering students and applied mathematicians. It includes detailed examples from actual mission designs to help ease the transition from theory to practice, and also provides prototype algorithms that are readily available on the author’s website. Subject matter includes both theoretical derivations and practical implementation of spacecraft attitude determination and control systems. It provides detailed derivations for attitude kinematics and dynamics, and provides detailed description of the most widely used attitude parameterization, the quaternion. This title also provides a thorough treatise of attitu...

  9. Satellite Attitude Control Using Only Electromagnetic Actuation

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    when a satellite is on a throughout this thesis. Confined computer capacity and a limit on electrical power supply were separate obstacles.They demanded computational simplicity and power optimality from the attitude control system. The design of quasi optimal controllers for a real-time implementation...... to provide four stable equilibria, one of which was the desired orientation. It was explained how the equilibria depended on the ratio of the satellite's moments of inertia. It was further investigated how to control the attitude, such that the satellite was globally asymptotically stable in the desired...

  10. Spacecraft Attitude Control in Hamiltonian Framework

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    The objective of this paper is to give a design scheme for attitude control algorithms of a generic spacecraft. Along with the system model formulated in the Hamilton's canonical form the algorithm uses information about a required potential energy and a dissipative term. The control action...

  11. Aircraft Pitch Attitude Control using Backstepping

    OpenAIRE

    Härkegård, Ola; Glad, Torkel

    2000-01-01

    A nonlinear approach to the automatic pitch attitude control problem for a generic fighter aircraft is presented. A nonlinear model describing the longitudinal equations of motion in strict feedback form is derived. Backstepping is utilized for the construction of a globally stabilizing controller with a number of free design parameters. Two tuning schemes are proposed based on the desired locally linear controller properties. The controller is evaluated using the HIRM fighter aircraft model.

  12. Advanced Attitude Control af Pico Sized Satellites

    DEFF Research Database (Denmark)

    Larsen, Jesper A.; Amini, Rouzbeh; Izadi-Zamanabadi, Roozbeh

    2005-01-01

    accuracy of better than 5 degrees. Cost, size, weight and power requirements, on the other hand, impose selecting relative simple sensors and actuators which leads to an attitude control requirement of less than 1 degree. This precision is obtained by a combination of magnetorquers and momentum wheels...

  13. Chaotic satellite attitude control by adaptive approach

    Science.gov (United States)

    Wei, Wei; Wang, Jing; Zuo, Min; Liu, Zaiwen; Du, Junping

    2014-06-01

    In this article, chaos control of satellite attitude motion is considered. Adaptive control based on dynamic compensation is utilised to suppress the chaotic behaviour. Control approaches with three control inputs and with only one control input are proposed. Since the adaptive control employed is based on dynamic compensation, faithful model of the system is of no necessity. Sinusoidal disturbance and parameter uncertainties are considered to evaluate the robustness of the closed-loop system. Both of the approaches are confirmed by theoretical and numerical results.

  14. Architecture for Combined Energy and Attitude Control System

    OpenAIRE

    Ibrahim M. Mehedi; Renuganth Varatharajoo; Harlisya Harun; Mohd N. Filipski

    2005-01-01

    Combining the energy and attitude control system is a feasible technology for small satellites to improve the space missions. In this Combined Energy and Attitude Control System (CEACS) a double rotating flywheel is used to replace the conventional battery for energy storage as well as to control the attitude of an earth oriented satellite. Each flywheel is to be controlled in the torque mode. The energy and attitude inputs for the flywheels' control architecture are also ...

  15. Attitude Determination and Control Systems

    Science.gov (United States)

    Starin, Scott R.; Eterno, John

    2011-01-01

    designing and operating spacecraft pointing (i.e. attitude) systems.

  16. Flexible Satellite Attitude Control via Adaptive Fuzzy Linearization

    Institute of Scientific and Technical Information of China (English)

    GUAN Ping; LIU Xiang-dong; CHEN Jia-bin; LIU Xiao-he

    2005-01-01

    The adaptive fuzzy control is combined with input-output linearization control to constitute the hybrid controller. The control method is then applied to the attitude maneuver control of the flexible satellite.The basic control structure is given. The rules of the controller parameter selection, which guarantee the attitude stabilization of the satellite with parameter uncertainties, have been analyzed. Simulation results show that the precise attitude control is accomplished in spite of the uncertainty in the system.

  17. Lorentz Force Based Satellite Attitude Control

    Science.gov (United States)

    Giri, Dipak Kumar; Sinha, Manoranjan

    2016-07-01

    Since the inception of attitude control of a satellite, various active and passive control strategies have been developed. These include using thrusters, momentum wheels, control moment gyros and magnetic torquers. In this present work, a new technique named Lorentz force based Coulombic actuators for the active control is proposed. This method uses electrostatic charged shells, which interact with the time varying earth's magnetic field to establish a full three axes control of the satellite. It is shown that the proposed actuation mechanism is similar to a satellite actuated by magnetic coils except that the resultant magnetic moment vanishes under two different conditions. The equation for the required charges on the the Coulomb shells attached to the satellite body axes is derived, which is in turn used to find the available control torque for actuating the satellite along the orbit. Stability of the proposed system for very high initial angular velocity and exponential stability about the origin are proved for a proportional-differential control input. Simulations are carried out to show the efficacy of the proposed system for the attitude control of the earth-pointing satellite.

  18. Small Satellite Passive Magnetic Attitude Control

    Science.gov (United States)

    Gerhardt, David T.

    Passive Magnetic Attitude Control (PMAC) is capable of aligning a satellite within 5 degrees of the local magnetic field at low resource cost, making it ideal for a small satellite. However, simulation attempts to date have not been able to predict the attitude dynamics at a level sufficient for mission design. Also, some satellites have suffered from degraded performance due to an incomplete understanding of PMAC system design. This dissertation alleviates these issues by discussing the design, inputs, and validation of PMAC systems for small satellites. Design rules for a PMAC system are defined using the Colorado Student Space Weather Experiment (CSSWE) CubeSat as an example. A Multiplicative Extended Kalman Filter (MEKF) is defined for the attitude determination of a PMAC satellite without a rate gyro. After on-orbit calibration of the off-the-shelf magnetometer and photodiodes and an on-orbit fit to the satellite magnetic moment, the MEKF regularly achieves a three sigma attitude uncertainty of 4 degrees or less. CSSWE is found to settle to the magnetic field in seven days, verifying its attitude design requirement. A Helmholtz cage is constructed and used to characterize the CSSWE bar magnet and hysteresis rods both individually and in the flight configuration. Fitted parameters which govern the magnetic material behavior are used as input to a PMAC dynamics simulation. All components of this simulation are described and defined. Simulation-based dynamics analysis shows that certain initial conditions result in abnormally decreased settling times; these cases may be identified by their dynamic response. The simulation output is compared to the MEKF output; the true dynamics are well modeled and the predicted settling time is found to possess a 20 percent error, a significant improvement over prior simulation.

  19. Observer-based Satellite Attitude Control and Simulation Researches

    Institute of Scientific and Technical Information of China (English)

    王子才; 马克茂

    2002-01-01

    Observer design method is applied to the realization of satellite attitude control law baaed on simplified control model. Exact mathematical model of the satellite attitude control system is also constructed, together with the observer-based control law, to conduct simulation research. The simulation results justify the effectiveness andfeasibility of the observer-based control method.

  20. Robust Adaptive Attitude Control for Airbreathing Hypersonic Vehicle with Attitude Constraints and Propulsive Disturbance

    Directory of Open Access Journals (Sweden)

    Jian Fu

    2015-01-01

    Full Text Available A robust adaptive backstepping attitude control scheme, combined with invariant-set-based sliding mode control and fast-nonlinear disturbance observer, is proposed for the airbreathing hypersonic vehicle with attitude constraints and propulsive disturbance. Based on the positive invariant set and backstepping method, an innovative sliding surface is firstly developed for the attitude constraints. And the propulsive disturbance of airbreathing hypersonic vehicle is described as a differential equation which is motivated by attitude angles in this paper. Then, an adaptive fast-nonlinear disturbance observer for the proposed sliding surface is designed to estimate this kind of disturbance. The convergence of all closed-loop signals is rigorously proved via Lyapunov analysis method under the developed robust attitude control scheme. Finally, simulation results are given to illustrate the effectiveness of the proposed attitude control scheme.

  1. Mechanism of Attitude Control Device for Floating Object

    OpenAIRE

    辻, 俊明; 大西, 公平

    2003-01-01

    This paper describes the new mechanism on attitude control device for unfixed objects. Flywheel is a common attitude control device on spacecraft that provides precise control at an easy rate. However, rapid response is hardly achieved since low reaction torque is available applying flywheel. The purpose in this paper is to improve the response of attitude control device with flywheel. Brake equipment is mounted on the flywheel in order to raise the maximum torque. Maximum torque is raised dr...

  2. MAP Attitude Control System Design and Analysis

    Science.gov (United States)

    Andrews, S. F.; Campbell, C. E.; Ericsson-Jackson, A. J.; Markley, F. L.; ODonnell, J. R., Jr.

    1997-01-01

    The Microwave Anisotropy Probe (MAP) is a follow-on to the Differential Microwave Radiometer (DMR) instrument on the Cosmic Background Explorer (COBE) spacecraft. The MAP spacecraft will perform its mission in a Lissajous orbit around the Earth-Sun L(sub 2) Lagrange point to suppress potential instrument disturbances. To make a full-sky map of cosmic microwave background fluctuations, a combination fast spin and slow precession motion will be used. MAP requires a propulsion system to reach L(sub 2), to unload system momentum, and to perform stationkeeping maneuvers once at L(sub 2). A minimum hardware, power and thermal safe control mode must also be provided. Sufficient attitude knowledge must be provided to yield instrument pointing to a standard deviation of 1.8 arc-minutes. The short development time and tight budgets require a new way of designing, simulating, and analyzing the Attitude Control System (ACS). This paper presents the design and analysis of the control system to meet these requirements.

  3. Optimal Sliding Mode Controllers for Attitude Stabilization of Flexible Spacecraft

    Directory of Open Access Journals (Sweden)

    Chutiphon Pukdeboon

    2011-01-01

    Full Text Available The robust optimal attitude control problem for a flexible spacecraft is considered. Two optimal sliding mode control laws that ensure the exponential convergence of the attitude control system are developed. Integral sliding mode control (ISMC is applied to combine the first-order sliding mode with optimal control and is used to control quaternion-based spacecraft attitude manoeuvres with external disturbances and an uncertainty inertia matrix. For the optimal control part the state-dependent Riccati equation (SDRE and optimal Lyapunov techniques are employed to solve the infinite-time nonlinear optimal control problem. The second method of Lyapunov is used to guarantee the stability of the attitude control system under the action of the proposed control laws. An example of multiaxial attitude manoeuvres is presented and simulation results are included to verify the usefulness of the developed controllers.

  4. Spacecraft Attitude Control in Hamiltonian Framework

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    The objective of this paper is to give a design scheme for attitude control algorithms of a generic spacecraft. Along with the system model formulated in the Hamilton's canonical form the algorithm uses information about a required potential energy and a dissipative term. The control action...... is the sum of the gradient of the potential energy and the dissipative force. It is shown that this control law makes the system uniformly asymptotically stable to the desired reference point. Three problems were addressed in the paper: spacecraft stabilization in the inertial frame, libration damping...... with the use of electromagnetic coils and a slew maneuver with an additional objective of avoiding undesirable regions e.g. causing blindness of optical sensors...

  5. Verification of Spin Magnetic Attitude Control System using air-bearing-based attitude control simulator

    Science.gov (United States)

    Ousaloo, H. S.; Nodeh, M. T.; Mehrabian, R.

    2016-09-01

    This paper accomplishes one goal and it was to verify and to validate a Spin Magnetic Attitude Control System (SMACS) program and to perform Hardware-In-the-Loop (HIL) air-bearing experiments. A study of a closed-loop magnetic spin controller is presented using only magnetic rods as actuators. The magnetic spin rate control approach is able to perform spin rate control and it is verified with an Attitude Control System (ACS) air-bearing MATLAB® SIMULINK® model and a hardware-embedded LABVIEW® algorithm that controls the spin rate of the test platform on a spherical air bearing table. The SIMULINK® model includes dynamic model of air-bearing, its disturbances, actuator emulation and the time delays caused by on-board calculations. The air-bearing simulator is employed to develop, improve, and carry out objective tests of magnetic torque rods and spin rate control algorithm in the experimental framework and to provide a more realistic demonstration of expected performance of attitude control as compared with software-based architectures. Six sets of two torque rods are used as actuators for the SMACS. It is implemented and simulated to fulfill mission requirement including spin the satellite up to 12 degs-1 around the z-axis. These techniques are documented for the full nonlinear equations of motion of the system and the performances of these techniques are compared in several simulations.

  6. The Spartan attitude control system - Control electronics assembly

    Science.gov (United States)

    Stone, R. W.

    1986-01-01

    The Spartan attitude control system (ACS) represents an evolutionary development of the previous STRAP-5 ACS through the use of state-of-the-art microprocessors and hardware. Despite a gyro rate signal noise problem that caused the early depletion of argon gas, the Spartan 101 experiment was able to collect several hours of data from two targets. Attention is presently given to the ACS sequencer module, sensor interface box, valve driver box, control electronics software, jam tables, and sequencer programs.

  7. Satellite cascade attitude control via fuzzy PD controller with active force control under momentum dumping

    Science.gov (United States)

    Ismail, Z.; Varatharajoo, R.

    2016-10-01

    In this paper, fuzzy proportional-derivative (PD) controller with active force control (AFC) scheme is studied and employed in the satellite attitude control system equipped with reaction wheels. The momentum dumping is enabled via proportional integral (PI) controller as the system is impractical without momentum dumping control. The attitude controllers are developed together with their governing equations and evaluated through numerical treatment with respect to a reference satellite mission. From the results, it is evident that the three axis attitudes accuracies can be improved up to ±0.001 degree through the fuzzy PD controller with AFC scheme for the attitude control. In addition, the three-axis wheel angular momentums are well maintained during the attitude control tasks.

  8. Attitude Control Performance of IRVE-3

    Science.gov (United States)

    Dillman, Robert A.; Gsell, Valerie T.; Bowden, Ernest L.

    2013-01-01

    The Inflatable Reentry Vehicle Experiment 3 (IRVE-3) launched July 23, 2012, from NASA Wallops Flight Facility and successfully performed its mission, demonstrating both the survivability of a hypersonic inflatable aerodynamic decelerator in the reentry heating environment and the effect of an offset center of gravity on the aeroshell's flight L/D. The reentry vehicle separated from the launch vehicle, released and inflated its aeroshell, reoriented for atmospheric entry, and mechanically shifted its center of gravity before reaching atmospheric interface. Performance data from the entire mission was telemetered to the ground for analysis. This paper discusses the IRVE-3 mission scenario, reentry vehicle design, and as-flown performance of the attitude control system in the different phases of the mission.

  9. Locus of Control, Attitudes toward Education, and Teaching Behaviors.

    Science.gov (United States)

    Kremer, Lya

    1982-01-01

    Tests 191 elementary school teachers in northern Israel for the relationships among locus of control, traditional and progressive educational attitudes, and related teaching behaviors. Finds external and internal locus of control explain the variance in traditional and progressive attitudes, respectively, and teaching behaviors. (Author/LC)

  10. New attitude penalty functions for spacecraft optimal control problems

    Energy Technology Data Exchange (ETDEWEB)

    Schaub, H.; Junkins, J.L. [Texas A and M Univ., College Station, TX (United States). Dept. of Aerospace Engineering; Robinett, R.D. [Sandia National Labs., Albuquerque, NM (United States)

    1996-03-01

    A solution of a spacecraft optimal control problem, whose cost function relies on an attitude description, usually depends on the choice of attitude coordinates used. A problem could be solved using 3-2-1 Euler angles or using classical Rodriguez parameters and yield two different ``optimal`` solutions, unless the performance index in invariant with respect to the attitude coordinate choice. Another problem arising with many attitude coordinates is that they have no sense of when a body has tumbled beyond 180{degrees} from the reference attitude. In many such cases it would be easier (i.e. cost less) to let the body complete the revolution than to force it to reverse the rotation and return to the desired attitude. This paper develops a universal attitude penalty function g() whose value is independent of the attitude coordinates chosen to represent it. Furthermore, this function will achieve its maximum value only when a principal rotation of {plus_minus}180{degrees} from the target state is performed. This will implicitly permit the g() function to sense the shortest rotational distance back to the reference state. An attitude penalty function which depends on the Modified Rodriguez Parameters (MRP) will also be presented. These recently discovered MRPs are a non-singular three-parameter set which can describe any three-attitude. This MRP penalty function is simpler than the attitude coordinate independent g() function, but retains the useful property of avoiding lengthy principal rotations of more than {plus_minus}180{degrees}.

  11. Architecture for Combined Energy and Attitude Control System

    Directory of Open Access Journals (Sweden)

    Ibrahim M. Mehedi

    2005-01-01

    Full Text Available Combining the energy and attitude control system is a feasible technology for small satellites to improve the space missions. In this Combined Energy and Attitude Control System (CEACS a double rotating flywheel is used to replace the conventional battery for energy storage as well as to control the attitude of an earth oriented satellite. Each flywheel is to be controlled in the torque mode. The energy and attitude inputs for the flywheels' control architecture are also in the torque mode. All related mathematical representation along with the relevant transfer functions and the required numerical calculation are developed. The goals are to analyze the attitude performance with respect to the ideal and non-ideal test cases for a chosen reference mission.

  12. Adaptive Jacobian Fuzzy Attitude Control for Flexible Spacecraft Combined Attitude and Sun Tracking System

    Science.gov (United States)

    Chak, Yew-Chung; Varatharajoo, Renuganth

    2016-07-01

    Many spacecraft attitude control systems today use reaction wheels to deliver precise torques to achieve three-axis attitude stabilization. However, irrecoverable mechanical failure of reaction wheels could potentially lead to mission interruption or total loss. The electrically-powered Solar Array Drive Assemblies (SADA) are usually installed in the pitch axis which rotate the solar arrays to track the Sun, can produce torques to compensate for the pitch-axis wheel failure. In addition, the attitude control of a flexible spacecraft poses a difficult problem. These difficulties include the strong nonlinear coupled dynamics between the rigid hub and flexible solar arrays, and the imprecisely known system parameters, such as inertia matrix, damping ratios, and flexible mode frequencies. In order to overcome these drawbacks, the adaptive Jacobian tracking fuzzy control is proposed for the combined attitude and sun-tracking control problem of a flexible spacecraft during attitude maneuvers in this work. For the adaptation of kinematic and dynamic uncertainties, the proposed scheme uses an adaptive sliding vector based on estimated attitude velocity via approximate Jacobian matrix. The unknown nonlinearities are approximated by deriving the fuzzy models with a set of linguistic If-Then rules using the idea of sector nonlinearity and local approximation in fuzzy partition spaces. The uncertain parameters of the estimated nonlinearities and the Jacobian matrix are being adjusted online by an adaptive law to realize feedback control. The attitude of the spacecraft can be directly controlled with the Jacobian feedback control when the attitude pointing trajectory is designed with respect to the spacecraft coordinate frame itself. A significant feature of this work is that the proposed adaptive Jacobian tracking scheme will result in not only the convergence of angular position and angular velocity tracking errors, but also the convergence of estimated angular velocity to

  13. Attitude towards Responsibility and Teacher Locus of Control: Predicting Teacher Stress and Attitudes. Research Paper ERU-2-88.

    Science.gov (United States)

    Soh, Kay-cheng

    The relationships between teachers' attitudes toward responsibility and locus of control and other characteristics such as stress, educational attitudes, and attitudes toward change were studied in 54 (35 female and 19 male) experienced primary and secondary school teachers taking a course on classroom-based research. Attitude toward…

  14. Periodic H-2 Synthesis for Spacecraft Attitude Control with Magnetometers

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Stoustrup, Jakob

    2004-01-01

    between the Earth´s magnetic field and an artificial magnetic field generated by the coils produces a control torque. The magnetic attitude control is intrinsically periodic due to cyclic variation of the geomagnetic field in orbit. The control performance is specified by the generalized H2 operator norm....... A linear matrix inequality-based algorithm is proposed for attitude control synthesis. Simulation results are provided, showing the prospect of the concept for onboard implementation....

  15. Pulsed Electrogasdynamic Thruster for Attitude Control and Orbit Maneuver Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In the Phase I program we successfully demonstrated the feasibility of the Pulsed ElectroGasdynamic (PEG) thruster for attitude control and orbital maneuvering. In...

  16. Pulsed Electrogasdynamic Thruster for Attitude Control and Orbit Maneuver Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new pulsed electric thruster, named "pulsed electrogasdynamic thruster," for attitude control and orbit maneuver is proposed. In this thruster, propellant gas is...

  17. Variable structure attitude maneuver and vibration control of flexible spacecraft

    Institute of Scientific and Technical Information of China (English)

    HU Qing-lei; MA Cuang-fu

    2008-01-01

    A dual-stage control system design method is presented for the three-axis-rotational maneuver and vibration stabilization of a spacecraft with flexible appendages embedded with piezoceramics as sensor and actuator.In this design approach,the attitude control and the vibration suppression sub-systems ale designed separately using the lower order model.The design of attitude controller is based on the variable structure control (VSC)theory leading to a discontinuous control law.This controller accomplishes asymptotic attitude maneuvering in the closed-loop system and is insensitive to the interaction of elastic modes and uncertainty in the system.To actively suppress the flexible vibrations,the modal velocity feedback control method is presented by using piezoelectric materials as additional sensor and actuator bonded on the surface of the flexible appendages.In addition,a special configuration of actuators for three-axis attitude control is also investigated:the pitch attitude controlled by a momentum wheel,and the roll/yaw control achieved by on-off thrustem.which is modulated by pulse width pulse frequency modulation technique to construct the proper control torque history.Numerical simulations performed show that the rotational maneuver and vibration suppression ale accomplished in spite of the presence of disturbance torque and parameter uncertainty.

  18. Sliding Mode Attitude Control for Magnetic Actuated Satellite

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    1998-01-01

    control torques can only be generated perpendicular to the local geomagnetic field vector. This has been a serious obstacle for using magnetorquer based control for three-axis attitude control. This paper deals with three-axis stabilization of a low earth orbit satellite. The problem of controlling...... the spacecraft attitude using only magnetic torquing is realized in the form of the sliding mode control. A three dimensional sliding manifold is proposed, and it is shown that the satellite motion on the sliding manifold is asymptotically stable...

  19. Two Axis Pointing System (TAPS) attitude acquisition, determination, and control

    Science.gov (United States)

    Azzolini, John D.; McGlew, David E.

    1990-12-01

    The Two Axis Pointing System (TAPS) is a 2 axis gimbal system designed to provide fine pointing of Space Transportation System (STS) borne instruments. It features center-of-mass instrument mounting and will accommodate instruments of up to 1134 kg (2500 pounds) which fit within a 1.0 by 1.0 by 4.2 meter (40 by 40 by 166 inch) envelope. The TAPS system is controlled by a microcomputer based Control Electronics Assembly (CEA), a Power Distribution Unit (PDU), and a Servo Control Unit (SCU). A DRIRU-II inertial reference unit is used to provide incremental angles for attitude propagation. A Ball Brothers STRAP star tracker is used for attitude acquisition and update. The theory of the TAPS attitude determination and error computation for the Broad Band X-ray Telescope (BBXRT) are described. The attitude acquisition is based upon a 2 star geometric solution. The acquisition theory and quaternion algebra are presented. The attitude control combines classical position, integral and derivative (PID) control with techniques to compensate for coulomb friction (bias torque) and the cable harness crossing the gimbals (spring torque). Also presented is a technique for an adaptive bias torque compensation which adjusts to an ever changing frictional torque environment. The control stability margins are detailed, with the predicted pointing performance, based upon simulation studies. The TAPS user interface, which provides high level operations commands to facilitate science observations, is outlined.

  20. Robustness and Actuator Bandwidth of MRP-Based Sliding Mode Control for Spacecraft Attitude Control Problems

    Science.gov (United States)

    Keum, Jung-Hoon; Ra, Sung-Woong

    2009-12-01

    Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.

  1. ISS Contingency Attitude Control Recovery Method for Loss of Automatic Thruster Control

    Science.gov (United States)

    Bedrossian, Nazareth; Bhatt, Sagar; Alaniz, Abran; McCants, Edward; Nguyen, Louis; Chamitoff, Greg

    2008-01-01

    In this paper, the attitude control issues associated with International Space Station (ISS) loss of automatic thruster control capability are discussed and methods for attitude control recovery are presented. This scenario was experienced recently during Shuttle mission STS-117 and ISS Stage 13A in June 2007 when the Russian GN&C computers, which command the ISS thrusters, failed. Without automatic propulsive attitude control, the ISS would not be able to regain attitude control after the Orbiter undocked. The core issues associated with recovering long-term attitude control using CMGs are described as well as the systems engineering analysis to identify recovery options. It is shown that the recovery method can be separated into a procedure for rate damping to a safe harbor gravity gradient stable orientation and a capability to maneuver the vehicle to the necessary initial conditions for long term attitude hold. A manual control option using Soyuz and Progress vehicle thrusters is investigated for rate damping and maneuvers. The issues with implementing such an option are presented and the key issue of closed-loop stability is addressed. A new non-propulsive alternative to thruster control, Zero Propellant Maneuver (ZPM) attitude control method is introduced and its rate damping and maneuver performance evaluated. It is shown that ZPM can meet the tight attitude and rate error tolerances needed for long term attitude control. A combination of manual thruster rate damping to a safe harbor attitude followed by a ZPM to Stage long term attitude control orientation was selected by the Anomaly Resolution Team as the alternate attitude control method for such a contingency.

  2. Advanced Integrated Power and Attitude Control System (IPACS) study

    Science.gov (United States)

    Oglevie, R. E.; Eisenhaure, D. B.

    1985-01-01

    Integrated Power and Attitude Control System (IPACS) studies performed over a decade ago established the feasibility of simultaneously satisfying the demands of energy storage and attitude control through the use of rotating flywheels. It was demonstrated that, for a wide spectrum of applications, such a system possessed many advantages over contemporary energy storage and attitude control approaches. More recent technology advances in composite material rotors, magnetic suspension systems, and power control electronics have triggered new optimism regarding the applicability and merits of this concept. This study is undertaken to define an advanced IPACS and to evaluate its merits for a space station application. System and component designs are developed to establish the performance of this concept and system trade studies conducted to examine the viability of this approach relative to conventional candidate systems. It is clearly demonstrated that an advanced IPACS concept is not only feasible, but also offers substantial savings in mass and life-cycle cost for the space station mission.

  3. Fuzzy robust attitude controller design for hydrofoil catamaran

    Institute of Scientific and Technical Information of China (English)

    Ren Junsheng; Yang Yansheng

    2005-01-01

    A robust attitude controller for hydrofoil catamaran throughout its operating envelope is proposed, based on Tagaki-Sugeno (T-S) fuzzy model. Firstly, T-S fuzzy model and robust attitude control strategy for hydrofoil catamaran is presented by use of linear matrix inequality (LMI) techniques. Secondly, a nonlinear mathematical model of hydrofoil catamaran is established, acting as the platform for further researches. The specialty in interpolation of T-S fuzzy model guarantees that feedback gain can be obtained smoothly, while boat's speed is shifting over the operating envelope. The external disturbances are also attenuated to achieve H∞ control performance, meanwhile. Finally, based on such a boat,HC200B-A1, simulation researches demonstrate the design procedures and the effectiveness of fuzzy robust attitude controller.

  4. NASA Workshop on Hybrid (Mixed-Actuator) Spacecraft Attitude Control

    Science.gov (United States)

    Dennehy, Cornelius J.; Kunz, Nans

    2014-01-01

    At the request of the Science Mission Directorate Chief Engineer, the NASA Technical Fellow for Guidance, Navigation & Control assembled and facilitated a workshop on Spacecraft Hybrid Attitude Control. This multi-Center, academic, and industry workshop, sponsored by the NASA Engineering and Safety Center (NESC), was held in April 2013 to unite nationwide experts to present and discuss the various innovative solutions, techniques, and lessons learned regarding the development and implementation of the various hybrid attitude control system solutions investigated or implemented. This report attempts to document these key lessons learned with the 16 findings and 9 NESC recommendations.

  5. Precision Attitude Control for the BETTII Balloon-Borne Interferometer

    Science.gov (United States)

    Benford, Dominic J.; Fixsen, Dale J.; Rinehart. Stephen

    2012-01-01

    The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter baseline far-infrared interferometer to fly on a high altitude balloon. Operating at wavelengths of 30-90 microns, BETTII will obtain spatial and spectral information on science targets at angular resolutions down to less than half an arcsecond, a capability unmatched by other far-infrared facilities. This requires attitude control at a level ofless than a tenth of an arcsecond, a great challenge for a lightweight balloon-borne system. We have designed a precision attitude determination system to provide gondola attitude knowledge at a level of 2 milliarcseconds at rates up to 100Hz, with accurate absolute attitude determination at the half arcsecond level at rates of up to 10Hz. A mUlti-stage control system involving rigid body motion and tip-tilt-piston correction provides precision pointing stability to the level required for the far-infrared instrument to perform its spatial/spectral interferometry in an open-loop control. We present key aspects of the design of the attitude determination and control and its development status.

  6. High Accuracy Attitude Control of a Spacecraft Using Feedback Linearization

    Science.gov (United States)

    1992-05-01

    and Spacecraft Body from Gyro Measurements ......... .................................. 119 D.2 An Approximation to Exact Linearization using IPSRU...31 2-4 Attitude Determination and Control System Architecture ................. 33 3-1 Exact Linearization Using Nonlinear Feedback...though basic techniques were adapted from recent references on the use of exact linearization (such as [8] and [27]), the specific control approach

  7. SDRE Based Attitude Control Using Modified Rodriguez Parameters

    CERN Document Server

    Doruk, R Ozgur

    2011-01-01

    The purpose of this paper is to present an application of the State Dependent Riccati Equation (SDRE) method to satellite attitude control where the satellite kinematics is modeled by Modified Rodriguez Parameters (MRP). The SDRE methodology is applicable on special forms of nonlinear systems where satellite model is one of the candidates. It is not easy to find an analytical solution from the SDRE. Thus point wise solutions are interpolated with respect to the operating conditions. The point wise solutions are obtained from the MATLAB algorithms which are derived from the positive definite solutions of the SDRE. The global stability analysis is difficult due to the nature of the methodology. The resultant attitude controllers outside the breakpoints (the selected operating conditions for interpolation) are suboptimal. The performance of the designs is examined by simulations on MATLAB - Simulink environment. The simulation results show that, the designed attitude controllers are working satisfactorily even i...

  8. Neural adaptive attitude tracking controller for flexible spacecraft

    Institute of Scientific and Technical Information of China (English)

    XIAO Bing; HU Qing-lei; MA Guang-fu

    2010-01-01

    In this paper,a neural network adaptive controller is proposed for attitude tracking of flexible spacecraft in presence of unknown inertial matrix and external disturbance.In this approach,neural network technique is employed to approximate the unknown system dynamics with finite combinations of some basis functions,and a robust controller is also designed to attenuate the effect of approximation error,more specially,the knowledge of angular velocity is not required.In the closed-loop system,Lyapunov stability analysis shows that the attitude trajectories asymptotically follow the reference output trajectories.Finally,simulation results are presented for the attitude tracking of a flexible spacecraft to show the excellent performance of the proposed controller and illustrate its robustness in face of external disturbances and unknown dynamics.

  9. Youth Attitudes towards Tobacco Control Laws: The Influence of Smoking Status and Grade in School

    Science.gov (United States)

    Williams, Terrinieka T.; Jason, Leonard A.; Pokorny, Steven B.

    2008-01-01

    This study examined adolescent attitudes towards tobacco control laws. An exploratory factor analysis, using surveys from over 9,000 students, identified the following three factors: (1) youth attitudes towards the efficacy of tobacco control laws, (2) youth attitudes towards tobacco possession laws and (3) youth attitudes towards tobacco sales…

  10. Attitude stabilization of a rigid spacecraft using two control torques: A nonlinear control approach based on the spacecraft attitude dynamics

    Science.gov (United States)

    Krishnan, Hariharan; Reyhanoglu, Mahmut; McClamroch, Harris

    1994-06-01

    The attitude stabilization problem of a rigid spacecraft using control torques supplied by gas jet actuators about only two of its principal axes is considered. If the uncontrolled principal axis of the spacecraft is not an axis of symmetry, then the complete spacecraft dynamics are small time locally controllable. However, the spacecraft cannot be asymptotically stabilized to any equilibrium attitude using time-invariant continuous feedback. A discontinuous stabilizing feedback control strategy is constructed which stabilizes the spacecraft to any equilibrium attitude. If the uncontrolled principal axis of the spacecraft is an axis of symmetry, the complete spacecraft dynamics are not even assessible. However, the spacecraft dynamics are strongly accessible and small time locally controllable in a reduced sense. The reduced spacecraft dynamics cannot be asymptotically stabilized to any equilibrium attitude using time-invariant continuous feedback, but again a discontinuous stabilizing feedback control strategy is constructed. In both cases, the discontinuous feedback controllers are constructed by switching between several feedback functions which are selected to accomplish a sequence of spacecraft maneuvers. The results of the paper show that although standard nonlinear control techniques are not applicable, it is possible to construct a nonlinear discontinuous control law based on the dynamics of the particular physical system.

  11. An Artificial Neural Network Control System for Spacecraft Attitude Stabilization

    Science.gov (United States)

    1990-06-01

    NAVAL POSTGRADUATE SCHOOL Monterey, California ’-DTIC 0 ELECT f NMARO 5 191 N S, U, THESIS B . AN ARTIFICIAL NEURAL NETWORK CONTROL SYSTEM FOR...NO. NO. NO ACCESSION NO 11. TITLE (Include Security Classification) AN ARTIFICIAL NEURAL NETWORK CONTROL SYSTEM FOR SPACECRAFT ATTITUDE STABILIZATION...obsolete a U.S. G v pi.. iim n P.. oiice! toog-eo.5s43 i Approved for public release; distribution is unlimited. AN ARTIFICIAL NEURAL NETWORK CONTROL

  12. Stabilization of rotational motion with application to spacecraft attitude control

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    on a Riemannian manifold. The Lyapnov stability theory is adapted and reformulated to fit to the new framework of Riemannian manifolds. Toillustrate the results a spacecraft attitude control problem is considered. Firstly, a global canonical representation for the spacecraft motion is found, then three spacecraft...

  13. Cassini at Saturn Proximal Orbits - Attitude Control Challenges

    Science.gov (United States)

    Burk, Thomas A.

    2013-01-01

    The Cassini mission at Saturn will come to an end in the spring and summer of 2017 with a series of 22 orbits that will dip inside the rings of Saturn. These are called proximal orbits and will conclude with spacecraft disposal into the atmosphere of the ringed world on September 15, 2017. These unique orbits that cross the ring plane only a few thousand kilometers above the cloud tops of the planet present new attitude control challenges for the Cassini operations team. Crossing the ring plane so close to the inner edge of the rings means that the Cassini orientation during the crossing will be tailored to protect the sensitive electronics bus of the spacecraft. This orientation will put the sun sensors at some extra risk so this paper discusses how the team prepares for dust hazards. Periapsis is so close to the planet that spacecraft controllability with RCS thrusters needs to be evaluated because of the predicted atmospheric torque near closest approach to Saturn. Radiation during the ring plane crossings will likely trigger single event transients in some attitude control sensors. This paper discusses how the attitude control team deals with radiation hazards. The angular size and unique geometry of the rings and Saturn near periapsis means that star identification will be interrupted and this paper discusses how the safe mode attitude is selected to best deal with these large bright bodies during the proximal orbits.

  14. Feedforward attitude control for a TDRS with mobile antennas

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, feedforward attitude control law for a Tracking and Data Relay Satellite (TDRS) with mobile antennas is proposed. To track or point the target spacecraft with median/law orbit, the large mobile antennas have to move in a wide range. The movement of such mobile antennas disturbs the satellite attitude consequently. Conventionally, the main body of the satellite and the mobile antennas are controlled independently.The proposed controller first estimates the angular momentum which the mobile antennas will produce based on the momentum conservation equation. Next, it computes the desired velocity of reaction wheels to compensate the disturbance due to the antenna motion. It then adds the error of the wheels' velocity between a desired one and a current value as a feedforward signal to the control system. The proposed controller is demonstrated using a mathematical simulation, of which these results coincide well with analytical results.

  15. Orbit and attitude control of spacecraft formation flying

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-guo; LI Jun-feng

    2008-01-01

    Formation flying is a novel concept of distributing the flmctionality of large spacecraft among several smaller, less expensive, cooperative satellites. Some applica-tions require that a controllable satellite keeps relative position and attitude to observe a specific surface of another satellite among the cluster. Specially, the target space vehi- cle is malfunctioning. The present paper focuses on the problem that how to control a chaser satellite to fly around an out-of-work target satellite closely in earth orbit and to track a specific surface. Relative attitude and first approximate relative orbital dynamics equations are presented. Control strategy is derived based on feedback linearization and Lyapunov theory of stability. Further, considering the uncertainty of inertia, an adaptive control method is developed to obtain the correct inertial ratio. The numerical simulation is given to verify the validity of proposed control scheme.

  16. The SAS-3 attitude control system

    Science.gov (United States)

    Mobley, F. F.; Konigsberg, R.; Fountain, G. H.

    1975-01-01

    SAS-3 uses a reaction wheel to provide torque to control the spin rate. If the wheel speed becomes too great or too small, it must be restored to its nominal rate by momentum dumping which is done by magnetic torquing against the earth's magnetic field by the satellite's magnetic coils. A small rate-integrating gyro is used to sense the spin rate so that closed loop control of the spin rate can be achieved. These various systems are described in detail including the reaction wheel system, the gyro system, along with control modes (spin rate control and the star lock mode).

  17. Integrated power and single axis attitude control system with two flywheels

    Science.gov (United States)

    Han, Bangcheng

    2012-05-01

    The existing research of the integrated power and attitude control system (IPACS) in satellites mainly focuses on the IPACS concept, which aims at solving the coupled problem between the attitude control and power tracking. In the IPACS, the configuration design of IPACS is usually not considered, and the coupled problem between two flywheels during the attitude control and energy storage has not been resolved. In this paper, an integrated power and single axis attitude control system using two counter rotating magnetically suspended flywheels mounted to an air table is designed. The control method of power and attitude control using flywheel is investigated and the coupling problem between energy storage and attitude control is resolved. A computer simulation of an integrated power and single axis attitude control system with two flywheels is performed, which consists of two counter rotating magnetically suspended flywheels mounted to an air rotary table. Both DC bus and a single axis attitude are the regulation goals. An attitude & DC bus coordinator is put forward to separate DC bus regulation and attitude control problems. The simulation results of DC bus regulation and attitude control are presented respectively with a DC bus regulator and a simple PD attitude controller. The simulation results demonstrate that it is possible to integrate power and attitude control simultaneously for satellite using flywheels. The proposed research provides theory basis for design of the IPACS.

  18. Design and Stability of an On-Orbit Attitude Control System Using Reaction Control Thrusters

    Science.gov (United States)

    Hall, Robert A.; Hough, Steven; Orphee, Carolina; Clements, Keith

    2016-01-01

    NASA is providing preliminary design and requirements for the Space Launch System Exploration Upper Stage (EUS). The EUS will provide upper stage capability for vehicle ascent as well as on-orbit control capability. Requirements include performance of on-orbit burn to provide Orion vehicle with escape velocity. On-orbit attitude control is accommodated by a on-off Reaction Control System (RCS). Paper provides overview of approaches for design and stability of an attitude control system using a RCS.

  19. Stabilization of rotational motion with application to spacecraft attitude control

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2001-01-01

    on a Riemannian manifold. The Lyapnov stability theory is adapted and reformulated to fit to the new framework of Riemannian manifolds. Toillustrate the results a spacecraft attitude control problem is considered. Firstly, a global canonical representation for the spacecraft motion is found, then three spacecraft...... control problems are addressed: stabilization in the inertial frame, magnetic libration damping for the gravity gradient stabilization and a slew maneuver with obstacle avoidance...

  20. Attitude Control of a Satellite by using Digital Signal Processing

    Directory of Open Access Journals (Sweden)

    Adirelle C. Santana

    2012-03-01

    Full Text Available This article has discussed the development of a three-axis attitude digital controller for an artificial satellite using a digital signal processor. The main motivation of this study is the attitude control system of the satellite Multi-Mission Platform, developed by the Brazilian National Institute for Space Research for application in different sort of missions. The controller design was based on the theory of the Linear Quadratic Gaussian Regulator, synthesized from the linearized model of the motion of the satellite, i.e., the kinematics and dynamics of attitude. The attitude actuators considered in this study are pairs of cold gas jets powered by a pulse width/pulse frequency modulator. In the first stage of the project development, a system controller for continuous time was studied with the aim of testing the adequacy of the adopted control. The next steps had included an analysis of discretization techniques, the setting time of sampling rate, and the testing of the digital version of the Linear Quadratic Gaussian Regulator controller in the MATLAB/SIMULINK. To fulfill the study, the controller was implemented in a digital signal processor, specifically the Blackfin BF537 from Analog Devices, along with the pulse width/pulse frequency modulator. The validation tests used a scheme of co-simulation, where the model of the satellite was simulated in MATLAB/SIMULINK, while the controller and modulator were processed in the digital signal processor with a tool called Processor-In-the-Loop, which acted as a data communication link between both environments.function and required time to achieve a given mission accuracy are determined, and results are provided as illustration.

  1. Autonomous Attitude Determination and Control System for the Ørsted Satellite

    DEFF Research Database (Denmark)

    Bak, Thomas; Wisniewski, Rafal; Blanke, M.

    1996-01-01

    The Ørsted Satellite mission imposes comparatively high requirements on autonomy of the attitude control system.......The Ørsted Satellite mission imposes comparatively high requirements on autonomy of the attitude control system....

  2. Attitude-Control Algorithm for Minimizing Maneuver Execution Errors

    Science.gov (United States)

    Acikmese, Behcet

    2008-01-01

    A G-RAC attitude-control algorithm is used to minimize maneuver execution error in a spacecraft with a flexible appendage when said spacecraft must induce translational momentum by firing (in open loop) large thrusters along a desired direction for a given period of time. The controller is dynamic with two integrators and requires measurement of only the angular position and velocity of the spacecraft. The global stability of the closed-loop system is guaranteed without having access to the states describing the dynamics of the appendage and with severe saturation in the available torque. Spacecraft apply open-loop thruster firings to induce a desired translational momentum with an extended appendage. This control algorithm will assist this maneuver by stabilizing the attitude dynamics around a desired orientation, and consequently minimize the maneuver execution errors.

  3. Integrated Power and Attitude Control Systems for Space Station

    Science.gov (United States)

    Oglevie, R. E.; Eisenhaure, D. B.

    1985-01-01

    Integrated Power and Attitude Control Systems (IPACS) studies performed over a decade ago established the feasibility of simultaneously storing electrical energy in wheels and utilizing the resulting momentum for spacecraft attitude control. It was shown that such a system possessed many advantages over other contemporary energy storage and attitude control systems in many applications. More recent technology advances in composite rotors, magnetic bearings, and power control electronics have triggered new optimism regarding the feasibility and merits of such a system. The paper presents the results of a recent study whose focus was to define an advanced IPACS and to evaluate its merits for the Space Station application. A system and component design concept is developed to establish the system performance capability. A system level trade study, including life-cycle costing, is performed to define the merits of the system relative to two other candidate systems. It is concluded that an advanced IPACS concept is not only feasible, but offers substantial savings in mass, and life-cycle cost.

  4. Small unmanned helicopter's attitude controller by an on-line adaptive fuzzy control system

    Institute of Scientific and Technical Information of China (English)

    GAO Tong-yue; RAO Jin-jun; GONG Zhen-bang; LUO Jun

    2009-01-01

    Since small unmanned helicopter flight attitude control process has strong time-varying characteristics and there are random disturbances, the conventional control methods with unchanged parameters are often unworkable. An on-line adaptive fuzzy control system (AFCS) was designed, in a way that does not depend on a process model of the plant or its approximation in the form of a Jacobian matrix. Neither is it necessary to know the desired response at each instant of time. AFCS implement a simultaneous on-line tuning of fuzzy rules and output scale of fuzzy control system. The two cascade controller design with an inner (attitude controller) and outer controller (navigation controller) of the small unmanned helicopter was proposed. At last, an attitude controller based on AFCS was implemented. The flight experiment showed that the proposed fuzzy logic controller provides quicker response, smaller overshoot, higher precision, robustness and adaptive ability. It satisfies the needs of autonomous flight.

  5. School teachers' attitude toward population control.

    Science.gov (United States)

    Vaswani, N V; Kapoor, I

    1977-01-01

    A report on a study of 412 school teachers in the Bombay area of India. 82 of the teachers were tested initially, and found to have unclear ideas about the meaning of "population control." As a result, the definition of the term adopted by UNESCO in 1970 was incorporated into the questionnaire, and translated into Hindi/Marathi and Gujarti. The 1st 82 teachers were considered as a pretest group, and the remaining teachers were given a 3-part questionnaire. This included identification data, questions on their opinions and reactions toward teaching population education, and their own views on age of marriage and family size. Tables break down the results in several ways. The main conclusions are that a majority of the teachers responding were still unclear about the meaning of population education, and felt that they were unqualified to teach the subject, while they believed in its importance.

  6. Attitude and Translation Control of a Solar Sail Vehicle

    Science.gov (United States)

    Singh, Gurkirpal

    2008-01-01

    A report discusses the ability to control the attitude and translation degrees-of-freedom of a solar sail vehicle by changing its center of gravity. A movement of the spacecraft s center of mass causes solar-pressure force to apply a torque to the vehicle. At the compact core of the solar-sail vehicle lies the spacecraft bus which is a large fraction of the total vehicle mass. In this concept, the bus is attached to the spacecraft by two single degree-of-freedom linear tracks. This allows relative movement of the bus in the sail plane. At the null position, the resulting solar pressure applies no torque to the vehicle. But any deviation of the bus from the null creates an offset between the spacecraft center of mass and center of solar radiation pressure, resulting in a solar-pressure torque on the vehicle which changes the vehicle attitude. Two of the three vehicle degrees of freedom can be actively controlled in this manner. The third, the roll about the sunline, requires a low-authority vane/propulsive subsystem. Translation control of the vehicle is achieved by directing the solar-pressure-induced force in the proper inertial direction. This requires attitude control. Attitude and translation degrees-of-freedom are therefore coupled. A guidance law is proposed, which allows the vehicle to stationkeep at an appropriate point on the inertially-rotating Sun-Earth line. Power requirements for moving the bus are minimal. Extensive software simulations have been performed to demonstrate the feasibility of this concept.

  7. Fault tolerant programmable digital attitude control electronics study

    Science.gov (United States)

    Sorensen, A. A.

    1974-01-01

    The attitude control electronics mechanization study to develop a fault tolerant autonomous concept for a three axis system is reported. Programmable digital electronics are compared to general purpose digital computers. The requirements, constraints, and tradeoffs are discussed. It is concluded that: (1) general fault tolerance can be achieved relatively economically, (2) recovery times of less than one second can be obtained, (3) the number of faulty behavior patterns must be limited, and (4) adjoined processes are the best indicators of faulty operation.

  8. The Spartan attitude control system - Ground support computer

    Science.gov (United States)

    Schnurr, R. G., Jr.

    1986-01-01

    The Spartan Attitude Control System (ACS) contains a command and control computer. This computer is optimized for the activities of the flight and contains very little human interface hardware and software. The computer system provides the technicians testing of Spartan ACS with a convenient command-oriented interface to the flight ACS computer. The system also decodes and time tags data automatically sent out by the flight computer as key events occur. The duration and magnitude of all system maneuvers is also derived and displayed by this system. The Ground Support Computer is also the primary Ground Support Equipment for the flight sequencer which controls all payload maneuvers, and long term program timing.

  9. Colloid Thruster for Attitude Control Systems (ACS) and Tip-off Control Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop and test key technologies needed for an integrated, high thrust colloid thruster system with no moving parts, for spacecraft attitude control...

  10. Position and attitude tracking control for a quadrotor UAV.

    Science.gov (United States)

    Xiong, Jing-Jing; Zheng, En-Hui

    2014-05-01

    A synthesis control method is proposed to perform the position and attitude tracking control of the dynamical model of a small quadrotor unmanned aerial vehicle (UAV), where the dynamical model is underactuated, highly-coupled and nonlinear. Firstly, the dynamical model is divided into a fully actuated subsystem and an underactuated subsystem. Secondly, a controller of the fully actuated subsystem is designed through a novel robust terminal sliding mode control (TSMC) algorithm, which is utilized to guarantee all state variables converge to their desired values in short time, the convergence time is so small that the state variables are acted as time invariants in the underactuated subsystem, and, a controller of the underactuated subsystem is designed via sliding mode control (SMC), in addition, the stabilities of the subsystems are demonstrated by Lyapunov theory, respectively. Lastly, in order to demonstrate the robustness of the proposed control method, the aerodynamic forces and moments and air drag taken as external disturbances are taken into account, the obtained simulation results show that the synthesis control method has good performance in terms of position and attitude tracking when faced with external disturbances.

  11. Local controllability and stabilization of spacecraft attitude by two single-gimbal control moment gyros

    Institute of Scientific and Technical Information of China (English)

    Gui Haichao; Jin Lei; Xu Shijie

    2013-01-01

    The attitude control problem of a spacecraft underactuated by two single-gimbal control moment gyros (SGCMGs) is investigated. Small-time local controllability (STLC) of the attitude dynamics of the spacecraft-SGCMGs system is analyzed via nonlinear controllability theory. The conditions that guarantee STLC of the spacecraft attitude by two non-coaxial SGCMGs are obtained with the momentum of the SGCMGs as inputs, implying that the spacecraft attitude is STLC when the total angular momentum of the whole system is zero. Moreover, our results indi-cate that under the zero-momentum restriction, full attitude stabilization is possible for a spacecraft using two non-coaxial SGCMGs. For the case of two coaxial SGCMGs, the STLC property of the spacecraft cannot be determined. In this case, an improvement to the previous full attitude stabiliz-ing control law, which requires zero-momentum presumption, is proposed to account for the singu-larity of SGCMGs and enhance the steady state performance. Numerical simulation results demonstrate the effectiveness and advantages of the new control law.

  12. Satellite Attitude Control System Design considering the Fuel Slosh Dynamics

    Directory of Open Access Journals (Sweden)

    Luiz Carlos Gadelha de Souza

    2014-01-01

    Full Text Available The design of the satellite attitude control system (ACS becomes more complex when the satellite structure has different type of components like, flexible solar panels, antennas, mechanical manipulators, and tanks with fuel. A crucial interaction can occur between the fuel slosh motion and the satellite rigid motion during translational and/or rotational manoeuvre since these interactions can change the satellite centre of mass position damaging the ACS pointing accuracy. Although, a well-designed controller can suppress such disturbances quickly, the controller error pointing may be limited by the minimum time necessary to suppress such disturbances thus affecting the satellite attitude acquisition. As a result, the design of the satellite controller needs to explore the limits between the conflicting requirements of performance and robustness. This paper investigates the effects of the interaction between the liquid motion (slosh and the satellite dynamics in order to predict what the damage to the controller performance and robustness is. The fuel slosh dynamics is modelled by a pendulum which parameters are identified using the Kalman filter technique. This information is used to design the satellite controller by the linear quadratic regulator (LQR and linear quadratic Gaussian (LQG methods to perform a planar manoeuvre assuming thrusters are actuators.

  13. Observer Based Sliding Mode Attitude Control: Theoretical and Experimental Results

    Directory of Open Access Journals (Sweden)

    U. Jørgensen

    2011-07-01

    Full Text Available In this paper we present the design of a sliding mode controller for attitude control of spacecraft actuated by three orthogonal reaction wheels. The equilibrium of the closed loop system is proved to be asymptotically stable in the sense of Lyapunov. Due to cases where spacecraft do not have angular velocity measurements, an estimator for the generalized velocity is derived and asymptotic stability is proven for the observer. The approach is tested on an experimental platform with a sphere shaped Autonomous Underwater Vehicle SATellite: AUVSAT, developed at the Norwegian University of Science and Technology.

  14. Fuzzy attitude control for a nanosatellite in leo orbit

    Science.gov (United States)

    Calvo, Daniel; Laverón-Simavilla, Ana; Lapuerta, Victoria; Aviles, Taisir

    Fuzzy logic controllers are flexible and simple, suitable for small satellites Attitude Determination and Control Subsystems (ADCS). In this work, a tailored fuzzy controller is designed for a nanosatellite and is compared with a traditional Proportional Integrative Derivative (PID) controller. Both control methodologies are compared within the same specific mission. The orbit height varies along the mission from injection at around 380 km down to a 200 km height orbit, and the mission requires pointing accuracy over the whole time. Due to both the requirements imposed by such a low orbit, and the limitations in the power available for the attitude control, a robust and efficient ADCS is required. For these reasons a fuzzy logic controller is implemented as the brain of the ADCS and its performance and efficiency are compared to a traditional PID. The fuzzy controller is designed in three separated controllers, each one acting on one of the Euler angles of the satellite in an orbital frame. The fuzzy memberships are constructed taking into account the mission requirements, the physical properties of the satellite and the expected performances. Both methodologies, fuzzy and PID, are fine-tuned using an automated procedure to grant maximum efficiency with fixed performances. Finally both methods are probed in different environments to test their characteristics. The simulations show that the fuzzy controller is much more efficient (up to 65% less power required) in single maneuvers, achieving similar, or even better, precision than the PID. The accuracy and efficiency improvement of the fuzzy controller increase with orbit height because the environmental disturbances decrease, approaching the ideal scenario. A brief mission description is depicted as well as the design process of both ADCS controllers. Finally the validation process and the results obtained during the simulations are described. Those results show that the fuzzy logic methodology is valid for small

  15. Attitudes towards self-control with urinalysis in juvenile diabetes.

    Science.gov (United States)

    Ludvigsson, J; Svensson, P G

    1980-01-01

    Urinary glucose excretion reflects the blood glucose levels and is therefore recommended and used as a relevant and practical method for self-control in juvenile diabetes. The purpose of this study was to estimate the attitudes of of diabetic children and their parents towards such daily urinalysis. In 1975 69 juvenile diabetics 6-18 years old and their parents were studied and three years later another 69 patients were added. Still a year later 31 of the children were studied again. Standardized interviews, questionnaires and a special attitude test were used. The results indicate that a great majority of the patients and the parents accept the self-testing method and regard it as a valuable tool in the management of the disease. Almost nobody experienced the urine tests as a psychological problem. As urinalysis has become established as a self-evident part of the treatment, the attitudes have become even more positive among a growing number of patients. Parallel to this feeling of usefulness the patients are honest and the urine tests thus give reliable information.

  16. Singularity-free integral-augmented sliding mode control for combined energy and attitude control system

    Science.gov (United States)

    Eshghi, Samira; Varatharajoo, Renuganth

    2017-01-01

    A combined energy and attitude control system (CEACS) is a synergized system in which flywheels are used as attitude control actuators and simultaneously as a power storage system. This paper, a subsequent to previous research on CEACS, addresses the attitude-tracking problem. Integral Augmented Sliding Mode Control with Boundary-Layer (IASMC-BL), a locally asymptotically stable controller, is developed to provide a robust and accurate solution for the CEACS's attitude-tracking problem. The controller alleviates the chattering phenomenon associated with the sliding mode using a boundary-layer technique. Simultaneously, it reduces the steady-state error using an integral action. This paper highlights the uncertainty of inertia matrix as a contributing factor to singularity problem. The inversion of the uncertain inertia matrix in simulation of a spacecraft dynamics is also identified as a leading factor to a singular situation. Therefore, an avoidance strategy is proposed in this paper to guarantee a singular-free dynamics behavior in faces of the uncertainties. This maiden work attempts to employ the singularity-free Integral Augmented Sliding Mode Control with Boundary-Layer (IASMC-BL) to provide a robust, accurate and nonsingular attitude-tracking solution for CEACS.

  17. An active attitude control system for a drag sail satellite

    Science.gov (United States)

    Steyn, Willem Herman; Jordaan, Hendrik Willem

    2016-11-01

    The paper describes the development and simulation results of a full ADCS subsystem for the deOrbitSail drag sail mission. The deOrbitSail satellite was developed as part of an European FP7 collaboration research project. The satellite was launched and commissioning started on 10th July 2015. Various new actuators and sensors designed for this mission will be presented. The deOrbitSail satellite is a 3U CubeSat to deploy a 4 by 4 m drag sail from an initial 650 km circular polar low earth orbit. With an active attitude control system it will be shown that by maximising the drag force, the expected de-orbiting period from the initial altitude will be less than 50 days. A future application of this technology will be the use of small drag sails as low-cost devices to de-orbit LEO satellites, when they have reached their end of life, without having to use expensive propulsion systems. Simulation and Hardware-in-Loop experiments proved the feasibility of the proposed attitude control system. A magnetic-only control approach using a Y-Thomson spin, is used to detumble the 3U Cubesat with stowed sail and subsequently to 3-axis stabilise the satellite to be ready for the final deployment phase. Minituarised torquer rods, a nano-sized momentum wheel, attitude sensor hardware (magnetometer, sun, earth) developed for this phase will be presented. The final phase will be to deploy and 3-axis stabilise the drag sail normal to the satellite's velocity vector, using a combined Y-momentum wheel and magnetic controller. The design and performance improvements when using a 2-axis translation stage to adjust the sail centre-of-pressure to satellite centre-of-mass offset, will also be discussed, although for launch risk reasons this stage was not included in the final flight configuration. To accurately determine the drag sail's attitude during the sunlit part of the orbit, an accurate wide field of view dual sensor to measure both the sun and nadir vector direction was developed for

  18. Passive Magnetic Attitude Control System for the Munin Nanosatellite

    Science.gov (United States)

    Ovchinnikov, M. Yu.; Penkov, V. I.

    2002-03-01

    The instrumental and applied problems related to the design of a passive magnetic attitude control system for the Munin nanosatellite are considered. The system is constructed from a strong permanent magnet and a set of hysteresis rods. These rods are made of magnetically soft material using a special technology, and they allow us to support the satellite orientation with respect to the local magnetic field vector with a given accuracy and time response. By using asymptotic and numerical methods, we investigate the satellite dynamics for different models of hysteresis. The issues concerning the arrangement of the rods and their interaction with the fields of permanent magnets mounted onboard the satellite are discussed.

  19. Attitude control of a small satellite using magnetic bearing momentum wheel

    OpenAIRE

    Terui, Fuyuto; Nakajima, Atsushi; 照井 冬人; 中島 厚

    1996-01-01

    An attitude controller for a 50 kg-class micro satellite which could be launched by H-2 rocket as a piggyback payload of a main satellite is considered. The survey of the proposals of the mission using a micro satellite from national institutes, universities and private companies shows that the development of a small, light and inexpensive three axis attitude controller is widely expected. One of the candidate configurations for such an attitude controller is bias momentum control using a mag...

  20. Coordinated Multiple Spacecraft Attitude Control with Communication Time Delays and Uncertainties

    Institute of Scientific and Technical Information of China (English)

    LI Guiming; LIU Liangdong

    2012-01-01

    In this paper,we consider the coordinated attitude control problem of spacecraft formation with communication delays,model and disturbance uncertainties,and propose novel synchronized control schemes.Since the attitude motion is essential in non-Euclidean space,thus,unlike the existing designs which describe the delayed relative attitude via linear algorithm,we treat the attitude error and the local relative attitude on the nonlinear manifold-Lie group,and attempt to obtain coupling attitude information by the natural quatemion multiplication.Our main focus is to address two problems:1) Propose a coordinated attitude controller to achieve the synchronized attitude maneuver,i.e.,synchronize multiple spacecraft attitudes and track a time-varying desired attitude; 2) With known model information,we achieve the synchronized attitude maneuver with disturbances under angular velocity constraints.Especially,if the formation does not have any uncertainties,the designer can simply set the controller via an appropriate choice of control gains to avoid system actuator saturation.Our controllers are proposed based on the Lyapunov-Krasovskii method and simulation of a spacecraft formation is conducted to demonstrate the effectiveness of theoretical results.

  1. Framework of Combined Adaptive and Non-adaptive Attitude Control System for a Helicopter Experimental System

    Institute of Scientific and Technical Information of China (English)

    Akira Inoue; Ming-Cong Deng

    2006-01-01

    This paper presents a framework of a combined adaptive and non-adaptive attitude control system for a helicopter experimental system. The design method is based on a combination of adaptive nonlinear control and non-adaptive nonlinear control. With regard to detailed attitude control system design, two schemes are shown for different application cases.

  2. Health literacy and parent attitudes about weight control for children.

    Science.gov (United States)

    Liechty, Janet M; Saltzman, Jaclyn A; Musaad, Salma M

    2015-08-01

    The purpose of this study was to examine associations between parental health literacy and parent attitudes about weight control strategies for young children. Parental low health literacy has been associated with poor child health outcomes, yet little is known about its relationship to child weight control and weight-related health information-seeking preferences. Data were drawn from the STRONG Kids Study, a Midwest panel survey among parents of preschool aged children (n = 497). Parents endorsed an average of 4.3 (SD =2.8) weight loss strategies, 53% endorsed all three recommended weight loss strategies for children, and fewer than 1% of parents endorsed any unsafe strategies. Parents were most likely to seek child weight loss information from healthcare professionals but those with low (vs. adequate) health literacy were significantly less likely to use the Internet or books and more likely to use minister/clergy as sources. Poisson and logistic regressions showed that higher health literacy was associated with endorsement of more strategies overall, more recommended strategies, and greater odds of endorsing each specific recommended strategy for child weight control, after adjusting for parent age, education, race/ethnicity, income, marital status, weight concern, and child BMI percentile. Findings suggest that health literacy impacts parental views about child weight loss strategies and health information-seeking preferences. Pediatric weight loss advice to parents should include assessment of parent attitudes and prior knowledge about child weight control and facilitate parent access to reliable sources of evidence-informed child weight control information.

  3. Gaining control over responses to implicit attitude tests: Implementation intentions engender fast responses on attitude-incongruent trials.

    Science.gov (United States)

    Webb, Thomas L; Sheeran, Paschal; Pepper, John

    2012-03-01

    The present research investigated whether forming implementation intentions could promote fast responses to attitude-incongruent associations (e.g., woman-manager) and thereby modify scores on popular implicit measures of attitude. Expt 1 used the Implicit Association Test (IAT) to measure associations between gender and science versus liberal arts. Planning to associate women with science engendered fast responses to this category-attribute pairing and rendered summary scores more neutral compared to standard IAT instructions. Expt 2 demonstrated that forming egalitarian goal intentions is not sufficient to produce these effects. Expt 3 extended these findings to a different measure of implicit attitude (the Go/No-Go Association Task) and a different stereotypical association (Muslims-terrorism). In Expt 4, managers who planned to associate women with superordinate positions showed more neutral IAT scores relative to non-planners and effects were maintained 3 weeks later. In sum, implementation intentions enable people to gain control over implicit attitude responses.

  4. A comparing design of satellite attitude control system based on reaction wheel

    Institute of Scientific and Technical Information of China (English)

    CHENG Hao; GE Sheng-min; SHEN Yi

    2008-01-01

    The disturbance caused by the reaction wheel with a current controller greatly influences the accuracy and stability of the satellite attitude control system.To solve this problem,the idea of speed feedback compensation control reaction wheel is put forward.This paper introduces the comparison on design and performance of two satellite attitude control systems,which are separately based on the current control reaction wheel and the speed feedback compensation control reaction wheel.Analysis shows that the speed feedback compensation control flywheel system may effectively suppress the torque fluctuation.Simulation results indicate that the satellite attitude control system with the speed feedback compensation control flywheel has improved performance.

  5. Neural network-based distributed attitude coordination control for spacecraft formation flying with input saturation.

    Science.gov (United States)

    Zou, An-Min; Kumar, Krishna Dev

    2012-07-01

    This brief considers the attitude coordination control problem for spacecraft formation flying when only a subset of the group members has access to the common reference attitude. A quaternion-based distributed attitude coordination control scheme is proposed with consideration of the input saturation and with the aid of the sliding-mode observer, separation principle theorem, Chebyshev neural networks, smooth projection algorithm, and robust control technique. Using graph theory and a Lyapunov-based approach, it is shown that the distributed controller can guarantee the attitude of all spacecraft to converge to a common time-varying reference attitude when the reference attitude is available only to a portion of the group of spacecraft. Numerical simulations are presented to demonstrate the performance of the proposed distributed controller.

  6. Attitude tracking control for spacecraft formation with time-varying delays and switching topology

    Science.gov (United States)

    Yang, Hongjiu; You, Xiu; Hua, Changchun

    2016-09-01

    This paper investigates attitude dynamic tracking control for spacecraft formation in the presence of unmeasurable velocity information with time-varying delays and switching topology. Based on an extended state observer, a nonlinear attitude tracking control approach is developed for spacecraft attitude model formulated by Euler-Lagrangian equations. The attitude tracking controller allows for external disturbances and absence of angular velocity information. Both auto-stable region techniques and a Lyapunov function approach are developed to prove ultimately bounded tracking. Simulation results demonstrate effectiveness of the nonlinear control techniques proposed in this paper.

  7. GPS IIF yaw attitude control during eclipse season

    Science.gov (United States)

    Dilssner, F.; Springer, T.; Enderle, W.

    2011-12-01

    On May 27, 2010, the first satellite of the Block II "follow-on" (Block IIF) series, the fourth generation of Global Positioning System (GPS) spacecraft, has been successfully placed into orbit. GPS IIF-1, also referred to as space vehicle number (SVN) 62, has been injected into orbital plane B, slot position 2 of the GPS constellation. After completing three months of comprehensive in-orbit testing, the satellite entered service for the US Air Force (USAF) on August 26, 2010. A little over a year after the inaugural launch of GPS IIF-1, the USAF has now launched the second spacecraft of the IIF series (SVN-63). The IIF series includes a total of 12 satellites: SVN-62 through SVN-73. Despite having many technical advances over their predecessors such as enhanced rubidium frequency standards, more precise and powerful signals and an extended design life, the three-axis stabilized Block IIF satellites follow a completely different yaw attitude scheme, when passing through the Earth's shadow, to the Block IIA and IIR spacecraft. We will describe how high-rate carrier phase and pseudo-range measurements from a global GPS tracking network can be exploited to precisely monitor the yaw attitude behavior of SVN-62 and SVN-63 during their solar eclipse phases. The insights gained from this study have led to the development of a new GPS Block IIF yaw attitude model. We will show that the yaw rate of a Block IIF space vehicle is kept constant to the value needed to get the satellite back to near its nominal attitude when leaving the Earth's shadow and that a IIF satellite being in deep eclipse therefore needs to yaw significantly faster than an eclipsing IIF space vehicle passing only partly through the Earth's shadow. How the satellites' attitude control system (ACS) exactly computes this dynamical yaw rate parameter will be discussed here as well. Moreover, we will report on yaw attitude anomalies occurring when the GPS Block IIF satellites are shaded from the Sun by the

  8. Motor Control of Two Flywheels Enabling Combined Attitude Control and Bus Regulation

    Science.gov (United States)

    Kenny, Barbara H.

    2004-01-01

    This presentation discussed the flywheel technology development work that is ongoing at NASA GRC with a particular emphasis on the flywheel system control. The "field orientation" motor/generator control algorithm was discussed and explained. The position-sensorless angle and speed estimation algorithm was presented. The motor current response to a step change in command at low (10 kRPM) and high (60 kRPM) was discussed. The flywheel DC bus regulation control was explained and experimental results presented. Finally, the combined attitude control and energy storage algorithm that controls two flywheels simultaneously was presented. Experimental results were shown that verified the operational capability of the algorithm. shows high speed flywheel energy storage (60,000 RPM) and the successful implementation of an algorithm to simultaneously control both energy storage and a single axis of attitude with two flywheels. Overall, the presentation demonstrated that GRC has an operational facility that

  9. Attitude control of an object commonly held by multiple robot arms - A Lyapunov approach

    Science.gov (United States)

    Kreutz, Kenneth; Wen, John T.

    1988-01-01

    Multiple robot arms moving a commonly held object can be viewed as complex actuators whose purpose is to provide net forces and moments to the object. These forces and moments can be used to control the orientation, or attitude, of the object via the Euler equation describing attitude evolution in response to applied moments at the mass center. In contrast to the common approach that feedback-linearizes the attitude dynamics to a double integrator form with respect to some three-parameter local representation of orientation, the authors control the object using a globally nonsingular representation. Using an energy-motivated Liapunov function, globally stable control of attitude is shown.

  10. Disturbance observer-based fuzzy control for flexible spacecraft combined attitude & sun tracking system

    Science.gov (United States)

    Chak, Yew-Chung; Varatharajoo, Renuganth; Razoumny, Yury

    2017-04-01

    This paper investigates the combined attitude and sun-tracking control problem in the presence of external disturbances and internal disturbances, caused by flexible appendages. A new method based on Pythagorean trigonometric identity is proposed to drive the solar arrays. Using the control input and attitude output, a disturbance observer is developed to estimate the lumped disturbances consisting of the external and internal disturbances, and then compensated by the disturbance observer-based controller via a feed-forward control. The stability analysis demonstrates that the desired attitude trajectories are followed even in the presence of external disturbance and internal flexible modes. The main features of the proposed control scheme are that it can be designed separately and incorporated into the baseline controller to form the observer-based control system, and the combined attitude and sun-tracking control is achieved without the conventional attitude actuators. The attitude and sun-tracking performance using the proposed strategy is evaluated and validated through numerical simulations. The proposed control solution can serve as a fail-safe measure in case of failure of the conventional attitude actuator, which triggered by automatic reconfiguration of the attitude control components.

  11. ROBUST ATTITUDE CONTROL OF A 3DOF HELICOPTER WITH MULTI-OPERATION POINTS

    Institute of Scientific and Technical Information of China (English)

    Yao YU; Yisheng ZHONG

    2009-01-01

    A 3DOF (three degrees of freedom) helicopter attitude control system with multi-operation points is described as a MIMO time-varying uncertain nonlinear system with unknown constant param-eters, bounded disturbance and nonlinear uncertainty, and a robust output feedback control method based on signal compensation is proposed. A controller designed by this method consists of a nominal controller and a robust compensator. The controller is linear time-invariant and can be realized easily. Robust attitude tracking property of closed-loop system is proven and experimental results show that the designed control system can guarantee high precision robust attitude control under multi-operation points.

  12. Attitude dynamics and control of spacecraft using geomagnetic Lorentz force

    CERN Document Server

    Abdel-Aziz, Yehia A

    2014-01-01

    The attitude stabilization of a charged rigid spacecraft in Low Earth Orbit (LEO) using torques due to Lorentz force in pitch and roll directions is considered. A spacecraft that generates an electrostatic charge on its surface in the Earth magnetic field will be subject to perturbations from Lorentz force. The Lorentz force acting on an electrostatically charged spacecraft may provide a useful thrust for controlling a spacecraft's orientation. We assume that the spacecraft is moving in the Earth's magnetic field in an elliptical orbit under the effects of the gravitational, geomagnetic and Lorentz torques. The magnetic field of the Earth is modeled as a non-tilted dipole. A model incorporating all Lorentz torques as a function of orbital elements has been developed on the basis of electric and magnetic fields. The stability of the spacecraft orientation is investigated both analytically and numerically. The existence and stability of equilibrium positions is investigated for different values of the charge to...

  13. Dynamic attitude command and control of the TOPEX/Poseidon spacecraft

    Science.gov (United States)

    Zimbelman, D. F.; Lee, B. B.; Welch, R. V.

    1991-01-01

    The dynamic control laws utilized by the TOPEX/Poseidon (T/P) spacecraft attitude determination and control subsystem to command and maneuver the satellite during normal mission mode (NMM) laws are described. Results show that the vehicle is able to respond to the dynamic attitude commands while at the same time providing ample disturbance rejection capability.

  14. Orion Launch Abort Vehicle Attitude Control Motor Testing

    Science.gov (United States)

    Murphy, Kelly J.; Brauckmann, Gregory J.; Paschal, Keith B.; Chan, David T.; Walker, Eric L.; Foley, Robert; Mayfield, David; Cross, Jared

    2011-01-01

    Current Orion Launch Abort Vehicle (LAV) configurations use an eight-jet, solid-fueled Attitude Control Motor (ACM) to provide required vehicle control for all proposed abort trajectories. Due to the forward position of the ACM on the LAV, it is necessary to assess the effects of jet-interactions (JI) between the various ACM nozzle plumes and the external flow along the outside surfaces of the vehicle. These JI-induced changes in flight control characteristics must be accounted for in developing ACM operations and LAV flight characteristics. A test program to generate jet interaction aerodynamic increment data for multiple LAV configurations was conducted in the NASA Ames and NASA Langley Unitary Plan Wind Tunnels from August 2007 through December 2009. Using cold air as the simulant gas, powered subscale models were used to generate interaction data at subsonic, transonic, and supersonic test conditions. This paper presents an overview of the complete ACM JI experimental test program for Orion LAV configurations, highlighting ACM system modeling, nozzle scaling assumptions, experimental test techniques, and data reduction methodologies. Lessons learned are discussed, and sample jet interaction data are shown. These data, in conjunction with computational predictions, were used to create the ACM JI increments for all relevant flight databases.

  15. Semi-active Attitude Control and Off-line Attitude Determination for the SSETI-Express Student Micro-satellite

    DEFF Research Database (Denmark)

    Alminde, Lars

    2005-01-01

    This paper concerns the development of the Attitude Determination and Control System (ADCS) for the SSETI-Express micro-satellite mission. The mission is an educational project involving 14 universities and the European Space Agency (ESA). The satellite has been designed and built, by students...

  16. Semi-active Attitude Control and Off-line Attitude Determination for the SEETI-Express Student Micro-satellite

    DEFF Research Database (Denmark)

    Alminde, Lars

    This paper concerns the development of the Attitude Determination and Control System (ADCS) for the SSETI-Express micro-satellite mission. The mission is an educational project involving 14 universities and the European Space Agency (ESA). The satellite has been designed and built, by students...

  17. Control synthesis for polynomial nonlinear systems and application in attitude control

    Institute of Scientific and Technical Information of China (English)

    Chang-fei TONG; Hui ZHANG; You-xian SUN

    2008-01-01

    A method for positive polynomial validation based on polynomial decomposition is proposed to deal with control synthesis problems. Detailed algorithms for decomposition are given which mainly consider how to convert coefficients of a polynomial to a matrix with free variables. Then, the positivity of a polynomial is checked by the decomposed matrix with semidefinite programming solvers. A nonlinear control law is presented for single input polynomial systems based on the Lyapunov stability theorem. The control synthesis method is advanced to multi-input systems further. An application in attitude control is finally presented. The proposed control law achieves effective performance as illustrated by the numerical example.

  18. Adaptive fuzzy logic controller with direct action type structures for InnoSAT attitude control system

    Science.gov (United States)

    Bakri, F. A.; Mashor, M. Y.; Sharun, S. M.; Bibi Sarpinah, S. N.; Abu Bakar, Z.

    2016-10-01

    This study proposes an adaptive fuzzy controller for attitude control system (ACS) of Innovative Satellite (InnoSAT) based on direct action type structure. In order to study new methods used in satellite attitude control, this paper presents three structures of controllers: Fuzzy PI, Fuzzy PD and conventional Fuzzy PID. The objective of this work is to compare the time response and tracking performance among the three different structures of controllers. The parameters of controller were tuned on-line by adjustment mechanism, which was an approach similar to a PID error that could minimize errors between actual and model reference output. This paper also presents a Model References Adaptive Control (MRAC) as a control scheme to control time varying systems where the performance specifications were given in terms of the reference model. All the controllers were tested using InnoSAT system under some operating conditions such as disturbance, varying gain, measurement noise and time delay. In conclusion, among all considered DA-type structures, AFPID controller was observed as the best structure since it outperformed other controllers in most conditions.

  19. Finite-Time Reentry Attitude Control Using Time-Varying Sliding Mode and Disturbance Observer

    OpenAIRE

    Xuzhong Wu; Shengjing Tang; Jie Guo; Yao Zhang

    2015-01-01

    This paper presents the finite-time attitude control problem for reentry vehicle with redundant actuators in consideration of planet uncertainties and external disturbances. Firstly, feedback linearization technique is used to cancel the nonlinearities of equations of motion to construct a basic mode for attitude controller. Secondly, two kinds of time-varying sliding mode control methods with disturbance observer are integrated with the basic mode in order to enhance the control performance ...

  20. General Attitude Control Algorithm for Spacecraft Equipped with Star Camera and Reaction Wheels

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    A configuration consisting of a star camera, four reaction wheels and magnetorquers for momentum unloading has become standard for many spacecraft missions. This popularity has motivated numerous agencies and private companies to initiate work on the design of an imbedded attitude control system...... realized on an integrated circuit. This paper considers two issues: slew maneuver with a feature of avoiding direct exposure of the camera's CCD chip to the Sun %, three-axis attitude control and optimal control torque distribution in a reaction wheel assembly. The attitude controller is synthesized...

  1. Attitude dynamics and control of a spacecraft using shifting mass distribution

    Science.gov (United States)

    Ahn, Young Tae

    Spacecraft need specific attitude control methods that depend on the mission type or special tasks. The dynamics and the attitude control of a spacecraft with a shifting mass distribution within the system are examined. The behavior and use of conventional attitude control actuators are widely developed and performing at the present time. However, the advantage of a shifting mass distribution concept can complement spacecraft attitude control, save mass, and extend a satellite's life. This can be adopted in practice by moving mass from one tank to another, similar to what an airplane does to balance weight. Using this shifting mass distribution concept, in conjunction with other attitude control devices, can augment the three-axis attitude control process. Shifting mass involves changing the center-of-mass of the system, and/or changing the moments of inertia of the system, which then ultimately can change the attitude behavior of the system. This dissertation consists of two parts. First, the equations of motion for the shifting mass concept (also known as morphing) are developed. They are tested for their effects on attitude control by showing how shifting the mass changes the spacecraft's attitude behavior. Second, a method for optimal mass redistribution is shown using a combinatorial optimization theory under constraints. It closes with a simple example demonstrating an optimal reconfiguration. The procedure of optimal reconfiguration from one mass distribution to another to accomplish attitude control has been demonstrated for several simple examples. Mass shifting could work as an attitude controller for fine-tuning attitude behavior in small satellites. Various constraints can be applied for different situations, such as no mass shift between two tanks connected by a failed pipe or total amount of shifted mass per pipe being set for the time optimum solution. Euler angle changes influenced by the mass reconfiguration are accomplished while stability

  2. Attitude Stabilization Control of a Quadrotor UAV by Using Backstepping Approach

    Directory of Open Access Journals (Sweden)

    Xing Huo

    2014-01-01

    Full Text Available The modeling and attitude stabilization control problems of a four-rotor vertical takeoff and landing unmanned air vehicle (UAV known as the quadrotor are investigated. The quadrotor’s attitude is represented by the unit quaternion rather than Euler angles to avoid singularity problem. Taking dynamical behavior of motors into consideration and ignoring aerodynamic effect, a nonlinear controller is developed to stabilize the attitude. The control design is accomplished by using backstepping control technique. The proposed control law is based on the compensation for the Coriolis and gyroscope torques. Applying Lyapunov stability analysis proves that the closed-loop attitude system is asymptotic stable. Moreover, the controller can guarantee that all the states of the system are uniformly ultimately bounded in the presence of external disturbance torque. The effectiveness of the proposed control approach is analytically authenticated and also validated via simulation study.

  3. X-33 Attitude Control System Design for Ascent, Transition, and Entry Flight Regimes

    Science.gov (United States)

    Hall, Charles E.; Gallaher, Michael W.; Hendrix, Neal D.

    1998-01-01

    The Vehicle Control Systems Team at Marshall Space Flight Center, Systems Dynamics Laboratory, Guidance and Control Systems Division is designing under a cooperative agreement with Lockheed Martin Skunkworks, the Ascent, Transition, and Entry flight attitude control system for the X-33 experimental vehicle. Ascent flight control begins at liftoff and ends at linear aerospike main engine cutoff (NECO) while Transition and Entry flight control begins at MECO and concludes at the terminal area energy management (TAEM) interface. TAEM occurs at approximately Mach 3.0. This task includes not only the design of the vehicle attitude control systems but also the development of requirements for attitude control system components and subsystems. The X-33 attitude control system design is challenged by a short design cycle, the design environment (Mach 0 to about Mach 15), and the X-33 incremental test philosophy. The X-33 design-to-launch cycle of less than 3 years requires a concurrent design approach while the test philosophy requires design adaptation to vehicle variations that are a function of Mach number and mission profile. The flight attitude control system must deal with the mixing of aerosurfaces, reaction control thrusters, and linear aerospike engine control effectors and handle parasitic effects such as vehicle flexibility and propellant sloshing from the uniquely shaped propellant tanks. The attitude control system design is, as usual, closely linked to many other subsystems and must deal with constraints and requirements from these subsystems.

  4. Propellantless Attitude Control of Solar Sail Technology Utilizing Reflective Control Devices

    Science.gov (United States)

    Munday, Jeremy

    2016-01-01

    Solar sails offer an opportunity for a CubeSatscale, propellant-free spacecraft technology that enables long-term and long-distance missions not possible with traditional methods. Solar sails operate using the transfer of linear momentum from photons of sunlight reflected from the surface of the sail. To propel the spacecraft, no mechanically moving parts, thrusters, or propellant are needed. However, attitude control, or orientation, is still performed using traditional methods involving reaction wheels and propellant ejection, which severely limit mission lifetime. For example, the current state of the art solutions employed by upcoming missions couple solar sails with a state of the art propellant ejection gas system. Here, the use of the gas thruster has limited the lifetime of the mission. To solve the limited mission lifetime problem, the Propellantless Attitude Control of Solar Sail Technology Utilizing Reflective Control Devices project team is working on propellantless attitude control using thin layers of material, an optical film, electrically switchable from transparent to reflective. The technology is based on a polymer-dispersed liquid crystal (PDLC), which allows this switch upon application of a voltage. This technology removes the need for propellant, which reduces weight and cost while improving performance and lifetime.

  5. Algorithm of Attitude Control and Its Simulation of Free-Flying Space Robot

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Reaction wheel or reaction thruster is employed to maintain the attitude of the base of space robot fixed in attitude control of free-flying space robot.However, in this method, a large amount of fuel will be consumed, and it will shorten the on-orbit life span of space robot, it also vibrate the system and make the system unsteady.The restricted minimum disturbance map (RMDM) based algorithm of attitude control is presented to keep the attitude of the base fixed during the movement of the manipulator.In this method it is realized by planning motion trajectory of the end-effector of manipulator without using reaction wheel or reaction thruster.In order to verify the feasibility and effectiveness of the algorithm attitude control presented in this paper, computer simulation experiments have been made and the experimental results demonstrate that this algorithm is feasible.

  6. Attitude dynamics and control of spacecraft using geomagnetic Lorentz force

    Science.gov (United States)

    Abdel-Aziz, Yehia A.; Shoaib, Muhammad

    2015-01-01

    Attitude stabilization of a charged rigid spacecraft in Low Earth Orbit using torques due to Lorentz force in pitch and roll directions is considered. A spacecraft that generates an electrostatic charge on its surface in the Earth's magnetic field will be subject to perturbations from the Lorentz force. The Lorentz force acting on an electrostatically charged spacecraft may provide a useful thrust for controlling a spacecraft's orientation. We assume that the spacecraft is moving in the Earth's magnetic field in an elliptical orbit under the effects of gravitational, geomagnetic and Lorentz torques. The magnetic field of the Earth is modeled as a non-tilted dipole. A model incorporating all Lorentz torques as a function of orbital elements has been developed on the basis of electric and magnetic fields. The stability of the spacecraft orientation is investigated both analytically and numerically. The existence and stability of equilibrium positions is investigated for different values of the charge to mass ratio (α*). Stable orbits are identified for various values of α*. The main parameters for stabilization of the spacecraft are α* and the difference between the components of the moment of inertia for the spacecraft.

  7. Attitudes of Chinese women towards sexuality and birth control.

    Science.gov (United States)

    Ellis, D; Ho, M S

    1982-03-01

    A small survey was conducted in the Vancouver area by the authors to determine some of the current beliefs and attitudes of Chinese women toward birth control and sexuality. 10 Chinese women aged from 16-72 were interviewed. Traditional beliefs in filial piety and in the concepts of Yin (negative, female force) and Yang (positive, male force) were subscribed to by the eldest women who also perceived a lack of fairness in the double standard permitting male promiscuity while prohibiting female sexual freedom. The elder women also felt that the balance of Yin and Yang would promote sexual satisfaction and good health (homosexuality represented an imbalance and was therefore unhealthy). Only 1 woman had received sex education in the home since most sex-related topics were considered taboo. The Canadian born women had been educated in school regarding sex and felt that this experience made them more responsible in sexual matters. Strict rules about behavior during menstruation were adhered to by the eldest women: no hair-brushing, eating of hot foods, or sexual intercourse; they also viewed masturbation as acceptable in women since their Yin is a renewable resource. Masturbation in men was frowned upon since it would lead to a depletion of Yang and possibly cause infertility. The Canadian born women viewed masturbation as a normal sexual act. Contraception was seen as negative by the 1st generation women whereas the younger women valued family planning as an improvement in thier lives. Coitus before marriage was viewed as acceptable and during marriage and pregnancy as enjoyable by the younger women; the elders felt that premarital intercourse resulted in a loss of prestige whereas marital coitus was seen as a duty and intercourse during and after pregnancy as dangerous for the unborn child and the mother. The ease with which these women dealt with the conflict of adhering to their culture while assimilating into a new environment was influenced by age, language

  8. High Accuracy Attitude Control System Design for Satellite with Flexible Appendages

    Directory of Open Access Journals (Sweden)

    Wenya Zhou

    2014-01-01

    Full Text Available In order to realize the high accuracy attitude control of satellite with flexible appendages, attitude control system consisting of the controller and structural filter was designed. When the low order vibration frequency of flexible appendages is approximating the bandwidth of attitude control system, the vibration signal will enter the control system through measurement device to bring impact on the accuracy or even the stability. In order to reduce the impact of vibration of appendages on the attitude control system, the structural filter is designed in terms of rejecting the vibration of flexible appendages. Considering the potential problem of in-orbit frequency variation of the flexible appendages, the design method for the adaptive notch filter is proposed based on the in-orbit identification technology. Finally, the simulation results are given to demonstrate the feasibility and effectiveness of the proposed design techniques.

  9. Nonlinear Attitude Control of Planar Structures in Space Using Only Internal Controls

    Science.gov (United States)

    Reyhanoglu, Mahmut; Mcclamroch, N. Harris

    1993-01-01

    An attitude control strategy for maneuvers of an interconnection of planar bodies in space is developed. It is assumed that there are no exogeneous torques and that torques generated by joint motors are used as means of control so that the total angular momentum of the multibody system is a constant, assumed to be zero. The control strategy utilizes the nonintegrability of the expression for the angular momentum. Large angle maneuvers can be designed to achieve an arbitrary reorientation of the multibody system with respect to an inertial frame. The theoretical background for carrying out the required maneuvers is summarized.

  10. Chattering-Free Adaptive Sliding Mode Control for Attitude Tracking of Spacecraft with External Disturbance

    Directory of Open Access Journals (Sweden)

    Xuxi Zhang

    2014-01-01

    Full Text Available The attitude tracking problem of spacecraft in the presence of unknown disturbance is investigated. By using the adaptive control technique and the Lyapunov stability theory, a chattering-free adaptive sliding mode control law is proposed for the attitude tracking problem of spacecraft with unknown disturbance. Simulation results are employed to demonstrate the effectiveness of the proposed control design technique in this paper.

  11. Reaction Wheel Installation Deviation Compensation for Overactuated Spacecraft with Finite-Time Attitude Control

    Directory of Open Access Journals (Sweden)

    Aihua Zhang

    2013-01-01

    Full Text Available A novel attitude tracking control scheme is presented for overactuated spacecraft to address the attitude stabilization problem in presence of reaction wheel installation deviation, external disturbance and uncertain mass of moment inertia. An adaptive sliding mode control technique is proposed to track the uncertainty. A Lyapunov-based analysis shows that the compensation control law can guarantee that the desired attitude trajectories are followed in finite-time. The key feature of the proposed control strategy is that it globally asymptotically stabilizes the system, even in the presence of reaction wheel installation deviation, external disturbances, and uncertain mass of moment inertia. The attitude track performance using the proposed finite-time compensation control is evaluated through a numerical example.

  12. Quaternion-based adaptive output feedback attitude control of spacecraft using Chebyshev neural networks.

    Science.gov (United States)

    Zou, An-Min; Dev Kumar, Krishna; Hou, Zeng-Guang

    2010-09-01

    This paper investigates the problem of output feedback attitude control of an uncertain spacecraft. Two robust adaptive output feedback controllers based on Chebyshev neural networks (CNN) termed adaptive neural networks (NN) controller-I and adaptive NN controller-II are proposed for the attitude tracking control of spacecraft. The four-parameter representations (quaternion) are employed to describe the spacecraft attitude for global representation without singularities. The nonlinear reduced-order observer is used to estimate the derivative of the spacecraft output, and the CNN is introduced to further improve the control performance through approximating the spacecraft attitude motion. The implementation of the basis functions of the CNN used in the proposed controllers depends only on the desired signals, and the smooth robust compensator using the hyperbolic tangent function is employed to counteract the CNN approximation errors and external disturbances. The adaptive NN controller-II can efficiently avoid the over-estimation problem (i.e., the bound of the CNNs output is much larger than that of the approximated unknown function, and hence, the control input may be very large) existing in the adaptive NN controller-I. Both adaptive output feedback controllers using CNN can guarantee that all signals in the resulting closed-loop system are uniformly ultimately bounded. For performance comparisons, the standard adaptive controller using the linear parameterization of spacecraft attitude motion is also developed. Simulation studies are presented to show the advantages of the proposed CNN-based output feedback approach over the standard adaptive output feedback approach.

  13. Finite-Time Control for Attitude Tracking Maneuver of Rigid Satellite

    Directory of Open Access Journals (Sweden)

    Mingyi Huo

    2014-01-01

    Full Text Available The problem of finite-time control for attitude tracking maneuver of a rigid spacecraft is investigated. External disturbance, unknown inertia parameters are addressed. As stepping stone, a sliding mode controller is designed. It requires the upper bound of the lumped uncertainty including disturbance and inertia matrix. However, this upper bound may not be easily obtained. Therefore, an adaptive sliding mode control law is then proposed to release that drawback. Adaptive technique is applied to estimate that bound. It is proved that the closed-loop attitude tracking system is finite-time stable. The tracking errors of the attitude and the angular velocity are asymptotically stabilized. Moreover, the upper bound on the lumped uncertainty can be exactly estimated in finite time. The attitude tracking performance with application of the control scheme is evaluated through a numerical example.

  14. Interior and exterior ballistics coupled optimization with constraints of attitude control and mechanical-thermal conditions

    Science.gov (United States)

    Liang, Xin-xin; Zhang, Nai-min; Zhang, Yan

    2016-07-01

    For solid launch vehicle performance promotion, a modeling method of interior and exterior ballistics associated optimization with constraints of attitude control and mechanical-thermal condition is proposed. Firstly, the interior and external ballistic models of the solid launch vehicle are established, and the attitude control model of the high wind area and the stage of the separation is presented, and the load calculation model of the drag reduction device is presented, and thermal condition calculation model of flight is presented. Secondly, the optimization model is established to optimize the range, which has internal and external ballistic design parameters as variables selected by sensitivity analysis, and has attitude control and mechanical-thermal conditions as constraints. Finally, the method is applied to the optimal design of a three stage solid launch vehicle simulation with differential evolution algorithm. Simulation results are shown that range capability is improved by 10.8%, and both attitude control and mechanical-thermal conditions are satisfied.

  15. Plug-and-Play Compatibility for CubeSat Attitude Determination and Control Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The development of Plug-and-play Compatibility for CubeSat Attitude Determination and Control Systems (ADACS) is proposed. Existing Maryland Aerospace (MAI) ADACS...

  16. A summary of the Dynamics Explorer /DE/-2 spacecraft attitude control operations and dynamics

    Science.gov (United States)

    Stengle, T. H.

    1982-01-01

    A summary of attitude control operations and observed attitude dynamics for the Dynamics Explorer (DE)-2 spacecraft is presented. By performing a systematic analysis of spacecraft drift and through optimization of modeling parameters in dynamics simulators, insight is given into spacecraft dynamics, techniques for reducing drift, and methods for streamlining operational procedures. This paper discusses how attitude and momentum drift were reduced for DE-2 by changing spacecraft geometry, altering operational procedures and making timely use of the control modes available. Attempts to correlate spacecraft drift activity with known environmental variables are made with only limited success.

  17. Advanced numerical study of the three-axis magnetic attitude control and determination with uncertainties

    Science.gov (United States)

    Ivanov, D. S.; Ovchinnikov, M. Yu.; Penkov, V. I.; Roldugin, D. S.; Doronin, D. M.; Ovchinnikov, A. V.

    2017-03-01

    Attitude motion of a satellite equipped with magnetic control system is considered. System comprises of three magnetorquers and one three-axis magnetometer. Satellite is stabilized in orbital reference frame using PD controller and extended Kalman filter. Three-axis attitude is analyzed numerically with advanced assumptions: inertia tensor uncertainty, disturbances of unknown nature, magnetometer errors are taken into account. Stabilization and determination accuracy dependence on orbit inclination is studied.

  18. Inverse optimal sliding mode control of spacecraft with coupled translation and attitude dynamics

    Science.gov (United States)

    Pukdeboon, Chutiphon

    2015-10-01

    This paper proposes two robust inverse optimal control schemes for spacecraft with coupled translation and attitude dynamics in the presence of external disturbances. For the first controller, an inverse optimal control law is designed based on Sontag-type formula and the control Lyapunov function. Then a robust inverse optimal position and attitude controller is designed by using a new second-order integral sliding mode control method to combine a sliding mode control with the derived inverse optimal control. The global asymptotic stability of the proposed control law is proved by using the second method of Lyapunov. For the other control law, a nonlinear H∞ inverse optimal controller for spacecraft position and attitude tracking motion is developed to achieve the design conditions of controller gains that the control law becomes suboptimal H∞ state feedback control. The ultimate boundedness of system state is proved by using the Lyapunov stability theory. Both developed robust inverse optimal controllers can minimise a performance index and ensure the stability of the closed-loop system and external disturbance attenuation. An example of position and attitude tracking manoeuvres is presented and simulation results are included to show the performance of the proposed controllers.

  19. Improved optimal steering law for SGCMG and adaptive attitude control of flexible spacecraft

    Institute of Scientific and Technical Information of China (English)

    Lu Wang; Yu Guo; Liping Wu; Qingwei Chen

    2015-01-01

    The issue of attitude maneuver of a flexible spacecraft is investigated with single gimbaled control moment gyroscopes (SGCMGs) as an actuator. To solve the inertia uncertainty of the system, an adaptive attitude control algorithm is designed by ap-plying a radial basis function (RBF) neural network. An improved steering law for SGCMGs is proposed to achieve the optimal out-put torque. It enables the SGCMGs not only to avoid singularity, but also to output more precise torque. In addition, global, uniform, ultimate bounded stability of the attitude control system is proved via the Lyapunov technique. Simulation results demonstrate the effectiveness of the new steering law and the algorithm of attitude maneuver of the flexible spacecraft.

  20. Line-of-sight based formation keeping and attitude control of two spacecraft

    Science.gov (United States)

    Warier, Rakesh R.; Sinha, Arpita; Sukumar, Srikant

    2016-10-01

    We consider coupled attitude and position control of two spacecraft where absolute attitudes are not available. The objective is to attain a formation requiring a desired distance between two spacecraft and alignment of attitudes along the inertial line-of-sight (LOS) direction between the center of masses of the spacecraft. A relative attitude and position control scheme is developed using LOS vectors measured in each spacecraft's body frame. The current work differs from past research in the sense that the relative positions of the two spacecraft are not assumed to be fixed and all control laws are obtained in respective body fixed frames. The state feedback laws put forth in this work guarantee almost semi-global asymptotic stability of the desired closed-loop equilibrium configuration.

  1. Attitude-Tracking Control with Path Planning for Agile Satellite Using Double-Gimbal Control Moment Gyros

    Directory of Open Access Journals (Sweden)

    Peiling Cui

    2012-01-01

    Full Text Available In view of the issue of rapid attitude maneuver control of agile satellite, this paper presents an attitude-tracking control algorithm with path planning based on the improved genetic algorithm, adaptive backstepping control as well as sliding mode control. The satellite applies double gimbal control moment gyro as actuator and is subjected to the external disturbance and uncertain inertia properties. Firstly, considering the comprehensive mathematical model of the agile satellite and the double gimbal control moment gyro, an improved genetic algorithm is proposed to solve the attitude path-planning problem. The goal is to find an energy optimal path which satisfies certain maneuverability under the constraints of the input saturation, actuator saturation, slew rate limit and singularity measurement limit. Then, the adaptive backstepping control and sliding mode control are adopted in the design of the attitude-tracking controller to track accurately the desired path comprised of the satellite attitude quaternion and velocity. Finally, simulation results indicate the robustness and good tracking performance of the derived controller as well as its ability to avert the singularity of double gimbal control moment gyro.

  2. Adaptive variable structure control based on backstepping for spacecraft with reaction wheels during attitude maneuver

    Institute of Scientific and Technical Information of China (English)

    SONG Bin; MA Guang-fu; LI Chuan-jiang

    2009-01-01

    An adaptive variable structure control method based on backstepping is proposed for the attitude maneuver problem of rigid spacecraft with reaction wheel dynamics in the presence of uncertain inertia matrix and external disturbances. The proposed control approach is a combination of the backstepping and the adaptive variable structure control. The cascaded structure of the attitude maneuver control system with reaction wheel dynamics gives the advantage for applying the backstepping method to construct Lyapunov functions. The robust stability to external disturbances and parametric uncertainty is guaranteed by the adaptive variable structure control. To validate the proposed control algorithm, numerical simulations using the proposed approach are performed for the attitude maneuver mission of rigid spacecraft with a configuration consisting of four reaction wheels for actuator and three magnetorquers for momentum unloading. Simulation results verify the effectiveness of the proposed control algorithm.

  3. Coupled attitude-orbit dynamics and control for an electric sail in a heliocentric transfer mission.

    Directory of Open Access Journals (Sweden)

    Mingying Huo

    Full Text Available The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail.

  4. Coupled attitude-orbit dynamics and control for an electric sail in a heliocentric transfer mission.

    Science.gov (United States)

    Huo, Mingying; Zhao, Jun; Xie, Shaobiao; Qi, Naiming

    2015-01-01

    The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail.

  5. Robust Finite-Time Control for Spacecraft with Coupled Translation and Attitude Dynamics

    Directory of Open Access Journals (Sweden)

    Guo-Qiang Wu

    2013-01-01

    Full Text Available Robust finite-time control for spacecraft with coupled translation and attitude dynamics is investigated in the paper. An error-based spacecraft motion model in six-degree-of-freedom is firstly developed. Then a finite-time controller based on nonsingular terminal sliding mode control technique is proposed to achieve translation and attitude maneuvers in the presence of model uncertainties and environmental perturbations. A finite-time observer is designed and a modified controller is then proposed to deal with uncertainties and perturbations and alleviate chattering. Numerical simulations are finally provided to illustrate the performance of the proposed controllers.

  6. Demonstration of Single Axis Combined Attitude Control and Energy Storage Using Two Flywheels

    Science.gov (United States)

    Kenny, Barbara H.; Jansen, Ralph; Kascak, Peter; Dever, Timothy; Santiago, Walter

    2004-01-01

    The energy storage and attitude control subsystems of the typical satellite are presently distinct and separate. Energy storage is conventionally provided by batteries, either NiCd or NiH, and active attitude control is accomplished with control moment gyros (CMGs) or reaction wheels. An overall system mass savings can be realized if these two subsystems are combined using multiple flywheels for simultaneous kinetic energy storage and momentum transfer. Several authors have studied the control of the flywheels to accomplish this and have published simulation results showing the feasibility and performance. This paper presents the first experimental results showing combined energy storage and momentum control about a single axis using two flywheels.

  7. Decentralized attitude synchronization tracking control for multiple spacecraft under directed communication topology

    Institute of Scientific and Technical Information of China (English)

    Zheng Zhong; Xu Ying; Zhang Lisong; Song Shenmin

    2016-01-01

    This paper studies the attitude synchronization tracking control of spacecraft formation flying with a directed communication topology and presents three different controllers. By introduc-ing a novel error variable associated with rotation matrix, a decentralized attitude synchronization controller, which could obtain almost global asymptotical stability of the closed-loop system, is developed. Then, considering model uncertainties and unknown external disturbances, we propose a robust adaptive attitude synchronization controller by designing adaptive laws to estimate the unknown parameters. After that, the third controller is proposed by extending this method to the case of time-varying communication delays via Lyapunov–Krasovskii analysis. The distinctive feature of this work is to address attitude coordinated control with model uncertainties, unknown disturbances and time-varying delays in a decentralized framework, with a strongly connected direc-ted information flow. It is shown that tracking and synchronization of an arbitrary desired attitude can be achieved when the stability condition is satisfied. Simulation results are provided to demon-strate the effectiveness of the proposed control schemes.

  8. Fixed-Star Tracking Attitude Control of Spacecraft Using Single-Gimbal Control Moment Gyros

    Directory of Open Access Journals (Sweden)

    Sangwon Kwon

    2010-01-01

    Full Text Available Problem statement: A cluster of small-sized Single-Gimbal Control Moment Gyros (SGCMGs is proposed as an attitude control actuator for high-speed maneuver of small satellites. There exists a singularity problem what is peculiar to the CMG system. Approach: This study presented a simple singularity avoidance steering law using the Singular Value Decomposition (SVD algorithm. Results: Capability of the present steering method in singularity avoidance was demonstrated with numerical simulations for fixed-star tracking control of a small satellite using four SGCMGs. Conclusion: The proposed steering law utilizes the singular value decomposition to obtain singular vectors and generates the command gimbal rate that keeps the command torque in the direction orthogonal to the singular direction with a maximum gain.

  9. Integration of a Motion Capture System into a Spacecraft Simulator for Real-Time Attitude Control

    Science.gov (United States)

    2016-08-16

    Attitude Control* Benjamin L. Reifler University at Buffalo, Buffalo, New York 1st Lt Dylan R. Penn Air Force Research Laboratory, Kirtland Air Force...on a low-friction spherical air bearing. It is designed to test the behavior of integrated hardware and software for at- titude determination and...sensors and to validate attitude estimation performance. This paper describes the suite of software programs that has been developed to transmit

  10. Periodic H2 Synthesis for Spacecraft Attitude Determination and Control with a Vector Magnetometer and Magnetorquers

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Stoustrup, Jakob

    2001-01-01

    A control synthesis for a spacecraft equipped with a set of mutually perpendicular coils and a vector magnetometer is addressed in this paper. The interaction between the Earth's magnetic field and an artificial magnetic field generated by the coils produces a control torque. Comparison between...... the expected magnetic field vector and the true magnetometer data is used for the attitude determination. The magnetic attitude control and determination is intrinsically periodic due to periodic nature of the geomagnetic field variation in orbit. The control performance is specified by the generalized H2...... operator norm. The paper proposes an LMI solution to this problem...

  11. STABILIZED CONTROLLER DESIGN FOR ATTITUDE AND ALTITUDE CONTROLLING OF QUAD-ROTOR UNDER DISTURBANCE AND NOISY CONDITIONS

    Directory of Open Access Journals (Sweden)

    M. Hassan Tanveer

    2013-01-01

    Full Text Available This article presents a control approach to obtain the better stabilization in attitude and altitude of quad-rotor under different disturbance conditions. In the standard Quad-rotor rotor type UAV, controlling of attitude and altitude is one of the most critical tasks and appropriate controller for stabilization of UAV is essential and necessary. These two controls under various conditions of disturbances was a field of research stimulating for the researchers. The controller proposed is contingent on the PID feedback structure with Extended Kalman Filter (EKF. From Lyapunov Stability Theorem, it is proved that quad-rotor proposed altitude control system is asymptotic as well exponentially stability. Extended Kalman Filter (EKF is used to filter out the sensors and system noises. Finally, the simulations carried out on MATLAB and the result proved the effectiveness of proposed recommended method for stabilization of attitude and altitude of quad-rotor.

  12. Crew exploration vehicle (CEV) attitude control using a neural-immunology/memory network

    Science.gov (United States)

    Weng, Liguo; Xia, Min; Wang, Wei; Liu, Qingshan

    2015-01-01

    This paper addresses the problem of the crew exploration vehicle (CEV) attitude control. CEVs are NASA's next-generation human spaceflight vehicles, and they use reaction control system (RCS) jet engines for attitude adjustment, which calls for control algorithms for firing the small propulsion engines mounted on vehicles. In this work, the resultant CEV dynamics combines both actuation and attitude dynamics. Therefore, it is highly nonlinear and even coupled with significant uncertainties. To cope with this situation, a neural-immunology/memory network is proposed. It is inspired by the human memory and immune systems. The control network does not rely on precise system dynamics information. Furthermore, the overall control scheme has a simple structure and demands much less computation as compared with most existing methods, making it attractive for real-time implementation. The effectiveness of this approach is also verified via simulation.

  13. Predictive Sliding Mode Control for Attitude Tracking of Hypersonic Vehicles Using Fuzzy Disturbance Observer

    Directory of Open Access Journals (Sweden)

    Xianlei Cheng

    2015-01-01

    Full Text Available We propose a predictive sliding mode control (PSMC scheme for attitude control of hypersonic vehicle (HV with system uncertainties and external disturbances based on an improved fuzzy disturbance observer (IFDO. First, for a class of uncertain affine nonlinear systems with system uncertainties and external disturbances, we propose a predictive sliding mode control based on fuzzy disturbance observer (FDO-PSMC, which is used to estimate the composite disturbances containing system uncertainties and external disturbances. Afterward, to enhance the composite disturbances rejection performance, an improved FDO-PSMC (IFDO-PSMC is proposed by incorporating a hyperbolic tangent function with FDO to compensate for the approximate error of FDO. Finally, considering the actuator dynamics, the proposed IFDO-PSMC is applied to attitude control system design for HV to track the guidance commands with high precision and strong robustness. Simulation results demonstrate the effectiveness and robustness of the proposed attitude control scheme.

  14. A computed torque method based attitude control with optimal force distribution for articulated body mobile robots

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Edwardo F.; Hirose, Shigeo [Tokyo Inst. of Tech. (Japan)

    2000-05-01

    This paper introduces an attitude control scheme based in optimal force distribution using quadratic programming which minimizes joint energy consumption. This method shares similarities with force distribution for multifingered hands, multiple coordinated manipulators and legged walking robots. In particular, an attitude control scheme was introduced inside the force distribution problem, and successfully implemented for control of the articulated body mobile robot KR-II. This is an actual mobile robot composed of cylindrical segments linked in series by prismatic joints and has a long snake-like appearance. These prismatic joints are force controlled so that each segment's vertical motion can automatically follow the terrain irregularities. An attitude control is necessary because this system acts like a system of wheeled inverted pendulum carts connected in series, being unstable by nature. The validity and effectiveness of the proposed method is verified by computer simulation and experiments with the robot KR-II. (author)

  15. Autonomous attitude coordinated control for spacecraft formation with input constraint, model uncertainties, and external disturbances

    Institute of Scientific and Technical Information of China (English)

    Zheng Zhong; Song Shenmin

    2014-01-01

    To synchronize the attitude of a spacecraft formation flying system, three novel auton-omous control schemes are proposed to deal with the issue in this paper. The first one is an ideal autonomous attitude coordinated controller, which is applied to address the case with certain mod-els and no disturbance. The second one is a robust adaptive attitude coordinated controller, which aims to tackle the case with external disturbances and model uncertainties. The last one is a filtered robust adaptive attitude coordinated controller, which is used to overcome the case with input con-straint, model uncertainties, and external disturbances. The above three controllers do not need any external tracking signal and only require angular velocity and relative orientation between a space-craft and its neighbors. Besides, the relative information is represented in the body frame of each spacecraft. The controllers are proved to be able to result in asymptotical stability almost every-where. Numerical simulation results show that the proposed three approaches are effective for atti-tude coordination in a spacecraft formation flying system.

  16. Direct Lyapunov-based control law design for spacecraft attitude maneuvers

    Institute of Scientific and Technical Information of China (English)

    HU Likun; ANG Qingchao

    2006-01-01

    A direct Lyapunov-based control law is presented to perform on-orbit stability for spacecraft attitude maneuvers. Spacecraft attitude kinematic equations and dynamic equations are coupled, nonlinear, multi-input multi-output(MIMO), which baffles controller design. Orbit angular rates are taken into account in kinematic equations and influence of gravity gradient moments and disturbance moments on the spacecraft attitude in dynamic equations is considered to approach the practical environment, which enhance the problem complexity to some extent. Based on attitude tracking errors and angular rates, a Lyapunov function is constructed, through which the stabilizing feedback control law is deduced via Lie derivation of the Lyapunov function. The proposed method can deal with the case that the spacecraft is subjected to mass property variations or centroidal inertia matrix variations due to fuel assumption or flexibility, and disturbance moments, which shows the proposed controller is robust for spacecraft attitude maneuvers. The unlimited controller and the limited controller are taken into account respectively in simulations. Simulation results are demonstrated to validate effectiveness and feasibility of the proposed method.

  17. Rigid Body Attitude Control Based on a Manifold Representation of Direction Cosine Matrices

    Science.gov (United States)

    Nakath, David; Clemens, Joachim; Rachuy, Carsten

    2017-01-01

    Autonomous systems typically actively observe certain aspects of their surroundings, which makes them dependent on a suitable controller. However, building an attitude controller for three degrees of freedom is a challenging task, mainly due to singularities in the different parametrizations of the three dimensional rotation group SO(3). Thus, we propose an attitude controller based on a manifold representation of direction cosine matrices: In state space, the attitude is globally and uniquely represented as a direction cosine matrix R ∈ SO(3). However, differences in the state space, i.e., the attitude errors, are exposed to the controller in the vector space ℝ3. This is achieved by an operator, which integrates the matrix logarithm mapping from SO(3) to so(3) and the map from so(3) to ℝ3. Based on this representation, we derive a proportional and derivative feedback controller, whose output has an upper bound to prevent actuator saturation. Additionally, the feedback is preprocessed by a particle filter to account for measurement and state transition noise. We evaluate our approach in a simulator in three different spacecraft maneuver scenarios: (i) stabilizing, (ii) rest-to-rest, and (iii) nadir-pointing. The controller exhibits stable behavior from initial attitudes near and far from the setpoint. Furthermore, it is able to stabilize a spacecraft and can be used for nadir-pointing maneuvers.

  18. Design and simulation of satellite attitude control system based on Simulink and VR

    Science.gov (United States)

    Zhang, Yang; Gan, Qingbo; Kang, Jingshu

    2016-01-01

    In order to research satellite attitude control system design and visual simulation, the simulation framework of satellite dynamics and attitude control using Simulink were established. The design of satellite earth-oriented control system based on quaternion feedback was completed. The 3D scene based on VR was created and models in the scene were driven by simulation data of Simulink. By coordinate transformation. successful observing the scene in inertial coordinate system, orbit coordinate system and body coordinate system. The result shows that application of simulation method of Simulink combined with VR in the design of satellite attitude control system field, has the advantages of high confidence level, hard real-time property, multi-perspective and multi-coordinate system observing the scene, and improves the comprehensibility and accuracy of the design.

  19. Orbit and Attitude Control of Asymmetric Satellites in Polar Near-Circular Orbit

    Directory of Open Access Journals (Sweden)

    Wei Zhao

    2009-10-01

    Full Text Available In this paper, the general problem about the orbit and attitude dynamic model is discussed. A feedback linearization control method is introduced for this model. Due to the asymmetric structure, the orbital properties of such satellites are the same as traditional symmetric ones, but the attitude properties are greatly different from the symmetric counterparts. With perturbations accumulate with time, the attitude angles increase periodically with time, but the orbital elements change much slower than the attitude angles. In the attitude dynamic model, chaos could appear. Traditional linear controllers can not compensate enough for asymmetric satellite when the mission is complex, especially in maneuver missions. Thus nonlinear control method is required to solve such problem in large scale. A feedback linearization method, one robust nonlinear control method, is introduced and applied to the asymmetric satellite in this paper. Some simulations are also given and the results show that feedback linearization controller not only stabilizes the system, but also exempt the chaos in the system.

  20. Robust attitude control for rapid multi-target tracking in spacecraft formation flying

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A robust attitude tracking control scheme for spacecraft formation flying is presented.The leader spacecraft with a.rapid mobile antenna and a camera is modeled.While the camera is tracking the ground target,the antenna is tracking the follower spacecraft.By an angular velocity constraint and an angular constraint,two methods are proposed to compute the reference attitude profiles of the camera and antenna,respectively.To simplify the control design problem,this paper first derives the desired inverse system (DIS),which can convert the attitude tracking problem of 3D space into the regulator problem.Based on DIS and sliding mode control (SMC),a robust attitude tracking controller is developed in the presence of mass parameter uncertainties and external disturbance.By Lyapunov stability theory,the closed loop system stability can be achieved.The numerical simulations show that the proposed robust control scheme exhibits significant advantages for the multi-target attitude tracking of a two-spacecraft formation.

  1. Adaptive-Gain Second-Order Sliding Mode Control of Attitude Tracking of Flexible Spacecraft

    Directory of Open Access Journals (Sweden)

    Chutiphon Pukdeboon

    2014-01-01

    finite-time second-order sliding mode control algorithms are presented to solve this problem. For the first controller, a novel second-order sliding mode control scheme is developed to achieve high-precision tracking performance. For the second control law, an adaptive-gain second-order sliding mode control algorithm combing an adaptive law with second-order sliding mode control strategy is designed to relax the requirement of prior knowledge of the bound of the system uncertainties. The rigorous proofs show that the proposed controllers provide finite-time convergence of the attitude and angular velocity tracking errors. Numerical simulations on attitude tracking control are presented to demonstrate the performance of the developed controllers.

  2. Attitude Control of Quad-rotor by Improving the Reliability of Multi-Sensor System

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Dong Hyeon; Chong, Kil To [Chon-bok National University, Jeonju (Korea, Republic of); Park, Jong Ho [Seonam University, Namwon (Korea, Republic of); Ryu, Ji Hyoung [ETRI, Daejeon (Korea, Republic of)

    2015-05-15

    This paper presents the results of study for improving the reliability of quadrotor attitude control by applying a multi-sensor along with a data fusion algorithm. First, a mathematical model of the quadrotor dynamics was developed. Then, using the quadrotor mathematical model, simulations were performed using the improved reliability multi-sensor data as the inputs. From the simulation results, we designed a Gimbal-equipped quadrotor system. With the quadrotor in a hover state, we performed experiments according to the angle change of the user's specifications . We then calculated the attitude control data from the actual experimental data. Furthermore, with additional simulations, we verified the performance of the designed quadrotor attitude control system with multiple sensors.

  3. International Space Station Attitude Control and Energy Storage Experiment: Effects of Flywheel Torque

    Science.gov (United States)

    Roithmayr, Carlos M.

    1999-01-01

    The Attitude Control and Energy Storage Experiment is currently under development for the International Space Station; two counter-rotating flywheels will be levitated with magnetic bearings and placed in vacuum housings. The primary objective of the experiment is to store and discharge energy, in combination with existing batteries, into the electrical power system. The secondary objective is to use the flywheels to exert torque on the Station; a simple torque profile has been designed so that the Station's Control Moment Gyroscopes will be assisted in maintaining torque equilibrium attitude. Two energy storage contingencies could result in the inadvertent application of torque by the flywheels to the Station: an emergency shutdown of one flywheel rotor while the other remains spinning, and energy storage with only one rotor instead of the counterrotating pair. Analysis of these two contingencies shows that attitude control and the microgravity environment will not be adversely affected.

  4. Passification based simple adaptive control of quadrotor attitude: Algorithms and testbed results

    Science.gov (United States)

    Tomashevich, Stanislav; Belyavskyi, Andrey; Andrievsky, Boris

    2017-01-01

    In the paper, the results of the Passification Method with the Implicit Reference Model (IRM) approach are applied for designing the simple adaptive controller for quadrotor attitude. The IRM design technique makes it possible to relax the matching condition, known for habitual MRAC systems, and leads to simple adaptive controllers, ensuring fast tuning the controller gains, high robustness with respect to nonlinearities in the control loop, to the external disturbances and the unmodeled plant dynamics. For experimental evaluation of the adaptive systems performance, the 2DOF laboratory setup has been created. The testbed allows to safely test new control algorithms in the laboratory area with a small space and promptly make changes in cases of failure. The testing results of simple adaptive control of quadrotor attitude are presented, demonstrating efficacy of the applied simple adaptive control method. The experiments demonstrate good performance quality and high adaptation rate of the simple adaptive control system.

  5. Development of a Hardware-in-the-loop Simulator for Spacecraft Attitude Control Using Thrusters

    Science.gov (United States)

    Koh, Dong-Wook; Park, Sang-Young; Kim, Do-Hee; Choi, Kyu-Hong

    2009-03-01

    In this study, a Hardware-In-the-Loop (HIL) simulator using thrusters is developed to validate the spacecraft attitude system. To control the attitude of the simulator, eight cold gas thrusters are aligned with roll, pitch and yaw axis. Also linear actuators are applied to the HIL simulator for automatic mass balancing to compensate the center of mass offset from the center of rotation. The HIL simulator consists of an embedded computer (Onboard PC) for simulator system control, a wireless adapter for wireless network, a rate gyro sensor to measure 3-axis attitude of the simulator, an inclinometer to measure horizontal attitude, and a battery set to supply power for the simulator independently. For the performance test of the HIL simulator, a bang-bang controller and Pulse-Width Pulse-Frequency (PWPF) modulator are evaluated successfully. The maneuver of 68 deg. in yaw axis is tested for the comparison of the both controllers. The settling time of the bang-bang controller is faster than that of the PWPF modulator by six seconds in the experiment. The required fuel of the PWPF modulator is used as much as 51% of bang-bang controller in the experiment. Overall, the HIL simulator is appropriately developed to validate the control algorithms using thrusters.

  6. Adaptive backstepping control for three axis microsatellite attitude pointing under actuator faults

    Science.gov (United States)

    MOHAMMED, M. A. SI; BOUSSADIA, H.; BELLAR, A.; ADNANE, A.

    2017-01-01

    This paper presents the design of Low Earth Orbit (LEO) micro-satellite attitude controller using reaction wheels, and under actuator faults. Firstly, a backstepping controller is developed when the actuator is fault-free. Then, a fault tolerant controller is designed to compensate the actuator fault. Two types of this latter are considered (additive and multiplicative faults). The presented control strategy is based on adaptive backstepping technique. The simulation results clearly demonstrate the effectiveness of the presented technique.

  7. Microsatellite Attitude Determination and Control Subsystem Design and Implementation: Software-in-the-Loop Approach

    Directory of Open Access Journals (Sweden)

    Ho-Nien Shou

    2014-01-01

    Full Text Available The paper describes the development of a microsatellite attitude determination and control subsystem (ADCS and verification of its functionality by software-in-the-loop (SIL method. The role of ADCS is to provide attitude control functions, including the de-tumbling and stabilizing the satellite angular velocity, and as well as estimating the orbit and attitude information during the satellite operation. In Taiwan, Air Force Institute of Technology (AFIT, dedicating for students to design experimental low earth orbit micro-satellite, called AFITsat. For AFITsat, the operation of the ADCS consists of three modes which are initialization mode, detumbling mode, and normal mode, respectively. During the initialization mode, ADCS collects the early orbit measurement data from various sensors so that the data can be downlinked to the ground station for further analysis. As particularly emphasized in this paper, during the detumbling mode, ADCS implements the thrusters in plus-wide modulation control method to decrease the satellite angular velocity. ADCS provides the attitude determination function for the estimation of the satellite state, during normal mode. The three modes of microsatellite adopted Kalman filter algorithm estimate microsatellite attitude. This paper will discuss using the SIL validation ADCS function and verify its feasibility.

  8. Dynamics and Control of Attitude, Power, and Momentum for a Spacecraft Using Flywheels and Control Moment Gyroscopes

    Science.gov (United States)

    Roithmayr, Carlos M.; Karlgaard, Christopher D.; Kumar, Renjith R.; Seywald, Hans; Bose, David M.

    2003-01-01

    Several laws are designed for simultaneous control of the orientation of an Earth-pointing spacecraft, the energy stored by counter-rotating flywheels, and the angular momentum of the flywheels and control moment gyroscopes used together as an integrated set of actuators for attitude control. General, nonlinear equations of motion are presented in vector-dyadic form, and used to obtain approximate expressions which are then linearized in preparation for design of control laws that include feedback of flywheel kinetic energy error as a means of compensating for damping exerted by rotor bearings. Two flywheel steering laws are developed such that torque commanded by an attitude control law is achieved while energy is stored or discharged at the required rate. Using the International Space Station as an example, numerical simulations are performed to demonstrate control about a torque equilibrium attitude, and illustrate the benefits of kinetic energy error feedback. Control laws for attitude hold are also developed, and used to show the amount of propellant that can be saved when flywheels assist the CMGs. Nonlinear control laws for large-angle slew maneuvers perform well, but excessive momentum is required to reorient a vehicle like the International Space Station.

  9. Self-control, perceived opportunity, and attitudes as predictors of academic dishonesty.

    Science.gov (United States)

    Bolin, Aaron U

    2004-03-01

    Academic dishonesty is a persistent and pervasive problem on college campuses. Researchers have suggested a variety of factors that influence academic dishonesty. The present study is an examination of the roles of self-control, attitude toward academic dishonesty, and perceived opportunity in predicting academic dishonesty. The dataset consisted of 853 survey responses from university students across the United States. The results showed that attitude toward academic dishonesty mediated the relationship between self-control and academic dishonesty and also between perceived opportunity and academic dishonesty. Implications of these findings are briefly discussed.

  10. Finite-Time Anti-Disturbance Inverse Optimal Attitude Tracking Control of Flexible Spacecraft

    Directory of Open Access Journals (Sweden)

    Chutiphon Pukdeboon

    2013-01-01

    Full Text Available We propose a new robust optimal control strategy for flexible spacecraft attitude tracking maneuvers in the presence of external disturbances. An inverse optimal control law is designed based on a Sontag-type formula and a control Lyapunov function. An adapted extended state observer is used to compensate for the total disturbances. The proposed controller can be expressed as the sum of an inverse optimal control and an adapted extended state observer. It is shown that the developed controller can minimize a cost functional and ensure the finite-time stability of a closed-loop system without solving the associated Hamilton-Jacobi-Bellman equation directly. For an adapted extended state observer, the finite-time convergence of estimation error dynamics is proven using a strict Lyapunov function. An example of multiaxial attitude tracking maneuvers is presented and simulation results are included to show the performance of the developed controller.

  11. Adaptive finite-time backstepping control for attitude tracking of spacecraft based on rotation matrix

    Directory of Open Access Journals (Sweden)

    Guo Yong

    2014-04-01

    Full Text Available This paper investigates two finite-time controllers for attitude control of spacecraft based on rotation matrix by an adaptive backstepping method. Rotation matrix can overcome the drawbacks of unwinding which makes a spacecraft perform a large-angle maneuver when a small-angle maneuver in the opposite rotational direction is sufficient to achieve the objective. With the use of adaptive control, the first robust finite-time controller is continuous without a chattering phenomenon. The second robust finite-time controller can compensate external disturbances with unknown bounds. Theoretical analysis shows that both controllers can make a spacecraft following a time-varying reference attitude signal in finite time and guarantee the stability of the overall closed-loop system. Numerical simulations are presented to demonstrate the effectiveness of the proposed control schemes.

  12. Investigation of the dynamics of angular motion and construction of algorithms for controlling the angular momentum of spacecraft using a magnetic attitude control system

    Science.gov (United States)

    Egorov, Yu. G.; Kulkov, V. M.; Terentyev, V. V.; Firsyuk, S. O.; Shemyakov, A. O.

    2016-11-01

    The problem of controlling the angular momentum of spacecraft using magnetic attitude control systems interacting with the Earth's magnetic field is considered. A mathematical model for the angular motion dynamics of a spacecraft has been constructed. An approach to determining the parameters of the control law for a spacecraft attitude control and stabilization system that ensures angular momentum dissipation is proposed.

  13. Finite-Time Reentry Attitude Control Using Time-Varying Sliding Mode and Disturbance Observer

    Directory of Open Access Journals (Sweden)

    Xuzhong Wu

    2015-01-01

    Full Text Available This paper presents the finite-time attitude control problem for reentry vehicle with redundant actuators in consideration of planet uncertainties and external disturbances. Firstly, feedback linearization technique is used to cancel the nonlinearities of equations of motion to construct a basic mode for attitude controller. Secondly, two kinds of time-varying sliding mode control methods with disturbance observer are integrated with the basic mode in order to enhance the control performance and system robustness. One method is designed based on boundary layer technique and the other is a novel second-order sliding model control method. The finite-time stability analyses of both resultant closed-loop systems are carried out. Furthermore, after attitude controller produces the torque commands, an optimization control allocation approach is introduced to allocate them into aerodynamic surface deflections and on-off reaction control system thrusts. Finally, the numerical simulation results demonstrate that both of the time-varying sliding mode control methods are robust to uncertainties and disturbances without chattering phenomenon. Moreover, the proposed second-order sliding mode control method possesses better control accuracy.

  14. Singularity Avoidance Strategies For Satellite Mounted Manipulators Using Attitude Control

    Science.gov (United States)

    1998-05-01

    assumed that 6c = 0. This allows a stabilizing control law using only a feedforward velocity term. If Hie assumption is not made, the control law...configuration, a reasonable first choice is to let Cavg = 0. The resulting control law is r = -K2e2 (200) This is also the stabilizing control law that

  15. Model-free Adaptive Control for Spacecraft Attitude

    Institute of Scientific and Technical Information of China (English)

    Ran Xie; Ting Song; Peng Shi; Yushan Zhao

    2016-01-01

    A model⁃free adaptive control method is proposed for the spacecrafts whose dynamical parameters change over time and cannot be acquired accurately. The algorithm is based on full form dynamic linearization. A dimension reduction matrix is introduced to construct an augmented system with the same dimension input and output. The design of the controller depends on the system input and output data rather than the knowledge of the controlled plant. The numerical simulation results show that the improved controller can deal with different models with the same set of controller parameters, and the controller performance is better than that of PD controller for the time⁃varying system with disturbance.

  16. Attitude Controller for the Atmospheric Entry of the Mars Science Laboratory

    Science.gov (United States)

    Brugarolas, Paul B.; San Martin, A. Miguel; Wong, Edward C.

    2008-01-01

    This paper describes the attitude controller for the atmospheric entry of the Mars Science Laboratory (MSL). The controller will command 8 RCS thrusters to control the 3- axis attitude of the entry capsule. The Entry Controller is formulated as three independent channels in the control frame, which is nominally aligned with the stability frame. Each channel has a feedfoward and a feedback path. The feedforward path enables fast response to large bank commands. The feedback path stabilizes the vehicle angle of attack and sideslip around its trim position, and tracks bank commands. The feedback path has a PD/D control structure with deadbands that minimizes fuel usage. The performance of this design is demonstrated via computer simulations.

  17. A study of interceptor attitude control based on adaptive wavelet neural networks

    Science.gov (United States)

    Li, Da; Wang, Qing-chao

    2005-12-01

    This paper engages to study the 3-DOF attitude control problem of the kinetic interceptor. When the kinetic interceptor enters into terminal guidance it has to maneuver with large angles. The characteristic of interceptor attitude system is nonlinearity, strong-coupling and MIMO. A kind of inverse control approach based on adaptive wavelet neural networks was proposed in this paper. Instead of using one complex neural network as the controller, the nonlinear dynamics of the interceptor can be approximated by three independent subsystems applying exact feedback-linearization firstly, and then controllers for each subsystem are designed using adaptive wavelet neural networks respectively. This method avoids computing a large amount of the weights and bias in one massive neural network and the control parameters can be adaptive changed online. Simulation results betray that the proposed controller performs remarkably well.

  18. Mixed H2/H∞ State Feedback Attitude Control of Microsatellite Based on Extended LMI Method

    Institute of Scientific and Technical Information of China (English)

    Keke Shi; Chuang Liu; Feng Wang∗; Zhaowei Sun

    2016-01-01

    For the appearance of the additive perturbation of controller gain when the controller parameter has minute adjustment at the initial running stage of system, to avoid the adverse effects, this paper investigates the mixed H2/H∞ state feedback attitude control problem of microsatellite based on extended LMI method. Firstly, the microsatellite attitude control system is established and transformed into corresponding state space form. Then, without the equivalence restriction of the two Lyapunov variables of H2 and H∞ performance, this paper introduces additional variables to design the mixed H2/H∞ control method based on LMI which can also reduce the conservatives. Finally, numerical simulations are analyzed to show that the proposed method can make the satellite stable within 20 s whether there is additive perturbation of the controller gain or not. The comparative analysis of the simulation results between extended LMI method and traditional LMI method also demonstrates the effectiveness and feasibility of the proposed method in this paper.

  19. Attitude Estimation and Position Control of VTOL UAVs using IMU and GPS Measurements

    CERN Document Server

    Roberts, Andrew

    2011-01-01

    We address two fundamental problems associated with the control of vertical take-off and landing (VTOL) unmanned airborne vehicles (UAVs): attitude estimation and position control. We propose two velocity-aided attitude observers which utilize a global-positioning system (GPS) in addition to an inertial measurement unit (IMU). The `velocity-aided' class of observer uses an accelerometer to measure the system \\emph{apparent acceleration} (instead of the gravity vector), and is therefore better suited for applications where the rigid-body (aircraft) is subjected to significant linear accelerations (which is to be expected for VTOL UAVs). We also propose a position controller which utilizes the accelerometer in a similar fashion. More precisely, rather than using the system orientation (as is usually done in the existing position controllers), we use the vector measurements (accelerometer and magnetometer measurements) directly in the position control law. Consequently, the proposed position controller does not ...

  20. Increasing Slew Performance of Reaction Wheel Attitude Control Systems

    Science.gov (United States)

    2013-09-01

    based software package for solving optimal control problems [21]. A huge advantage of DIDO is that the optimal control problem from Equation (153...Beginner’s Guide to DIDO: A MATLAB Application Package for Solving Optimal Control Problems .” V7.3, Doc. TR-711, Monterey, CA: Elissar, 2007. [22] N. S

  1. Adaptive backstepping finite-time sliding mode control of spacecraft attitude tracking

    Institute of Scientific and Technical Information of China (English)

    Chutiphon Pukdeboon

    2015-01-01

    This paper investigates the finite-time attitude tracking problem for rigid spacecraft. Two backstepping finite-time slid-ing mode control laws are proposed to solve this problem in the presence of inertia uncertainties and external disturbances. The first control scheme is developed by combining sliding mode con-trol with a backstepping technique to achieve fast and accurate tracking responses. To obtain higher tracking precision and relax the requirement of the upper bounds on the uncertainties, a se-cond control law is also designed by combining the second or-der sliding mode control and an adaptive backstepping technique. This control law provides complete compensation of uncertainty and disturbances. Although it assumes that the uncertainty and disturbances are bounded, the proposed control law does not require information about the bounds on the uncertainties and disturbances. Finite-time convergence of attitude tracking errors and the stability of the closed-loop system are ensured by the Lya-punov approach. Numerical simulations on attitude tracking control of spacecraft are provided to demonstrate the performance of the proposed control ers.

  2. Using Automatic Code Generation in the Attitude Control Flight Software Engineering Process

    Science.gov (United States)

    McComas, David; O'Donnell, James R., Jr.; Andrews, Stephen F.

    1999-01-01

    This paper presents an overview of the attitude control subsystem flight software development process, identifies how the process has changed due to automatic code generation, analyzes each software development phase in detail, and concludes with a summary of our lessons learned.

  3. Solar attitude control including active nutation damping in a fixed-momentum wheel satellite

    Science.gov (United States)

    Azor, Ruth

    1992-08-01

    In geostationary cruise of a momentum biased satellite, it is necessary to stabilize the roll/yaw attitude due to disturbances, caused mainly by solar pressure. This work presents a roll/yaw control, which is obtained by the use of solar arrays and fixed flaps as actuators, with a horizon sensor for roll measurement. The design also includes an active nutation damping.

  4. Locus of Control and Computer Attitude: The Effect of User Involvement.

    Science.gov (United States)

    Hawk, Stephen R.

    1989-01-01

    Describes study that was conducted to investigate the relationship between locus of control and user attitude toward computer based information systems (CBIS) used at work. The impact of user involvement is examined, the hypotheses tested are described, and implications for introducing CBIS into organizations are discussed. (14 references) (LRW)

  5. Solar Anomalous and Magnetospheric Particle Explorer attitude control electronics box design and performance

    Science.gov (United States)

    Chamberlin, K.; Clagett, C.; Correll, T.; Gruner, T.; Quinn, T.; Shiflett, L.; Schnurr, R.; Wennersten, M.; Frederick, M.; Fox, S. M.

    1993-01-01

    The attitude Control Electronics (ACE) Box is the center of the Attitude Control Subsystem (ACS) for the Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX) satellite. This unit is the single point interface for all of the Attitude Control Subsystem (ACS) related sensors and actuators. Commands and telemetry between the SAMPEX flight computer and the ACE Box are routed via a MIL-STD-1773 bus interface, through the use of an 80C85 processor. The ACE Box consists of the flowing electronic elements: power supply, momentum wheel driver, electromagnet driver, coarse sun sensor interface, digital sun sensor interface, magnetometer interface, and satellite computer interface. In addition, the ACE Box also contains an independent Safehold electronics package capable of keeping the satellite pitch axis pointing towards the sun. The ACE Box has dimensions of 24 x 31 x 8 cm, a mass of 4.3 kg, and an average power consumption of 10.5 W. This set of electronics was completely designed, developed, integrated, and tested by personnel at NASA GSFC. SAMPEX was launched on July 3, 1992, and the initial attitude acquisition was successfully accomplished via the analog Safehold electronics in the ACE Box. This acquisition scenario removed the excess body rates via magnetic control and precessed the satellite pitch axis to within 10 deg of the sun line. The performance of the SAMPEX ACS in general and the ACE Box in particular has been quite satisfactory.

  6. Passivity Based Nonlinear Attitude Control of the Rømer Satellite

    DEFF Research Database (Denmark)

    Quottrup, Michael Melholt; Krogh-Sørensen, J.; Wisniewski, Rafal

    2001-01-01

    This paper suggests nonlinear attitude control of the Danish satellite Rømer. This satellite will be designed to fulfil two scientific objectives: The observation of stellar oscillations and the detection and localisation of gamma-ray bursts. The satellite will be equipped with a tetrahedron...

  7. Passivity based nonlinear attitude control of the Rømer satellite

    DEFF Research Database (Denmark)

    Quottrup, Michael Melholt; Krogh-Sørensen, J.; Wisniewski, Rafal

    This paper suggests nonlinear attitude control of the Danish satellite Rømer. This satellite will be designed to fulfil two scientific objectives: The observation of stellar oscillations and the detection and localisation of gamma-ray bursts. The satellite will be equipped with a tetrahedron...

  8. Time-varying Sliding Mode Controls in Rigid Spacecraft Attitude Tracking

    Institute of Scientific and Technical Information of China (English)

    Jin Yongqiang; Liu Xiangdong; Qiu Wei; Hou Chaozhen

    2008-01-01

    To solve the problem of attitude tracking of a rigid spacecraft with an either known or measurable desired attitude trajectory, three types of time-varying sliding mode controls are introduced under consideration of control input constraints. The sliding surfaces of the three types initially pass arbitrary initial values of the system, and then shift or rotate to reach predetermined ones. This way, the system trajectories are always on the sliding surfaces, and the system work is guaranteed to have robustness against paramour uncertainty and external disturbances all the time. The controller parameters are optimized by means of genetic algorithm to minimize the index consisting of the weighted index of squared error (ISE) of the system and the weighted penalty term of violation of control input constraint. The stability is verified with Lyapunov method. Compared with the conventional sliding mode control, simulation results show the proposed algorithm having better robustness against inertia matrix uncertainty and external disturbance torques.

  9. Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

    Institute of Scientific and Technical Information of China (English)

    GAO; Junshan; DENG; Liwei; SONG; Shenmin

    2016-01-01

    This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and external disturbances. The controller is based on the fractional calculus and nonsingular terminal sliding mode control technique,and it guarantees the convergence of attitude tracking error in finite time rather than in the asymptotic sense. With respect to the controller,a fractional order sliding surface is given,the corresponding control scheme is proposed based on Lyapunov stability theory to guarantee the sliding condition,and the finite time stability of the whole close loop system is also proven. Finally,numerical simulations are presented to illustrate the performance of the proposed scheme.

  10. CHAOTIC ATTITUDE MOTION OF A MAGNETIC RIGID SPACECRAFT IN AN ELLIPTIC ORBIT AND ITS CONTROL

    Institute of Scientific and Technical Information of China (English)

    刘延柱; 陈立群

    2003-01-01

    This paper deals with the chaotic attitude motion of a magnetic rigid spacecraft with internal damping in an elliptic orbit. The dynamical model of the spacecraft is established. The Melnikov analysis is carried out to prove the existence of a complicated nonwandering Cantor set. The dynamical behaviors are numerically investigated by means of time history, Poincare map, Lyapunov exponents and power spectrum. Numerical simulations demonstrate the chaotic motion of the system.The input-output feedback linearization method and its modified version are applied, respectively, to control the chaotic attitude motions to the given fixed point or periodic motion.

  11. Attitude angle anti-windup control of small size unmanned helicopter

    Science.gov (United States)

    Shao, Taizhou; Long, Haihui; Zhao, Jiankang; Xia, Xuan; Yang, Guang

    2017-01-01

    This paper researches the small-size unmanned helicopter attitude control problem with actuator saturation limit. Traditional approach for this problem is often based on an accurate dynamic model which is complicated and difficult to achieve in engineering. In this paper, we propose an anti-windup PID approach which does not rely on sophicated helicopter dynamic model. The anti-windup PID controller is established by adding a phase-lead compensator to the conventional PID controller. The performance and merits of this proposed controller are exemplified by the simulations between the conventional PID controller and the anti-windup PID controller.

  12. Adaptive Integral-type Sliding Mode Control for Spacecraft Attitude Maneuvering Under Actuator Stuck Failures

    Institute of Scientific and Technical Information of China (English)

    HU Qinglei; ZHANG Youmin; HUO Xing; XIAO Bing

    2011-01-01

    A fault tolerant control (FTC) design technique against actuator stuck faults is investigated using integral-type sliding mode control (ISMC) with application to spacecraft attitude maneuvering control system. The principle of the proposed FTC scheme is to design an integral-type sliding mode attitude controller using on-line parameter adaptive updating law to compensate for the effects of stuck actuators. This adaptive law also provides both the estimates of the system parameters and external disturbances such that a prior knowledge of the spacecraft inertia or boundedness of disturbances is not required. Moreover, by including the integral feedback term, the designed controller can not only tolerate actuator stuck faults, but also compensate the disturbances with constant components. For the synthesis of controller, the fault time, patterns and values are unknown in advance, as motivated from a practical spacecraft control application. Complete stability and performance analysis are presented and illustrative simulation results of application to a spacecraft show that high precise attitude control with zero steady-error is successfully achieved using various scenarios of stuck failures in actuators.

  13. Attitude control for part actuator failure of agile small satellite

    Institute of Scientific and Technical Information of China (English)

    J. R. Zhang; A. Rachid; Y. Zhang

    2008-01-01

    The stability and singularity problem of agile small satellite (ASS) with actuator failure is discussed in this paper. Firstly, the three-axis stabilized controller of an ASS is designed, where micro control moment gyros (MCMG's) in pyramid configuration (PC) is used as the actuator. By using the same controller and steering law, the control results before and after one gyro fails are compared by simulation. The variation of singular momentum envelope before and after one gyro fails is also compared. The simulation results show that the failure intensively decreases the capacity of output torque, which leads to the emergence of more singular points and the rapid saturation of MCMG's. Finally, the parameters of system controller are changed to compare the control effect.

  14. Coupled Attitude and Orbit Dynamics and Control in Formation Flying Systems

    Science.gov (United States)

    Xu, Yun-Jun; Fitz-Coy, Norman; Mason, Paul

    2003-01-01

    Formation flying systems can range from global constellations offering extended service coverage to clusters of highly coordinated vehicles that perform distributed sensing. Recently, the use of groups of micro-satellites in the areas of near Earth explorations, deep space explorations, and military applications has received considerable attention by researchers and practitioners. To date, most proposed control strategies are based on linear models (e.g., Hill-Clohessy-Wiltshire equations) or nonlinear models that are restricted to circular reference orbits. Also, all models in the literature are uncoupled between relative position and relative attitude. In this paper, a generalized dynamic model is proposed. The reference orbit is not restricted to the circular case. In this formulation, the leader or follower satellite can be in either a circular or an elliptic orbit. In addition to maintaining a specified relative position, the satellites are also required to maintain specified relative attitudes. Thus the model presented couples vehicle attitude and orbit requirements. Orbit perturbations are also included. In particular, the J(sub 2) effects are accounted in the model. Finally, a sliding mode controller is developed and used to control the relative attitude of the formation and the simulation results are presented.

  15. Attitude Control of Satellite With Pulse-Width Pulse- Frequency (PWPF Modulator Using Generalized Incremental Predictive Control

    Directory of Open Access Journals (Sweden)

    Ehsan Chegeni

    2014-09-01

    Full Text Available In this paper, we use generalized incremental predictive control (GIPC to stabilize attitude of satellite. We compare Generalized Predictive Control (GPC with GIPC algorithm and present that GIPC has better performance. The three-axis attitude control systems are activated in pulse mode. Consequently, a modulation of the torque command is compelling in order to avoid high non-linear control action. This work considers the Pulse-Width Pulse-Frequency modulator (PWPF is composed of a Schmitt trigger, a first order filter, and a feedback loop. PWPF modulator has several advantages over classical bang-bang controllers such as close to linear operation, high accuracy, and reduced propellant consumption

  16. Anti-disturbance inverse optimal control for spacecraft position and attitude maneuvers with input saturation

    Directory of Open Access Journals (Sweden)

    Chutiphon Pukdeboon

    2016-05-01

    Full Text Available In this article, a new anti-disturbance inverse optimal translation and rotation control scheme for a rigid spacecraft with external disturbances and actuator constraint is presented. An inverse optimal controller with input saturations is designed to achieve asymptotic convergence to the desired translation and attitude and avoid the unwinding phenomenon. The derived optimal control law can minimize a given cost functional and guarantee the stability of the closed-loop system. Later, a new sliding mode disturbance observer is also proposed to compensate for the total disturbances. A rigorous Lyapunov analysis is employed to ensure the finite-time convergence of observer error dynamics. A numerical simulation of position and attitude maneuvers is given to verify the performance of the developed controller.

  17. Knowledge, Attitude and Performance of Shiraz General Dentists about Infection Control Principles during Preparing Intraoral Radiographies

    Directory of Open Access Journals (Sweden)

    Abdolaziz Hagh Negahdar

    2017-02-01

    Full Text Available Background & Objective: Infection control in dental centers is affected by the persons’ attitude and knowledge about mechanisms of infection transmission. This study was designed to evaluate the knowledge and the attitude of Shiraz dentists about infection control during intraoral radiographies preparation. Materials & Methods: In this cross-sectional, and analytical research, the attitude and the knowledge of 45 male and 25 female, randomly selected dentists, were obtained through completion of a researcher- planed questioner which its validity and reliability had been confirmed. Data were analyzed using Cronbach`s alpha, one-way ANOVA, student’s t-test, and Pearson’s correlation coefficient in SPSS (V.21. Results: The average of the dentists’ age was 40.59±10.72 and their average occupational experience was 13.49±9.75 years. The mean score obtained for knowledge about infection control during intraoral radiographic procedures was less than fifty percent of total obtainable score, and was assessed as weak knowledge. There was no significant difference in the level of knowledge between studied male and female dentists (P>0.05. In addition, no significant relationship was detected between level, age/experience, and the university of education (P>0.05. The attitude of the dentists about infection control during intraoral radiography preparation assessed as moderate to good level. Conclusions: The results showed that the main reason for the present problems is insufficient knowledge of the dentists in related subjects. Therefore, the solution, which is recommended among dentists, is to raise their awareness and to change their attitudes and culture in order to improve their performance.

  18. Solar sail attitude control including active nutation damping in a fixed-momentum wheel satellite

    Science.gov (United States)

    Azor, Ruth

    1992-02-01

    In the geostationary cruise of a momentum biased satellite, it is necessary to stabilize the roll/yaw attitude due to disturbances caused by solar radiation pressure. This work presents a roll/yaw control system with a horizon sensor for roll measurement. Roll/yaw control is obtained by the use of solar arrays and fixed flaps as actuators. The design also includes an active nutation damping method.

  19. Inertia-independent generalized dynamic inversion feedback control of spacecraft attitude maneuvers

    Science.gov (United States)

    Bajodah, Abdulrahman H.

    2011-06-01

    The generalized dynamic inversion control methodology is applied to the spacecraft attitude trajectory tracking problem. It is shown that the structure of the skew symmetric cross product matrix alleviates the need to include the inertia matrix in the control law. Accordingly, the proposed control law depends solely on attitude and angular velocity measurements, and it neither requires knowledge of the spacecraft's inertia parameters nor it works towards estimating these parameters. A linear time-varying attitude deviation dynamics in the multiplicative error quaternion is inverted for the control variables using the generalized inversion-based Greville formula. The resulting control law is composed of auxiliary and particular parts acting on two orthogonally complement subspaces of the three dimensional Euclidean space. The particular part drives the attitude variables to their desired trajectories. The auxiliary part is affine in a free null-control vector, and is designed by utilizing a semidefinite control Lyapunov function that exploits the geometric structure of the control law to provide closed loop stability. The generalized inversion singularity avoidance is made by augmenting the generalized inverse with an asymptotically stable fast mode that is driven by angular velocity error's norm from reference angular velocity. Asymptotic tracking is achieved for detumbling maneuvers as the stable augmented mode subdues singularity. If the steady state desired quaternion trajectories are time varying, then asymptotic tracking is lost in favor of close ultimately bounded tracking because the stable augmented mode continues to be excited during steady state phase of response. A rest-to-rest slew and a trajectory tracking maneuver examples are provided to illustrate the methodology.

  20. Appendage modal coordinate truncation criteria in hybrid coordinate dynamic analysis. [for spacecraft attitude control

    Science.gov (United States)

    Likins, P.; Ohkami, Y.; Wong, C.

    1976-01-01

    The paper examines the validity of the assumption that certain appendage-distributed (modal) coordinates can be truncated from a system model without unacceptable degradation of fidelity in hybrid coordinate dynamic analysis for attitude control of spacecraft with flexible appendages. Alternative truncation criteria are proposed and their interrelationships defined. Particular attention is given to truncation criteria based on eigenvalues, eigenvectors, and controllability and observability. No definitive resolution of the problem is advanced, and exhaustive study is required to obtain ultimate truncation criteria.

  1. Guidance and adaptive-robust attitude & orbit control of a small information satellite

    Science.gov (United States)

    Somov, Ye.; Butyrin, S.; Somov, S.; Somova, T.; Testoyedov, N.; Rayevsky, V.; Titov, G.; Yakimov, Ye.; Ovchinnikov, A.; Mathylenko, M.

    2017-01-01

    We consider a small information satellite which may be placed on an orbit with altitude from 600 up to 1000 km. The satellite attitude and orbit control system contains a strap-down inertial navigation system, cluster of four reaction wheels, magnetic driver and a correcting engine unit with eight electro-reaction engines. We study problems on design of algorithms for spatial guidance, in-flight identification and adaptive-robust control of the satellite motion on sun-synchronous orbit.

  2. Adaptive Attitude Control of the Crew Launch Vehicle

    Science.gov (United States)

    Muse, Jonathan

    2010-01-01

    An H(sub infinity)-NMA architecture for the Crew Launch Vehicle was developed in a state feedback setting. The minimal complexity adaptive law was shown to improve base line performance relative to a performance metric based on Crew Launch Vehicle design requirements for all most all of the Worst-on-Worst dispersion cases. The adaptive law was able to maintain stability for some dispersions that are unstable with the nominal control law. Due to the nature of the H(sub infinity)-NMA architecture, the augmented adaptive control signal has low bandwidth which is a great benefit for a manned launch vehicle.

  3. A Comparative Study of Actuator Configurations for Satellite Attitude Control

    Directory of Open Access Journals (Sweden)

    Raymond Kristiansen

    2005-10-01

    Full Text Available In this paper a controllability study of different actuator configurations consisting of magnetic torquers, reaction wheels and a gravity boom is presented. The theoretical analysis is performed with use of controllability gramians, and simulation results with the different configurations are presented and compared regarding settling time and power consumption to substantiate the theoretical analysis. A reference model is also introduced to show how the power consumption can he lowered to the same magnitude as when magnetic torquers are used, without degrading the satellite response significantly.

  4. Attitude control of an underactuated spacecraft using quaternion feedback regulator and tube-based MPC

    Science.gov (United States)

    Mirshams, M.; Khosrojerdi, M.

    2017-03-01

    Feasibility of achieving 3-axis stabilization of an asymmetric spacecraft for cases where there is no control available in one axis (underactuated spacecraft) is explored in this paper. A novel control design methodology is presented which can stabilize the underactuated spacecraft and steer it to the origin. A passive fault tolerant control (FTC) is defined which controls and maintains the attitude of the spacecraft near the desired point in presence of uncertainties, disturbances, control constraints and actuator faults. Considering the general conditions of the underactuated spacecraft, a hybrid controller combining a quaternion feedback regulator (QFR) with a tube-based model predictive controller (MPC) is developed based on the nonlinear kinematic and dynamic equations of the spacecraft motion. The hybrid controller is composed of two control stages. At the first stage, QFR decreases the angular velocities and brings the state vector to an acceptable region for the next stage. Then, tube-based MPC solves two optimal control problems, a standard problem for the nominal system to define a central guide path, and an ancillary problem to steer the state vector towards the central path with semi-optimal control effort. Numerical simulation results obtained for the underactuated spacecraft merely indicate effectiveness of the proposed attitude control method.

  5. Design of Attitude Control Actuators for a Simulated Spacecraft

    Science.gov (United States)

    2011-03-24

    SimSat I provided a solid platform for research, by 2007 it was beginning to show its age. To quote Roach, Rohe, and Welty : 12 SIMSAT (I) did have...Katsuhiko Ogata. Modern Control Engineering. Prentice-Hall, New Jersey, 4th edition, 2002. 172 25. Neal R. Roach, Wayne C. Rohe, and Nathan F. Welty . A

  6. Rotating Space Debris Tracking Based on The Orbit-Attitude Coordinated Control

    Science.gov (United States)

    Wang, Shuquan; Zhu, Lingchao

    2016-07-01

    This paper investigates the rotating space debris tracking problem. Active capturing and removal of space debris are challenging because the space debris is noncoorperating. The scenario considered is that a rotating space debris is the target to be captured by a spacecraft with a robotic arm. One rough approach is to capture the space debris with a strong arm then detumble the rotation of the whole system using the attitude control system on board. In this way the arm and the spacecraft have to be strong enough to withstand the impact caused by the relative orbital and attitude motions. Another way is to at first track the motion of the characterized surface, which should be easier to capture, of the debris. Then the robotic arm is engaged to capture the debris. In this way, the impact applied on the robotic arm is greatly reduced such that the possibility of causing new debris is also reduced. The orbit-attitude coordinated controller is developed to track the motion of the space debris. The controller is assymptotically stable without considering the boundness of the control efforts. The stability in the situation of bounded control inputs is analyzed. Analytical criterion for a successful tracking is obtained in the situation that rotational motion of the space debris is percession.

  7. Integrated power and attitude control of a rigid satellite with onboard magnetic bearing suspended rigid flywheels

    Science.gov (United States)

    Kim, Yeonkyu

    2003-10-01

    A system of differential equations governing the translational and rotational motion of a system model consisting of a rigid satellite and multiple MB suspended rigid flywheels in general configuration is developed. Flywheel modules are contained in a housing rigidly mounted on the satellite and floated by an active MB suspension system, therefore each flywheel module has six degrees of freedom (DOF) as well as the satellite module. Equations of motion for the satellite and flywheels are naturally coupled and the satellite rotational motion and translational motion are coupled. A nonlinear state feedback tracking control law, which is globally asymptotically stable, is developed following a Lyapunov stability theory for integrated power and attitude control using the MB suspended flywheels. The stability, robustness, and tracking and disturbance rejection performance of the present control law with respect to initial attitude error, system modeling error, an imbalance disturbance, is demonstrated by case studies. The satellite departure motion equation derived from the definition of the angular velocity error and the system dynamics equations is presented. Application study of existing power tracking algorithm with this control law shows perfect power tracking for both power charging from and power delivery to the satellite operations and the power tracking can be performed simultaneously with and independent of the attitude control function.

  8. Information Fusion-Based Optimal Attitude Control for an Alterable Thrust Direction Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Ziyang Zhen

    2013-01-01

    Full Text Available Attitude control is the inner‐loop and the most important part of the automatic flight control system of an unmanned aerial vehicle (UAV. The information fusion‐based optimal control method is applied in a UAV flight control system in this work. Firstly, a nonlinear model of alterable thrust direction UAV (ATD‐UAV is established and linearized for controller design. The longitudinal controller and lateral controller are respectively designed based on information fusion‐based optimal control, and then the information fusion flight control system is built up. Finally, the simulation of a nonlinear model described as ATD‐UAV is carried out, the results of which show the superiority of the information fusion‐based control strategy when compared to the single‐loop design method. We also show that the ATD technique improves the anti‐disturbance capacity of the UAV.

  9. Robust Adaptive Geometric Tracking Controls on SO(3) with an Application to the Attitude Dynamics of a Quadrotor UAV

    CERN Document Server

    Lee, Taeyoung

    2011-01-01

    This paper provides new results for a robust adaptive tracking control of the attitude dynamics of a rigid body. Both of the attitude dynamics and the proposed control system are globally expressed on the special orthogonal group, to avoid complexities and ambiguities associated with other attitude representations such as Euler angles or quaternions. By designing an adaptive law for the inertia matrix of a rigid body, the proposed control system can asymptotically follow an attitude command without the knowledge of the inertia matrix, and it is extended to guarantee boundedness of tracking errors in the presence of unstructured disturbances. These are illustrated by numerical examples and experiments for the attitude dynamics of a quadrotor UAV.

  10. Finite-time sliding mode attitude control for a reentry vehicle with blended aerodynamic surfaces and a reaction control system

    Institute of Scientific and Technical Information of China (English)

    Geng Jie; Sheng Yongzhi; Liu Xiangdong

    2014-01-01

    This paper proposes a finite-time robust flight controller, targeting for a reentry vehicle with blended aerodynamic surfaces and a reaction control system (RCS). Firstly, a novel finite-time attitude controller is pointed out with the introduction of a nonsingular finite-time sliding mode manifold. The attitude tracking errors are mathematically proved to converge to zero within finite time which can be estimated. In order to improve the performance, a second-order finite-time slid-ing mode controller is further developed to effectively alleviate chattering without any deterioration of robustness and accuracy. Moreover, an optimization control allocation algorithm, using linear programming and a pulse-width pulse-frequency (PWPF) modulator, is designed to allocate torque commands for all the aerodynamic surface deflections and on-off switching-states of RCS thrusters. Simulations are provided for the reentry vehicle considering uncertain parameters and external disturbances for practical purposes, and the results demonstrate the effectiveness and robustness of the attitude control system.

  11. Attitude Control Considering Variable Input Saturation Limit for a Spacecraft Equipped with Flywheels

    Institute of Scientific and Technical Information of China (English)

    TIAN Lin; XU Shijie

    2012-01-01

    A new attitude controller is proposed for spacecraft whose actuator has variable input saturation limit.There are three identical flywheels orthogonally mounted on board.Each rotor is driven by a brushless DC motor (BLDCM).Models of spacecraft attitude dynamics and flywheel rotor driving motor electromechanics are discussed in detail.The controller design is similar to saturation limit linear assignment.An auxiliary parameter and a boundary coefficient are imported into the controller to guarantee system stability and improve control performance.A time-varying and state-dependent flywheel output torque saturation limit model is established.Stability of the closed-loop control system and asymptotic convergence of system states are proved via Lyapunov methods and LaSalle invarianee principle.Boundedness of the auxiliary parameter ensures that the control objective can be achieved,while the boundary parameter's value makes a balance between system control performance and flywheel utilization efficiency.Compared with existing controllers,the newly developed controller with variable torque saturation limit can bring smoother control and faster system response.Numerical simulations validate the effectiveness of the controller.

  12. Small satellite attitude control for sun-oriented operations utilizing a momentum bias with magnetic actuators

    Science.gov (United States)

    Wolfe, Scott M.

    1995-03-01

    The feasibility of using a three axis control, momentum bias system with magnetic actuators for sun-oriented operations is explored. Relevant equations of motion are developed for a sun-oriented coordinate system and control laws are developed for initial spacecraft capture after launch vehicle separation; reorientation from Earth oriented to a sun oriented operations mode; sun-oriented attitude control; and momentum wheel control. Simulations demonstrating the stability and time responsiveness of the system are performed. Sensor noise input tests are performed to investigate the systems susceptibility to imperfect conditions. Cross product of inertia effects are also input to test for system instability.

  13. Direct Self-Repairing Control for Quadrotor Helicopter Attitude Systems

    Directory of Open Access Journals (Sweden)

    Huiliao Yang

    2014-01-01

    Full Text Available A quadrotor helicopter with uncertain actuator faults, such as loss of effectiveness and lock-in-place, is studied in this paper. An adaptive fuzzy sliding mode controller based on direct self-repairing control is designed for such nonlinear system to track the desired output signal, when any actuator of this quadrotor helicopter is loss of effectiveness or stuck at some place. Moreover, using the Lyapunov stability theory, the stability of the whole system and the convergence of the tracking error can be guaranteed. Finally, the availability of the proposed method is verified by simulation on 3-DOF hover to ensure that the system performance under faulty conditions can be quickly recovered to its normal level. And this proposed method is also proved to be better than that of LQR through simulation.

  14. Design of a high density cold gas attitude control system

    Science.gov (United States)

    Hall, Sarah E.; Lewis, Mark J.; Akin, David L.

    1993-01-01

    A comparison of the experimental results of a nitrous oxide cold gas thruster with the predicted performance from a numerical simulation of nozzle operations is discussed. Tests were conducted in a vacuum chamber to verify analytical predictions of both nitrogen and nitrous oxide. Preliminary results indicate an Isp for N2O of 61, and an Isp of 69 for N2. Based on the results of this research, parameters are presented for a nitrous oxide-based reaction control system for a small spacecraft currently under development.

  15. Fault Tolerant Attitude Control for spacecraft with SGCMGs under actuator partial failure and actuator saturation

    Science.gov (United States)

    Zhang, Fuzhen; Jin, Lei; Xu, Shijie

    2017-03-01

    A Fault Tolerant Attitude Control algorithm for the spacecraft using Single Gimbal Control Moment Gyros (SGCMGs) as actuator is proposed. The controller is designed using the sliding mode control theory to control the gimbal rate directly and there is no singular point in the control algorithm, which means that we don't need to design the steering laws again and the singularity problems can be avoided. Also the gimbal rate saturation is considered when designing the control method. The adaptive control algorithm is used to estimate the disturbance and the boundary of the fault and saturation, which means that no prior information of the fault is needed. Although the controller is designed based on the SGCMGs, it can also be employed when reaction wheels work as the actuator of the spacecraft. Also the complete failure of several SGCMGs is allowed. It is proved based on the Lyapunov stability theorem that the designed control algorithm can achieve the attitude asymptotic stability both on the fault or fault-free condition. The simulation results show that the proposed method has a strong robustness.

  16. Inertial attitude control of a bat-like morphing-wing air vehicle.

    Science.gov (United States)

    Colorado, J; Barrientos, A; Rossi, C; Parra, C

    2013-03-01

    This paper presents a novel bat-like unmanned aerial vehicle inspired by the morphing-wing mechanism of bats. The goal of this paper is twofold. Firstly, a modelling framework is introduced for analysing how the robot should manoeuvre by means of changing wing morphology. This allows the definition of requirements for achieving forward and turning flight according to the kinematics of the wing modulation. Secondly, an attitude controller named backstepping+DAF is proposed. Motivated by biological evidence about the influence of wing inertia on the production of body accelerations, the attitude control law incorporates wing inertia information to produce desired roll (ϕ) and pitch (θ) acceleration commands (desired angular acceleration function (DAF)). This novel control approach is aimed at incrementing net body forces (F(net)) that generate propulsion. Simulations and wind-tunnel experimental results have shown an increase of about 23% in net body force production during the wingbeat cycle when the wings are modulated using the DAF as a part of the backstepping control law. Results also confirm accurate attitude tracking in spite of high external disturbances generated by aerodynamic loads at airspeeds up to 5 ms⁻¹.

  17. Some optimal considerations in attitude control systems. [evaluation of value of relative weighting between time and fuel for relay control law

    Science.gov (United States)

    Boland, J. S., III

    1973-01-01

    The conventional six-engine reaction control jet relay attitude control law with deadband is shown to be a good linear approximation to a weighted time-fuel optimal control law. Techniques for evaluating the value of the relative weighting between time and fuel for a particular relay control law is studied along with techniques to interrelate other parameters for the two control laws. Vehicle attitude control laws employing control moment gyros are then investigated. Steering laws obtained from the expression for the reaction torque of the gyro configuration are compared to a total optimal attitude control law that is derived from optimal linear regulator theory. This total optimal attitude control law has computational disadvantages in the solving of the matrix Riccati equation. Several computational algorithms for solving the matrix Riccati equation are investigated with respect to accuracy, computational storage requirements, and computational speed.

  18. Analysis of Pan-European attitudes to the eradication and control of bovine viral diarrhoea.

    Science.gov (United States)

    Heffernan, C; Misturelli, F; Nielsen, L; Gunn, G J; Yu, J

    2009-02-07

    At present, national-level policies concerning the eradication and control of bovine viral diarrhoea (BVD) differ widely across Europe. Some Scandinavian countries have enacted strong regulatory frameworks to eradicate the disease, whereas other countries have few formal policies. To examine these differences, the attitudes of stakeholders and policy makers in 17 European countries were investigated. A web-based questionnaire was sent to policy makers, government and private sector veterinarians, and representatives of farmers' organisations. In total, 131 individuals responded to the questionnaire and their responses were analysed by applying a method used in sociolinguistics: frame analysis. The results showed that the different attitudes of countries that applied compulsory or voluntary frameworks were associated with different views about the attribution or blame for BVD and the roles ascribed to farmers and other stakeholders in its eradication and control.

  19. Development of a Simple Attitude Control System for Newly Constructed Balloon-Borne Experiments

    Science.gov (United States)

    Saito, Yoshitaka; Iijima, Issei; Nonaka, Naoki; Yamada, Kazuhiko; Ishikawa, Yuji; Kan'no, Makoto; Kishimoto, Yuji; Gunji, Shuichi; Sato, Tetsuya; Mihara, Tatehiro; Anabuki, Naohisa; Ohta, Yukihiro; Yamauchi, Manabu; Hayashida, Kiyoshi

    A simple attitude control system for a balloon experiment has been developed. This system aims to achieve an accuracy of 0.1 deg in azimuth for a small payload with a diameter of 1.5 m and a moment of inertia of 100 kg·m2. It will be first flown with the Polarimetry for High ENErgy X-rays (PHENEX) experiment, which is to observe the polarization of astronomical objects in the hard X-ray energy region. The system is composed of the attitude sensors (sun sensors, geomagnetic aspect sensors, and an optical fiber gyro), read-out modules, CPU, output modules (PC104 based boards), and actuators (a torsion relief motor and a reaction wheel motor with their drivers). In this paper, after introducing these modules, the properties of the sensors and the control system based on the ground will be reviewed.

  20. Inertial attitude control of a bat-like morphing-wing micro air vehicle

    OpenAIRE

    2013-01-01

    This article presents a novel bat-like micro air vehicle inspired by the morphing-wing mechanism of bats. The goal of this paper is twofold. Firstly, a modelling framework is introduced for analysing how the robot should maneuver by means of changing wing morphology. This allows the definition of requirements for achieving forward and turning flight according to the kinematics of the wing modulation. Secondly, an attitude controller named backstepping+DAF is proposed. Motivated by the biologi...

  1. On the Elastic Vibration Model for High Length-Diameter Ratio Rocket with Attitude Control System

    Institute of Scientific and Technical Information of China (English)

    朱伯立; 杨树兴

    2003-01-01

    An elastic vibration model for high length-diameter ratio spinning rocket with attitude control system which can be used for trajectory simulation is established. The basic theory of elastic dynamics and vibration dynamics were both used to set up the elastic vibration model of rocket body. In order to study the problem more conveniently, the rocket's body was simplified to be an even beam with two free ends. The model was validated by simulation results and the test data.

  2. Cassini Attitude Control Flight Software: from Development to In-Flight Operation

    Science.gov (United States)

    Brown, Jay

    2008-01-01

    The Cassini Attitude and Articulation Control Subsystem (AACS) Flight Software (FSW) has achieved its intended design goals by successfully guiding and controlling the Cassini-Huygens planetary mission to Saturn and its moons. This paper describes an overview of AACS FSW details from early design, development, implementation, and test to its fruition of operating and maintaining spacecraft control over an eleven year prime mission. Starting from phases of FSW development, topics expand to FSW development methodology, achievements utilizing in-flight autonomy, and summarize lessons learned during flight operations which can be useful to FSW in current and future spacecraft missions.

  3. Indirect Adaptive Attitude Control for a Ducted Fan Vertical Takeoff and Landing Microaerial Vehicle

    Directory of Open Access Journals (Sweden)

    Shouzhao Sheng

    2015-01-01

    Full Text Available The present paper addresses an attitude tracking control problem of a ducted fan microaerial vehicle. The proposed indirect adaptive controller can greatly reduce tracking error in the initial stage of the adaptive learning process by using an error compensation strategy and can achieve good capability to eliminate the adverse effect of measurement noises on the convergence of adjustable parameters. Moreover, the learning rate adaptation strategy is proposed to further minimize the adverse effect of large learning rates on the convergence of adjustable parameters. The experimental tests have illustrated the effectiveness of the proposed adaptive controller.

  4. Predicting healthcare employees' participation in an office redesign program: Attitudes, norms and behavioral control

    Directory of Open Access Journals (Sweden)

    Lukas Carol

    2008-11-01

    Full Text Available Abstract Background The study examined the extent to which components based on a modified version of the theory of planned behavior explained employee participation in a new clinical office program designed to reduce patient waiting times in primary care clinics. Methods We regressed extent of employee participation on attitudes about the program, group norms, and perceived behavioral control along with individual and clinic characteristics using a hierarchical linear mixed model. Results Perceived group norms were one of the best predictors of employee participation. Attitudes about the program were also significant, but to a lesser degree. Behavioral control, however, was not a significant predictor. Respondents with at least one year of clinic tenure, or who were team leaders, first line supervisor, or managers had greater participation rates. Analysis at the clinic level indicated clinics with scores in the highest quartile clinic scores on group norms, attitudes, and behavioral control scores were significantly higher on levels of overall participation than clinics in the lowest quartile. Conclusion Findings suggest that establishing strong norms and values may influence employee participation in a change program in a group setting. Supervisory level was also significant with greater responsibility being associated with greater participation.

  5. Development and test of the ASAT Bipropellant Attitude Control System (ACS) engine

    Science.gov (United States)

    Hodge, K. F.; Allen, K. A.; Hemmings, B.

    1993-06-01

    The recent Kinetic Energy Anti-Satellite (KE ASAT) Bipropellant Attitude Control System (ACS) Engine testing demonstrated and characterized performance and operational durability. Within the ASAT mission, the bipropellant engines are used to despin the missile after shroud deployment and to provide attitude control of the Kill Vehicle (KV) during all phases of the KV free flight. These engines provide all attitude control thrust from booster separation until target intercept. The ASAT ACS engine is unique both in the amount of on-time that the engine sees during a tactical mission scenario and the high thermal loads which result from performing two diametrically opposed missions with a single thruster - long steady state burns and very short response time pulse mode operations. Two flightweight ASAT ACS Bipropellant engines were individually tested in a developmental test program. Testing was conducted at ambient conditions. Hot-fire testing consisted of steady-state, mission duty cycle (MDC), Chamber Pressure (Pc) excursion, mixture ratio excursion, and pulse performance. Testing was conducted by Rockwell's Rocketdyne Division at the Santa Susana Field Laboratory (SSFL), Systems Test Laboratory IV (STL IV), Cell 37A. Two additional engine tests are planned and will include altitude testing. This paper will summarize engine development, component development testing, valve orificing and cold flow calibration, and engine hot-fire testing approach and results.

  6. The Gravity Probe B Drag-free and Attitude Control System

    Science.gov (United States)

    Adams, Michael; Debra, Daniel

    2007-04-01

    The Gravity Probe B is first space vehicle provide active control of the vehicle's six degrees of freedom (DOF), three in translation and three in attitude. The Attitude and Translation Control (ATC) uses helium boil-off gas from the cryogenic system as a propellant for 16 proportional cold gas thrusters. Differential thruster operation provides forces and torques on the vehicle, common mode operation controls the net flow rate from the dewar that is used in turn to control the liquid helium bath temperature. The pointing system controls the pointing of the guide star tracking telescope to 30 marc-sec at the space vehicle roll period (77.5) and maintained roll phase to 40 arc-sec. The translation control system used acceleration measurements from one science gyroscope's suspension system to null out the effects of external forces from the on-orbit environment (solar wind, radiation pressure, etc). In this way, the vehicle was controlled to fly in a near-perfect gravitational orbit; transverse accelerations on the science gyroscopes were reduced to the 5x10-12 g level. The precise pointing and orbital geometry are essential for minimizing disturbances to the science gyroscopes, and the dewar control is important in maximizing the length of the data collection period..

  7. Reusable Reentry Satellite (RRS) system design study. Phase B, appendix E: Attitude control system study

    Science.gov (United States)

    1991-01-01

    A study which consisted of a series of design analyses for an Attitude Control System (ACS) to be incorporated into the Re-usable Re-entry Satellite (RRS) was performed. The main thrust of the study was associated with defining the control laws and estimating the mass and power requirements of the ACS needed to meet the specified performance goals. The analyses concentrated on the different on-orbit control modes which start immediately after the separation of the RRS from the launch vehicle. The three distinct on-orbit modes considered for these analyses are as follows: (1) Mode 1 - A Gravity Gradient (GG) three-axis stabilized spacecraft with active magnetic control; (2) Mode 2 - A GG stabilized mode with a controlled yaw rotation rate ('rotisserie') using three-axis magnetic control and also incorporating a 10 N-m-s momentum wheel along the (Z) yaw axis; and (3) Mode 3 - A spin stabilized mode of operation with the spin about the pitch (Y) axis, incorporating a 20 N-m-s momentum wheel along the pitch (Y) axis and attitude control via thrusters. To investigate the capabilities of the different controllers in these various operational modes, a series of computer simulations and trade-off analyses have been made to evaluate the achievable performance levels, and the necessary mass and power requirements.

  8. A simple attitude control of quadrotor helicopter based on Ziegler-Nichols rules for tuning PD parameters.

    Science.gov (United States)

    He, ZeFang; Zhao, Long

    2014-01-01

    An attitude control strategy based on Ziegler-Nichols rules for tuning PD (proportional-derivative) parameters of quadrotor helicopters is presented to solve the problem that quadrotor tends to be instable. This problem is caused by the narrow definition domain of attitude angles of quadrotor helicopters. The proposed controller is nonlinear and consists of a linear part and a nonlinear part. The linear part is a PD controller with PD parameters tuned by Ziegler-Nichols rules and acts on the quadrotor decoupled linear system after feedback linearization; the nonlinear part is a feedback linearization item which converts a nonlinear system into a linear system. It can be seen from the simulation results that the attitude controller proposed in this paper is highly robust, and its control effect is better than the other two nonlinear controllers. The nonlinear parts of the other two nonlinear controllers are the same as the attitude controller proposed in this paper. The linear part involves a PID (proportional-integral-derivative) controller with the PID controller parameters tuned by Ziegler-Nichols rules and a PD controller with the PD controller parameters tuned by GA (genetic algorithms). Moreover, this attitude controller is simple and easy to implement.

  9. Nonlinear control of marine vehicles using only position and attitude measurements

    Energy Technology Data Exchange (ETDEWEB)

    Paulsen, Marit Johanne

    1996-12-31

    This thesis presents new results on the design and analysis of nonlinear output feedback controllers for auto pilots and dynamic positioning systems for ships and underwater vehicles. Only position and attitude measurements of the vehicle are used in the control design. The underlying idea of the work is to use certain structural properties of the equations of motion in the controller design and analysis. New controllers for regulation and tracking have been developed and the stability of the resulting closed-loop systems has been rigorously established. The results are supported by simulations. The following problems have been investigated covering design of passive controller for regulation, comparison of two auto pilots, nonlinear damping compensation for tracking, tracking control for nonlinear ships, and output tracking control with wave filtering for multivariable models of possibly unstable vehicles. 97 refs., 32 figs.

  10. Sliding Mode Implementation of an Attitude Command Flight Control System for a Helicopter in Hover

    Directory of Open Access Journals (Sweden)

    D. J. McGeoch

    2005-01-01

    Full Text Available This paper presents an investigation into the design of a flight control system, using a decoupled non-linear sliding mode control structure, designed using a linearised, 9th order representation of the dynamics of a PUMA helicopter in hover. The controllers are then tested upon a higher order, non-linear helicopter model, called RASCAL. This design approach is used for attitude command flight control implementation and the control performance is assessed in the terms of handling qualities through the Aeronautical Design Standards for Rotorcraft (ADS-33. In this context a linearised approximation of the helicopter system is used to design an SMC control scheme. These controllers have been found to yield a system that satisfies the Level 1 handling qualities set out by ADS-33. 

  11. Hardware-in-Loop-Simulator for InnoSAT Attitude Control System

    Directory of Open Access Journals (Sweden)

    S. M. Sharun

    2016-10-01

    Full Text Available After launching, the initial condition of satellite is unknown and tends to be in a tumbling state. At this moment, the satellite needs to reduce the tumbling rate so that the satellite can enter a stable and unruffled state. The satellite also must maintain a certain attitude while orbiting in order to allow precise pointing of the antenna toward the earth. In[D1]  this study, a hardware-in-loop-simulator was devised for the purpose of improving the design and verifying attitude control concepts for Innovative Satellite (InnoSAT system. A new software architecture and algorithm was developed based on the controller, InnoSAT plant, actuator and sensor. Firstly, the controller, actuator and sensor was modelled in the MATLAB program together with InnoSAT plant. The actuator and sensor were assumed to be ideal. However, some properties of the actuator and sensor were simulated in the software simulator. If the software simulation performed satisfactorily, the control algorithm will be embedded into Rabbit Micro Controller (RCM4100 using Dynamic C language. This is the part where the hardware simulation is developed which is creating hardware-in-loop-simulation technique for verification of InnoSAT Attitude Control System (ACS performance. [D2] The satellite simulator was tested using simulated data in order to observe the performances of the controller in real time simulation. The results show that the InnoSAT ACS simulator can produce as good result as a MATLAB simulation for the InnoSAT plants. From the results, it is adequate to verify that the developed protocol working satisfyingly and seems to be possible to be implemented on the actual flight.[D3]  [D1]1 sentence on problem statement would be better.. [D2]Need to rewrite…. [D3]Need to rewrite…..

  12. Thrust distribution for attitude control in a variable thrust propulsion system with four ACS nozzles

    Science.gov (United States)

    Lim, Yeerang; Lee, Wonsuk; Bang, Hyochoong; Lee, Hosung

    2017-04-01

    A thrust distribution approach is proposed in this paper for a variable thrust solid propulsion system with an attitude control system (ACS) that uses a reduced number of nozzles for a three-axis attitude maneuver. Although a conventional variable thrust solid propulsion system needs six ACS nozzles, this paper proposes a thrust system with four ACS nozzles to reduce the complexity and mass of the system. The performance of the new system was analyzed with numerical simulations, and the results show that the performance of the system with four ACS nozzles was similar to the original system while the mass of the whole system was simultaneously reduced. Moreover, a feasibility analysis was performed to determine whether a thrust system with three ACS nozzles is possible.

  13. Dynamic modeling and optimal control of spacecraft with flexible structures undergoing general attitude maneuvers

    Science.gov (United States)

    Lin, Yiing-Yuh; Lin, Gern-Liang

    1992-08-01

    In this research, the dynamics and control of a rigid spacecraft with flexible structures were studied for the case of optimal simultaneous multiaxis reorientation. A model spacecraft consisting of a rigid hub in the middle and two solid bodies symmetrically connected to either side of the hub through uniformly distributed flexible beams is considered for the dynamic analysis and control simulation. To optimally reorienting the spacecraft, an optimal nominal control trajectory is found first through an iterative procedure. Linear flexural deformations are assumed for the beam structures and the assumed modes method is applied to find the vibration control law of the beams. The system overall optimal attitude control is achieved by following the open loop optimal reference control trajectory with an stabilizing guidance law.

  14. Attitudes toward Placebo-Controlled Clinical Trials of Patients with Schizophrenia in Japan.

    Directory of Open Access Journals (Sweden)

    Norio Sugawara

    Full Text Available Although the use of placebo in clinical trials of schizophrenia patients is controversial because of medical and ethical concerns, placebo-controlled clinical trials are commonly used in the licensing of new drugs.The objective of this study was to assess the attitudes toward placebo-controlled clinical trials among patients with schizophrenia in Japan.Using a cross-sectional design, we recruited patients (n = 251 aged 47.7±13.2 (mean±SD with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder who were admitted to six psychiatric hospitals from December 2013 to March 2014. We employed a 14-item questionnaire specifically developed to survey patients' attitudes toward placebo-controlled clinical trials.The results indicated that 33% of the patients would be willing to participate in a placebo-controlled clinical trial. Expectations for improvement of disease, a guarantee of hospital treatment continuation, and encouragement by family or friends were associated with the willingness to participate in such trials, whereas a belief of additional time required for medical examinations was associated with non-participation.Fewer than half of the respondents stated that they would be willing to participate in placebo-controlled clinical trials. Therefore, interpreting the results from placebo-controlled clinical trials could be negatively affected by selection bias.

  15. Enceladus Plume Density Modeling and Reconstruction for Cassini Attitude Control System

    Science.gov (United States)

    Sarani, Siamak

    2010-01-01

    In 2005, Cassini detected jets composed mostly of water, spouting from a set of nearly parallel rifts in the crust of Enceladus, an icy moon of Saturn. During an Enceladus flyby, either reaction wheels or attitude control thrusters on the Cassini spacecraft are used to overcome the external torque imparted on Cassini due to Enceladus plume or jets, as well as to slew the spacecraft in order to meet the pointing needs of the on-board science instruments. If the estimated imparted torque is larger than it can be controlled by the reaction wheel control system, thrusters are used to control the spacecraft. Having an engineering model that can predict and simulate the external torque imparted on Cassini spacecraft due to the plume density during all projected low-altitude Enceladus flybys is important. Equally important is being able to reconstruct the plume density after each flyby in order to calibrate the model. This paper describes an engineering model of the Enceladus plume density, as a function of the flyby altitude, developed for the Cassini Attitude and Articulation Control Subsystem, and novel methodologies that use guidance, navigation, and control data to estimate the external torque imparted on the spacecraft due to the Enceladus plume and jets. The plume density is determined accordingly. The methodologies described have already been used to reconstruct the plume density for three low-altitude Enceladus flybys of Cassini in 2008 and will continue to be used on all remaining low-altitude Enceladus flybys in Cassini's extended missions.

  16. Attitude stabilization of flexible spacecrafts via extended disturbance observer based controller

    Science.gov (United States)

    Yan, Ruidong; Wu, Zhong

    2017-04-01

    To achieve the high-precision attitude stabilization for the flexible spacecraft in the presence of space environmental disturbances, unmodeled dynamics, and the disturbances caused by the elastic vibration of flexible appendages, an extended disturbance observer (EDO) based controller is proposed. The proposed controller is formulated by combining EDO and a backstepping feedback controller. EDO is used to estimate the disturbance, which is modeled as an unknown high-order differentiable equation and the rth-order derivative of the disturbance is assumed to be bounded. Compared to the conventional first-order disturbance observer, the higher order EDO offers improvement in estimate accuracy, if the absolute values of poles for EDO transfer function are chosen larger than the frequency content of the disturbance. Then, the output of EDO plus the backstepping feedback controller are applied to stabilize the attitude with high precision by rejecting disturbances for the flexible spacecraft. Finally, numerical simulations have been conducted to verify the effectiveness of the proposed controller.

  17. Motion coordination for VTOL unmanned aerial vehicles attitude synchronisation and formation control

    CERN Document Server

    Abdessameud, Abdelkader

    2013-01-01

    Motion Coordination for VTOL Unmanned Aerial Vehicles develops new control design techniques for the distributed coordination of a team of autonomous unmanned aerial vehicles. In particular, it provides new control design approaches for the attitude synchronization of a formation of rigid body systems. In addition, by integrating new control design techniques with some concepts from nonlinear control theory and multi-agent systems, it presents  a new theoretical framework for the formation control of a class of under-actuated aerial vehicles capable of vertical take-off and landing. Several practical problems related to the systems’ inputs, states measurements, and  restrictions on the interconnection  topology  between the aerial vehicles in the team  are addressed. Worked examples with sufficient details and simulation results are provided to illustrate the applicability and effectiveness of the theoretical results discussed in the book. The material presented is primarily intended for researchers an...

  18. Composite control method for stabilizing spacecraft attitude in terms of Rodrigues parameters

    Institute of Scientific and Technical Information of China (English)

    Sun Haibin; Li Shihua

    2013-01-01

    In this paper,the attitude stabilization problem of a rigid spacecraft described by Rodrigues parameters is investigated via a composite control strategy,which combines a feedback control law designed by a finite time control technique with a feedforward compensator based on a linear disturbance observer (DOB) method.By choosing a suitable coordinate transformation,the spacecraft dynamics can be divided into three second-order subsystems.Each subsystem includes a certain part and an uncertain part.By using the finite time control technique,a continuous finite time controller is designed for the certain part.The uncertain part is considered to be a lumped disturbance,which is estimated by a DOB,and a corresponding feedforward design is then implemented to compensate the disturbance.Simulation results are employed to confirm the effectiveness of the proposed approach.

  19. Knowledge, Attitudes, and Practice of Infection Control among Dental Students at Sana’a University, Yemen

    Science.gov (United States)

    Halboub, Esam Saleh; Al-Maweri, Sadeq Ali; Al-Jamaei, Aisha Ahmed; Tarakji, Bassel; Al-Soneidar, Walid Ahmed

    2015-01-01

    Background: The aim of this study was to evaluate knowledge, attitudes, and practices regarding infection control procedures among senior dental students. Materials and Methods: A questionnaire-based cross-sectional survey was conducted among 145 4th- and 5th-year dental students at the Faculty of Dentistry, Sana’a University, Yemen. The self-administered questionnaire was comprised of 20 open- and close-ended items regarding barrier techniques, vaccination status, infection control practices, and awareness. Data were analyzed with a Chi-square test. A P ≤ 0.05 was considered significant. Results: The response rate was 72% (145 out of 204 potential respondents). Overall, 71.7% of the students had been vaccinated for hepatitis B and only 9.5% were tested for post-hepatitis B virus immunization serology. While the vast majority (96.6%) reported always wearing gloves for all dental procedures, the use of face masks and eyewear were reported by only 53.8% and 14.0% of students, respectively, with no significant difference between genders and year of study (P > 0.05). A significantly higher percentage of 5th-year students (58.9%) showed positive attitudes toward the treatment of patients with infectious diseases, as compared to only 31.0% of 4th year students (P < 0.01). A great number of students (62%) reported non-sterile occupational percutaneous and mucous injuries while treating their patients. Conclusions: These unsatisfactory findings highlight the necessity of continued infection control education in order to improve knowledge, attitudes, and practices regarding infection control among dental students at Sana’a University. PMID:26028896

  20. Evaluation and modeling of autonomous attitude thrust control for the Geostation Operational Environmental Satellite (GOES)-8 orbit determination

    Science.gov (United States)

    Forcey, W.; Minnie, C. R.; Defazio, R. L.

    1995-01-01

    The Geostationary Operational Environmental Satellite (GOES)-8 experienced a series of orbital perturbations from autonomous attitude control thrusting before perigee raising maneuvers. These perturbations influenced differential correction orbital state solutions determined by the Goddard Space Flight Center (GSFC) Goddard Trajectory Determination System (GTDS). The maneuvers induced significant variations in the converged state vector for solutions using increasingly longer tracking data spans. These solutions were used for planning perigee maneuvers as well as initial estimates for orbit solutions used to evaluate the effectiveness of the perigee raising maneuvers. This paper discusses models for the incorporation of attitude thrust effects into the orbit determination process. Results from definitive attitude solutions are modeled as impulsive thrusts in orbit determination solutions created for GOES-8 mission support. Due to the attitude orientation of GOES-8, analysis results are presented that attempt to absorb the effects of attitude thrusting by including a solution for the coefficient of reflectivity, C(R). Models to represent the attitude maneuvers are tested against orbit determination solutions generated during real-time support of the GOES-8 mission. The modeling techniques discussed in this investigation offer benefits to the remaining missions in the GOES NEXT series. Similar missions with large autonomous attitude control thrusting, such as the Solar and Heliospheric Observatory (SOHO) spacecraft and the INTELSAT series, may also benefit from these results.

  1. Cassini Attitude Control Fault Protection Design: Launch to End of Prime Mission Performance

    Science.gov (United States)

    Meakin, Peter C.

    2008-01-01

    The Cassini Attitude and Articulation Control Subsystem (AACS) Fault Protection (FP) has been successfully supporting operations for over 10 years from launch through the end of the prime mission. Cassini's AACS FP is complex, containing hundreds of error monitors and thousands of tunable parameters. Since launch there have been environmental, hardware, personnel and mission event driven changes which have required AACS FP to adapt and be robust to a variety of scenarios. This paper will discuss the process of monitoring, maintaining and updating the AACS FP during Cassini's lengthy prime mission as well as provide some insight into lessons learned during tour operations.

  2. Research on Instantaneous Thrust Measurement for Attitude-control Solid Rocket Motor

    Institute of Scientific and Technical Information of China (English)

    OUYANG Hua-bing; WANG Jian-ping; LIN Feng; XU Wen-gan

    2008-01-01

    In order to measure the instantaneous thrust of a certain attitude-control solid rocket motor, based on the analysis of the measurement principles, the difference between the instantaneous thrust and steady thrust measurements is pointed out. According to the measurement characteristics, a dynamic digital filter compensation method is presented. Combined the identification-modeling, dynamic compensation and simulation, the system's dynamic mathematic model is established. And then, a compensation digital filter is also designed. Thus, the dynamic response of the system is improved and the instantaneous thrust measurement can be implemented. The measurement results for the rocket motor show that the digital filter compensation is effective in the instantaneous thrust measurement.

  3. Farmer attitudes to vaccination and culling of badgers in controlling bovine tuberculosis.

    Science.gov (United States)

    Warren, M; Lobley, M; Winter, M

    2013-07-13

    Controversy persists in England, Wales and Northern Ireland concerning methods of controlling the transmission of bovine tuberculosis (bTB) between badgers and cattle. The National Trust, a major land-owning heritage organisation, in 2011, began a programme of vaccinating badgers against bTB on its Killerton Estate in Devon. Most of the estate is farmed by 18 tenant farmers, who thus have a strong interest in the Trust's approach, particularly as all have felt the effects of the disease. This article reports on a study of the attitudes to vaccination of badgers and to the alternative of a culling programme, using face-to-face interviews with 14 of the tenants. The results indicated first that the views of the respondents were more nuanced than the contemporary public debate about badger control would suggest. Secondly, the attitude of the interviewees to vaccination of badgers against bTB was generally one of resigned acceptance. Thirdly, most respondents would prefer a combination of an effective vaccination programme with an effective culling programme, the latter reducing population of density sufficiently (and preferably targeting the badgers most likely to be diseased) for vaccination to have a reasonable chance of success. While based on a small sample, these results will contribute to the vigorous debate concerning contrasting policy approaches to bTB control in England, Wales and Northern Ireland.

  4. Eating on impulse: Implicit attitudes, self-regulatory resources, and trait self-control as determinants of food consumption.

    Science.gov (United States)

    Wang, Yan; Wang, Lei; Cui, Xianghua; Fang, Yuan; Chen, Qianqiu; Wang, Ya; Qiang, Yao

    2015-12-01

    Self-regulatory resources and trait self-control have been found to moderate the impulse-behavior relationship. The current study investigated whether the interaction of self-regulatory resources and trait self-control moderates the association between implicit attitudes and food consumption. One hundred twenty female participants were randomly assigned to either a depletion condition in which their self-regulatory resources were reduced or a no-depletion condition. Participants' implicit attitudes for chocolate were measured with the Single Category Implicit Association Test and self-report measures of trait self-control were collected. The dependent variable was chocolate consumption in an ostensible taste and rate task. Implicit attitudes predicted chocolate consumption in depleted participants but not in non-depleted participants. However, this predictive power of implicit attitudes on eating in depleted condition disappeared in participants with high trait self-control. Thus, trait self-control and self-regulatory resources interact to moderate the prediction of implicit attitude on eating behavior. Results suggest that high trait self-control buffers the effect of self-regulatory depletion on impulsive eating.

  5. Attitude control and sloshing suppression for liquid-filled spacecraft in the presence of sinusoidal disturbance

    Science.gov (United States)

    Zhang, Honghua; Wang, Zeguo

    2016-11-01

    The attitude regulation for a liquid-filled spacecraft in the presence of low frequency sinusoidal disturbance is considered in this paper. The liquid-filled spacecraft is modelled as a rigid body attached with a simple pendulum. A novel control scheme is proposed, which is composed of Active Disturbance Rejection Control (ADRC), Positive Position Feedback (PPF), Extended State Observer (ESO) and Singular Spectrum Analysis (SSA). The unknown sloshing mode could be estimated from the combined ESO and SSA, and accordingly ADRC and PPF controller is designed for the stabilization of the spacecraft. Particularly, the parameters of the disturbance are not required as long as its frequency is lower than the sloshing one. The proposed approach could provide stabilization for the spacecraft, rejection for the disturbance, and active damping for the sloshing. Its effectiveness is validated by numerical simulations.

  6. Control of nonlinear systems with applications to constrained robots and spacecraft attitude stabilization

    Science.gov (United States)

    Krishnan, Hariharan

    1993-01-01

    This thesis is organized in two parts. In Part 1, control systems described by a class of nonlinear differential and algebraic equations are introduced. A procedure for local stabilization based on a local state realization is developed. An alternative approach to local stabilization is developed based on a classical linearization of the nonlinear differential-algebraic equations. A theoretical framework is established for solving a tracking problem associated with the differential-algebraic system. First, a simple procedure is developed for the design of a feedback control law which ensures, at least locally, that the tracking error in the closed loop system lies within any given bound if the reference inputs are sufficiently slowly varying. Next, by imposing additional assumptions, a procedure is developed for the design of a feedback control law which ensures that the tracking error in the closed loop system approaches zero exponentially for reference inputs which are not necessarily slowly varying. The control design methodologies are used for simultaneous force and position control in constrained robot systems. The differential-algebraic equations are shown to characterize the slow dynamics of a certain nonlinear control system in nonstandard singularly perturbed form. In Part 2, the attitude stabilization (reorientation) of a rigid spacecraft using only two control torques is considered. First, the case of momentum wheel actuators is considered. The complete spacecraft dynamics are not controllable. However, the spacecraft dynamics are small time locally controllable in a reduced sense. The reduced spacecraft dynamics cannot be asymptotically stabilized using continuous feedback, but a discontinuous feedback control strategy is constructed. Next, the case of gas jet actuators is considered. If the uncontrolled principal axis is not an axis of symmetry, the complete spacecraft dynamics are small time locally controllable. However, the spacecraft attitude

  7. Racism, gun ownership and gun control: biased attitudes in US whites may influence policy decisions.

    Directory of Open Access Journals (Sweden)

    Kerry O'Brien

    Full Text Available OBJECTIVE: Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty. This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. METHOD: The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. RESULTS: After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58 was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46, which likely represents self-interest in retaining property (guns. CONCLUSIONS: Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites' paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions.

  8. Venusian atmospheric and Magellan properties from attitude control data. M.S. Thesis

    Science.gov (United States)

    Croom, Christopher A.; Tolson, Robert H.

    1994-01-01

    Results are presented of the study of the Venusian atmosphere, Magellan aerodynamic moment coefficients, moments of inertia, and solar moment coefficients. This investigation is based upon the use of attitude control data in the form of reaction wheel speeds from the Magellan spacecraft. As the spacecraft enters the upper atmosphere of Venus, measurable torques are experienced due to aerodynamic effects. Solar and gravity gradient effects also cause additional torques throughout the orbit. In order to maintain an inertially fixed attitude, the control system counteracts these torques by changing the angular rates of three reaction wheels. Model reaction wheel speeds are compared to observed Magellan reaction wheel speeds through a differential correction procedure. This method determines aerodynamic, atmospheric, solar pressure, and mass moment of inertia parameters. Atmospheric measurements include both base densities and scale heights. Atmospheric base density results confirm natural variability as measured by the standard orbital decay method. Potential inconsistencies in free molecular aerodynamic moment coefficients are identified. Moments of inertia are determined with a precision better than 1 percent of the largest principal moment of inertia.

  9. Estimation of Gravitation Parameters of Saturnian Moons Using Cassini Attitude Control Flight Data

    Science.gov (United States)

    Krening, Samantha C.

    2013-01-01

    A major science objective of the Cassini mission is to study Saturnian satellites. The gravitational properties of each Saturnian moon is of interest not only to scientists but also to attitude control engineers. When the Cassini spacecraft flies close to a moon, a gravity gradient torque is exerted on the spacecraft due to the mass of the moon. The gravity gradient torque will alter the spin rates of the reaction wheels (RWA). The change of each reaction wheel's spin rate might lead to overspeed issues or operating the wheel bearings in an undesirable boundary lubrication condition. Hence, it is imperative to understand how the gravity gradient torque caused by a moon will affect the reaction wheels in order to protect the health of the hardware. The attitude control telemetry from low-altitude flybys of Saturn's moons can be used to estimate the gravitational parameter of the moon or the distance between the centers of mass of Cassini and the moon. Flight data from several low altitude flybys of three Saturnian moons, Dione, Rhea, and Enceladus, were used to estimate the gravitational parameters of these moons. Results are compared with values given in the literature.

  10. Simultaneous state and actuator fault estimation for satellite attitude control systems

    Institute of Scientific and Technical Information of China (English)

    Cheng Yao; Wang Rixin; Xu Minqiang; Li Yuqing

    2016-01-01

    In this paper, a new nonlinear augmented observer is proposed and applied to satellite attitude control systems. The observer can estimate system state and actuator fault simultaneously. It can enhance the performances of rapidly-varying faults estimation. Only original system matrices are adopted in the parameter design. The considered faults can be unbounded, and the proposed augmented observer can estimate a large class of faults. Systems without disturbances and the fault whose finite times derivatives are zero piecewise are initially considered, followed by a discussion of a general situation where the system is subject to disturbances and the finite times derivatives of the faults are not null but bounded. For the considered nonlinear system, convergence conditions of the observer are provided and the stability analysis is performed using Lyapunov direct method. Then a feasible algorithm is explored to compute the observer parameters using linear matrix inequalities (LMIs). Finally, the effectiveness of the proposed approach is illustrated by considering an example of a closed-loop satellite attitude control system. The simulation results show satisfactory perfor-mance in estimating states and actuator faults. It also shows that multiple faults can be estimated successfully.

  11. Design, dynamics and control of an Adaptive Singularity-Free Control Moment Gyroscope actuator for microspacecraft Attitude Determination and Control System

    Science.gov (United States)

    Viswanathan, Sasi Prabhakaran

    Design, dynamics, control and implementation of a novel spacecraft attitude control actuator called the "Adaptive Singularity-free Control Moment Gyroscope" (ASCMG) is presented in this dissertation. In order to construct a comprehensive attitude dynamics model of a spacecraft with internal actuators, the dynamics of a spacecraft with an ASCMG, is obtained in the framework of geometric mechanics using the principles of variational mechanics. The resulting dynamics is general and complete model, as it relaxes the simplifying assumptions made in prior literature on Control Moment Gyroscopes (CMGs) and it also addresses the adaptive parameters in the dynamics formulation. The simplifying assumptions include perfect axisymmetry of the rotor and gimbal structures, perfect alignment of the centers of mass of the gimbal and the rotor etc. These set of simplifying assumptions imposed on the design and dynamics of CMGs leads to adverse effects on their performance and results in high manufacturing cost. The dynamics so obtained shows the complex nonlinear coupling between the internal degrees of freedom associated with an ASCMG and the spacecraft bus's attitude motion. By default, the general ASCMG cluster can function as a Variable Speed Control Moment Gyroscope, and reduced to function in CMG mode by spinning the rotor at constant speed, and it is shown that even when operated in CMG mode, the cluster can be free from kinematic singularities. This dynamics model is then extended to include the effects of multiple ASCMGs placed in the spacecraft bus, and sufficient conditions for non-singular ASCMG cluster configurations are obtained to operate the cluster both in VSCMG and CMG modes. The general dynamics model of the ASCMG is then reduced to that of conventional VSCMGs and CMGs by imposing the standard set of simplifying assumptions used in prior literature. The adverse effects of the simplifying assumptions that lead to the complexities in conventional CMG design, and

  12. Three-axis attitude control by two-step rotations using only magnetic torquers in a low Earth orbit near the magnetic equator

    Science.gov (United States)

    Inamori, Takaya; Otsuki, Kensuke; Sugawara, Yoshiki; Saisutjarit, Phongsatorn; Nakasuka, Shinichi

    2016-11-01

    This study proposes a novel method for three-axis attitude control using only magnetic torquers (MTQs). Previously, MTQs have been utilized for attitude control in many low Earth orbit satellites. Although MTQs are useful for achieving attitude control at low cost and high reliability without the need for propellant, these electromagnetic coils cannot be used to generate an attitude control torque about the geomagnetic field vector. Thus, conventional attitude control methods using MTQs assume the magnetic field changes in an orbital period so that the satellite can generate a required attitude control torque after waiting for a change in the magnetic field direction. However, in a near magnetic equatorial orbit, the magnetic field does not change in an inertial reference frame. Thus, satellites cannot generate a required attitude control torque in a single orbital period with only MTQs. This study proposes a method for achieving a rotation about the geomagnetic field vector by generating a torque that is perpendicular to it. First, this study shows that the three-axis attitude control using only MTQs is feasible with a two-step rotation. Then, the study proposes a method for controlling the attitude with the two-step rotation using a PD controller. Finally, the proposed method is assessed by examining the results of numerical simulations.

  13. A survey of cross-infection control procedures: knowledge and attitudes of Turkish dentists

    Directory of Open Access Journals (Sweden)

    Emir Yüzbasioglu

    2009-12-01

    Full Text Available OBJECTIVES: The objective of this study was to investigate the knowledge, attitudes and behavior of Turkish dentists in Samsun City regarding cross-infection control. MATERIAL AND METHODS: A questionnaire was designed to obtain information about procedures used for the prevention of cross-infection in dental practices and determine the attitudes and perceptions of respondent dental practitioners to their procedures. The study population included all dentists in the city of Samsun, Turkey, in April 2005 (n=184. The questionnaire collected data on sociodemographic characteristics, knowledge and practice of infection control procedures, sterilization, wearing of gloves, mask, use of rubber dam, method of storing instruments and disposal methods of contaminated material, etc. Questionnaire data was entered into a computer and analyzed by SPSS statistical software. RESULTS: From the 184 dentists to whom the questionnaires were submitted, 135 participated in the study (overall response rate of 73.36%. As much as 74.10% dentists expressed concern about the risk of cross-infection from patients to themselves and their dental assistants. Forty-three percent of the participants were able to define "cross-infection" correctly. The greatest majority of the respondents (95.60% stated that all patients have to be considered as infectious and universal precautions must apply to all of them. The overall responses to the questionnaire showed that the dentists had moderate knowledge of infection control procedures. CONCLUSIONS: Improved compliance with recommended infection control procedures is required for all dentists evaluated in the present survey. Continuing education programs and short-time courses about cross-infection and infection control procedures are suitable to improve the knowledge of dentists.

  14. Application of the concept of dynamic trim control and nonlinear system inverses to automatic control of a vertical attitude takeoff and landing aircraft

    Science.gov (United States)

    Smith, G. A.; Meyer, G.

    1981-01-01

    A full envelope automatic flight control system based on nonlinear inverse systems concepts has been applied to a vertical attitude takeoff and landing (VATOL) fighter aircraft. A new method for using an airborne digital aircraft model to perform the inversion of a nonlinear aircraft model is presented together with the results of a simulation study of the nonlinear inverse system concept for the vertical-attitude hover mode. The system response to maneuver commands in the vertical attitude was found to be excellent; and recovery from large initial offsets and large disturbances was found to be very satisfactory.

  15. Testing of the on-board attitude determination and control algorithms for SAMPEX

    Science.gov (United States)

    McCullough, Jon D.; Flatley, Thomas W.; Henretty, Debra A.; Markley, F. Landis; San, Josephine K.

    1993-02-01

    Algorithms for on-board attitude determination and control of the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) have been expanded to include a constant gain Kalman filter for the spacecraft angular momentum, pulse width modulation for the reaction wheel command, an algorithm to avoid pointing the Heavy Ion Large Telescope (HILT) instrument boresight along the spacecraft velocity vector, and the addition of digital sun sensor (DSS) failure detection logic. These improved algorithms were tested in a closed-loop environment for three orbit geometries, one with the sun perpendicular to the orbit plane, and two with the sun near the orbit plane - at Autumnal Equinox and at Winter Solstice. The closed-loop simulator was enhanced and used as a truth model for the control systems' performance evaluation and sensor/actuator contingency analysis. The simulations were performed on a VAX 8830 using a prototype version of the on-board software.

  16. Cassini Spacecraft In-Flight Swap to Backup Attitude Control Thrusters

    Science.gov (United States)

    Bates, David M.

    2010-01-01

    NASA's Cassini Spacecraft, launched on October 15th, 1997 and arrived at Saturn on June 30th, 2004, is the largest and most ambitious interplanetary spacecraft in history. In order to meet the challenging attitude control and navigation requirements of the orbit profile at Saturn, Cassini is equipped with a monopropellant thruster based Reaction Control System (RCS), a bipropellant Main Engine Assembly (MEA) and a Reaction Wheel Assembly (RWA). In 2008, after 11 years of reliable service, several RCS thrusters began to show signs of end of life degradation, which led the operations team to successfully perform the swap to the backup RCS system, the details and challenges of which are described in this paper. With some modifications, it is hoped that similar techniques and design strategies could be used to benefit other spacecraft.

  17. Optimality of incompletely measurable active and passive attitude control systems. [for satellites

    Science.gov (United States)

    Schiehlen, W.; Popp, K.

    1973-01-01

    Passive attitude control systems and active systems with incomplete state measurements are only suboptimal systems in the sense of optimal control theory, since optimal systems require complete state measurements or state estimations. An optimal system, then, requires additional hardware (especially in the case of flexible spacecraft) which results in higher costs. Therefore, it is a real engineering problem to determine how much an optimal system exceeds the suboptimal system, or in other words, what is the suboptimal system's degree of optimality. The problem will be treated in three steps: (1) definition of the degree of optimality for linear, time-invariant systems; (2) a computation method using the quadratic cost functional; (3) application to a gravity-gradient stabilized three-body satellite and a spinning flexible satellite.

  18. Linear Time Varying Approach to Satellite Attitude Control Using only Electromagnetic Actuation

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    1997-01-01

    and the magnetic field generated by the coils. A key challenge is the fact that the mechanical torque can only be produced in a plane perpendicular to the local geomagnetic field vector, therefore the satellite is not controllable when considered at fixed time. Availability of design methods for time varying......Recently small satellite missions have gained considerable interest due to low-cost launch opportunities and technological improvement of micro-electronics. Required pointing accuracy of small, inexpensive satellites is often relatively loose, within a couple of degrees. Application of cheap......, lightweight, and power efficient actuators is therefore crucial and viable. This paper discusses linear attitude control strategies for a low earth orbit satellite actuated by a set of mutually perpendicular electromagnetic coils. The principle is to use the interaction between the Earth's magnetic field...

  19. Linear Time Varying Approach to Satellite Attitude Control Using only Electromagnetic Actuation

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    and the magnetic field generated by the coils. A key challenge is the fact that the mechanical torque can only be produced in a plane perpendicular to the local geomagnetic field vector, therefore the satellite is not controllable at fixed time. Avaliability of design methods for time varying systems is limited......Recently small satellite missions have gained considerable interest due to low-cost launch opportunities and technological improvemant of micro-electronics. Required pointing accuracy of small, inexpensive satellites is often relatively loose, within a couple of degrees. Application of cheap......, lightweight, and power efficient actuators is therefore crucial and viable. This paper discusser linear attitude control strategies for a low earth orbit satellite actuated by a set of mutually perpendicular electromagnetic coils. The principle is to use the interaction between the Earth's magnetic field...

  20. Attitudes and behavioral response toward key tobacco control measures from the FCTC among Chinese urban residents

    Directory of Open Access Journals (Sweden)

    Li Fuzhong

    2007-09-01

    Full Text Available Abstract Background The Chinese National People's Congress ratified the WHO Framework Convention on Tobacco Control (FCTC on 27 August 2005, signaling China's commitment to implement tobacco control policies and legislation consistent with the treaty. This study was designed to examine attitudes towards four WHO FCTC measures among Chinese urban residents. Methods In a cross-sectional design study, survey data were collected from two Chinese urban cities involving a sample of 3,003 residents aged 15 years or older. Through a face-to-face interview, respondents were asked about attitudes toward four tobacco control measures developed by the WHO FCTC. Data on the four dependent measures were analyzed using multivariate logistic regression analyses. Using descriptive statistics, potential change in smoking behavior that smokers might make in response to increasing cigarette prices is also reported. Results 81.8% of the respondents in the study sample supported banning smoking in public places, 68.8% favored increasing the cigarette tax, 85.1% supported health warnings on cigarette packages, and 85.7% favored banning tobacco advertising. The likelihood to support these measures was associated with gender, educational level, and personal income. Smokers were less likely to support these measures than non-smokers, with decreased support expressed by daily smokers compared to occasional smokers, and heavy smokers compared to light smokers. The proportion of switching to cheaper cigarette brands, decreasing smoking, and quitting smoking altogether with increased cigarette prices were 29.1%, 30.90% and 40.0% for occasional smokers, respectively; and 30.8%, 32.7% and 36.5% for daily smokers, respectively. Conclusion Results from this study indicate strong public support in key WHO FCTC measures and that increases in cigarette price may reduce tobacco consumption among Chinese urban residents. Findings from this study have implications with respect to

  1. Electrospray Thrusters for Attitude Control of a 1-U CubeSat

    Science.gov (United States)

    Timilsina, Navin

    With a rapid increase in the interest in use of nanosatellites in the past decade, finding a precise and low-power-consuming attitude control system for these satellites has been a real challenge. In this thesis, it is intended to design and test an electrospray thruster system that could perform the attitude control of a 1-unit CubeSat. Firstly, an experimental setup is built to calculate the conductivity of different liquids that could be used as propellants for the CubeSat. Secondly, a Time-Of-Flight experiment is performed to find out the thrust and specific impulse given by these liquids and hence selecting the optimum propellant. On the other hand, a colloidal thruster system for a 1-U CubeSat is designed in Solidworks and fabricated using Lathe and CNC Milling Machine. Afterwards, passive propellant feeding is tested in this thruster system. Finally, the electronic circuit and wireless control system necessary to remotely control the CubeSat is designed and the final testing is performed. Among the propellants studied, Ethyl ammonium nitrate (EAN) was selected as the best propellant for the CubeSat. Theoretical design and fabrication of the thruster system was performed successfully and so was the passive propellant feeding test. The satellite was assembled for the final experiment but unfortunately the microcontroller broke down during the first test and no promising results were found out. However, after proving that one thruster works with passive feeding, it could be said that the ACS testing would have worked if we had performed vacuum compatibility tests for other components beforehand.

  2. Integrated Power/Attitude Control System (IPACS) study. Volume 1: Feasibility studies. [application of flywheels for power storage and generation

    Science.gov (United States)

    Notti, J. E.; Cormack, A., III; Schmill, W. C.

    1974-01-01

    An Integrated Power/Attitude Control System (IPACS) concept consisting of an array of spinning flywheels, with or without gimbals, capable of performing the dual function of power storage and generation, as well as attitude control has been investigated. This system provides attitude control through momentum storage, and replaces the storage batteries onboard the spacecraft. The results of the investigation are presented in two volumes. The trade-off studies performed to establish the feasibility, cost effectiveness, required level of development, and boundaries of application of IPACS to a wide variety of spacecraft are discussed. The conceptual designs for a free-flying research application module (RAM), and for a tracking and data relay satellite (TDRS) are presented. Results from dynamic analyses and simulations of the IPACS conceptual designs are included.

  3. Knowledge, Attitude, Practice, and Status of Infection Control among Iranian Dentists and Dental Students: A Systematic Review

    Science.gov (United States)

    Moradi Khanghahi, Behnam; Jamali, Zahra; Pournaghi Azar, Fatemeh; Naghavi Behzad, Mohammad; Azami-Aghdash, Saber

    2013-01-01

    Background and aims Infection control is an important issue in dentistry, and the dentists are primarily responsible for observing the relevant procedures. Therefore, the present study evaluated knowledge, attitude, practice, and status of infection control among Iranian dentists through systematic review of published results. Materials and methods In this systematic review, the required data was collected searching for keywords including infection, infection control, behavior, performance, practice, attitude, knowledge, dent*, prevention, Iran* and their Persian equivalents in PubMed, Science Direct, Iranmedex, SID, Medlib, and Magiran databases with a time limit of 1985 to 2012. Out of 698 articles, 15 completely related articles were finally considered and the rest were excluded due to lake of relev-ance to the study goals. The required data were extracted and summarized in an Extraction Table and were analyzed ma-nually. Results Evaluating the results of studies indicated inappropriate knowledge, attitude, and practice regarding infection control among Iranian dentists and dental students. Using personal protection devices and observing measures required for infection control were not in accordance with global standards. Conclusion The knowledge, attitudes, and practice of infection control in Iranian dental settings were found to be inadequate. Therefore, dentists should be educated more on the subject and special programs should be in place to monitor the dental settings for observing infection control standards. PMID:23875081

  4. A Lyapunov-based three-axis attitude intelligent control approach for unmanned aerial vehicle

    Institute of Scientific and Technical Information of China (English)

    A.H. Mazinan

    2015-01-01

    A novel Lyapunov-based three-axis attitude intelligent control approach via allocation scheme is considered in the proposed research to deal with kinematics and dynamics regarding the unmanned aerial vehicle systems. There is a consensus among experts of this field that the new outcomes in the present complicated systems modeling and control are highly appreciated with respect to state-of-the-art. The control scheme presented here is organized in line with a new integration of the linear-nonlinear control approaches, as long as the angular velocities in the three axes of the system are accurately dealt with in the inner closed loop control. And the corresponding rotation angles are dealt with in the outer closed loop control. It should be noted that the linear control in the present outer loop is first designed through proportional based linear quadratic regulator (PD based LQR) approach under optimum coefficients, while the nonlinear control in the corresponding inner loop is then realized through Lyapunov-based approach in the presence of uncertainties and disturbances. In order to complete the inner closed loop control, there is a pulse-width pulse-frequency (PWPF) modulator to be able to handle on-off thrusters. Furthermore, the number of these on-off thrusters may be increased with respect to the investigated control efforts to provide the overall accurate performance of the system, where the control allocation scheme is realized in the proposed strategy. It may be shown that the dynamics and kinematics of the unmanned aerial vehicle systems have to be investigated through the quaternion matrix and its corresponding vector to avoid presenting singularity of the results. At the end, the investigated outcomes are presented in comparison with a number of potential benchmarks to verify the approach performance.

  5. Control of antenna-feed attitude and reflector vibrations in large spaceborne antennas by mechanical decoupling and movable dampers

    Science.gov (United States)

    Wang, P. K. C.; Hong, E. C.; Sarina, J. S.

    1983-07-01

    Simple, practical methods for damping reflector vibrations and designing antenna-feed attitude control systems in large deployable spaceborne antennas are proposed. The former involves a movable damper which is positioned so that the rate-of-change of total vibrational energy is minimized. The latter introduces a mechanical decoupler between the flexible boom and the antenna-feed, whereby the feed-attitude control system can be designed independent of boom dynamics. The validity of these approaches are substantiated by analytical studies, computer simulation, and experimental studies.

  6. Solar Sail Attitude Control System for the NASA Near Earth Asteroid Scout Mission

    Science.gov (United States)

    Orphee, Juan; Diedrich, Ben; Stiltner, Brandon; Becker, Chris; Heaton, Andrew

    2017-01-01

    An Attitude Control System (ACS) has been developed for the NASA Near Earth Asteroid (NEA) Scout mission. The NEA Scout spacecraft is a 6U cubesat with an eighty-six square meter solar sail for primary propulsion that will launch as a secondary payload on the Space Launch System (SLS) Exploration Mission 1 (EM-1) and rendezvous with a target asteroid after a two year journey, and will conduct science imagery. The spacecraft ACS consists of three major actuating subsystems: a Reaction Wheel (RW) control system, a Reaction Control System (RCS), and an Active Mass Translator (AMT) system. The reaction wheels allow fine pointing and higher rates with low mass actuators to meet the science, communication, and trajectory guidance requirements. The Momentum Management System (MMS) keeps the speed of the wheels within their operating margins using a combination of solar torque and the RCS. The AMT is used to adjust the sign and magnitude of the solar torque to manage pitch and yaw momentum. The RCS is used for initial de-tumble, performing a Trajectory Correction Maneuver (TCM), and performing momentum management about the roll axis. The NEA Scout ACS is able to meet all mission requirements including attitude hold, slews, pointing for optical navigation and pointing for science with margin and including flexible body effects. Here we discuss the challenges and solutions of meeting NEA Scout mission requirements for the ACS design, and present a novel implementation of managing the spacecraft Center of Mass (CM) to trim the solar sail disturbance torque. The ACS we have developed has an applicability to a range of potential missions and does so in a much smaller volume than is traditional for deep space missions beyond Earth.

  7. Roles of superconducting magnetic bearings and active magnetic bearings in attitude control and energy storage flywheel

    Science.gov (United States)

    Tang, Jiqiang; Fang, Jiancheng; Ge, Shuzhi Sam

    2012-12-01

    Compared with conventional energy storage flywheel, the rotor of attitude control and energy storage flywheel (ACESF) used in space not only has high speed, but also is required to have precise and stable direction. For the presented superconducting magnetic bearing (SMB) and active magnetic bearing (AMB) suspended ACESF, the rotor model including gyroscopic couples is established originally by taking the properties of SMB and AMB into account, the forces of SMB and AMB are simplified by linearization within their own neighbors of equilibrium points. For the high-speed rigid discal rotor with large inertia, the negative effect of gyroscopic effect of rotor is prominent, the radial translation and tilting movement of rotor suspended by only SMB, SMB with equivalent PMB, or SMB together with PD controlled AMB are researched individually. These analysis results proved originally that SMB together with AMB can make the rotor be stable and make the radial amplitude of the vibration of rotor be small while the translation of rotor suspended by only SMB or SMB and PM is not stable and the amplitude of this vibration is large. For the stability of the high-speed rotor in superconducting ACESF, the AMB can suppress the nutation and precession of rotor effectively by cross-feedback control based on the separated PD type control or by other modern control methods.

  8. Attitude Dynamics and Tracking Control of Spacecraft in the Presence of Gravity Oblateness Perturbations

    Directory of Open Access Journals (Sweden)

    Achim IONITA

    2016-03-01

    Full Text Available The orbital docking represents a problem of great importance in aerospace engineering. The paper aims to perform an analysis of docking maneuvers between a chaser vehicle and a target vehicle in permanent LEO (low earth orbit. The work begins with a study of the attitude dynamics modeling intended to define the strategy that facilitates the chaser movement toward a docking part of the target. An LQR (linear quadratic regulator approach presents an optimal control design that provides linearized closed-loop error dynamics for tracking a desired quaternion. The control law formulation is combined with the control architecture based on SDRE (State Dependent Riccati equation technique for rotational maneuvers, including the Earth oblateness perturbation. The chaser body-fixed frame must coincide with the target body-fixed frame at the docking moment. Then the implementation of the control architecture based on LQR technique using the computational tool MATLAB is carried out. In simulation of the docking strategy V-R bar operations are analyzed and the minimum accelerations needs the control of chaser vehicle. The simulation analysis of those maneuvers considered for a chaser vehicle and a target vehicle in LEO orbit is validated in a case study.

  9. Spacecraft attitude control systems with dynamic methods and structures for processing star tracker signals

    Science.gov (United States)

    Liu, Yong (Inventor); Wu, Yeong-Wei Andy (Inventor); Li, Rongsheng (Inventor)

    2001-01-01

    Methods are provided for dynamically processing successively-generated star tracker data frames and associated valid flags to generate processed star tracker signals that have reduced noise and a probability greater than a selected probability P.sub.slctd of being valid. These methods maintain accurate spacecraft attitude control in the presence of spurious inputs (e.g., impinging protons) that corrupt collected charges in spacecraft star trackers. The methods of the invention enhance the probability of generating valid star tracker signals because they respond to a current frame probability P.sub.frm by dynamically selecting the largest valid frame combination whose combination probability P.sub.cmb satisfies a selected probability P.sub.slctd. Noise is thus reduced while the probability of finding a valid frame combination is enhanced. Spacecraft structures are also provided for practicing the methods of the invention.

  10. The Effects of Step-by-Step Self-regulation on Controlling Study Behavior, Attitude to Study and Academic Achievement

    Directory of Open Access Journals (Sweden)

    Gholamreza Sharifiniya

    2014-01-01

    Full Text Available Using personal potential is one of the key elements in behavior modification and the purpose of this research was to study the effects of a new method in changing human attitude and behavior in school context. Following this goal, in current research the authors have tried to examine the role of Step-by-Step Self-Regulation on studying behavior control, attitude to study and students' academic achievement. The total sample size was 120 high school male students in Hamedan. The subjects were divided into two groups: experimental group and control group. Then step-by-step self-regulation method were taught and carried out for eight sessions over the experimental group. Researcher made questionnaires were used for gathering data on study behavior control and students’ attitude to study and for evaluating students’ academic achievement their scholastic scores were used. In testing research hypotheses, a multivariate three-way ANOVA and independent and paired t tests were used. Comparing experimental and control groups data show that applying step-by-step self-regulation improves the personal ability to control study behavior while it does not have any meaningful effect on attitudes to study and students' academic achievement.

  11. Knowledge, Attitude, Practice, and Status of Infection Control among Iranian Dentists and Dental Students: A Systematic Review

    OpenAIRE

    Moradi Khanghahi, Behnam; Jamali, Zahra; Pournaghi Azar, Fatemeh; Naghavi Behzad, Mohammad; Azami-Aghdash, Saber

    2013-01-01

    Background and aims Infection control is an important issue in dentistry, and the dentists are primarily responsible for observing the relevant procedures. Therefore, the present study evaluated knowledge, attitude, practice, and status of infection control among Iranian dentists through systematic review of published results. Materials and methods In this systematic review, the required data was collected searching for keywords including infection, infection control, behavior, performance, p...

  12. Docking Offset Between the Space Shuttle and the International Space Station and Resulting Impacts to the Transfer of Attitude Reference and Control

    Science.gov (United States)

    Helms, W. Jason; Pohlkamp, Kara M.

    2011-01-01

    The Space Shuttle does not dock at an exact 90 degrees to the International Space Station (ISS) x-body axis. This offset from 90 degrees, along with error sources within their respective attitude knowledge, causes the two vehicles to never completely agree on their attitude, even though they operate as a single, mated stack while docked. The docking offset can be measured in flight when both vehicles have good attitude reference and is a critical component in calculations to transfer attitude reference from one vehicle to another. This paper will describe how the docking offset and attitude reference errors between both vehicles are measured and how this information would be used to recover Shuttle attitude reference from ISS in the event of multiple failures. During STS-117, ISS on-board Guidance, Navigation and Control (GNC) computers began having problems and after several continuous restarts, the systems failed. The failure took the ability for ISS to maintain attitude knowledge. This paper will also demonstrate how with knowledge of the docking offset, the contingency procedure to recover Shuttle attitude reference from ISS was reversed in order to provide ISS an attitude reference from Shuttle. Finally, this paper will show how knowledge of the docking offset can be used to speed up attitude control handovers from Shuttle to ISS momentum management. By taking into account the docking offset, Shuttle can be commanded to hold a more precise attitude which better agrees with the ISS commanded attitude such that start up transients with the ISS momentum management controllers are reduced. By reducing start-up transients, attitude control can be transferred from Shuttle to ISS without the use of ISS thrusters saving precious on-board propellant, crew time and minimizing loads placed upon the mated stack.

  13. Adaptive Control of Space Robot System with an Attitude Controlled Base

    Science.gov (United States)

    1991-08-01

    linearly on these parameters, research on adaptive robot control can now take full consideration of the nonlinear, time-varying and coupled robot dynamics . As...Khatib, J.J. Craig, and T. Lozano-Perez. The robotics review. MIT Press, 1989. [8] P. Khosla and T. Kanade. Parameter identification of robot dynamics . In...and W. Li. Applied nonlinear control. New Jersey: Printice Hall, 1991. [13] M.W. Spong and M. Vidyasagar. Robot dynamics and control. John Wiley

  14. Adaptive Hierarchical Sliding Mode Control with Input Saturation for Attitude Regulation of Multi-satellite Tethered System

    Science.gov (United States)

    Ma, Zhiqiang; Sun, Guanghui

    2016-11-01

    This paper proposes a novel adaptive hierarchical sliding mode control for the attitude regulation of the multi-satellite inline tethered system, where the input saturation is taken into account. The governing equations for the attitude dynamics of the three-satellite inline tethered system are derived firstly by utilizing Lagrangian mechanics theory. Considering the fact that the attitude of the central satellite can be adjusted by using the simple exponential stabilization scheme, the decoupling of the central satellite and the terminal ones is presented, and in addition, the new adaptive sliding mode control law is applied to stabilize the attitude dynamics of the two terminal satellites based on the synchronization and partial contraction theory. In the adaptive hierarchical sliding mode control design, the input is modeled as saturated input due to the fact that the flywheel torque is bounded, and meanwhile, an adaptive update rate is introduced to eliminate the effect of the saturated input and the external perturbation. The proposed control scheme can be applied on the two-satellite system to achieve fixed-point rotation. Numerical results validate the effectiveness of the proposed method.

  15. Relations of Children's Effortful Control and Teacher-Child Relationship Quality to School Attitudes in a Low-Income Sample

    Science.gov (United States)

    Silva, Kassondra M.; Spinrad, Tracy L.; Eisenberg, Nancy; Sulik, Michael J.; Valiente, Carlos; Huerta, Snjezana; Edwards, Alison; Eggum, Natalie D.; Kupfer, Anne S.; Lonigan, Christopher J.; Phillips, Beth M.; Wilson, Shauna B.; Clancy-Menchetti, Jeanine; Landry, Susan H.; Swank, Paul R.; Assel, Michael A.; Taylor, Heather B.

    2011-01-01

    Research Findings: The purpose of this study was to examine the relations of children's effortful control and quality of relationships with teachers to school attitudes longitudinally in an ethnically diverse and economically disadvantaged sample. Data were collected as part of a larger intervention project during mid-fall, winter, and late spring…

  16. Computer program for post-flight evaluation of the control surface response for an attitude controlled missile

    Science.gov (United States)

    Knauber, R. N.

    1982-01-01

    A FORTRAN IV coded computer program is presented for post-flight analysis of a missile's control surface response. It includes preprocessing of digitized telemetry data for time lags, biases, non-linear calibration changes and filtering. Measurements include autopilot attitude rate and displacement gyro output and four control surface deflections. Simple first order lags are assumed for the pitch, yaw and roll axes of control. Each actuator is also assumed to be represented by a first order lag. Mixing of pitch, yaw and roll commands to four control surfaces is assumed. A pseudo-inverse technique is used to obtain the pitch, yaw and roll components from the four measured deflections. This program has been used for over 10 years on the NASA/SCOUT launch vehicle for post-flight analysis and was helpful in detecting incipient actuator stall due to excessive hinge moments. The program is currently set up for a CDC CYBER 175 computer system. It requires 34K words of memory and contains 675 cards. A sample problem presented herein including the optional plotting requires eleven (11) seconds of central processor time.

  17. Knowledge and attitude towards the health effects of tobacco and measures of tobacco control

    Directory of Open Access Journals (Sweden)

    Shrestha Mohan

    2014-10-01

    Full Text Available Background: Tobacco is a major public health threat the world has ever faced. It is a risk factor for six of the eight leading causes of death in the world. Without the effective implementation of tobacco regulation policy, the risk itself cannot be minimized. The aim of this study is to provide the adolescents knowledge of the health effects of active and passive smoking, and knowledge and attitudes towards tobacco control measures. Materials and Methods: A descriptive type of study was conducted in December 2013 in one of the government school of Palpa district, one of the rural areas of the Western region. Data entry and analysis was done using SPSS 17 version. Microsoft Excel 2007 is also used for the data processing. Results: There is substantial support for the government taking measure towards tobacco control (96%. Furthermore, strong supports are there regarding ban of smoking in public places and public transport (95% followed by increasing price of tobacco products (87%, banning sales of tobacco to and by minors (82% and ban of tobacco advertising, promotion and sponsorship (73%. Conclusion: The study focuses the effective implementation of the Tobacco Control and Regulation Act 2011, Nepal and health education should be provided to the adolescents with the facts and skills that will enable them to protect themselves from the harmful effects of tobacco related exposure.

  18. Sliding mode attitude control with L 2-gain performance and vibration reduction of flexible spacecraft with actuator dynamics

    Science.gov (United States)

    Hu, Qinglei

    2010-09-01

    This paper presents a dual-stage control system design method for the rotational maneuver control and vibration stabilization of a flexible spacecraft. In this design approach, the sub-systems of attitude control and vibration suppression are designed separately using the low order model. Based on the sliding mode control (SMC) theory, a discontinuous attitude control law in the form of the input voltage of the reaction wheel is derived to control the orientation of the spacecraft, incorporating the L 2-gain performance criterion constraint. The resulting closed-loop system is proven to be uniformly ultimately bounded stability and the effect of the external disturbance on both attitude quaternion and angular velocity can be attenuated to the prescribed level as well. In addition, an adaptive version of the control law is designed for adapting the unknown upper bounds of the lumped disturbance such that the limitation of knowing the bound of the disturbance in advance is released. For actively suppressing the induced vibration, strain rate feedback control method is also investigated by using piezoelectric materials as additional sensors and actuators bonded on the surface of the flexible appendages. Numerical simulations are performed to show that rotational maneuver and vibration suppression are accomplished in spite of the presence of disturbance and uncertainty.

  19. Optimal Attitude Control of Agile Spacecraft Using Combined Reaction Wheel and Control Moment Gyroscope Arrays

    Science.gov (United States)

    2015-12-01

    Finally, research objectives and an overview of the entire document are given. 1.1 Motivation: Satellite Tracking Mission The satellite imagery business ...has been booming and shows no trend of decline [15– 19]. As seen from the recent search for missing Malaysia Airlines Flight 370, significant amounts...to achieve the pointing accuracy and completion time in the family of the other controllers. In fact, the PID controller completes the mission 7

  20. Attitudes and attitude change.

    Science.gov (United States)

    Bohner, Gerd; Dickel, Nina

    2011-01-01

    Attitudes and attitude change remain core topics of contemporary social psychology. This selective review emphasizes work published from 2005 to 2009. It addresses constructionist and stable-entity conceptualizations of attitude, the distinction between implicit and explicit measures of attitude, and implications of the foregoing for attitude change. Associative and propositional processes in attitude change are considered at a general level and in relation to evaluative conditioning. The role of bodily states and physical perceptions in attitude change is reviewed. This is followed by an integrative perspective on processing models of persuasion and the consideration of meta-cognitions in persuasion. Finally, effects of attitudes on information processing, social memory, and behavior are highlighted. Core themes cutting across the areas reviewed are attempts at integrative theorizing bringing together formerly disparate phenomena and viewpoints.

  1. The effect of family climate on risky driving of young novices: the moderating role of attitude and locus of control.

    Science.gov (United States)

    Carpentier, Aline; Brijs, Kris; Declercq, Katrien; Brijs, Tom; Daniels, Stijn; Wets, Geert

    2014-12-01

    The aim of the study was to examine the relative importance of young novice drivers' family climate on their driving behavior. A sample of young novice drivers (N=171) between the age of 17 and 24, who held their permanent (or temporary) driver's license for no longer than one year, participated. The questionnaire included items related to the participants' family climate, 3 socio-cognitive determinants (i.e., attitude, locus of control and social norm), and risky driving behaviors. We expected both family climate and the socio-cognitive determinants to exert a direct effect on risky driving. Furthermore we hypothesized that the socio-cognitive determinants would moderate the impact of family climate on risky driving. The results showed that the effect of family climate on risky driving only originated from one single factor (i.e., noncommitment). Besides that, the results confirmed the importance of the three socio-cognitive determinants to the degree that attitude, locus of control, and social norm significantly predicted the self-reported risky driving. In line of what we hypothesized, attitude moderated the relationship between noncommitment and risky driving. Lastly, we found an unexpected three-way interaction which indicated that locus of control moderated the relation between noncommitment and risky driving only when young drivers' attitude was risk-supportive. We recommend scholars and practitioners to take into account the interaction between external sources of influence (such as an individual's family climate) and more personally oriented dispositions (such as an individual's attitude, social norm and locus of control) when trying to explain and change young novices' risky driving.

  2. Robust Fault-Tolerant Control for Satellite Attitude Stabilization Based on Active Disturbance Rejection Approach with Artificial Bee Colony Algorithm

    OpenAIRE

    Fei Song; Shiyin Qin

    2014-01-01

    This paper proposed a robust fault-tolerant control algorithm for satellite stabilization based on active disturbance rejection approach with artificial bee colony algorithm. The actuating mechanism of attitude control system consists of three working reaction flywheels and one spare reaction flywheel. The speed measurement of reaction flywheel is adopted for fault detection. If any reaction flywheel fault is detected, the corresponding fault flywheel is isolated and the spare reaction flywhe...

  3. Design for robustness using the μ-synthesis applied to launcher attitude and vibration control

    Science.gov (United States)

    Morita, Yasuhiro; Goto, Shinichi

    2008-01-01

    The M-V launch vehicle of Japan Aerospace Exploration Agency (JAXA) has successfully injected Japan's fifth X-ray space telescope "SUZAKU" into its low earth orbit in this past July. The attitude and vibration control algorithm of the M-V rocket used to be highlighted by its H∞ robust stability since its first flight conducted in 1997. Beyond this, its robustness character has been further enhanced using the μ-synthesis approach to get better robust characteristics not only in stability but in tracking performance under uncertainty of the system dynamics. The performance has been validated by the latest back-to-back successful flights of the vehicle: in May 2003 to directly inject Japan's first asteroid sample return spaceship "HAYABUSA" into the planned inter-planetary trajectory and in this past July to launch the telescope. The μ-synthesis has been applied for the first time ever for Japan's launcher control beyond the reliable H∞ design. The plant dynamics has an extremely high-order and unstable characteristics, thus the standard μ-synthesis format cannot be directly applied. The paper gives a unique methodology to apply the theory to such a real high-order complicated system.

  4. Integrated Orbit, Attitude, and Structural Control Systems Design for Space Solar Power Satellites

    Science.gov (United States)

    Wie, Bong; Roithmayr, Carlos M.

    2001-01-01

    The major objective of this study is to develop an integrated orbit, attitude, and structural control systems architecture for very large Space Solar Power Satellites (SSPS) in geosynchronous orbit. This study focuses on the 1.2-GW Abacus SSPS concept characterized by a 3.2 x 3.2 km solar-array platform, a 500-m diameter microwave beam transmitting antenna, and a 500 x 700 m earth-tracking reflector. For this baseline Abacus SSPS configuration, we derive and analyze a complete set of mathematical models, including external disturbances such as solar radiation pressure, microwave radiation, gravity-gradient torque, and other orbit perturbation effects. The proposed control systems architecture utilizes a minimum of 500 1-N electric thrusters to counter, simultaneously, the cyclic pitch gravity-gradient torque, the secular roll torque caused by an offset of the center-of-mass and center-of-pressure, the cyclic roll/yaw microwave radiation torque, and the solar radiation pressure force whose average value is about 60 N.

  5. Attitude Control of a Satellite Simulator Using Reaction Wheels and a PID Controller

    Science.gov (United States)

    2010-03-01

    Rohe, and Welty in the development of AFIT’s second- generation satellite simulator, SimSat II [40]. Instead of building another dumbbell-style spherical...Nathan F. Welty . A Systems Engineering Approach to the Design of a Spacecraft Dynamics and Control Testbed. MS thesis, Air Force Institute of

  6. Simulation of Attitude and Trajectory Dynamics and Control of Multiple Spacecraft

    Science.gov (United States)

    Stoneking, Eric T.

    2009-01-01

    Agora software is a simulation of spacecraft attitude and orbit dynamics. It supports spacecraft models composed of multiple rigid bodies or flexible structural models. Agora simulates multiple spacecraft simultaneously, supporting rendezvous, proximity operations, and precision formation flying studies. The Agora environment includes ephemerides for all planets and major moons in the solar system, supporting design studies for deep space as well as geocentric missions. The environment also contains standard models for gravity, atmospheric density, and magnetic fields. Disturbance force and torque models include aerodynamic, gravity-gradient, solar radiation pressure, and third-body gravitation. In addition to the dynamic and environmental models, Agora supports geometrical visualization through an OpenGL interface. Prototype models are provided for common sensors, actuators, and control laws. A clean interface accommodates linking in actual flight code in place of the prototype control laws. The same simulation may be used for rapid feasibility studies, and then used for flight software validation as the design matures. Agora is open-source and portable across computing platforms, making it customizable and extensible. It is written to support the entire GNC (guidance, navigation, and control) design cycle, from rapid prototyping and design analysis, to high-fidelity flight code verification. As a top-down design, Agora is intended to accommodate a large range of missions, anywhere in the solar system. Both two-body and three-body flight regimes are supported, as well as seamless transition between them. Multiple spacecraft may be simultaneously simulated, enabling simulation of rendezvous scenarios, as well as formation flying. Built-in reference frames and orbit perturbation dynamics provide accurate modeling of precision formation control.

  7. Use of hormonal contraceptives to control menstrual bleeding: attitudes and practice of Brazilian gynecologists

    Science.gov (United States)

    Makuch, María Y; D Osis, Maria José; de Pádua, Karla Simonia; Bahamondes, Luis

    2013-01-01

    Background The purpose of this study was to assess the attitudes and prescribing practices of Brazilian obstetricians and gynecologists regarding use of contraceptive methods to interfere with menstruation and/or induce amenorrhea. Methods We undertook a nationwide survey of Brazilian obstetricians and gynecologists selected using a computer-generated randomization system. Participants completed a questionnaire on prescription of contraceptives and extended/continuous regimens of combined oral contraceptives (COCs). Results In total, 79.2% of Brazilian obstetricians and gynecologists reported that 20%–40% of their patients consulted them for menstrual-related complaints and 26%–34% of the gynecologists reported that 21%–40% of their patients consulted them for reduction in the intensity, frequency, and/or duration of menstrual bleeding. Overall, 93% stated that medically induced amenorrhea represents no risk to women’s health and 82.5% said that they prescribed contraceptives to control menstruation or induce amenorrhea. The contraceptives most commonly prescribed were extended-cycle 24/4 or 26/2 COC regimens and the levonorgestrel-releasing intrauterine system. Poisson regression analysis showed that Brazilian obstetricians and gynecologists prescribing contraceptives to control menstruation or induce amenorrhea consider extended-use or continuous-use COC regimens to be effective for both indications (prevalence ratio 1.23 [95% confidence interval 1.09–1.40] and prevalence ratio 1.28 [95% confidence interval 1.13–1.46], respectively). They also prescribed COCs with an interval of 24/4 or 26/2 to control bleeding patterns (prevalence ratio 1.10 [95% confidence interval 1.01–1.21]). Conclusion Brazilian obstetricians and gynecologists were favorably disposed toward prescribing extended-use or continuous-use COC regimens for control of menstrual bleeding or to induce amenorrhea on patient demand. PMID:24399887

  8. Geometric Collocation Method on SO(3 with Application to Optimal Attitude Control of a 3D Rotating Rigid Body

    Directory of Open Access Journals (Sweden)

    Xiaojia Xiang

    2015-01-01

    Full Text Available The collocation method is extended to the special orthogonal group SO(3 with application to optimal attitude control (OAC of a rigid body. A left-invariant rigid-body attitude dynamical model on SO(3 is established. For the left invariance of the attitude configuration equation in body-fixed frame, a geometrically exact numerical method on SO(3, referred to as the geometric collocation method, is proposed by deriving the equivalent Lie algebra equation in so(3 of the left-invariant configuration equation. When compared with the general Gauss pseudo-spectral method, the explicit RKMK, and Lie group variational integrator having the same order and stepsize in numerical tests for evolving a free-floating rigid-body attitude dynamics, the proposed method is higher in accuracy, time performance, and structural conservativeness. In addition, the numerical method is applied to solve a constrained OAC problem on SO(3. The optimal control problem is transcribed into a nonlinear programming problem, in which the equivalent Lie algebra equation is being considered as the defect constraints instead of the configuration equation. The transcription method is coordinate-free and does not need chart switching or special handling of singularities. More importantly, with the numerical advantage of the geometric collocation method, the proposed OAC method may generate satisfying convergence rate.

  9. Attitudes and attitude change

    DEFF Research Database (Denmark)

    Scholderer, Joachim

    2010-01-01

    An attitude can be defined as the evaluation of an object as positive or negative. The term "object" in this definition should be understood in a broad sense; an attitude object may be any concrete or abstract entity that is in some way represented in our thoughts and memory. In other words......, attitude objects are simply the things we like or dislike. Consumer researchers are mainly interested in attitude objects of two classes, products and services, including the attributes, issues, persons, communications, situations, and behaviours related to them. Research on consumer attitudes takes two...... perspectives: Understanding attitude structure: how is an attitude cognitively represented in a consumer's mind, including its components (intra-attitudinal structure) and its associations with other psychological variables (inter-attitudinal structure)? Understanding information processing: what...

  10. Knowledge, attitudes and practices (KAP about rabies prevention and control: a community survey in Tanzania.

    Directory of Open Access Journals (Sweden)

    Maganga Sambo

    2014-12-01

    Full Text Available Despite being entirely preventable, canine rabies still kills 55,000 people/year in developing countries. Information about local beliefs and practices can identify knowledge gaps that may affect prevention practices and lead to unnecessary deaths.We investigated knowledge, attitudes and practices related to rabies and its prevention and control amongst a cross-section of households (n = 5,141 in urban and rural areas of central, southern and northern Tanzania. Over 17% of respondents owned domestic dogs (average of 2.3 dogs/household,>95% had heard about rabies, and>80% knew that rabies is transmitted through dog bites. People who (1 had greater education, (2 originated from areas with a history of rabies interventions, (3 had experienced exposure by a suspect rabid animal, (4 were male and (5 owned dogs were more likely to have greater knowledge about the disease. Around 80% of respondents would seek hospital treatment after a suspect bite, but only 5% were aware of the need for prompt wound cleansing after a bite. Although>65% of respondents knew of dog vaccination as a means to control rabies, only 51% vaccinated their dogs. Determinants of dog vaccination included (1 being a male-headed household, (2 presence of children, (3 low economic status, (4 residing in urban areas, (5 owning livestock, (6 originating from areas with rabies interventions and (7 having purchased a dog. The majority of dog-owning respondents were willing to contribute no more than US$0.31 towards veterinary services.We identified important knowledge gaps related to, and factors influencing the prevention and control of rabies in Tanzania. Increasing knowledge regarding wound washing, seeking post-exposure prophylaxis and the need to vaccinate dogs are likely to result in more effective prevention of rabies; however, greater engagement of the veterinary and medical sectors is also needed to ensure the availability of preventative services.

  11. An Evaluation of Teachers' Attitudes and Beliefs Levels on Classroom Control in Terms of Teachers' Sense of Efficacy (The Sample of Biology Teachers in Turkey)

    Science.gov (United States)

    Kurt, Hakan

    2014-01-01

    The aim of this study is to evaluate biology teachers' attitudes and belief levels on classroom control in terms of teachers' sense of efficacy. The screening model was used in the study. The study group was comprised of 135 biology teachers. In this study, Teachers' Sense of Efficacy Scale (TSES) and The Attitudes and Beliefs on Classroom Control…

  12. Eating attitudes, weight control behaviors and risk factors for eating disorders among Chinese female dance students

    Directory of Open Access Journals (Sweden)

    Zhuoli Tao

    Full Text Available Background and Objectives: Along with the economic development, eating disorders begin to appear in China. In this context, we study potential risks for eating disorders. Methods: 1,199 Chinese students, aged 12-25 years, were randomly selected in spring 2006 from a survey with a series of scales (EAT-26, EDI that were used as a screening examination for eating attitudes, weight control behaviors and risk factors. Among them were 31 female Chinese dance students. The dancer students were compared with the female high risk group of eating disorders (EAT ≥ 20 and the female low risk group (EAT 0-9 according to their scores on EAT-26 and EDI. Results: There were just 3 dancers (10% with scores on the EAT-26 who were over the cut-off point of 20 for high risk of an eating disorder. The dance group also showed significantly higher scores than the low risk group (EAT 0-9 not only on the subscales Dieting, and EAT-26 total scores on the EAT-26, but also on the subscales Perfectionism and Maturity Fears on the EDI. Conclusions: Among the group of female Chinese dance students, most participants did not show a high risk for eating disorders and their high scores on some subscales on the EAT-26 and EDI could be caused by their occupation.

  13. Innovative power management, attitude determination and control tile for CubeSat standard NanoSatellites

    Science.gov (United States)

    Ali, Anwar; Mughal, M. Rizwan; Ali, Haider; Reyneri, Leonardo

    2014-03-01

    Electric power supply (EPS) and attitude determination and control subsystem (ADCS) are the most essential elements of any aerospace mission. Efficient EPS and precise ADCS are the core of any spacecraft mission. So keeping in mind their importance, they have been integrated and developed on a single tile called CubePMT module. Modular power management tiles (PMTs) are already available in the market but they are less efficient, heavier in weight, consume more power and contain less number of subsystems. Commercial of the shelf (COTS) components have been used for CubePMT implementation which are low cost and easily available from the market. CubePMT is developed on the design approach of AraMiS architecture: a project developed at Politecnico di Torino that provides low cost and higher performance space missions with dimensions larger than CubeSats. The feature of AraMiS design approach is its modularity. These modules can be reused for multiple missions which helps in significant reduction of the overall budget, development and testing time. One has just to reassemble the required subsystems to achieve the targeted specific mission.

  14. Cassini Attitude Control Operations Flight Rules and How They are Enforced

    Science.gov (United States)

    Burk, Thomas; Bates, David

    2008-01-01

    The Cassini spacecraft was launched on October 15, 1997 and arrived at Saturn on June 30, 2004. It has performed detailed observations and remote sensing of Saturn, its rings, and its satellites since that time. Cassini deployed the European-built Huygens probe which descended through the Titan atmosphere and landed on its surface on January 14, 2005. Operating the Cassini spacecraft is a complex scientific, engineering, and management job. In order to safely operate the spacecraft, a large number of flight rules were developed. These flight rules must be enforced throughout the lifetime of the Cassini spacecraft. Flight rules are defined as any operational limitation imposed by the spacecraft system design, hardware, and software, violation of which would result in spacecraft damage, loss of consumables, loss of mission objectives, loss and/or degradation of science, and less than optimal performance. Flight rules require clear description and rationale. Detailed automated methods have been developed to insure the spacecraft is continuously operated within these flight rules. An overview of all the flight rules allocated to the Cassini Attitude Control and Articulation Subsystem and how they are enforced is presented in this paper.

  15. Attitude Determination and Control Subsystem (ADCS) Preparations for the EPOXI Flyby of Comet Haley 2

    Science.gov (United States)

    Luna, Michael E.; Collins, Stephen M.

    2011-01-01

    On November 4, 2010 the already "in-flight" Deep Impact spacecraft flew within 700km of comet 103P/Hartley 2 as part of its extended mission EPOXI, the 5th time to date any spacecraft visited a comet. In 2005, the spacecraft had previously imaged a probe impact comet Tempel 1. The EPOXI flyby marked the first time in history that two comets were explored with the same instruments on a re-used spacecraft-with hardware and software originally designed and optimized for a different mission. This made the function of the attitude determination and control subsystem (ADCS) critical to the successful execution of the EPOXI flyby. As part of the spacecraft team preparations, the ADCS team had to perform thorough sequence reviews, key spacecraft activities and onboard calibrations. These activities included: review of background sequences for the initial conditions vector, sun sensor coefficients, and reaction wheel assembly (RWA) de-saturations; design and execution of 10 trajectory correction maneuvers; science calibration of the two telescope instruments; a flight demonstration of the fastest turns conducted by the spacecraft between Earth and comet point; and assessment of RWA health (given RWA problems on other spacecraft).

  16. Attitude Determination and Control Subsystem (ADCS) Preparations for the EPOXI Flyby of Comet Hartley 2

    Science.gov (United States)

    Luna, Michael E.; Collins, Steven M.

    2011-01-01

    On November 4, 2010 the former "Deep Impact" spacecraft, renamed "EPOXI" for its extended mission, flew within 700km of comet 103P/Hartley 2. In July 2005, the spacecraft had previously imaged a probe impact of comet Tempel 1. The EPOXI flyby was the fifth close encounter of a spacecraft with a comet nucleus and marked the first time in history that two comet nuclei were imaged at close range with the same suite of onboard science instruments. This challenging objective made the function of the attitude determination and control subsystem (ADCS) critical to the successful execution of the EPOXI flyby.As part of the spacecraft flyby preparations, the ADCS operations team had to perform meticulous sequence reviews, implement complex spacecraft engineering and science activities and perform numerous onboard calibrations. ADCS contributions included design and execution of 10 trajectory correction maneuvers, the science calibration of the two telescopic instruments, an in-flight demonstration of high-rate turns between Earth and comet point, and an ongoing assessment of reaction wheel health. The ADCS team was also responsible for command sequences that included updates to the onboard ephemeris and sun sensor coefficients and implementation of reaction wheel assembly (RWA) de-saturations.

  17. Integration and Testing of the Lunar Reconnaissance Orbiter Attitude Control System

    Science.gov (United States)

    Simpson, Jim; Badgley, Jason; McCaughey, Ken; Brown, Kristen; Calhoun, Philip; Davis, Edward; Garrick, Joseph; Gill, Nathaniel; Hsu, Oscar; Jones, Noble; Oritz-Cruz, Gerardo; Raymond, Juan; Roder, Russell; Shah, Neerav; Wilson, John

    2010-01-01

    Throughout the Lunar Reconnaissance Orbiter (LRO) Integration and Testing (I&T) phase of the project, the Attitude Control System (ACS) team completed numerous tests on each hardware component in ever more flight like environments. The ACS utilizes a select group of attitude sensors and actuators. This paper chronicles the evolutionary steps taken to verify each component was constantly ready for flight as well as providing invaluable trending experience with the actual hardware. The paper includes a discussion of each ACS hardware component, lessons learned of the various stages of I&T, a discussion of the challenges that are unique to the LRO project, as well as a discussion of work for future missions to consider as part of their I&T plan. LRO ACS sensors were carefully installed, tested, and maintained over the 18 month I&T and prelaunch timeline. Care was taken with the optics of the Adcole Coarse Sun Sensors (CSS) to ensure their critical role in the Safe Hold mode was fulfilled. The use of new CSS stimulators provided the means of testing each CSS sensor independently, in ambient and vacuum conditions as well as over a wide range of thermal temperatures. Extreme bright light sources were also used to test the CSS in ambient conditions. The integration of the two SELEX Galileo Star Trackers was carefully planned and executed. Optical ground support equipment was designed and used often to check the performance of the star trackers throughout I&T in ambient and thermal/vacuum conditions. A late discovery of potential contamination of the star tracker light shades is discussed in this paper. This paper reviews how each time the spacecraft was at a new location and orientation, the Honeywell Miniature Inertial Measurement Unit (MIMU) was checked for data output validity. This gyro compassing test was performed at several key testing points in the timeline as well as several times while LRO was on the launch pad. Sensor alignment tests were completed several

  18. Guidance and Control of Position and Attitude for Rendezvous and Dock/Berthing with a Noncooperative/Target Spacecraft

    Directory of Open Access Journals (Sweden)

    Gilberto Arantes

    2014-01-01

    Full Text Available Noncooperative target spacecrafts are those assets in orbit that cannot convey any information about their states (position, attitude, and velocities or facilitate rendezvous and docking/berthing (RVD/B process. Designing a guidance, navigation, and control (GNC module for the chaser in a RVD/B mission with noncooperative target should be inevitably solved for on-orbit servicing technologies. The proximity operations and the guidance for achieving rendezvous problems are addressed in this paper. The out-of-plane maneuvers of proximity operations are explored with distinct subphases, including a chaser far approach in the target’s orbit to the first hold point and a closer approach to the final berthing location. Accordingly, guidance solutions are chosen for each subphase from the standard Hill based Closhessy-Willtshire (CW solution, elliptical fly-around, and Glideslope algorithms. The control is based on a linear quadratic regulator approach (LQR. At the final berthing location, attitude tracker based on a proportional derivative (PD form is tested to synchronize the chaser and target attitudes. The paper analyzes the performance of both controllers in terms of the tracking ability and the robustness. Finally, it prescribes any restrictions that may be imposed on the guidance during any subphase which can help to improve the controllers tracking ability.

  19. 考虑姿态禁忌约束的航天器安全姿态跟踪控制%Spacecraft safe attitude tracking control by considering attitude forbidden constraint

    Institute of Scientific and Technical Information of China (English)

    郑重; 宋申民; 张保群

    2013-01-01

    Considering the attitude constraint problem during spacecraft attitude tracking, a control algorithm based on potential function for safe attitude maneuver is presented. Different from the case of fixed-point maneuver, error quaternion and error angular velocity are introduced to construct the spacecraft attitude tracking error model. Quaternions are used to describe the region of forbidden attitude, and a new Gauss avoidant potential function is proposed using the minimum angle allowed by the forbidden attitude. A safe attitude maneuver controller is obtained by employing the avoidant potential function and an attractive potential function, meanwhile the Lyapunov stability of the closed-loop control system is analyzed with and without disturbance torque respectively. Finally, computer numerical simulations are carried out in attitude tracking with attitude constraint. Simulation results show that the proposed control approach can not only achieve the purpose of attitude tracking, but also guarantee the spacecraft far away the region of the forbidden attitude.%针对航天器姿态跟踪过程中的姿态约束问题,提出了一种基于势函数的安全姿态机动控制算法.与姿态定点机动的姿态约束问题不同,引入误差四元数和误差角速度,建立了航天器姿态跟踪误差模型.采用四元数描述了姿态禁忌区域,并根据禁止姿态最小允许角构造了一种新的规避高斯势函数.利用规避势函数和吸引势函数得到安全姿态机动控制器,对于无扰动和有扰动的情况分别分析了闭环控制系统的Lyapunov稳定性.最后,对于有约束的姿态跟踪情况进行了计算机数值仿真.仿真结果表明,所提出的控制方法既能实现姿态跟踪的目的,又能确保航天器在机动过程中不会进入姿态禁忌区域.

  20. Knowledge and attitudes of women regarding Sexually Transmitted Diseases, sexual health and preventive controls

    Directory of Open Access Journals (Sweden)

    Evaggelia Voltsi

    2014-04-01

    Full Text Available Both Greek and international literature suggest there is an increase in STDs worldwide, something that has motivated health agencies to design health promotion strategies. Aim: The aim of the present study was to assess knowledge and attitudes of women regarding STDs, as well as to correlate the findings with their sexual activity and gynecologic symptoms. Materials and Methods: Our reference population comprised of women residing in the city of Corinth. A specialized, valid and anonymous questionnaire was used, that included items concerning gynecologic diseases, STDs, prevention measures and birth control methods. Data collection took place from March to May 2013 and the SPSS 17.0 was used for the statistical analysis. Results: The majority of our sample (n=214 consisted of women aged 20 or younger (40.2%, without children (65.1%. 56.7% of the participants initiated sexual relationships at age 18 or older, while 55.2% said they always used condoms. Regarding STD history, 76.40% reported no such history. 67% thought that condoms were the safest birth control method, 64.4% said that casual relationships were the main cause for STD infections, 47.1% said that Pap tests should be done after menstruation, and 65.1% that mammograms should be a routine examination after the age of 30. Also, 65.4% of the participants said they consulted their gynecologist for anything regarding prevention examinations or gynecologic conditions. Conclusions: Despite some limitations, the present study concludes that many, mainly younger, women lack important information on such subjects and adopt high-risk behaviors. Consequently, the implementation of targeted, nation-wide sexual health programs and pre-symptomatic testing is deemed necessary.

  1. Attitudes towards obesity in the Swedish general population: the role of one's own body size, weight satisfaction, and controllability beliefs about obesity.

    Science.gov (United States)

    Hansson, Lena M; Rasmussen, Finn

    2014-01-01

    This study examined the associations of different socio-demographic and psychological factors with attitudes towards obesity. Individuals with different weight status (N=2436) were drawn from an annual population-based survey in Sweden, and data on attitudes towards obesity (ATOP) and predictor variables were assessed in 2008. The strongest predictor of ATOP was controllability beliefs about obesity (β=0.83). Thus, greater controllability beliefs about obesity predicted more negative attitudes. Sex and weight satisfaction were also independently associated with ATOP. However, there was no, or only a weak, association between weight satisfaction and ATOP among individuals with normal weight or overweight. And the higher the weight satisfactions of individuals with obesity, the more positive were their attitudes. It seems that stigma-reduction strategies in the general public should address the uncontrollable factors in the aetiology of obesity. However, more research is needed to understand the underlying causes of people's attitudes towards obesity.

  2. Impact of an Oral Health Education Workshop on Parents’ Oral Health Knowledge, Attitude, and Perceived Behavioral Control among African Immigrants

    Directory of Open Access Journals (Sweden)

    Maryam Amin

    2014-01-01

    Full Text Available Purpose. To evaluate the impact of an educational workshop on parental knowledge, attitude, and perceived behavioral control regarding their child’s oral health. Materials and Methods. A one-time oral health education workshop including audio/visual and hands-on components was conducted by a trained dentist and bilingual community workers in community locations. Participants were African parents of children who had lived in Canada for less than ten years. The impact of the workshop was evaluated by a questionnaire developed based on the theory of planned behavior. Results. A total of 105 parents participated in this study. Participants were mainly mothers (mean age 35.03±5.4 years who came to Canada as refugee (77.1% and had below high school education (70%. Paired t-test showed a significant difference in participants’ knowledge of caries, preventive measures, and benefits of regular dental visits after the workshop (P value<0.05. A significant improvement was also found in parental attitudes toward preventive measures and their perceived behavioral control (P<0.05. Parents’ intention to take their child to a dentist within six months significantly altered after the workshop (P value<0.05. Conclusions. A one-time hands-on training was effective in improving parental knowledge, attitude, perceived behavioral control, and intention with respect to their child’s oral health and preventive dental visits in African immigrants.

  3. Use of hormonal contraceptives to control menstrual bleeding: attitudes and practice of Brazilian gynecologists

    Directory of Open Access Journals (Sweden)

    Makuch MY

    2013-11-01

    Full Text Available María Y Makuch,1 Maria José D Osis,1 Karla Simonia de Pádua,1,2 Luis Bahamondes3 1Center for Research in Reproductive Health (CEMICAMP, 2Prof Dr José Aristodemo Pinotti Women's Hospital, University of Campinas, 3Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, and National Institute of Hormones and Women's Health, Campinas, São Paulo, Brazil Background: The purpose of this study was to assess the attitudes and prescribing practices of Brazilian obstetricians and gynecologists regarding use of contraceptive methods to interfere with menstruation and/or induce amenorrhea. Methods: We undertook a nationwide survey of Brazilian obstetricians and gynecologists selected using a computer-generated randomization system. Participants completed a questionnaire on prescription of contraceptives and extended/continuous regimens of combined oral contraceptives (COCs. Results: In total, 79.2% of Brazilian obstetricians and gynecologists reported that 20%–40% of their patients consulted them for menstrual-related complaints and 26%–34% of the gynecologists reported that 21%–40% of their patients consulted them for reduction in the intensity, frequency, and/or duration of menstrual bleeding. Overall, 93% stated that medically induced amenorrhea represents no risk to women's health and 82.5% said that they prescribed contraceptives to control menstruation or induce amenorrhea. The contraceptives most commonly prescribed were extended-cycle 24/4 or 26/2 COC regimens and the levonorgestrel-releasing intrauterine system. Poisson regression analysis showed that Brazilian obstetricians and gynecologists prescribing contraceptives to control menstruation or induce amenorrhea consider extended-use or continuous-use COC regimens to be effective for both indications (prevalence ratio 1.23 [95% confidence interval 1.09–1.40] and prevalence ratio 1.28 [95% confidence interval 1.13–1.46], respectively. They also

  4. Auto Code Generation for Simulink-Based Attitude Determination Control System

    Science.gov (United States)

    MolinaFraticelli, Jose Carlos

    2012-01-01

    This paper details the work done to auto generate C code from a Simulink-Based Attitude Determination Control System (ADCS) to be used in target platforms. NASA Marshall Engineers have developed an ADCS Simulink simulation to be used as a component for the flight software of a satellite. This generated code can be used for carrying out Hardware in the loop testing of components for a satellite in a convenient manner with easily tunable parameters. Due to the nature of the embedded hardware components such as microcontrollers, this simulation code cannot be used directly, as it is, on the target platform and must first be converted into C code; this process is known as auto code generation. In order to generate C code from this simulation; it must be modified to follow specific standards set in place by the auto code generation process. Some of these modifications include changing certain simulation models into their atomic representations which can bring new complications into the simulation. The execution order of these models can change based on these modifications. Great care must be taken in order to maintain a working simulation that can also be used for auto code generation. After modifying the ADCS simulation for the auto code generation process, it is shown that the difference between the output data of the former and that of the latter is between acceptable bounds. Thus, it can be said that the process is a success since all the output requirements are met. Based on these results, it can be argued that this generated C code can be effectively used by any desired platform as long as it follows the specific memory requirements established in the Simulink Model.

  5. Acoustic-Modal Testing of the Ares I Launch Abort System Attitude Control Motor Valve

    Science.gov (United States)

    Davis, R. Benjamin; Fischbach, Sean R.

    2010-01-01

    The Attitude Control Motor (ACM) is being developed for use in the Launch Abort System (LAS) of NASA's Ares I launch vehicle. The ACM consists of a small solid rocket motor and eight actuated pintle valves that directionally allocate.thrust_- 1t.has-been- predicted-that significant unsteady. pressure.fluctuations.will.exist. inside the-valves during operation. The dominant frequencies of these oscillations correspond to the lowest several acoustic natural frequencies of the individual valves. An acoustic finite element model of the fluid volume inside the valve has been critical to the prediction of these frequencies and their associated mode shapes. This work describes an effort to experimentally validate the acoustic finite model of the valve with an acoustic modal test. The modal test involved instrumenting a flight-like valve with six microphones and then exciting the enclosed air with a loudspeaker. The loudspeaker was configured to deliver broadband noise at relatively high sound pressure levels. The aquired microphone signals were post-processed and compared to results generated from the acoustic finite element model. Initial comparisons between the test data and the model results revealed that additional model refinement was necessary. Specifically, the model was updated to implement a complex impedance boundary condition at the entrance to the valve supply tube. This boundary condition models the frequency-dependent impedance that an acoustic wave will encounter as it reaches the end of the supply tube. Upon invoking this boundary condition, significantly improved agreement between the test data and the model was realized.

  6. Robust Fault-Tolerant Control for Satellite Attitude Stabilization Based on Active Disturbance Rejection Approach with Artificial Bee Colony Algorithm

    Directory of Open Access Journals (Sweden)

    Fei Song

    2014-01-01

    Full Text Available This paper proposed a robust fault-tolerant control algorithm for satellite stabilization based on active disturbance rejection approach with artificial bee colony algorithm. The actuating mechanism of attitude control system consists of three working reaction flywheels and one spare reaction flywheel. The speed measurement of reaction flywheel is adopted for fault detection. If any reaction flywheel fault is detected, the corresponding fault flywheel is isolated and the spare reaction flywheel is activated to counteract the fault effect and ensure that the satellite is working safely and reliably. The active disturbance rejection approach is employed to design the controller, which handles input information with tracking differentiator, estimates system uncertainties with extended state observer, and generates control variables by state feedback and compensation. The designed active disturbance rejection controller is robust to both internal dynamics and external disturbances. The bandwidth parameter of extended state observer is optimized by the artificial bee colony algorithm so as to improve the performance of attitude control system. A series of simulation experiment results demonstrate the performance superiorities of the proposed robust fault-tolerant control algorithm.

  7. Design and Test of an Attitude Determination and Control System for a 6U CubeSat using AFIT’s CubeSat Testbed

    Science.gov (United States)

    2015-03-01

    DESIGN AND TEST OF AN ATTITUDE DETERMINATION AND CONTROL SYSTEM FOR A 6U CUBESAT USING AFIT’S CUBESAT TESTBED THESIS Michael L. Tibbs, 2nd Lieutenant...work of the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENY-MS-15-M-240 DESIGN AND TEST OF AN ATTITUDE ...DISTRIBUTION STATEMENT A APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENY-MS-15-M-240 DESIGN AND TEST OF AN ATTITUDE DETERMINATION AND CONTROL

  8. A low-noise, high-bandwidth magnetically-levitated momentum-wheel for 3-axis attitude control from a single wheel

    OpenAIRE

    Seddon, Jon; Pechev, Alexandre

    2009-01-01

    This paper proposes a new concept for attitude actuation for small satellites that uses active magnetic bearings to support and tilt a spinning rotor to provide 3-axis attitude control of the satellite using a single actuator. A controlled 3D motion in the spinning rotor provides a conventional torque output about the momentum axis and a gyroscopic torque output about any direction in the plane normal to the spinning axis. Therefore, a single tilting momentum-wheel can generate torque along t...

  9. Design of Satellite Attitude Control Algorithm Based on the SDRE Method Using Gas Jets and Reaction Wheels

    Directory of Open Access Journals (Sweden)

    Luiz C. G. de Souza

    2013-01-01

    Full Text Available An experimental attitude control algorithm design using prototypes can minimize space mission costs by reducing the number of errors transmitted to the next phase of the project. The Space Mechanics and Control Division (DMC of INPE is constructing a 3D simulator to supply the conditions for implementing and testing satellite control hardware and software. Satellite large angle maneuver makes the plant highly nonlinear and if the parameters of the system are not well determined, the plant can also present some level of uncertainty. As a result, controller designed by a linear control technique can have its performance and robustness degraded. In this paper the standard LQR linear controller and the SDRE controller associated with an SDRE filter are applied to design a controller for a nonlinear plant. The plant is similar to the DMC 3D satellite simulator where the unstructured uncertainties of the system are represented by process and measurements noise. In the sequel the State-Dependent Riccati Equation (SDRE method is used to design and test an attitude control algorithm based on gas jets and reaction wheel torques to perform large angle maneuver in three axes. The SDRE controller design takes into account the effects of the plant nonlinearities and system noise which represents uncertainty. The SDRE controller performance and robustness are tested during the transition phase from angular velocity reductions to normal mode of operation with stringent pointing accuracy using a switching control algorithm based on minimum system energy. This work serves to validate the numerical simulator model and to verify the functionality of the control algorithm designed by the SDRE method.

  10. The development and demonstration of hybrid programmable attitude control electronics. [with adaptable analog/digital design approach

    Science.gov (United States)

    Smith, L. S.; Kopf, E. H., Jr.

    1974-01-01

    HYPACE provides an adaptable, analog/digital design approach that permits preflight and in-flight accommodation of mission changes, component performance variations, spacecraft changes, etc., through programing. This enabled broad multimission flexibility of application in a cost-effective manner. The HYPACE design, which was demonstrated in breadboard form on a single-axis gas-bearing spacecraft simulation, uses a single control channel to perform the attitude control functions sequentially, thus significantly reducing the number of component parts over hard-wired designs. The success of this effort resulted in the concept being selected for the Mariner/Jupiter/Saturn 1977 spacecraft application.

  11. Attitudes toward euthanasia and physician-assisted suicide: a study of the multivariate effects of healthcare training, patient characteristics, religion and locus of control.

    Science.gov (United States)

    Hains, Carrie-Anne Marie; Hulbert-Williams, Nicholas J

    2013-11-01

    Public and healthcare professionals differ in their attitudes towards euthanasia and physician-assisted suicide (PAS), the legal status of which is currently in the spotlight in the UK. In addition to medical training and experience, religiosity, locus of control and patient characteristics (eg, patient age, pain levels, number of euthanasia requests) are known influencing factors. Previous research tends toward basic designs reporting on attitudes in the context of just one or two potentially influencing factors; we aimed to test the comparative importance of a larger range of variables in a sample of nursing trainees and non-nursing controls. One hundred and fifty-one undergraduate students (early-stage nursing training, late-stage nursing training and non-nursing controls) were approached on a UK university campus and asked to complete a self-report questionnaire. Participants were of mixed gender and were on average 25.5 years old. No significant differences in attitude were found between nursing and non-nursing students. There was a significant positive correlation between higher religiosity and positive attitude toward euthanasia (r=0.19, peuthanasia and PAS, and confirm the importance of individual differences in determining these attitudes. The unexpected direction of association between religiosity and attitudes may reflect a broader cultural shift in attitudes since earlier research in this area. Furthermore, these findings suggest it possible that experience, more than training itself, may be a bigger influence on attitudinal differences in healthcare professionals.

  12. The Attitude of Papua New Guineans Towards Investigation, Control and Manipulation of Natural Phenomena

    Science.gov (United States)

    Maddock, M. N.

    1975-01-01

    Describes a study conducted with the "Environmental Phenomena Attitude Scale." The population included teachers college and high school students and Pidgin speaking, illiterate laborers. Results showed that there is a very strong relationship between memberships of the student or villager group and the score obtained on the scale. (MLH)

  13. BReastfeeding Attitude and Volume Optimization (BRAVO) trial : Study protocol for a randomized controlled trial

    NARCIS (Netherlands)

    Savitri, Ary I.; Idris, Nikmah S; Indawati, Wahyuni; Saldi, Siti Rizny F; Amelia, Dwirani; Baharuddin, Mohammad; Sastroasmoro, Sudigdo; Grobbee, Diederick E.; Uiterwaal, Cuno S P M

    2016-01-01

    Background: A growing body of evidence shows the short-term benefits of breastfeeding, which include protection against infections, allergies, and lung diseases. However, evidence on the long-term benefits of breastfeeding is scarce and often conflicting. The BReastfeeding Attitude and Volume Optimi

  14. Effect of an institutional development plan for user participation on professionals' knowledge, practice, and attitudes. A controlled study

    Directory of Open Access Journals (Sweden)

    Rise Marit By

    2011-11-01

    Full Text Available Abstract Background Governments in several countries attempt to strengthen user participation through instructing health care organisations to plan and implement activities such as user representation in administrational boards, improved information to users, and more individual user participation in clinical work. The professionals are central in implementing initiatives to enhance user participation in organisations, but no controlled studies have been conducted on the effect on professionals from implementing institutional development plans. The objective was to investigate whether implementing a development plan intending to enhance user participation in a mental health hospital had any effect on the professionals' knowledge, practice, or attitudes towards user participation. Methods This was a non-randomized controlled study including professionals from three mental health hospitals in Central Norway. A development plan intended to enhance user participation was implemented in one of the hospitals as a part of a larger re-organizational process. The plan included i.e. establishing a patient education centre and a user office, purchasing of user expertise, appointing contact professionals for next of kin, and improving of the centre's information and the professional culture. The professionals at the intervention hospital thus constituted the intervention group, while the professionals at two other hospitals participated as control group. All professionals were invited to answer the Consumer Participation Questionnaire (CPQ and additional questions, focusing on knowledge, practice, and attitudes towards user participation, two times with a 16 months interval. Results A total of 438 professionals participated (55% response rate. Comparing the changes in the intervention group with the changes in the control group revealed no statistically significant differences at a 0.05 level. The implementation of the development plan thus had no

  15. Attitudes, norms and controls influencing lifestyle risk factor management in general practice

    Directory of Open Access Journals (Sweden)

    McKenzie Suzanne H

    2009-08-01

    patient's motivation, and cost and accessibility of services to patients. Conclusion General practitioner attitudes, normative influences from both patients and the profession, and perceived external control factors (time, cost, availability and practice capacity all influence management of behavioural risk factors. Provider education, community awareness raising, support and capacity building may improve the uptake of lifestyle modification interventions.

  16. Advanced Materials and Fabrication Techniques for the Orion Attitude Control Motor

    Science.gov (United States)

    Gorti, Sridhar; Holmes, Richard; O'Dell, John; McKechnie, Timothy; Shchetkovskiy, Anatoliy

    2013-01-01

    Rhenium, with its high melting temperature, excellent elevated temperature properties, and lack of a ductile-to-brittle transition temperature (DBTT), is ideally suited for the hot gas components of the ACM (Attitude Control Motor), and other high-temperature applications. However, the high cost of rhenium makes fabricating these components using conventional fabrication techniques prohibitive. Therefore, near-net-shape forming techniques were investigated for producing cost-effective rhenium and rhenium alloy components for the ACM and other propulsion applications. During this investigation, electrochemical forming (EL-Form ) techniques were evaluated for producing the hot gas components. The investigation focused on demonstrating that EL-Form processing techniques could be used to produce the ACM flow distributor. Once the EL-Form processing techniques were established, a representative rhenium flow distributor was fabricated, and samples were harvested for material properties testing at both room and elevated temperatures. As a lower cost and lighter weight alternative to an all-rhenium component, rhenium- coated graphite and carbon-carbon were also evaluated. The rhenium-coated components were thermal-cycle tested to verify that they could withstand the expected thermal loads during service. High-temperature electroforming is based on electrochemical deposition of compact layers of metals onto a mandrel of the desired shape. Mandrels used for electro-deposition of near-net shaped parts are generally fabricated from high-density graphite. The graphite mandrel is easily machined and does not react with the molten electrolyte. For near-net shape components, the inner surface of the electroformed part replicates the polished graphite mandrel. During processing, the mandrel itself becomes the cathode, and scrap or refined refractory metal is the anode. Refractory metal atoms from the anode material are ionized in the molten electrolytic solution, and are deposited

  17. Modeling Attitude Dynamics in Simulink: A Study of the Rotational and Translational Motion of a Spacecraft Given Torques and Impulses Generated by RMS Hand Controllers

    Science.gov (United States)

    Mauldin, Rebecca H.

    2010-01-01

    In order to study and control the attitude of a spacecraft, it is necessary to understand the natural motion of a body in orbit. Assuming a spacecraft to be a rigid body, dynamics describes the complete motion of the vehicle by the translational and rotational motion of the body. The Simulink Attitude Analysis Model applies the equations of rigid body motion to the study of a spacecraft?s attitude in orbit. Using a TCP/IP connection, Matlab reads the values of the Remote Manipulator System (RMS) hand controllers and passes them to Simulink as specified torque and impulse profiles. Simulink then uses the governing kinematic and dynamic equations of a rigid body in low earth orbit (LE0) to plot the attitude response of a spacecraft for five seconds given known applied torques and impulses, and constant principal moments of inertia.

  18. A summary of the mechanical design, testing and performance of the IMP-H and J attitude control systems

    Science.gov (United States)

    Metzger, J. R.

    1974-01-01

    The main aspects of the attitude control system used on both the IMP-H and J spacecraft are presented. The mechanical configuration is described. Information on all the specific components comprising the flight system is provided. The acceptance and qualification testing of both individual components and the installed system are summarized. Functional information regarding the operation and performance in relation to the orbiting spacecraft and its mission is included. Related topics which are discussed are: (1) safety requirements, (2) servicing procedures, (3) anomalous behavior, and (4) pyrotechnic devices.

  19. Farmer Attitudes and Livestock Disease: Exploring Citizenship Behaviour and Peer Monitoring across Two BVD Control Schemes in the UK

    Science.gov (United States)

    Heffernan, Claire; Azbel-Jackson, Lena; Brownlie, Joe; Gunn, George

    2016-01-01

    The eradication of BVD in the UK is technically possible but appears to be socially untenable. The following study explored farmer attitudes to BVD control schemes in relation to advice networks and information sharing, shared aims and goals, motivation and benefits of membership, notions of BVD as a priority disease and attitudes toward regulation. Two concepts from the organisational management literature framed the study: citizenship behaviour where actions of individuals support the collective good (but are not explicitly recognised as such) and peer to peer monitoring (where individuals evaluate other’s behaviour). Farmers from two BVD control schemes in the UK participated in the study: Orkney Livestock Association BVD Eradication Scheme and Norfolk and Suffolk Cattle Breeders Association BVD Eradication Scheme. In total 162 farmers participated in the research (109 in-scheme and 53 out of scheme). The findings revealed that group helping and information sharing among scheme members was low with a positive BVD status subject to social censure. Peer monitoring in the form of gossip with regard to the animal health status of other farms was high. Interestingly, farmers across both schemes supported greater regulation with regard to animal health, largely due to the mistrust of fellow farmers following voluntary disease control measures. While group cohesiveness varied across the two schemes, without continued financial inducements, longer-term sustainability is questionable. PMID:27023269

  20. Chocolate cake. Guilt or celebration? Associations with healthy eating attitudes, perceived behavioural control, intentions and weight-loss.

    Science.gov (United States)

    Kuijer, Roeline G; Boyce, Jessica A

    2014-03-01

    Food and eating are often associated with ambivalent feelings: pleasure and enjoyment, but also worry and guilt. Guilt has the potential to motivate behaviour change, but may also lead to feelings of helplessness and loss of control. This study firstly examined whether a default association of either 'guilt' or 'celebration' with a prototypical forbidden food item (chocolate cake) was related to differences in attitudes, perceived behavioural control, and intentions in relation to healthy eating, and secondly whether the default association was related to weight change over an 18month period (and short term weight-loss in a subsample of participants with a weight-loss goal). This study did not find any evidence for adaptive or motivational properties of guilt. Participants associating chocolate cake with guilt did not report more positive attitudes or stronger intentions to eat healthy than did those associating chocolate cake with celebration. Instead, they reported lower levels of perceived behavioural control over eating and were less successful at maintaining their weight over an 18month period. Participants with a weight-loss goal who associated chocolate cake with guilt were less successful at losing weight over a 3month period compared to those associating chocolate cake with celebration.

  1. Farmer Attitudes and Livestock Disease: Exploring Citizenship Behaviour and Peer Monitoring across Two BVD Control Schemes in the UK.

    Science.gov (United States)

    Heffernan, Claire; Azbel-Jackson, Lena; Brownlie, Joe; Gunn, George

    2016-01-01

    The eradication of BVD in the UK is technically possible but appears to be socially untenable. The following study explored farmer attitudes to BVD control schemes in relation to advice networks and information sharing, shared aims and goals, motivation and benefits of membership, notions of BVD as a priority disease and attitudes toward regulation. Two concepts from the organisational management literature framed the study: citizenship behaviour where actions of individuals support the collective good (but are not explicitly recognised as such) and peer to peer monitoring (where individuals evaluate other's behaviour). Farmers from two BVD control schemes in the UK participated in the study: Orkney Livestock Association BVD Eradication Scheme and Norfolk and Suffolk Cattle Breeders Association BVD Eradication Scheme. In total 162 farmers participated in the research (109 in-scheme and 53 out of scheme). The findings revealed that group helping and information sharing among scheme members was low with a positive BVD status subject to social censure. Peer monitoring in the form of gossip with regard to the animal health status of other farms was high. Interestingly, farmers across both schemes supported greater regulation with regard to animal health, largely due to the mistrust of fellow farmers following voluntary disease control measures. While group cohesiveness varied across the two schemes, without continued financial inducements, longer-term sustainability is questionable.

  2. A close examination of under-actuated attitude control subsystem design for future satellite missions' life extension

    Science.gov (United States)

    Lam, Quang M.; Barkana, Itzhak

    2014-12-01

    Satellite mission life, maintained and prolonged beyond its typical norm of their expectancy, are primarily dictated by the state of health of its Reaction Wheel Assembly (RWA), especially for commercial GEO satellites since torquer bars are no longer applicable while thruster assistant is unacceptable due to pointing accuracy impact during jet firing. The RWA is the primary set of actuators (as compared to thrusters for orbit maintenance and maneuvering) mainly responsible for the satellite mission for accurately and precisely pointing its payloads to the right targets to conduct its mission operations. The RWA consisting of either a set of four in pyramid or three in orthogonal is the primary set of actuators to allow the satellite to achieve accurate and precise pointing of the satellite payloads towards the desired targets. Future space missions will be required to achieve much longer lives and are currently perceived by the GEO satellite community as an "expected norm" of 20 years or longer. Driven by customers' demands/goals and competitive market have challenged Attitude Control Subsystems (ACS) engineers to develop better ACS algorithms to address such an emerging need. There are two main directions to design satellite's under-actuated control subsystem: (1) Attitude Feedback with Zero Momentum Principle and (2) Attitude Control by Angular Velocity Tracking via Small Time Local Controllability concept. Successful applications of these control laws have been largely demonstrated via simulation for the rest to rest case. Limited accuracy and oscillatory behaviors are observed in three axes for non-zero wheel momentum while realistic loss of a wheel scenario (i.e., fully actuated to under-actuated) has not been closely examined! This study revisits the under-actuated control design with detailed set ups of multiple scenarios reflecting real life operating conditions which have put current under-actuated control laws mentioned earlier into a re-evaluation mode

  3. The influence of patient's consciousness regarding high blood pressure and patient's attitude in face of disease controlling medicine intake

    Directory of Open Access Journals (Sweden)

    Maria Aparecida A Moura Strelec

    2003-10-01

    Full Text Available OBJECTIVE: To assess the relation between blood pressure control and the following: the Morisky-Green test, the patient's consciousness regarding high blood pressure, the patient's attitude in face of medicine intake, the patient's attendance at medical consultations, and the subjective physician's judgment. METHODS: We studied 130 hypertensive patients with the following characteristics: 73% females, 60±11 years, 58% married, 70% white, 45% retired, 45% with incomplete elementary schooling, 64% had a familial income of 1 to 3 minimum wages, body mass index of 30±7 kg/m², consciousness regarding the disease for a mean period of 11±9.5 years, and mean treatment duration of 8 ±7 years. RESULTS: Only 35% of the hypertensive individuals had blood pressure under control and a longer duration of treatment (10±7 vs 7±6.5 years; P<0.05. The retiree predominated. The result of the Morisky-Green test did not relate to blood pressure control. In evaluating the attitude in face of medicine intake, the controlled patients achieved significantly higher scores than did the noncontrolled patients (8±1.9 vs 7 ±2, P<0.05. The hypertensive patients had higher levels of consciousness regarding their disease and its treatment, and most (70% patients attended 3 or 4 medical consultations, which did not influence blood pressure control. The physicians attributed significantly higher scores regarding adherence to treatment to controlled patients (6±0.8 vs 5±1.2; P<0.05. CONCLUSION: Consciousness regarding the disease, the Morisky-Green test, and attendance to medical consultations did not influence blood pressure control.

  4. A Near-Hover Adaptive Attitude Control Strategy of a Ducted Fan Micro Aerial Vehicle with Actuator Dynamics

    Directory of Open Access Journals (Sweden)

    Shouzhao Sheng

    2015-09-01

    Full Text Available The aerodynamic parameters of ducted fan micro aerial vehicles (MAVs are difficult and expensive to precisely measure and are, therefore, not available in most cases. Furthermore, the actuator dynamics with risks of potentially destabilizing the overall system are important but often neglected consideration factors in the control system design of ducted fan MAVs. This paper presents a near-hover adaptive attitude control strategy of a prototype ducted fan MAV with actuator dynamics and without any prior information about the behavior of the MAV. The proposed strategy consists of an online parameter estimation algorithm and an adaptive gain scheduling algorithm, with the former accommodating parametric uncertainties, and the latter approximately eliminating the coupling among axes and guaranteeing the control quality of the MAV. The effectiveness of the proposed strategy is verified numerically and experimentally.

  5. Relations among weight control behaviors and eating attitudes, social physique anxiety, and fruit and vegetable consumption in Turkish adolescents.

    Science.gov (United States)

    Baş, Murat; Kiziltan, Gül

    2007-01-01

    This study examined the relationship among dieting, eating attitudes, social physique anxiety, and fruit and vegetable consumption among Turkish adolescents. Abnormal eating behavior (EAT-26 > or =20) was found in 32.8% of the total sample; this included 26.4% of the males and 38.7% of the females. Weight-control and weight-related behaviors are associated with high fruit and vegetable consumption in adolescents. Dieting was significantly associated with types of consumption in female adolescents. In addition, EAT-26 scores were significantly positively correlated with high fruit and vegetable consumption, but this association was not observed in SPAS scores among adolescents. Adolescents who engage in dieting behaviors seem to consume more fruit and vegetables than do other adolescents. Female adolescents may be more likely to display abnormal eating attitudes and dieting behaviors than do males. Although some weight-control behaviors may be risky, adolescents who were practicing dieting behaviors engaged in the positive dietary behavior of consuming more servings of fruit and vegetables than did non-dieters.

  6. 基于势函数法的航天器自主姿态机动控制%Spacecraft Autonomous Attitude Maneuver Control by Potential Function Method

    Institute of Scientific and Technical Information of China (English)

    郭延宁; 李传江; 马广富

    2011-01-01

    主要研究存在禁止姿态的航天器自主姿态机动控制问题.首先,给出航天器的动力学和运动学模型,利用四元数描述航天器与机动姿态和禁止姿态的姿态偏差,用相应的欧拉转角描述不同姿态间的距离.为利用势函数完成禁止姿态回避,结合航天器的运动情况设计排斥势函数(RPF)存在条件后,根据禁止姿态最小允许夹角构造一种新的排斥势函数.接着,利用排斥及吸引势函数(APF)的共同作用得到虚拟指令角速度,利用反步法得到自主姿态机动控制器.此外,针对控制受限问题给出控制参数自适应规则,并设计回避势函数局部极小值情况的切换控制器.最后,通过对不同禁止姿态区域的数学仿真,验证了设计方法的有效性和通用性.%This article investigates the spacecraft autonomous attitude maneuver control in the presence of forbidden attitude. First, the dynamical and kinematic equations are introduced, in which a quaternion is adopted to represent the attitude deviation between the spacecraft attitude and maneuver or the forbidden attitude, with the corresponding Euler rotation angles describing the distance of various attitudes. Second, in order to avoid the forbidden attitude, the existence conditions for the repulsive potential function (RPF) are exploited by incorporating the spacecraft motions, and a novel RPF is proposed according to the minimum separation angle allowed for the forbidden attitude. The RPF as well as the attractive potential function (APF) are employed subsequently to derive a virtual angular velocity command. An autonomous attitude maneuver controller is obtained by means of backstepping. Meanwhile, some self-adaptive rules for the control parameters are developed to deal with control saturation. In addition, one switch controller is proposed to overcome the local minima of the potential function. Finally, numerical results for different forbidden attitude regions are

  7. Opportunities for improved chagas disease vector control based on knowledge, attitudes and practices of communities in the yucatan peninsula, Mexico.

    Directory of Open Access Journals (Sweden)

    Kathryn Rosecrans

    2014-03-01

    Full Text Available BACKGROUND: Chagas disease is a vector-borne parasitic disease of major public health importance. Current prevention efforts are based on triatomine vector control to reduce transmission to humans. Success of vector control interventions depends on their acceptability and value to affected communities. We aimed to identify opportunities for and barriers to improved vector control strategies in the Yucatan peninsula, Mexico. METHODOLOGY/PRINCIPAL FINDINGS: We employed a sequence of qualitative and quantitative research methods to investigate knowledge, attitudes and practices surrounding Chagas disease, triatomines and vector control in three rural communities. Our combined data show that community members are well aware of triatomines and are knowledgeable about their habits. However, most have a limited understanding of the transmission dynamics and clinical manifestations of Chagas disease. While triatomine control is not a priority for community members, they frequently use domestic insecticide products including insecticide spray, mosquito coils and plug-in repellents. Families spend about $32 US per year on these products. Alternative methods such as yard cleaning and window screens are perceived as desirable and potentially more effective. Screens are nonetheless described as unaffordable, in spite of a cost comparable to the average annual spending on insecticide products. CONCLUSION/SIGNIFICANCE: Further education campaigns and possibly financing schemes may lead families to redirect their current vector control spending from insecticide products to window screens. Also, synergism with mosquito control efforts should be further explored to motivate community involvement and ensure sustainability of Chagas disease vector control.

  8. Spacecraft Attitude Control under Control Constraint with Velocity-free%控制受限航天器无角速度反馈姿态控制

    Institute of Scientific and Technical Information of China (English)

    王岩; 唐强; 陈兴林

    2011-01-01

    重点研究了控制受限和角速度不可测情况下航天器姿态快速跟踪问题.首先定义了四元数辅助系统,并设计了包含实际误差四元数和观测误差四元数的双曲正切函数的非线性控制律;然后,证明了系统的稳定性以及控制量的有界性;最后通过数字仿真与已有的方法进行比较研究,说明该方法能大大提高卫星姿态跟踪精度和响应速度.%Attitude control of rigid spacecraft without the measurement of angular velocity was proposed in the case of physical limits of actuators. First a quaternion auxiliary dynamical system was defined, and then a nonlinear feedback control law of hyperbolic tangent function with real and estimated errors of unit-quaternion was presented. The stability of the tracking error system with bounded control effort was proved. The performance of the proposed control algorithm was verified through numerical simulations. It shows that both the satellite attitude accuracy and response speed can be improved greatly compared to other methods.

  9. Knowledge, awareness, and attitude regarding infection prevention and control among medical students: a call for educational intervention

    Directory of Open Access Journals (Sweden)

    Ibrahim AA

    2016-08-01

    Full Text Available Awab Ali Ibrahim,1 Sittana Shamseldin Elshafie,2 1Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, 2Aspetar, Laboratory Department, Qatar Orthopedic and Sports Medicine Hospital, Doha, Qatar Background: Medical students can be exposed to serious health care-associated infections, if they are not following infection prevention and control (IPC measures. There is limited information regarding the knowledge, awareness, and practices of medical students regarding IPC and the educational approaches used to teach them these practices. Aim: To evaluate the knowledge, awareness, and attitude of medical students toward IPC guidelines, and the learning approaches to help improve their knowledge. Methods: A cross-sectional, interview-based survey included 73 medical students from Weill Cornell Medical College, Qatar. Students completed a questionnaire concerning awareness, knowledge, and attitude regarding IPC practices. Students’ knowledge was assessed by their correct answers to the survey questions. Findings: A total of 48.44% of the respondents were aware of standard isolation precautions, 61.90% were satisfied with their training in IPC, 66.13% were exposed to hand hygiene training, while 85.48% had sufficient knowledge about hand hygiene and practiced it on a routine basis, but only 33.87% knew the duration of the hand hygiene procedure. Conclusion: Knowledge, attitude, and awareness of IPC measures among Weill Cornell Medical Students in Qatar were found to be inadequate. Multifaceted training programs may have to target newly graduated medical practitioners or the training has to be included in the graduate medical curriculum to enable them to adopt and adhere to IPC guidelines. Keywords: infection prevention, education, medical students

  10. Providers' knowledge, attitudes, and practices related to colorectal cancer control in Brazil.

    Science.gov (United States)

    Perin, Douglas M Puricelli; Saraiya, Mona; Thompson, Trevor D; de Moura, Lenildo; Simoes, Eduardo J; Parra, Diana C; Brownson, Ross C

    2015-12-01

    In Brazil, colorectal cancer (CRC) is the fourth most common cause of cancer-related death among men, and the third most common among women. We aimed to examine CRC screening-related knowledge, attitudes, and practices among physicians and nurses working in Brazil's network of health units, and to describe the capacity of these units for CRC screening. In 2011, 1600 health units were randomly selected from all 26 states and the Federal District. One coordinator and one health care provider were selected for the interview. Response rates were 78% for coordinators, 34% for physicians, and 65% for nurses. The Brazilian National Cancer Institute (INCA) recommendations for CRC screening were not often used in the health units, but screening outreach and use of CRC exams were more common in units that were using them. Physicians and nurses differed in most characteristics, and in their knowledge, attitudes, and practices of CRC screening. Forty-seven percent of physicians reported not conducting CRC screening compared to 65% of nurses. Fecal occult blood test was most often used by physicians and nurses, but fewer physicians than nurses perceived this exam as very effective in reducing CRC mortality. Physicians' gender, years since graduation, and geographical region of practice in Brazil were associated to CRC screening practice. The findings may reflect the low influence of INCA CRC screening recommendations, physicians receiving their medical education when CRC burden in Brazil was of low concern, and the lack of CRC screening capacity in some regions of Brazil.

  11. The Effects of Peer-Controlled or Moderated Online Collaboration on Group Problem Solving and Related Attitudes

    Directory of Open Access Journals (Sweden)

    Ke Zhang

    2003-10-01

    Full Text Available Abstract. This study investigated the relative benefits of peer-controlled and moderated online collaboration during group problem solving. Thirty-five self-selected groups of four or five students were randomly assigned to the two conditions, which used the same online collaborative tool to solve twelve problem scenarios in an undergraduate statistics course. A score for the correctness of the solutions and a reasoning score were analyzed. A survey was administered to reveal differences in students' related attitudes. Three conclusions were reached: 1. Groups assigned to moderated forums displayed significantly higher reasoning scores than those in the peer-controlled condition, but the moderation did not affect correctness of solutions. 2. Students in the moderated forums reported being more likely to choose to use an optional online forum for future collaborations. 3. Students who reported having no difficulty during collaboration reported being more likely to choose to use an optional online forum in the future.

  12. Changes in eating attitudes, body esteem and weight control behaviours during adolescence in a South African cohort.

    Directory of Open Access Journals (Sweden)

    Tabither M Gitau

    Full Text Available Failure to consume an adequate diet or over consumption during adolescence can disrupt normal growth and development, resulting in undesirable weight change. This leads to an increase in unhealthy weight control practices related to eating and exercise among both adolescent girls and boys to meet the societal 'ideal' body shape. This study therefore aims to examine the longitudinal changes in eating attitudes, body-esteem and weight control behaviours among adolescents between 13 and 17 years; and, to describe perceptions around body shape at age 17 years. A total of 1435 urban South African black and mixed ancestry boys and girls, who had data at both age 13 and 17 years from the Birth to Twenty cohort were included. Data were collected through self-administered questionnaires on eating attitudes (EAT-26, body esteem and weight control behaviours for either weight loss or muscle gain attempts. Height and weight were measured at both time points and BMI was calculated. Black females had a higher BMI (p<0.001 and an increased risk of developing eating disorders as well as significant increase in the prevalence of weight loss practices between the ages 13 and 17 years. At age 17 years both Mixed ancestry adolescents had lower body-esteem compared to black adolescents. The prevalence of possible eating disorders was 11% and 13.1% in early and late adolescents respectively. Males and females shared similar opinions on normal silhouettes being the 'best', 'getting respect' and being the 'happiest', while the obese silhouette was associated with the 'worst' and the 'unhappiest', and the underweight silhouette with the "weakest". Black females had a higher BMI and an increased risk of developing eating disorders. Adolescent females engaged more in weight loss practices whereas, males in muscle gain practices indicating that Western norms of thinness as the ideal are becoming more common in South Africa.

  13. Metabolic Control, Nutrition Knowledge, Attitude and Practice in Non-Insulin-dependent Diabetic Patients from Kohgiluyeh and Boyer-Ahmad Province, South-West of Iran

    Directory of Open Access Journals (Sweden)

    Janmohamad Malekzadeh

    2016-07-01

    Full Text Available Background and Objectives: Diabetes mellitus is among the most common causes of mortality in the world and an important risk factor for chronic kidney disease, foot amputation, ischemic heart disease and blindness among older adults. Diabetic patients mostly develop hyperlipidemia, which can result in cardiovascular diseases. Patient’s knowledge, attitude and practices toward diet are the core center for diabetes control and affect their metabolic control and complications. In the present study, we measured nutritional knowledge, attitude and practices and their relations to serum lipids, HbA1C, and fasting blood glucose in diabetic patients of Boirahmad County, southwest of Iran, where many people encounter increasing prevalence of diabetes. Materials and Methods: 198 IDDM patients from the rural and urban areas of Boirahmad County were invited to the health centers to be checked for their fasting blood glucose, serum total cholesterol, serum HDL cholesterol, serum triglyceride and also serum glycosylated hemoglobin. Their knowledge, attitude, and practices toward the diabetic diet were assessed using a validated questionnaire. The obtained scores were classified into three categories (Poor, average, and Good to show their knowledge, attitude and practice levels, and the serum parameters were compared between the levels to show the relevancies. Results: Our data showed that the patients’ knowledge and attitude on diabetic nutrition are mostly at the average level (79.3% and 47.1%, respectively but their practice scores are mostly at the poor level (43.8%, and just a minor proportion of the patients are at the appropriate levels (15.3, 33, and 23.1% of knowledge, attitude and practices, respectively. In addition, we found a significant reverse relationship between the patients’ nutritional knowledge and  serum HbA1C (p=0.003, and also between their attitude and serum triglyceride (p<0.05. Conclusions: Our data suggest that the knowledge

  14. Urban resident attitudes toward rodents, rodent control products, and environmental effects

    Science.gov (United States)

    Rodent control in urban areas can result in the inadvertent mortality of non-target species (e.g., bobcats). However, there is little detailed information about rodent control practices of urban residents. Our objective was to evaluate urban rodent control behaviors in two area...

  15. Application of hybrid robust three-axis attitude control approach to overactuated spacecraft-A quaternion based model

    Institute of Scientific and Technical Information of China (English)

    A. H. Mazinan

    2016-01-01

    A novel hybrid robust three-axis attitude control approach, namely HRTAC, is considered along with the well-known developments in the area of space systems, since there is a consensus among the related experts that the new insights may be taken into account as decision points to outperform the available materials. It is to note that the traditional control approaches may generally be upgraded, as long as a number of modifications are made with respect to state-of-the-art, in order to propose high-precision outcomes. Regarding the investigated issues, the robust sliding mode finite-time control approach is first designed to handle three-axis angular rates in the inner control loop, which consists of the pulse width pulse frequency modulations in line with the control allocation scheme and the system dynamics. The main subject to employ these modulations that is realizing in association with the control allocation scheme is to be able to handle a class of overactuated systems, in particular. The proportional derivative based linear quadratic regulator approach is then designed to handle three-axis rotational angles in the outer control loop, which consists of the system kinematics that is correspondingly concentrated to deal with the quaternion based model. The utilization of the linear and its nonlinear terms, simultaneously, are taken into real consideration as the research motivation, while the performance results are of the significance as the improved version in comparison with the recent investigated outcomes. Subsequently, there is a stability analysis to verify and guarantee the closed loop system performance in coping with the whole of nominal referenced commands. At the end, the effectiveness of the approach considered here is highlighted in line with a number of potential recent benchmarks.

  16. Using E-Portfolios in a Field Experience Placement: Examining Student-Teachers' Attitudes towards Learning in Relationship to Personal Value, Control and Responsibility

    Science.gov (United States)

    Shroff, Ronnie H.; Trent, John; Ng, Eugenia M. W.

    2013-01-01

    This study extends the ownership of learning model by using e-portfolios in a field experience placement to examine student-teachers' attitudes towards learning in relationship to personal value, feeling in control and taking responsibility. A research model is presented based on research into ownership of learning. The student e-portfolio…

  17. Microprocessor based implementation of attitude and shape control of large space structures

    Science.gov (United States)

    Reddy, A. S. S. R.

    1984-01-01

    The feasibility of off the shelf eight bit and 16 bit microprocessors to implement linear state variable feedback control laws and assessing the real time response to spacecraft dynamics is studied. The complexity of the dynamic model is described along with the appropriate software. An experimental setup of a beam, microprocessor system for implementing the control laws and the needed generalized software to implement any state variable feedback control system is included.

  18. Resistance test of high-speed ship by means of attitude control method. Part 2; Shisei seigyo hoshiki ni yoru kosokutei no teiko shiken. 2

    Energy Technology Data Exchange (ETDEWEB)

    Hayashida, S. [Nagasaki Institute of Applied Science, Nagasaki (Japan)

    1996-04-10

    The previous paper has proposed a resistance test method by controlling the attitude of a high-speed model ship using a personal computer without making a data base. For this method, the fluid force acting on the hull of model ship is measured, to change its attitude based on the measurement, and then, the fluid force is measured again, to change the attitude again. The traveling attitude is created by repeating this, to measure the force acting on the hull. Since the attitude is changed by calculating using the fluid force measured, various factors can be considered in the calculation process. For example, a test with an arbitrary displacement in an arbitrary position of center of gravity can be conducted in spite of actual displacement and position of center of gravity of the model ship. A test for a high-speed ship was conducted through this method, to obtain nearly satisfactory results compared with a usual resistance test. Occasionally, a lot of repetitions were required to satisfy the balancing condition of the force. In this study, the improvement of testing efficiency has been planned by modifying the analyzing program. 5 refs., 7 figs., 1 tab.

  19. Onboard Supervisor for the Ørsted Satellite Attitude Control System

    DEFF Research Database (Denmark)

    Bøgh, S.A.; Izadi-Zamanabadi, Roozbeh; Blanke, M.

    1995-01-01

    The increasing operational requirements for onboard autonomy in satellite control systems necessitates structural methods that support the design of a complete and reliable supervisory system.......The increasing operational requirements for onboard autonomy in satellite control systems necessitates structural methods that support the design of a complete and reliable supervisory system....

  20. Wave-Based Attitude Control of Spacecraft with Fuel Sloshing Dynamics

    Directory of Open Access Journals (Sweden)

    Thompson Joseph William

    2016-06-01

    Full Text Available Wave-Based Control has been previously applied successfully to simple under-actuated flexible mechanical systems. Spacecraft and rockets with structural flexibility and sloshing are examples of such systems but have added difficulties due to non-uniform structure, external disturbing forces and non-ideal actuators and sensors. The aim of this paper is to extend the application of WBC to spacecraft systems, to compare the performance of WBC to other popular controllers and to carry out experimental validation of the designed control laws. A mathematical model is developed for an upper stage accelerating rocket moving in a single plane. Fuel sloshing is represented by an equivalent mechanical pendulum model. A wave-based controller is designed for the upper stage AVUM of the European launcher Vega. In numerical simulations the controller successfully suppresses the sloshing motion. A major advantage of the strategy is that no measurement of the pendulum states (sloshing motion is required.

  1. Smoking Prevalence and Associated Factors as well as Attitudes and Perceptions towards Tobacco Control in Northeast China

    Directory of Open Access Journals (Sweden)

    Zhijun Li

    2015-07-01

    Full Text Available Objectives: The present study aimed to investigate the prevalence of smoking and environmental tobacco smoke (ETS, the associated factors of current smoking among adults, and their attitudes and perceptions towards tobacco control. Methods: A population-based cross-sectional survey was conducted in 2012 using a self-reported questionnaire. A representative sample of adults aged 18–79 years was collected in the Jilin Province of Northeast China by a multistage stratified random cluster sampling design. Descriptive data analysis was conducted, and 95% confidence intervals (CI of prevalence/frequency were calculated to enable comparisons between the alleged differences and similarities. Multivariable logistic regressions were used to examine the risk factors associated with current smoking. Results: 21,435 adults responded to the survey (response rate: 84.9%. The overall prevalence of ever smoking, current smoking, and former smoking or smoking cessation was 39.1% (95% CI: 38.3–39.9, 31.8% (95% CI 31.1–32.6, and 7.3% (95% CI: 6.9–7.7, respectively. The proportion of ETS exposure among adult non-smokers in Jilin Province was 61.1% (95% CI: 60.1–62.1, and 23.1% (95% CI: 22.3–24.0 of the non-smokers reported daily ETS exposure. The proportion of ETS exposure at home was 33.4% (95% CI: 32.5–34.4, but the proportion of ETS exposure at restaurants was lower (6.5% (95% CI: 6.0–7.1. More than 90% of the participants had positive attitudes and perceptions towards tobacco control, but 23.2% (95% CI: 22.5–24.0 of them did not agree with the perception of “smoking is fully quit in public places”, and almost half of the adults (49.5% (95% CI: 48.7–50.3 did not agree with the perception of “hazards of low-tar cigarettes are equal to general cigarettes”. Conclusions: Smoking and exposure to ETS are prevalent among adults from the Jilin Province of Northeast China. Our findings suggest that tobacco control should be advocated in

  2. Parasitic worms: knowledge, attitudes, and practices in Western Cote d'Ivoire with implications for integrated control.

    Directory of Open Access Journals (Sweden)

    Cinthia A Acka

    Full Text Available BACKGROUND: In the developing world where parasitic worm infections are pervasive, preventive chemotherapy is the key strategy for morbidity control. However, local knowledge, attitudes, and practices (KAP of parasitic worms are poorly understood, although such information is required for prevention and sustainable control. METHODS: We carried out KAP surveys in two rural communities of Côte d'Ivoire that were subjected to school-based and community-based research and control activities. We used qualitative and quantitative methods. The former included observations, in-depth interviews with key informants, and focus group discussions with school children and adults. Quantitative methods consisted of a structured questionnaire administered to household heads. PRINCIPAL FINDINGS: Access to clean water was lacking in both communities and only a quarter of the households had functioning latrines. There was a better understanding of soil-transmitted helminthiasis than intestinal schistosomiasis, but community-based rather than school-based interventions appeared to improve knowledge of schistosomiasis. In the villages with community-based interventions, three-quarters of household interviewees knew about intestinal schistosomiasis compared to 14% in the village where school-based interventions were implemented (P<0.001. Whereas two-thirds of respondents from the community-based intervention village indicated that the research and control project was the main source of information, only a quarter of the respondents cited the project as the main source. CONCLUSIONS/SIGNIFICANCE: Preventive chemotherapy targeting school-aged children has limitations, as older population segments are neglected, and hence lack knowledge about how to prevent and control parasitic worm infections. Improved access to clean water and sanitation is necessary, along with health education to make a durable impact against helminth infections.

  3. 编队卫星姿态的自适应协同控制%Adaptive Coordinated Control of Formation Spacecraft Attitude

    Institute of Scientific and Technical Information of China (English)

    李贵明; 刘良栋

    2011-01-01

    We address multiple rigid spacecraft attitude coordinated and tracking control under a general undirected interaction topology. Distributed attitude coordinated controllers are considered for multiple spacecraft without model parameter or disturbance uncertainties, and with unknown model parameter and constant external disturbances. For the first case, the controller designed based on the sliding mode guarantees that all group spacecraft can achieve synchronized attitude maneuver, I.e. , tracking a time-varying desired attitude while synchronizing their attitudes. For the second case, we design an adaptive coordinated attitude controller, to obtain synchronized attitude maneuver. Based on Lyapunov-Krasovskii method, our proposed controllers are robust to the constant communication delays existing in information exchange channels. Numerical simulations have demonstrated the effectiveness of our proposed approach.%研究了无向信息交互条件下的多卫星姿态同步和跟踪问题,分别在模型参数精确已知和存在模型参数不确定性的情形下设计分散式协同控制算法.当模型参数精确已知时,基于滑动模态变量设计的协同控制力矩,实现了编队卫星姿态的同步机动,即保证编队卫星姿态的同步,并同时跟踪期望的时变参考姿态轨迹.当在轨卫星存在模型参数不确定性和常值未知扰动力矩时,提出了一种自适应协同控制律,仍能实现多卫星姿态的同步机动.基于Lyapunov-Krasovskii的分析表明,当星间链路存在任意未知的定常通讯时延时,本文设计的控制器有效.数值仿真算例验证了本文提出的控制算法.

  4. Attitude control system synthesis for the Hoop/Column antenna using the LQG/LTR method. [loop transfer recovery

    Science.gov (United States)

    Sundararajan, N.; Joshi, S. M.; Armstrong, E. S.

    1986-01-01

    This paper investigates the application of the linear-quadratic-Gaussian (LQG)/loop transfer recovery (LTR) method to the problem of synthesizing a fine-pointing control system for a large flexible space anenna. The study is based on an antenna, which consists of three rigid-body rotational modes and the first ten elastic modes. A robust compensator design for achieving the required pointing performance in the presence of modeling uncertainties is obtained using the LQG/LTR method. For the Hoop/Column antenna, a satisfactory controller design meeting a desired bandwidth of .1 rad/sec and ensuring stability with unmodelled high frequency modes is obtained using only a collocated pair of 3-axis attitude sensors and torque actuators. This study also indicates that to achieve the desired performance bandwidth of 0.1 rad/sec. and to ensure stability in the presence of higher frequency elastic modes, the design model should include at least the first three flexible modes together with the rigid body modes.

  5. Attitude Control of a Single Tilt Tri-Rotor UAV System: Dynamic Modeling and Each Channel's Nonlinear Controllers Design

    Directory of Open Access Journals (Sweden)

    Juing-Shian Chiou

    2013-01-01

    Full Text Available This paper has implemented nonlinear control strategy for the single tilt tri-rotor aerial robot. Based on Newton-Euler’s laws, the linear and nonlinear mathematical models of tri-rotor UAVs are obtained. A numerical analysis using Newton-Raphson method is chosen for finding hovering equilibrium point. Back-stepping nonlinear controller design is based on constructing Lyapunov candidate function for closed-loop system. By imitating the linguistic logic of human thought, fuzzy logic controllers (FLCs are designed based on control rules and membership functions, which are much less rigid than the calculations computers generally perform. Effectiveness of the controllers design scheme is shown through nonlinear simulation model on each channel.

  6. Effects of a Lifestyle Modification Program on Knowledge, Attitude and Practice of Hypertensive Patients with Angioplasty: A Randomized Controlled Clinical Trial

    Science.gov (United States)

    Jafari, Fahimeh; Shahriari, Mohsen; Sabouhi, Fakhri; Khosravi Farsani, Alireza; Eghbali Babadi, Maryam

    2016-01-01

    ABSTRACT Background: Lack of knowledge, attitude and practice are some of the barriers of having a healthy lifestyle and controlling high blood pressure. This study aimed to determine the effectiveness of a lifestyle modification program on knowledge, attitude and practice of hypertensive patients with angioplasty. Methods: This study was a randomized controlled clinical trial conducted from November to April 2014 on 60 hypertensive patients with angioplasty in Shahid Chamran hospital of Isfahan, Iran. The samples were randomly assigned to two equal groups. Data collection was performed in three stages by a researcher-made questionnaire. The intervention plan was 6 education sessions and then follow up were done by phone call. The gathered data were analyzed via SPSS (V.20), using t-test, Chi-square, repeated measurement, and post hoc LSD test and ANOVA statistics. Results: The mean score of knowledge, attitude and practice in the experimental group immediately after the intervention was 77.8±7.2, 88.3±6.4 and 86.2±6.5, respectively and one month after the intervention was 80.8±7.4, 91.1±3.5 and 92.5±2.2, respectively. But in the control group, the mean score of knowledge, attitude and practice immediately after the intervention (34.90±11.23, 61.11±6.28, and 38.64±7.15) and one month after the intervention was (38.64±7.15, 59.56±6.31 and 37.27±7.26. Conclusion: Lifestyle modification program can be effective in promoting the knowledge, attitude and practice of hypertensive patients with angioplasty. Nurses can use this program in their care provision programs for these patients. Trial Registration Number:IRCT2015062420912N3 PMID:27713892

  7. Buddha as an eye opener: a link between prosocial attitude and attentional control

    NARCIS (Netherlands)

    Colzato, L.S.; Hommel, B.; van den Wildenberg, W.P.M.; Hsieh, S.

    2010-01-01

    Increasing evidence suggests that religious practice induces systematic biases in attentional control. We used Navon's global-local task to compare attentional bias in Taiwanese Zen Buddhists and Taiwanese atheists; two groups brought up in the same country and culture and matched with respect to ra

  8. Consumer attitudes regarding internet health information and communication: Gender, locus of control, and stress implications

    Directory of Open Access Journals (Sweden)

    Joshua Fogel

    2009-01-01

    Full Text Available Los estudiantes universitarios utilizan internet para comunicarse y obtener información sobre salud. Se realizó un estudio descriptivo mediante una encuesta a 227 estudiantes para determinar si había diferencias entre aquellos que utilizan internet y el correo electrónico para informarse sobre salud y aquellos que no. Las variables dependientes fueron la Escala de Estrés Percibido y las subescalas de la Escala Multidimensional de Locus de Control de la Salud. Las variables independientes incluyeron preguntas sobre la utilización de internet para informarse o comunicarse con otros sobre salud. Se realizaron análisis para el total de la muestra y por género. En los tres ítems de comunicación, los que utilizaban internet/correo electrónico mostraron un nivel de estrés percibido significativamente más alto. No hubo diferencias entre los que usaban internet para buscar información sobre salud. Estos resultados se mantuvieron para hombres y se acercaron a la significación para las mujeres. Los que utilizan internet para obtener información sobre salud puntuaron significativamente más alto en la subescala de locus de control interno. Estos resultados se mantuvieron en los varones, mientras que para las mujeres fue significativa la subescala de control por otros poderes. Los hombres con estrés percibido se comunican por correo electrónico o internet sobre salud, mientras que las mujeres no. Respecto al uso de información sobre salud en internet, los hombres utilizan un locus de control interno y las mujeres un locus de control por otros poderes. Estos resultados son útiles para los profesionales que asesoren a universitarios con problemas de salud.

  9. Fault tolerant attitude control of flexible spacecraft during orbit control%挠性航天器轨控期间姿态容错控制

    Institute of Scientific and Technical Information of China (English)

    杨婧; 侯建文; 史小平

    2015-01-01

    轨道调控期间,轨道控制推力会对挠性航天器的质心运动与姿态运动产生影响。针对轨道控制期间挠性航天器姿态控制系统的执行机构故障问题,提出了一种基于扩张状态观测器( ex-tended state observer, ESO)的滑模容错控制算法。该算法将执行器故障,系统干扰及参数摄动量视为未知动态,通过设计相应的扩张状态观测器,能有效的实现对滑模状态量及未知动态的估计;在此基础上,利用未知动态的估计信息,设计了滑模容错控制控制律。最后,针对轨控期间反作用飞轮故障的挠性航天器姿态系统进行了仿真研究,仿真结果表明该算法能够有效处理执行器故障并使闭环系统稳定。%The orbit control force would generate disturb torque which has impacts on the centroid and at-titude motion of flexible spacecraft during spacecraft orbit maneuver. A sliding mode fault tolerant control approach was proposed based on an extended state observer ( ESO ) for the flexible spacecraft attitude control system with actuator faults during orbit control. In this approach, unknown actuator faults, inter-nal and external disturbance, and parameter perturbation are considered as unknown dynamics. Based on the ESO design approach, sliding mode and unknown dynamics were effectively estimated, and sliding mode fault tolerant control approach was designed by using the estimating information. At last, the simu-lation results of flexible spacecraft were presented to demonstrate the effective of this approach.

  10. Nonlinear fractional order proportion-integral-derivative active disturbance rejection control method design for hypersonic vehicle attitude control

    Science.gov (United States)

    Song, Jia; Wang, Lun; Cai, Guobiao; Qi, Xiaoqiang

    2015-06-01

    Near space hypersonic vehicle model is nonlinear, multivariable and couples in the reentry process, which are challenging for the controller design. In this paper, a nonlinear fractional order proportion integral derivative (NFOPIλDμ) active disturbance rejection control (ADRC) strategy based on a natural selection particle swarm (NSPSO) algorithm is proposed for the hypersonic vehicle flight control. The NFOPIλDμ ADRC method consists of a tracking-differentiator (TD), an NFOPIλDμ controller and an extended state observer (ESO). The NFOPIλDμ controller designed by combining an FOPIλDμ method and a nonlinear states error feedback control law (NLSEF) is to overcome concussion caused by the NLSEF and conversely compensate the insufficiency for relatively simple and rough signal processing caused by the FOPIλDμ method. The TD is applied to coordinate the contradiction between rapidity and overshoot. By attributing all uncertain factors to unknown disturbances, the ESO can achieve dynamic feedback compensation for these disturbances and thus reduce their effects. Simulation results show that the NFOPIλDμ ADRC method can make the hypersonic vehicle six-degree-of-freedom nonlinear model track desired nominal signals accurately and fast, has good stability, dynamic properties and strong robustness against external environmental disturbances.

  11. AIRSHIP ATTITUDE TRACKING SYSTEM

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-liang; SHAN Xue-xiong

    2006-01-01

    The attitude tracking control problem for an airship with parameter uncertainties and external disturbances was considered in this paper. The mathematical model of the airship attitude is a multi-input/multi-output uncertain nonlinear system. Based on the characteristics of this system, a design method of robust output tracking controllers was adopted based on the upper-bounds of the uncertainties. Using the input/output feedback linearization approach and Liapunov method, a control law was designed, which guarantees that the system output exponentially tracks the given desired output. The controller is easy to compute and complement. Simulation results show that, in the closed-loop system, precise attitude control is accomplished in spite of the uncertainties and external disturbances in the system.

  12. 航天器连续非光滑姿态控制律设计%Design of Continuous Non-Smooth Attitude Control Laws for Spacecraft

    Institute of Scientific and Technical Information of China (English)

    马克茂

    2012-01-01

    为了提高航天器姿态控制系统的鲁棒性和动态特性,应用非光滑控制方法设计了连续的姿态控制律,使闭环姿态控制系统具有齐次性,且齐次度为负,实现了姿态控制系统的有限时间稳定,以保证系统状态的动态特性.分别针对标称系统渗数不确定性和外部扰动等情形进行了仿真验证,仿真结果表明所设计的控制律在保证标称系统有限时间稳定性的同时,针对系统的不确定性和扰动具有鲁棒性.%For the attitude control system of a spacecraft, non-smooth control technique is utilized to improve the robustness and dynamic performance. A continuous attitude control law is given to ensure the homogeneity of the closed-loop attitude control system with a negative degree of homogeneity. The resulting attitude control system is finite-time stable, thus guaranteeing the dynamic performance of state variables. Simulation is carried out under the cases of the nominal system and the systems with parameter uncertainties and external disturbances, respectively. The simulation results show that, under the designed control law, the nominal system is finite-time stable, and uncertain systems are robust against uncertainties and disturbances.

  13. Attitude maneuver of spacecraft with a variable-speed double-gimbal control moment gyro

    Science.gov (United States)

    Jikuya, Ichiro; Fujii, Kenta; Yamada, Katsuhiko

    2016-10-01

    In this paper, two types of computational procedures are presented for a rest-to-rest spacecraft maneuver using a variable-speed double-gimbal control moment gyro (VSDGCMG). The first procedure is a numerical computational procedure in which a quasi-time-optimal trajectory satisfying several physical constraints is obtained by repeating the Newton's method. The other procedure is an approximate computational procedure in which an analytical solution is obtained by approximately solving a series of linear optimal control problems. The two procedures play complementary roles: the former is suitable for implementation, and the latter can be used to select an initial value for use in the former. The effectiveness of the proposed procedures is demonstrated by plotting the surfaces of maneuvering time for all rotational axes and by plotting time responses for several maneuvering examples.

  14. LQG/LTR Optimal Attitude Control of Small Flexible Spacecraft Using Free-Free Boundary Conditions

    Science.gov (United States)

    2006-08-03

    engine vibrating . A high recovery force from an SMA can be compared to the stretching or com- pression of a spring, such as one found in a mattress or a...Singer. “ Vibration Reduction Using Multi-Hump Extra-Insensitive Input Shapers.” 1995 American Control Confer- ence. 3830–3834. Evanston, IL: American...13 1.12 AEC-Able Engineering’s CoilAble Boom [49] . . . . . . . . . . . . . . . 14 2.1 Rotational- Vibrational Constraint

  15. Tilted wheel satellite attitude control with air-bearing table experimental results

    Science.gov (United States)

    Inumoh, Lawrence O.; Forshaw, Jason L.; Horri, Nadjim M.

    2015-12-01

    Gyroscopic actuators for satellite control have attracted significant research interest over the years, but their viability for the control of small satellites has only recently started to become clear. Research on variable speed gyroscopic actuators has long been focused on single gimbal actuators; double gimbal actuators typically operate at constant wheel spin rate and allow tilt angle ranges far larger than the ranges needed to operate most satellite missions. This research examines a tilted wheel, a newly proposed type of inertial actuator that can generate torques in all three principal axes of a rigid satellite using a spinning wheel and a double tilt mechanism. The tilt mechanism tilts the angular momentum vector about two axes providing two degree of freedom control, while variation of the wheel speed provides the third. The equations of motion of the system lead to a singularity-free system during nominal operation avoiding the need for complex steering logic. This paper describes the hardware design of the tilted wheel and the experimental setup behind both standalone and spherical air-bearing tables used to test it. Experimental results from the air bearing table are provided with the results depicting the high performance capabilities of the proposed actuator in torque generation.

  16. First- and higher-order models of attitudes, normative influence, and perceived behavioural control in the theory of planned behaviour.

    Science.gov (United States)

    Hagger, Martin S; Chatzisarantis, Nikos L D

    2005-12-01

    The present study examined the validity of an augmented version of Ajzen's (1991) theory of planned behaviour (TPB), adopting second-order latent factors to explain relationships between the differentiated components of the theory constructs. This model was tested on data from two independent samples, for exercise and dieting behaviours, respectively. The affective and instrumental attitude, injunctive and descriptive norms, and perceived controllability and self-efficacy constructs all exhibited discriminant validity in the first instance. First- and second-order confirmatory factor analyses exhibited satisfactory fit with the observed data from both samples. There were no substantial differences in the fit indices across the first- and second-order models, and the second-order models exhibited the most optimal parsimony-corrected fit indices. The higher-order models could therefore not be rejected on the grounds of inferior fit or parsimony. First- and second-order structural equation models accounted for significant variance in intentions and behaviour. These results corroborate Ajzen's (2002a) and Bagozzi, Lee, and van Loo's (2001) premise that recent augmentations of the TPB that differentiate the model components can be subsumed by global, higher-order factors while still making the distinction at the subordinate level.

  17. Effects of a Lifestyle Modification Program on Knowledge, Attitude and Practice of Hypertensive Patients with Angioplasty: A Randomized Controlled Clinical Trial

    Directory of Open Access Journals (Sweden)

    Fahimeh Jafari

    2016-10-01

    Full Text Available Background: Lack of knowledge, attitude and practice are some of the barriers of having a healthy lifestyle and controlling high blood pressure. This study aimed to determine the effectiveness of a lifestyle modification program on knowledge, attitude and practice of hypertensive patients with angioplasty. Methods: This study was a randomizedcontrolledclinical trial conducted from November to April 2014 on 60 hypertensive patients with angioplasty in ShahidChamran hospital of Isfahan, Iran. The samples were randomly assigned to two equal groups. Data collection was performed in three stages by a researcher-made questionnaire. The intervention plan was 6 education sessions and then follow up were done by phone call. The gathered data were analyzed via SPSS (V.20, using t-test, Chi-square, repeated measurement, and post hoc LSD test andANOVA statistics. Results: The mean score of knowledge, attitude and practice in the experimental group immediately after the intervention was 77.8±7.2, 88.3±6.4 and 86.2±6.5, respectively and one month after the intervention was 80.8±7.4, 91.1±3.5 and 92.5±2.2, respectively. But in the control group, the mean score of knowledge, attitude and practice immediately after the intervention (34.90±11.23, 61.11±6.28, and 38.64±7.15 and one month after the intervention was (38.64±7.15, 59.56±6.31 and 37.27±7.26. Conclusion: Lifestyle modification program can be effective in promoting the knowledge, attitude and practice of hypertensive patients with angioplasty. Nurses can use this program in their care provision programs for these patients.

  18. An Overview on Aerospatiale Magnetic Bearing Products for Spacecraft Attitude Control and for Industry

    Science.gov (United States)

    Samuel, Alain; Lechable, Bernard

    1996-01-01

    Aerospatiale magnetic bearings are based on the use of permanent magnets and on the control of the rotor around a zero force equilibrium point. The present developments of magnetic bearing wheels for space applications focus on the versatility of a basic design which leads to a family of reaction and momentum wheels with tailored torque and kinetic momentum, leading to competitive mass and cost. The present industrial applications concern kinetic energy accumulators, medical x-ray rotating devices, avionics equipment, cryotechnic compressors and vacuum pumps.

  19. Nonlinear Feedforward Control for Spacecraft Relative Attitude Tracking%航天器相对姿态跟踪的非线性前馈控制

    Institute of Scientific and Technical Information of China (English)

    铁钰嘉; 杨伟; 岳晓奎

    2011-01-01

    The spacecraft relative attitude kinematics and dynamics based on modified rodrigues parameters(MRP) were proposed in the presence of serious nonlinear and controller design complexity during spacecraft relative attitude tracking control. A nonlinear feedforward controller was designed using Lyapunov method. The control law can not only ensure global asymptotic steady of close-loop system, but also make relative attitude tracking errors converge to zero field speedily. By using Matlab/Simulink programming, the modeling and simulation of spacecraft relative attitude tracking were discussed. Numerical simulations are exploited to verify the effectiveness of the model and control law.%针对航天器相对姿态跟踪过程中严重的非线性及控制器设计的复杂性,建立了基于修正罗德里格斯参数的航天器相对姿态运动学和动力学方程并根据Lyapunov直接法设计了非线性前馈控制律.设计的控制律不仅保证闭环系统稳定,还使得航天器相对姿态跟踪误差快速收敛到零点邻域内.通过在Matlab/Simulink环境下对航天器相对姿态跟踪进行数值仿真,验证了建立模型和设计控制律的有效性.

  20. Knowledge, Self-Confidence and Attitudes towards Suicidal Patients at Emergency and Psychiatric Departments: A Randomised Controlled Trial of the Effects of an Educational Poster Campaign

    Science.gov (United States)

    van Landschoot, Renate; Portzky, Gwendolyn; van Heeringen, Kees

    2017-01-01

    Educational posters are used to enhance knowledge, attitudes and self-confidence of patients. Little is known on their effectiveness for educating health care professionals. As these professionals may play an important role in suicide prevention, the effects of a poster and accompanying evaluation and triage guide on knowledge, self-confidence and attitudes regarding suicidal thoughts and behaviours, were studied in a multicentre cluster randomised controlled trial, involving staff from 39 emergency and 38 psychiatric departments throughout Flanders (n = 1171). Structured self-report questionnaires assessed the knowledge, confidence and beliefs regarding suicidal behaviour management, and attitudes. Data were analysed through a Solomon four-group design, with random assignment to the different conditions. Baseline scores for knowledge and provider confidence were high. The poster and accompanying evaluation and triage guide did not have an effect on knowledge about suicide and self-confidence in suicidal behaviour management. However, the poster campaign appeared to be beneficial for attitudes towards suicidal patients, but only among staff from mental health departments that were assigned to the un-pretested condition. Given the limited effects of the poster campaign in the studied population with a relatively high baseline knowledge, the evaluation of this poster as part of a multimodal educational programme in a more heterogeneous sample of health care professionals is recommended. PMID:28335446

  1. Public attitudes towards alcohol control policies in Scotland and England: Results from a mixed-methods study.

    Science.gov (United States)

    Li, Jessica; Lovatt, Melanie; Eadie, Douglas; Dobbie, Fiona; Meier, Petra; Holmes, John; Hastings, Gerard; MacKintosh, Anne Marie

    2017-03-01

    The harmful effects of heavy drinking on health have been widely reported, yet public opinion on governmental responsibility for alcohol control remains divided. This study examines UK public attitudes towards alcohol policies, identifies underlying dimensions that inform these, and relationships with perceived effectiveness. A cross-sectional mixed methods study involving a telephone survey of 3477 adult drinkers aged 16-65 and sixteen focus groups with 89 adult drinkers in Scotland and England was conducted between September 2012 and February 2013. Principal components analysis (PCA) was used to reduce twelve policy statements into underlying dimensions. These dimensions were used in linear regression models examining alcohol policy support by demographics, drinking behaviour and perceptions of UK drinking and government responsibility. Findings were supplemented with a thematic analysis of focus group transcripts. A majority of survey respondents supported all alcohol policies, although the level of support varied by type of policy. Greater enforcement of laws on under-age sales and more police patrolling the streets were strongly supported while support for pricing policies and restricting access to alcohol was more divided. PCA identified four main dimensions underlying support on policies: alcohol availability, provision of health information and treatment services, alcohol pricing, and greater law enforcement. Being female, older, a moderate drinker, and holding a belief that government should do more to reduce alcohol harms were associated with higher support on all policy dimensions. Focus group data revealed findings from the survey may have presented an overly positive level of support on all policies due to differences in perceived policy effectiveness. Perceived effectiveness can help inform underlying patterns of policy support and should be considered in conjunction with standard measures of support in future research on alcohol control policies.

  2. Buddha as an Eye Opener: A Link between Prosocial Attitude and Attentional Control.

    Science.gov (United States)

    Colzato, Lorenza S; Hommel, Bernhard; van den Wildenberg, Wery P M; Hsieh, Shulan

    2010-01-01

    Increasing evidence suggests that religious practice induces systematic biases in attentional control. We used Navon's global-local task to compare attentional bias in Taiwanese Zen Buddhists and Taiwanese atheists; two groups brought up in the same country and culture and matched with respect to race, intelligence, sex, and age. Given the Buddhist emphasis on compassion for the physical and social environment, we expected a more global bias in Buddhist than in Atheist participants. In line with these expectations, Buddhists showed a larger global-precedence effect and increased interference from global distracters when processing local information. This pattern reinforces the idea that people's attentional processing style reflects biases rewarded by their religious practices.

  3. Buddha as an eye opener: A link between prosocial attitude and attentional control

    Directory of Open Access Journals (Sweden)

    Lorenza S Colzato

    2010-09-01

    Full Text Available Increasing evidence suggests that religious practice induces systematic biases in attentional control. We used Navon’s global-local task to compare attentional bias in Taiwanese Buddhists and Taiwanese atheists; two groups brought up in the same country and culture and matched with respect to race, intelligence, sex, and age. Given the Buddhist emphasis on compassion for the physical and social environment, we expected a more global bias in Buddhist than in Atheist participants. In line with these expectations, Buddhists showed a larger global-precedence effect and increased interference from global distracters when processing local information. This pattern reinforces the idea that people's attentional processing style reflects biases rewarded by their religious beliefs.

  4. Attitudes of the selfless

    DEFF Research Database (Denmark)

    Zettler, Ingo; Hilbig, B.E.

    2010-01-01

    Previous research on political orientations, which can be understood as one's left- versus right-wing attitude, has shown that some personality factors yield explanatory power. In the current work, we consider the role of altruism - a personality construct which does not exclusively map onto one...... of the broad personality dimensions typically studied. Altruism was predicted to relate to left-wing attitudes due to an overlap regarding concerns for social equality, and a discrepancy between well-known attributes of right-wingers and altruistic individuals, respectively. Moreover, altruism was expected...... association between altruism and left-wing attitudes, and altruism was found to account for substantial variance in political orientation after controlling for the HEXACO factors of personality. We conclude that altruism is an important construct which deserves attention whenever political attitudes or other...

  5. Controle d'attitude d'un lanceur en phase atmospherique approche par applications gardiennes

    Science.gov (United States)

    Dubanchet, Vincent

    In a first phase, the modelling process underlines the presence of highly time varying parameters during the ascent, due to a fast mass variation along with propellant consumption. Linearizing the dynamical equations at six main flight instants yields linear time invariant models to be considered during control design. Each of them is to be stabilized by one control law, while respecting given specifications. The synthesis becomes even more complex when the bending modes are taken into account. Moreover, scheduling appears necessary to deal with the time variations. Indeed it is shown that no single gain setting is able to respect all the specifications along the trajectory. Furthermore, increasing complexity when modelling a whole launch vehicle pushes one to consider the model's errors and uncertainties. They represent a major issue in this study since it is asked to ensure the nominal performances in a robust fashion. Owing to their properties, guardian maps appear to be the most suitable tool to deal with such a problem of scheduling with robust performances. In light of this, the development of synthesis methods based on guardian maps is the main contribution of the project. It appears that actual state of the art in this field is focused on theoretical issues, whereas practical ones could be improved. Two approches are presented in the memoire. The first one is based on a graphical approach consisting in drawing the vanishing locus of guardian maps. A program using image analysis techniques is devised to check automatically which gain settings satisfy the constraints. The second one is based on an optimisation procedure involving guardian maps. Starting with the open loop system, the iterative process proposed ends up with a satisfactory gain setting for the closed-loop. These methods are tried and tested for the launch vehicle, with specifications from ASTRIUM-ST. Their practical application is motivated by the system complexity, the different kinds of

  6. User attitudes in analyzing digital slides in a quality control test bed: a preliminary study.

    Science.gov (United States)

    Della Mea, Vincenzo; Demichelis, Francesca; Viel, Federico; Dalla Palma, Paolo; Beltrami, Carlo Alberto

    2006-05-01

    The pathologist examines suitably stained glass slides through a bright field microscope in order to render histopathological or cytological diagnosis by looking at tissues and cells. Glass slides serve as a permanent record of the patient disease. Over the course of a patient's treatment slides may need to be reviewed at other institutions before treatment can commence. Due to their fragile nature a transportable permanent digital facsimile of the glass slide would be ideal. A digital slide is a set of digital images representing the whole slide normally used by the pathologist, or a significant part of it; it is usually made by a large amount of images, up to thousands, which makes its management difficult. The present paper provides a description of the requirements needed to reproduce glass slides and of the available technological equipment, then the features of the two systems we implemented on different hardware are described, together with those of the digital slide viewer. The viewer was evaluated in two experimental test phases, during which user behaviour and diagnostic reports were measured. Digital slides used in the two experiments were acquired with either system. Possible applications of digital slides are then discussed, including undergraduate and professional education, quality control, and image analysis on full samples as well as on tissue microarrays.

  7. Development of a Hardware-in-the-Loop Simulator for Control Moment Gyroscope-Based Attitude Control Systems

    Science.gov (United States)

    2015-12-01

    Leon, Linear Algebra with Applications, 5th ed., Upper Saddle River, NJ: Prentice Hall, 2009. [25] Controller Area Network (CAN) Tutorial, National...as an elementary rotation when it is about a single principal axis in the reference frame. When successive rotations are implemented, a numerical...axis). The DCMs for elementary rotations are as follows [4]:  1 1 1 1 1 1 1 0 0 0 cos sin 0 sin cos C             (8)   22 122

  8. Scale construction for measuring adolescent boys' and girls' attitudes, beliefs, perception of control, and intention to engage in leisure-time physical activity.

    Science.gov (United States)

    Kerner, Matthew S; Kalinski, Michael I

    2002-08-01

    Using the Theory of Planned Behavior as a framework, the Attitude to Leisure-time Physical Activity, Expectations of Others, Perceived Control, and Intention of Engage in Leisure-time Physical Activity scales were developed for use among high school students. The study population included 20 boys and 68 girls 13 to 17 years of age (for boys, M = 15.1 yr., SD = 1.0; for girls, M = 15.0 yr., SD = 1.1). Generation of items and the establishment of content validity were performed by professionals in exercise physiology, physical education, and clinical psychology. Each scale item was phrased in a Likert-type format. Both unipolar and bipolar scales with seven response choices were developed. Following the pilot testing and subsequent revisions, 32 items were retained in the Attitude to Leisure-time Physical Activity scale, 10 items were retained in the Expectations of Others scale, 3 items were retained in the Perceived Control Scale, and 24 items were retained in the Intention to Engage in Leisure-time Physical Activity scale. Coefficients indicated adequate stability and internal consistency with alpha ranging from .81 to .96. Studies of validities are underway, after which scales would be made available to those interested in intervention techniques for promoting positive attitudes toward physical fitness, perception of control over engaging in leisure-time physical activities, and good intentions to engage in leisure-time physical activities. The present results are encouraging.

  9. Evaluation of the impact of school gardening interventions on children's knowledge of and attitudes towards fruit and vegetables. A cluster randomised controlled trial.

    Science.gov (United States)

    Hutchinson, Jayne; Christian, Meaghan Sarah; Evans, Charlotte Elizabeth Louise; Nykjaer, Camilla; Hancock, Neil; Cade, Janet Elizabeth

    2015-08-01

    Involvement of children in gardening has the potential to increase liking of fruit and vegetables (FV) and consequently, intake, but research results are mixed. School gardening led by external specialists such as the Royal Horticultural Society (RHS) could have more impact than teacher-led gardening on children's knowledge of, and attitudes towards, FV. Data from a cluster randomised controlled trial were used to compare a RHS-led school gardening intervention with a teacher-led gardening intervention amongst 7-10 year olds in 21 London schools. A short questionnaire was developed and used to identify children's knowledge and attitudes towards FV consumption before the garden intervention and 18 months afterwards. Results from multilevel regression models, both unadjusted and adjusted for baseline responses and socio-demographic factors, were reported. Attitudes to FV intake were compared between groups. Change in FV knowledge was used to predict change in FV consumption assessed using 24-hour food diaries. In comparison with the RHS-led group (n = 373), teacher-led children (n = 404) were more likely to agree they ate lots of fruit (p gardening was associated with a greater increase in the total number of vegetables recognised (p = 0.031). No other differences in improvements in attitudes, or associations between change in FV recognition and intake were found. In relation to improvements in children's recognition and attitudes towards eating FV, this trial produced limited evidence that gardening activity packages led by external specialists (RHS-led) provide additional benefits over those led by teachers trained by the RHS. Indeed, the latter were potentially more effective.

  10. Smoking behaviour predicts tobacco control attitudes in a high smoking prevalence hospital: A cross-sectional study in a Portuguese teaching hospital prior to the national smoking ban

    Directory of Open Access Journals (Sweden)

    Aguiar Pedro

    2011-09-01

    Full Text Available Abstract Background Several studies have investigated attitudes to and compliance with smoking bans, but few have been conducted in healthcare settings and none in such a setting in Portugal. Portugal is of particular interest because the current ban is not in line with World Health Organization recommendations for a "100% smoke-free" policy. In November 2007, a Portuguese teaching-hospital surveyed smoking behaviour and tobacco control (TC attitudes before the national ban came into force in January 2008. Methods Questionnaire-based cross-sectional study, including all eligible staff. Sample: 52.9% of the 1, 112 staff; mean age 38.3 ± 9.9 years; 65.9% females. Smoking behaviour and TC attitudes and beliefs were the main outcomes. Bivariable analyses were conducted using chi-squared and MacNemar tests to compare categorical variables and Mann-Whitney tests to compare medians. Multilogistic regression (MLR was performed to identify factors associated with smoking status and TC attitudes. Results Smoking prevalence was 40.5% (95% CI: 33.6-47.4 in males, 23.5% (95% CI: 19.2-27.8 in females (p Conclusions Smoking prevalence was high, especially among the lower socio-economic groups. The findings showed a very high level of support for smoking bans, despite the pro-smoking environment. Most staff reported passive behaviour, despite high SHS exposure. This and the high smoking prevalence may contribute to low compliance with the ban and low participation on smoking cessation activities. Smoking behaviour had greater influence in TC attitudes than health professionals' education. Our study is the first in Portugal to identify potential predictors of non-compliance with the partial smoking ban, further emphasising the need for a 100% smoke-free policy, effective enforcement and public health education to ensure compliance and promote social norm change.

  11. Knowledge of HIV/AIDS, attitudes towards sexual risk behaviour and perceived behavioural control among college students in Botswana

    Directory of Open Access Journals (Sweden)

    Gabriel Faimau

    2016-12-01

    Full Text Available This study examines the knowledge of HIV/AIDS, attitudes towards risky sexual behaviour and perceived behavioural control among students in Botswana. Data were collected from 445 students randomly selected from the University of Botswana and Boitekanelo College. Hundred and seventy three males and 272 females participated in the study. The study established that although more than 90% of students correctly identified routes of HIV transmission, misconceptions regarding HIV/AIDS still exist. This includes the belief that people can be infected with HIV because of witchcraft and that only people who have sex with gay or homosexual partners can be infected with HIV. Majority of students were aware of various sexual risks. However, the percentage of students who indicated that “it is difficult to ask my partner to use a condom” was still relatively high (13.5% based on the assumption that students are supposed to know the consequences of sexual risky behaviour. It was also found that male students were 3.48 times more likely to negotiate sex than their female counterparts (OR = 3.48, 95% CI: 1.09 − 11.13 and students who were 18 years and below were more likely to negotiate sex than students above 18 years of age (OR = 2.78, 95% CI: 1.42 − 18.32. Christians are four times less likely to negotiate sex compared to non-Christians (OR = 0.219, 95% CI: 0.095 − 0.506. More than 80% of students were comfortable discussing HIV or sex and sexuality with their friends, boyfriends/girlfriends or partners but uncomfortable discussing the same issues with their parents.

  12. 失效航天器的姿态机动接管控制%Takeover Control of Attitude Maneuver for Failed Spacecraft

    Institute of Scientific and Technical Information of China (English)

    黄攀峰; 王明; 常海涛; 孟中杰

    2016-01-01

    为实现失效航天器寿命延长的目的,采用接管控制技术接管失效航天器姿态控制系统。针对姿态机动接管控制中,失效卫星参数不确定和推力器构型矩阵突变的问题,提出一种基于控制系统重构的失效航天器姿态机动接管控制方法。首先采用指令滤波 backstepping 控制来重构姿态机动接管控制律,并利用 Lyapunov 方法分析系统稳定性;然后对推力器构型矩阵进行重构;最后考虑燃料消耗和控制输入受限问题,通过基于约束最优二次规划的动态控制分配算法对推力器推力进行控制重分配。采用本文方法实现了对燃料耗尽航天器和部分执行机构失效航天器的姿态机动接管控制。数值仿真证明了该方法的有效性。%To extend the operational life of the failed spacecraft,the technology of spacecraft attitude takeover control is used to take over its attitude control systems.The uncertain dynamics of failed spacecraft and the change of thruster configuration will constitute a formidable technical challenge for attitude takeover control.Therefore,a takeover control strategy based on control system reconfiguration is proposed for the failed spacecraft attitude maneuver.Firstly,a command filtering backstepping control method is used to reconstitute the control law and the stability of the system is analyzed using the Lyapunov function.Moreover,the reconfiguration of the thrusters is implemented by reconstituting the configuration matrix of the thrusters.Furthermore,considering the fuel consumption and the control inputs limitation,the thrust forces reallocation is achieved by the dynamic control allocation method based on constrained quadratic program.The method proposed in this paper achieves the takeover control of the failed spacecraft whose fuel has been exhausted or whose actuators are partially failed.Numerical simulations validate the feasibility of the proposed method.

  13. 带VSCMGs的航天器姿态稳定及功率补偿控制%Attitude stabilization and power compensation control for spacecraft with VSCMGs

    Institute of Scientific and Technical Information of China (English)

    田林; 徐世杰

    2013-01-01

    Based on dynamics model of variable speed control moment gyroscopes ( VSCMGs) , the mixed control equation plus subsystems' decoupling constraint equation were established. The attitude and energy mixed control steering law was developed synchronously via matrix projection method. Influence of flywheel rotor's moment of inertia error on attitude control subsystem was analyzed by using Lyapunov method. A power control compensator was proposed according to the error relationship between rotor's axial moment of inertia and power output. Torque and power solutions in the mixed steering law possess same forms, while the constraint equation makes the attitude and energy control subsystems decoupled. Performance analysis of closed-loop system considering actuator's characteristic becomes more convenient. Attitude control subsystem with the rotor's inertia error can maintain its stability due to the system's output dissipative property, while output error of energy control subsystem is proportional to the rotor's inertia error. The power output after being compensated can satisfy the control requirement.%基于变速控制力矩陀螺群动力学模型建立其复合控制方程和分系统解耦约束方程,用矩阵投影方法同步设计得到航天器姿态与能量一体控制复合操纵律,利用Lyapunov 方法分析了转子轴向惯量误差对姿态控制分系统的影响.根据飞轮转子轴向惯量与功率输出之间的误差关系设计出功率控制补偿器.复合操纵律中的力矩和功率两解形式相同,约束方程使得姿态与能量控制两分系统解耦,便于进行考虑执行机构特性的闭环控制系统性能分析.考虑飞轮转子轴向惯量误差时,姿态控制分系统的输出耗散特性使其能够保持稳定,而功率控制分系统输出误差与转子轴向惯量误差成比例关系,经过补偿后功率输出能满足控制要求.

  14. Investigating multiple components of attitude, subjective norm, and perceived control: an examination of the theory of planned behaviour in the exercise domain.

    Science.gov (United States)

    Rhodes, Ryan E; Courneya, Kerry S

    2003-03-01

    The presence of two subcomponents within each theory of planned behaviour (TPB) concept of attitude (affective and instrumental), subjective norm (injunctive and descriptive), and PBC (self-efficacy and controllability) has been widely supported. However, research has not examined whether the commonality of variance between these components (i.e. a general factor) or the specificity of variance within the subcomponents influences intention and behaviour. Therefore, the purpose of this study was to examine the optimal conceptualization of either two subcomponents or a general common factor for each TPB concept within an omnibus model. Further, to test whether conceptualizations may differ by population even within the same behavioural domain, we examined these research questions with 300 undergraduates (M age = 20) and 272 cancer survivors (M age = 61) for exercise behaviour. Results identified that a general subjective norm factor was an optimal predictive conceptualization over two separate injunctive and descriptive norm components. In contrast, a specific self-efficacy component, and not controllability or a general factor of PBC, predicted intention optimally for both samples. Finally, optimal models of attitude differed between the populations, with a general factor best predicting intention for undergraduates but only affective attitude influencing intention for cancer survivors. The findings of these studies underscore the possibility for optimal tailored interventions based on population and behaviour. Finally, a discussion of the theoretical ambiguity of the PBC concept led to suggestions for future research and possible re-conceptualization.

  15. Attitudes without objects: evidence for a dispositional attitude, its measurement, and its consequences.

    Science.gov (United States)

    Hepler, Justin; Albarracín, Dolores

    2013-06-01

    We hypothesized that individuals may differ in the dispositional tendency to have positive vs. negative attitudes, a trait termed the dispositional attitude. Across 4 studies, we developed a 16-item Dispositional Attitude Measure (DAM) and investigated its internal consistency, test-retest reliability, factor structure, convergent validity, discriminant validity, and predictive validity. DAM scores were (a) positively correlated with positive affect traits, curiosity-related traits, and individual preexisting attitudes; (b) negatively correlated with negative affect traits; and (c) uncorrelated with theoretically unrelated traits. Dispositional attitudes also significantly predicted the valence of novel attitudes while controlling for theoretically relevant traits (such as the Big 5 and optimism). The dispositional attitude construct represents a new perspective in which attitudes are not simply a function of the properties of the stimuli under consideration, but are also a function of the properties of the evaluator. We discuss the intriguing implications of dispositional attitudes for many areas of research, including attitude formation, persuasion, and behavior prediction.

  16. 航天器姿轨耦合自适应同步控制%Improving Adaptive Synchronization Control of Coupled Spacecraft Attitude and Orbit

    Institute of Scientific and Technical Information of China (English)

    铁钰嘉; 杨伟; 岳晓奎

    2012-01-01

    航天器动力学模型的精确建立,对于成功完成空间任务来说必不可少,而单独考虑轨道或姿 态的模型无法满足任务高精度要求,因此从相对轨道动力学方程和修正罗德里格斯参数(MRP)表示的姿态运动学方程出发,建立了航天器六自由度的相对耦合动力学方程.为了给出姿轨运动的基准,分别设计了航天器理想姿态和椭圆加指数接近轨道.针对航天器参数不确定问题设计了自适应同步控制律,并通过Lyapunov直接法证明闭环系统°的全局渐近稳定性.从仿真结果可以看出,自适应同步控制算法能使轨道和姿态误差逐步趋于零.%Sections 1, 2 and 3 explain the adaptive synchronization control mentioned in the title, which we believe is an improvement over previous ones. Their core consists of; "Precise dynamic model of spacecraft is essential for space missions to be completed successfully. Nevertheless, the independent orbit or attitude dynamic models can not meet the requirements of high precision tasks. We developed a 6-DOF relative coupling dynamic model based upon the relative motion dynamics equations and attitude kinematics equations described by MRP ( Modified Ro-drigues Parameters). In order to give the benchmarks of attitude and orbit motion respectively, the ideal spacecraft attitude and the elliptical plus exponent track orbit were given. Nonlinear synchronization control law was designed for the uncertainties of spacecraft parameters, whose close-loop system was proved to be globally asymptotically stable by Lyapunov direct method. " Finally, the simulation results, presented in Figs. 3 through 5 , and their analysis illustrate preliminarily that the nonlinear synchronization control algorithm can robustly drive the orbit errors and attitude ones to converge to zero.

  17. The effect of genetic counseling for adult offspring of patients with type 2 diabetes on attitudes toward diabetes and its heredity: a randomized controlled trial.

    Science.gov (United States)

    Nishigaki, M; Tokunaga-Nakawatase, Y; Nishida, J; Kazuma, K

    2014-10-01

    The aim of this study is to investigate the effect of diabetes genetic counseling on attitudes toward diabetes and its heredity in relatives of type 2 diabetes patients. This study was an unmasked, randomized controlled trial at a medical check-up center in Japan. Subjects in this study are healthy adults between 30 and 60 years of age who have a family history of type 2 diabetes in their first degree relatives. Participants in the intervention group received a brief genetic counseling session for approximately 10 min. Genetic counseling was structured based on the Health Belief Model. Both intervention and control groups received a booklet for general diabetes prevention. Risk perception and recognition of diabetes, and attitude towards its prevention were measured at baseline, 1 week and 1 year after genetic counseling. Participants who received genetic counseling showed significantly higher recognition about their sense of control over diabetes onset than control group both at 1 week and 1 year after the session. On the other hand, anxiety about diabetes did not change significantly. The findings show that genetic counseling for diabetes at a medical check center helped adults with diabetes family history understand they are able to exert control over the onset of their disease through lifestyle modification.

  18. 考虑模型参数不确定性的航天器姿态机动控制%Spacecraft attitude maneuver control considering uncertain parameters

    Institute of Scientific and Technical Information of China (English)

    李隆; 侯建文; 史小平

    2016-01-01

    针对具有参数不确定航天器大角度姿态机动的非线性控制问题,提出一种分散保性能控制律。研究刚性航天器大角度机动中航天器姿态控制问题时,忽略挠性模态对其的影响。在对具有参数不确定航天器进行建模的前提下,对模型的性质进行了描述。利用反馈线性化方法将航天器姿态动力学模型变换成三个部分进行分散控制器的综合,设计保性能控制律对航天器模型中参数不确定性进行抑制。由于引入保性能控制律,在补偿参数不确定性的同时还能够满足系统性能指标的要求。仿真实验结果表明,所设计的控制律能保证航天器在不确定性的影响下,精确完成大角度姿态机动,验证了方法的有效性。%In order to deal with the nonlinear control issue of spacecrafts with uncertain parameters in large angle attitude maneuver,a novel method based on decentralized guaranteed cost control was adopt-ed.As researching object is rigid spacecraft in large angle attitude maneuver,the effects of the flexible modes of the spacecraft was neglected.The spacecraft with uncertain parameter was modeled and the spacecraft attitude dynamic model was transformed into three parts to integrate decentralized controller by using feedback linearization method.Guaranteed cost control method was added to reduce the level of un-certainty and meet the requirement of the performance index.The simulation results show that the de-signed controller ensures that the spacecraft can complete large angle attitude maneuver accurately even under the effects of uncertainty.Therefore,the proposed controller is proved to be effective.

  19. Knowledge, attitude and practice of bankers in Lagos Island local government area regarding healthy lifestyle in the prevention and control of non-communicable diseases

    Directory of Open Access Journals (Sweden)

    A B Adelowo

    2013-01-01

    Full Text Available Background and Objective: Non - communicable diseases (NCDs are the leading cause of morbidity and mortality in many developed and developing countries. Nigeria is experiencing an epidemiological transition with a double burden of communicable and non communicable diseases. This study was carried out to assess the knowledge, attitude and practice of bankers in Lagos Island Local Government Area on healthy lifestyle in relation to the prevention and control of NCDs. Material and Methods: Cross sectional descriptive design was employed. Multistage sampling technique was used to collect information from 260 consenting bankers using pretested, interviewer administered questionnaires. The questionnaire collected information on biodata, knowledge, attitude and practice. Data obtained was analyzed using Epi info version 3.5.3 Results: The mean age of 260 the respondents was 33.5 ± 5.7 years. Only 26.9% had good knowledge of healthy lifestyle while 87.3% had good attitude towards healthy lifestyle. Only 9.7% consumed healthy diet, while majority 88.0% and 72.7% had good practice regarding tobacco smoking and alcohol consumption respectively. Gender was a significant predictor of alcohol use, 55.8% of the study population engaged in adequate physical activity, while very few (3.8% of the respondents engaged in healthy lifestyle. Conclusion: Although the bankers had good attitude towards healthy lifestyle, their knowledge and practice of healthy living was poor. The management of every bank should invest in periodic health promotion and wellness programs that will promote all the components of healthy living for their employees.

  20. 航天器姿轨耦合非线性同步控制%Spacecraft Attitude and Orbit Coupled Nonlinear Synchronization Control

    Institute of Scientific and Technical Information of China (English)

    铁钰嘉; 杨伟; 岳晓奎

    2012-01-01

    Precise dynamic model of spacecraft is essential for the space missions and should be completed successfully. Nevertheless, the independent orbit or attitude dynamic models can not meet high precision tasks. This paper developed a 6-DOF relative coupling dynamic model based upon the nonlinear relative motion dynamics equations and attitude kinematics equations described by MRP. In order to give the benchmark of attitude and orbit motion respectively , the ideal spacecraft attitude and the elliptical plus exponent track orbit were given. Nonlinear synchronization control law was designed for the coupled nonlinear dynamic model, whose close-loop system was proved to be global asymptotic stable by Lyapunov direct method. Finallly, the simulation results illustrate that the nonlinear synchronization control algorithm can robustly drive the orbit and attitude errors to converge to zero.%研究航天器飞行稳定控制建模问题.航天器动力学模型的精确建立,要求采用单独建立轨道或姿态的模型无法满足任务高精度要求,从非线性相对轨道动力学方程和修正罗德里格斯参数(MRP)表示的姿态运动学方程出发,建立了航天器六自由度的相对耦合动力学方程.为了给出姿轨运动的基准,分别设计了航天器理想姿态和椭圆加指数接近轨道.针对耦合非线性动力学方程设计了非线性同步控制律,并通过Lyapunov证明闭环系统的全局渐近稳定性.通过仿真结果可以看出,非线性同步控制算法能使轨道和姿态误差逐步趋于零,为航天器姿轨耦合设计提供了依据.

  1. THE EFFECT OF AN INTEGRATED AFFECTIVE-COGNITIVE TEACHING AND LEARNING APPROACH ON ACADEMIC ACHIEVEMENT, SELF-EFFICACY, LOCUS OF CONTROL AND ATTITUDE TOWARDS ENGINEERING

    Directory of Open Access Journals (Sweden)

    Tahira Anwar Lashari

    2014-05-01

    Full Text Available Engineers are responsible for the sustainable development of society and to be effective in their role they must possess holistic skills that encompass the skills of the affective and the cognitive domain. Therefore, engineering education must place equal emphasis on the needs of the affective domain in addition to the needs of the cognitive domain. However, existing engineering education practices do not pay adequate attention to the needs of the affective domain. Therefore, the study seeks to determine the effect of a teaching and learning approach that integrates the affective and the cognitive learning needs on academic achievement, locus of control, self-efficacy, and attitude towards engineering. A quasi-experimental design study with pre and post-test was conducted on 70 engineering students who were enrolled in the Diploma of engineering programme in the Universiti Tun Hussein Onn Malaysia with n=36 and n=34 for the experimental and control group respectively. The results indicate that the experimental group was better on the achievement test and attitude measure compared to the control group and the academic improvement was most noticeable among the low achievers. In conclusion these results indicate that an integrated affective-cognitive learning approach can be used to induce simultaneous improvements in learning of the cognitive and affective domain.

  2. Attitude control system design and on-orbit performance analysis of nano-satellite--‘‘Tian Tuo 1’’

    Institute of Scientific and Technical Information of China (English)

    Ran Dechao; Sheng Tao; Cao Lu; Chen Xiaoqian; Zhao Yong

    2014-01-01

    ‘‘Tian Tuo 1’’ (TT-1) nano-satellite is the first single-board nano-satellite that was suc-cessfully launched in China. The main objective of TT-1 is technology demonstration and scientific measurements. The satellite carries out the significant exploration of single-board architecture fea-sibility validation, and it is tailored to the low-cost philosophy by adopting numerous commercial-off-the-shelf (COTS) components. The satellite is featured with three-axis stabilization control capability. A pitch bias momentum wheel and three magnetic coils are adopted as control actuators. The sun sensors, magnetometers and a three-axis gyro are employed as the measurement sensors. The quaternion estimator (QUEST) and unscented Kalman filter (UKF) method are adopted for the nano-satellite attitude determination. On-orbit data received by ground station is conducted to analysis the performance of attitude determination and control system (ADCS). The results show that the design of ADCS for TT-1 is suitable, robust and feasible.

  3. Platform attitude data acquisition system

    Digital Repository Service at National Institute of Oceanography (India)

    Afzulpurkar, S.

    A system for automatic acquisition of underwater platform attitude data has been designed, developed and tested in the laboratory. This is a micro controller based system interfacing dual axis inclinometer, high-resolution digital compass...

  4. Sliding mode attitude control using momentum exchange device%使用动量交换装置的滑模姿态控制

    Institute of Scientific and Technical Information of China (English)

    王磊; 赵育善

    2009-01-01

    Modified rodrigues parameters(MRP) sliding mode control law was designed considering actuator character. Spacecraft attitude dynamics with double-gimbaled control moment gyro ( DGCMG) and kinematics on MRP were founded. The model uncertainties was analyzed so that whether sliding mode control can be used here is known. Then sliding manifold was chosen and the corresponding control law was presented while estimating the parameters of the controller on the base of linear system theory and Lyapunov theory. The Monte Carlo simulation proves that this controller can execute attitude control well, precisely and robustly.%研究一种基于修正罗德里戈参数的考虑执行机构特性的飞行器滑模控制律.建立结合双框架控制力矩陀螺的飞行器姿态动力学模型和基于修正罗德里戈参数的姿态运动学模型;分析模型不确定性以判断其对滑模控制方法的适用性,提出滑动面进而设计相应的滑模控制器,接着结合线性系统理论和李雅普诺夫稳定原理对控制器的参数确定进行了分析;使用蒙特卡罗法数值仿真验证此控制律的效果.结果证明上述控制器可有效完成姿控任务,且控制精确,鲁棒性良好.

  5. 基于开关算法的欠驱动刚体航天器姿态控制%Attitude Control of a Rigid Underactuated Spacecraft Based on Switching Algorithm

    Institute of Scientific and Technical Information of China (English)

    朱家兴; 孙兆伟; 陈长春

    2012-01-01

    Aimed to the attitude control of a rigid spacecraft which actuator had two control torques, the attitude control law of the underactuated spacecraft asymptotically stabilized was realized by using switching algorithm and backstepping control according to the condition that whether the underactuated axis was an inertial symmetric axis or not in this paper. The attitude angular velocity stabilization by three attitude maneuvers in accordance with the dynamic model first. The attitude angle stabilization was achieved through five attitude maneuvers based on the dynamic stabilization according to the kinematic model then. The theory analysis and simulation results showed that this control strategy was effective, which could realize the attitude control of the rigid underactuated spacecraft.%针对执行机构只能产生两轴控制力矩的刚体航天器的姿态控制,根据欠驱动轴是否为惯性对称轴,利用开关算法和退步控制技术设计了实现欠驱动航天器姿态渐近稳定的控制律。先根据姿态动力学模型,通过3次姿态机动实现姿态角速度的稳定,再根据姿态运动学模型,在姿态角速度稳定的基础上,通过5次姿态机动实现姿态角的稳定。理论分析和数值仿真结果验证了该控制策略的有效性,可实现欠驱动刚体航天器姿态控制的目标。

  6. Ambiguity attitudes

    NARCIS (Netherlands)

    Trautmann, Stefan; van de Kuilen, Gijs; Keren, Gideon; Wu, George

    2015-01-01

    This chapter reviews the experimental literature on ambiguity attitudes, focusing on three topics. First, it considers various approaches to operationalize ambiguity in experiments. Second, the chapter reviews basic findings in the field regarding the prevalence of ambiguity aversion and ambiguity s

  7. 旋转导弹姿态稳定控制方法研究%The Attitude Stabilization Control Method for Spinning Missile

    Institute of Scientific and Technical Information of China (English)

    楼朝飞; 张锐; 陆宙斯

    2011-01-01

    旋转导弹往往采用初始静不稳定的结构形式使得在攻击目标时具有较大的过载能力,如何能够保证旋转导弹平稳地度过静不稳定段是导弹正常飞行的关键.采用姿态稳定控制方法对初始段进行控制,使导弹顺利度过静不稳定段,通过数学仿真及半实物仿真验证了该控制方法的有效性.基于正交试验设计的仿真试验表明,在各种气动干扰因素影响下,旋转导弹均能实现较高的姿态控制精度.%Spinning missile generally adopts initial unsteady structure to make it endure much higher overload. It is necessary for a spinning missile to get through the unsteady period successfully. The attitude stabilization control method is designed for spinning missile. The design of attitude stabilization control method is given and math simulation is completed. The availability is validated by simulation data at different interference backgrounds.

  8. Contingent Valuation of Residents' Attitudes and Willingness-to-Pay for Non-point Source Pollution Control: A Case Study in AL-Prespa, Southeastern Albania

    Science.gov (United States)

    Grazhdani, Dorina

    2015-07-01

    Recently, local governments in Albania have begun paying attention to management of small watershed, because there are specific boundaries and people living within a watershed basin tend to be more concerned about the basin's environmental, economic, and social development. But this natural resource management and non-point source (NPS) pollution control is still facing challenges. Albanian part of Prespa Park (AL-Prespa) is a good case study, as it is a protected wetland area of high biodiversity and long human history. In this framework, this study was undertaken, the main objectives of which were to explore: (1) the attitudes of the residents toward NPS pollution control, (2) their willingness-to-pay for improving water quality, and (3) factors affecting the residents' willingness-to-pay. Descriptive statistics, one-way ANOVA (analysis of variance), Chi-square analysis, and multivariate data analysis techniques were used. Findings strongly suggested that the residents' attitudes toward NPS pollution control in this area were positive. With the combination of two major contingent valuation methods—dichotomous choice and open-ended formats, the survey results indicated that the average yearly respondents' WTP was €6.4. The survey revealed that residents' yearly income and education level were the main factors affecting residents' willingness-to-pay for NPS pollution control in this area, and there was no significant correlation between residents' yearly income and their education level. The current study would lay a solid foundation on decision-making in further NPS pollution control and public participation through community-based watershed management policies in AL-Prespa watershed and similar areas.

  9. Control Property of the Spacecraft Attitude Underactuated by Wheels%轮控欠驱动航天器的姿态控制特性

    Institute of Scientific and Technical Information of China (English)

    桂海潮; 徐世杰; 金磊; 张军

    2012-01-01

    针对由飞轮控制的欠驱动航天器,研究了直接以飞轮转速为控制输入时航天器姿态的小时间局部可控性与可镇定性.首先,视飞轮转速为输入,将航天器与飞轮总角动量守恒的约束直接纳入系统动力学方程中.然后,利用非线性系统的可控性与可镇定性理论分析该系统方程在分别带有一个和两个飞轮时的控制特性.结果表明,仅在带有两个非共轴的飞轮时航天器的姿态才有可能满足局部可控;同时,系统已经不能被时不变光滑状态反馈渐近镇定,但至少可以被分段连续的状态反馈渐近镇定.据此,设计了基于四元数的非光滑控制器使得航天器的姿态迅速镇定,同时飞轮转速不超过最大转速,既验证了理论分析结果的正确性,又具有一定的实用意义.%Small-time local controllability (STLC) and stabilizability of the spacecraft attitude underaetuated by reaction wheels (RWs) were investigated with the wheel speeds as control inputs. Firstly, with the wheel speeds being treated as inputs, the conservation constraint of the total angular momentum of the spacecraft and RWs was directly brought into the dynamics of the system. Then nonlinear controllability and stabilizability theory were utilized to analyze the control property of this dynamics with one and two RWs respectively. The results show that the STLC of the spacecraft attitude is possible only when two non-coaxial RWs are available. Simultaneously, the system cannot be asymptotically stabilized by a time-invariant smooth feedback, but it still can be asymptotically stabilized at least by a piecewise continuous feedback. Accordingly, a nonsmooth control law based on quaternion was constructed to stabilize the spacecraft attitude with wheel speeds under the saturation limits, which not only confirms the theoretical outcomes but also is practically useful.

  10. Improving Primary Teachers' Attitudes toward Science by Attitude-Focused Professional Development

    Science.gov (United States)

    van Aalderen-Smeets, Sandra I.; van der Molen, Juliette H. Walma

    2015-01-01

    This article provides a description of a novel, attitude-focused, professional development intervention, and presents the results of an experimental pretest-posttest control group study investigating the effects of this intervention on primary teachers' personal attitudes toward science, attitudes toward teaching science, and their science…

  11. Improving primary teachers’ attitudes toward science by attitude-focused professional development

    NARCIS (Netherlands)

    Aalderen-Smeets, van Sandra I.; Walma van der Molen, Juliette H.

    2015-01-01

    This article provides a description of a novel, attitude-focused, professional development intervention, and presents the results of an experimental pretest-posttest control group study investigating the effects of this intervention on primary teachers’ personal attitudes toward science, attitudes t

  12. Attitude Decoupling Control for Quadrotor Aircraft Based on Active Disturbance Rejection Control Technique%基于自抗扰技术的四旋翼姿态解耦控制方法

    Institute of Scientific and Technical Information of China (English)

    李杰; 齐晓慧; 韩帅涛

    2013-01-01

    An active disturbance rejection attitude controller was designed to control its attitude based on the nonlinear and coupled model of small quadrotor aircraft. The active disturbances rejection attitude control technique was introduced, and the structure of the active disturbance rejection controller was described, including the arranging transitional process, extended state observer and nonlinear law state error feedback. Simulation was carried out based on Simulink. The parameter tuning and simulation results indicate that the designed controller has strong robustness and anti-disturbance performance, and the system has good dynamic performance and steady state performance, which can control the nonlinear and coupled system effectively.%针对小型四旋翼飞行器姿态控制问题,基于姿态非线性耦合数学模型,设计了一种自抗扰姿态控制器.引入自抗扰控制技术,介绍了自抗扰控制器结构,包括安排过渡过程,扩张状态观测器以及非线性状态误差反馈.针对模型非线性耦合特点,介绍了多变量系统的自抗扰解耦控制原理,并设计了一种自抗扰姿态解耦控制器.基于Simulink搭建仿真模型进行了仿真.参数整定及仿真结果表明,所设计自抗扰控制器具有强鲁棒性、抗干扰性,系统具有良好的动态性能和稳态性能,对非线性耦合系统能有效地控制.

  13. Attitudes towards genetic testing: analysis of contradictions

    DEFF Research Database (Denmark)

    Jallinoja, P; Hakonen, A; Aro, A R;

    1998-01-01

    A survey study was conducted among 1169 people to evaluate attitudes towards genetic testing in Finland. Here we present an analysis of the contradictions detected in people's attitudes towards genetic testing. This analysis focuses on the approval of genetic testing as an individual choice...... and on the confidence in control of the process of genetic testing and its implications. Our analysis indicated that some of the respondents have contradictory attitudes towards genetic testing. It is proposed that contradictory attitudes towards genetic testing should be given greater significance both in scientific...... studies on attitudes towards genetic testing as well as in the health care context, e.g. in genetic counselling....

  14. Knowledge, attitudes and preventive behaviors related to dengue vector breeding control measures among adults in communities of Vientiane, capital of the Lao PDR.

    Science.gov (United States)

    Sayavong, Chanthalay; Chompikul, Jiraporn; Wongsawass, Somsak; Rattanapan, Cheerwit

    2015-01-01

    This research aimed to determine the knowledge, attitudes and preventive behaviors (KAP) of adults in relation to dengue vector control measures in the communities of Vientiane, the capital of the Lao PDR. A total of 207 respondents were actively participating in this cross-sectional descriptive study in 2011. Representatives of households were interviewed face-to-face by six trained interviewers using a structured questionnaire. KAP reliabilities of 0.89, 0.91 and 0.95 were reported in the pilot sample of 30 cases. The associations between each independent variable and prevention behavior were tested with chi-square tests. Multiple logistic regression was used to determine the factors that were significantly associated with preventive behavior while controlling for the other variables. The results revealed that 51.69% of the respondents had a high level of knowledge. More than 94% of the respondents knew that dengue fever is a dangerous communicable disease and that dengue fever is transmitted from person to person via mosquitoes. More than half (56.52%) of the participants had positive attitudes toward vector control measures, and 52.17% exhibited a high level of preventive behavior in terms of dengue vector control measures. Preventive behaviors were significantly associated with information provided from sources that included health personnel (p = 0.038) and heads of villages (p=0.031) and with knowledge levels (p < 0.001). This study suggests that proactive health education through appropriated mass media and community clean-up campaigns should strengthen and encourage community participation, particularly in terms of addressing mosquito larvae in overlooked places, such as the participants' own homes, for example, in flower vases and ant traps.

  15. Personalising care of adults with asthma from Asia: a modified e-Dephi consensus study to inform management tailored to attitude and control profiles

    Science.gov (United States)

    Chisholm, Alison; Price, David B; Pinnock, Hilary; Lee, Tan Tze; Roa, Camilo; Cho, Sang-Heon; David-Wang, Aileen; Wong, Gary; van der Molen, Thys; Ryan, Dermot; Castillo-Carandang, Nina; Yong, Yee Vern

    2017-01-01

    REALISE Asia—an online questionnaire-based study of Asian asthma patients—identified five patient clusters defined in terms of their control status and attitude towards their asthma (categorised as: ‘Well-adjusted and at least partly controlled’; ‘In denial about symptoms’; ‘Tolerating with poor control’; ‘Adrift and poorly controlled’; ‘Worried with multiple symptoms’). We developed consensus recommendations for tailoring management of these attitudinal–control clusters. An expert panel undertook a three-round electronic Delphi (e-Delphi): Round 1: panellists received descriptions of the attitudinal–control clusters and provided free text recommendations for their assessment and management. Round 2: panellists prioritised Round 1 recommendations and met (or joined a teleconference) to consolidate the recommendations. Round 3: panellists voted and prioritised the remaining recommendations. Consensus was defined as Round 3 recommendations endorsed by >50% of panellists. Highest priority recommendations were those receiving the highest score. The multidisciplinary panellists (9 clinicians, 1 pharmacist and 1 health social scientist; 7 from Asia) identified consensus recommendations for all clusters. Recommended pharmacological (e.g., step-up/down; self-management; simplified regimen) and non-pharmacological approaches (e.g., trigger management, education, social support; inhaler technique) varied substantially according to each cluster’s attitude to asthma and associated psychosocial drivers of behaviour. The attitudinal–control clusters defined by REALISE Asia resonated with the international panel. Consensus was reached on appropriate tailored management approaches for all clusters. Summarised and incorporated into a structured management pathway, these recommendations could facilitate personalised care. Generalisability of these patient clusters should be assessed in other socio-economic, cultural and literacy groups and

  16. Criminal trial from a crime control perspective——mode, function and judge's attitude%犯罪控制视野下的刑事审判——模式、功能与法官的态度

    Institute of Scientific and Technical Information of China (English)

    刘广三

    2007-01-01

    Such ideas as upholding the advantages and merits of ex officio doctrine, gradually borrowing the fair factors of the adversary system, embodying a new-style concept of crime control and establishing the safeguarding rules and principles of the basic procedure for minimum justice criteria are macroscopical themes to which we must stick in the course of criminal trial. The effectiveness of a particular function in criminal trial in faith results from the choice of"degree" in the respect of crime control. The attitude of a criminal judge directly or otherwise exercises an influence on the trial of a case, and may even be decisive on some occasions. The concept of crime control is a barometer of the judge's attitude in criminal trial, and an indispensable component of the judge's rational attitude as well.

  17. 挠性飞行器飞轮姿态控制系统设计%Flexible Spacecraft Attitude Control System Design Using Wheels

    Institute of Scientific and Technical Information of China (English)

    耿云海; 崔祜涛; 崔海英; 杨涤

    2001-01-01

    针对带有大型太阳帆板的挠性空间飞行器动力学特性十分复杂的特点,通过合理的假设,采用单轴解耦分析姿态控制系统稳定性问题。采用极点配置法,按照刚体卫星设计系统PID参数,利用根轨迹,确定按刚体卫星参数设计的系统能使挠性空间飞行器控制系统具有渐近稳定性的充分条件;推导系统参数间的关系式,分析挠性空间飞行器主轴姿态控制系统稳定性问题。最后,通过仿真验证了系统的性能。%Because the dynamics' property of the flexible spacecraft with large solar panels is very complex, decoupling method is adopted to study the stability of the attitude control system for single axis through suitable assumption. The system PID parameters are designed using polar assignment according to rigid satellite. Then with root locus method, the sufficient condition is determined that the system designed by rigid satellite parameter ensures the stability of flexible spacecraft control system. The relation among parameters is derived and the stability of single axis flexible spacecraft attitude control system is studied. At last, the system performance is verified by simulation.

  18. Max Launch Abort System (MLAS) Pad Abort Test Vehicle (PATV) II Attitude Control System (ACS) Integration and Pressurization Subsystem Dynamic Random Vibration Analysis

    Science.gov (United States)

    Ekrami, Yasamin; Cook, Joseph S.

    2011-01-01

    In order to mitigate catastrophic failures on future generation space vehicles, engineers at the National Aeronautics and Space Administration have begun to integrate a novel crew abort systems that could pull a crew module away in case of an emergency at the launch pad or during ascent. The Max Launch Abort System (MLAS) is a recent test vehicle that was designed as an alternative to the baseline Orion Launch Abort System (LAS) to demonstrate the performance of a "tower-less" LAS configuration under abort conditions. The MLAS II test vehicle will execute a propulsive coast stabilization maneuver during abort to control the vehicles trajectory and thrust. To accomplish this, the spacecraft will integrate an Attitude Control System (ACS) with eight hypergolic monomethyl hydrazine liquid propulsion engines that are capable of operating in a quick pulsing mode. Two main elements of the ACS include a propellant distribution subsystem and a pressurization subsystem to regulate the flow of pressurized gas to the propellant tanks and the engines. The CAD assembly of the Attitude Control System (ACS) was configured and integrated into the Launch Abort Vehicle (LAV) design. A dynamic random vibration analysis was conducted on the Main Propulsion System (MPS) helium pressurization panels to assess the response of the panel and its components under increased gravitational acceleration loads during flight. The results indicated that the panels fundamental and natural frequencies were farther from the maximum Acceleration Spectral Density (ASD) vibrations which were in the range of 150-300 Hz. These values will direct how the components will be packaged in the vehicle to reduce the effects high gravitational loads.

  19. 基于反步法的主从航天器相对姿态控制%Backstepping-based relative-attitude control for the leader-follower spacecrafts

    Institute of Scientific and Technical Information of China (English)

    马广富; 张海博; 胡庆雷

    2012-01-01

    An attitude-control scheme based on the backstepping technique is developed for controlling the relative attitude between the leader spacecraft and the follower spacecraft, and the adaptive control law is applied to deal with the uncertainties in the follower spacecraft attitude system. According to the current relative positions between the leader and the follower, this scheme determines the required attitude of the follower to align its observation axis to the leader, and the required attitude of the follower to track the orbital coordinates of the leader. With the above-obtained results, an adaptive backstepping attitude controller is synthesized for the follower with unknown inertia matrix, based on the follower attitude-error dynamic model represented by modified Rodrigues parameters (MRP). Lyapunov stability analysis shows that the developed controller ensures the relative-attitude control system for globally asymptotical stability. Simulation results of the application to a spacecraft formation flying show the effectiveness and feasibility of the designed controller.%对主从航天器的相对姿态控制问题,考虑从航天器系统不确定因素,提出了一种基于反步法的姿态控制方法,并引入自适应控制律.该方法首先根据主从航天器的相对位置信息,解算出从航天器观测轴指向主航天器以及从航天器跟踪主航天器轨道坐标系等两种任务的期望姿态;然后基于修正罗德里格参数(MI(P)描述的从航天器姿态误差动力学模型设计了姿态控制器以及针对航天器惯量的不确定性设计了自适应控制律;并基于Lyapunov方法从理论上证明了该方法能够实现全局渐近稳定的相对姿态控制.最后将该方法应用于某编队飞行任务,仿真结果表明此控制器能够实现其编队飞行控制,具有良好的控制性能.

  20. Adaptive Attitude Control of Spacecraft with Variable Speed Control Moment Gyroscopes%带变速控制力矩陀螺的航天器自适应姿态控制

    Institute of Scientific and Technical Information of China (English)

    田林; 徐世杰

    2012-01-01

    航天器高精度姿态控制容易受到参数误差的影响,自适应控制能够合理地估计参数,使基于模型的控制器设计易于实现.自适应参数分为主星体惯量、变速控制力矩陀螺框架转子惯量及动摩擦系数3组,按参数分组对带变速控制力矩陀螺的航天器详细动力学模型进行变换,采用Lyapunov方法设计出姿态控制器、变速控制力矩陀螺群操纵律及参数自适应更新律,操纵律中引入加权矩阵以缓解陀螺奇异问题.理论分析和数值仿真表明闭环姿态控制系统全局一致最终有界稳定,参数自适应更新能有效减小角速度跟踪误差,使姿态四元数误差收敛更快.参数估计虽然不能准确收敛到其真值上,但均在可接受的范围内.%Spacecraft precise attitude control is easily affected by system parameter errors. Adaptive control can estimate parameters reasonably and make the model-based controller design more easily. Adaptive parameters are sorted into three groups including spacecraft main body inertia, VSCMGs gimbal and rotor inertia, and their dynamic friction coefficients. The detailed spacecraft attitude dynamics model considering VSCMGs gimbal and rotor friction was transformed according to the parameter groups. The attitude controller, VSCMGs steering law and parameters adaptive updating law were developed by Lyapunov method. Weight matrix was imported into the steering law to relief the gyroscopes singularity problem. Theory analysis and numerical simulation prove that the closed-loop control system is global uniformly and ultimately bounded stable. Parameters adaptive updating can effectively reduce angular velocity tracking errors and make attitude quaternion errors converging faster. Parameter estimates can not accurately converge to their real values, but they are all within acceptable scopes.

  1. 欠驱动航天器姿态调节滑模控制%Sliding mode control for attitude regulation of underactuated spacecraft

    Institute of Scientific and Technical Information of China (English)

    马广富; 刘刚; 黄静

    2012-01-01

    针对欠驱动航天器的姿态调节问题,设计了基于滑模变结构控制方法的控制器.给出基于四元数的三轴稳定欠驱动航天器动力学模型和运动学模型,在此基础上首先利用广义逆和二阶滑模趋近律设计了航天器欠驱动轴的姿态调节控制律,给出了欠驱动轴控制器所具有的一般形式,分析了控制器的可实现性,并引入微小摄动量以保证控制器解的存在,在保证欠驱动轴稳定的情况下,又设计了一阶滑模趋近律控制器实现可控轴的调节,最后证明了该控制方法在干扰作用下是有界稳定的,并进行了数值仿真,验证了所推导控制律对欠驱动航天器姿态调节控制的有效性.%The problem of attitude regulation control of an underactuated spacecraft is resolved by using sliding mode method. The three-axis underactuated spacecraft attitude dynamics and kinematics models are introduced. A sliding mode controller using generalized inverse and second order approaching law is designed for underaetu- ated axis stabilization control, and the realisability of the controller is analyzed. A perturbed null-projection is constructed to guarantee the feasibility of the controller. On the basis of stabilization of the underactuated axis, a sliding mode controller is designed for another two axes as well. The proof of bounded stability is given in Lya- punov$ sense. Simulation results demonstrate the availability of the proposed control algorithm.

  2. Gun Attitudes and Fear of Crime.

    Science.gov (United States)

    Heath, Linda; Weeks, Kyle; Murphy, Marie Mackay

    1997-01-01

    Using three studies, examined the relationship between attitudes toward guns and fear of crime. Findings indicate a connection between fear of crime and attitudes toward guns: people higher in fear of crime favored gun control. Results also established a relationship between stereotypical beliefs about gun victims and support for gun control. (RJM)

  3. Application of matrix singular value properties for evaluating gain and phase margins of multiloop systems. [stability margins for wing flutter suppression and drone lateral attitude control

    Science.gov (United States)

    Mukhopadhyay, V.; Newsom, J. R.

    1982-01-01

    A stability margin evaluation method in terms of simultaneous gain and phase changes in all loops of a multiloop system is presented. A universal gain-phase margin evaluation diagram is constructed by generalizing an existing method using matrix singular value properties. Using this diagram and computing the minimum singular value of the system return difference matrix over the operating frequency range, regions of guaranteed stability margins can be obtained. Singular values are computed for a wing flutter suppression and a drone lateral attitude control problem. The numerical results indicate that this method predicts quite conservative stability margins. In the second example if the eigenvalue magnitude is used instead of the singular value, as a measure of nearness to singularity, more realistic stability margins are obtained. However, this relaxed measure generally cannot guarantee global stability.

  4. 航天器非线性鲁棒自适应姿态机动控制律%Nonlinear robust adaptive attitude maneuver control law for spacecraft

    Institute of Scientific and Technical Information of China (English)

    王卫杰; 任元; 李怡勇; 罗元

    2015-01-01

    In the presence of uncertainties in the moment of inertia and the external disturbance torque,the nonlinear robust adaptive control law for the control torque and estimation of moment of inertia is designed com-bining the nonlinear backstepping and Lyapunovo stability.In the control law for the control torque,the nonlin-ear damping is added to compensate the external disturbance torque,and the globally uniformly ultimately bounded stability of the system is demonstrated.The nonlinear dynamic coefficient is introduced to increase the dynamic performance of the system,shortening the regulating time after fast attitude maneuver.By Matlab/Simulink programming,the simulation of spacecraft attitude manoeuver control is discussed,and the simulation results demonstrate the effectiveness and feasibility of the proposed controller.%针对存在未知转动惯量和外部干扰力矩的敏捷航天器快速大角度姿态机动问题,结合非线性反步法和 Lyapunovo 稳定性分析方法设计控制力矩和转动惯量估计值的非线性鲁棒自适应控制律。在控制力矩控制律中,加入非线性阻尼项对外部干扰力矩进行补偿,证明了系统的全局一致最终有界稳定性。引入非线性动系数增加系统的动态性能,提高了姿态快速机动后的快速稳定能力。在 Maltlab/Simulink 环境下进行航天器姿态机动控制仿真研究,仿真结果验证了所设计控制器的有效性和可行性。

  5. Entrepreneurial Attitudes among Potential Entrepreneurs

    Directory of Open Access Journals (Sweden)

    Akhtar Ali (Corresponding author

    2011-09-01

    Full Text Available This article explores entrepreneurial attitudes among potential entrepreneurs in Pakistan. Multi-stage sampling maximized representation. Four hundred and eighty masters of business administration (MBA students (potential entrepreneurs from six public sector Pakistani universities returned completed questionnaires. Three factors emerged: entrepreneurial acceptability, entrepreneurial intentions and personal factors. Moreover, the perceptions of the potential entrepreneurs on locus of control, self efficacy, subjective norms and instrumental readiness were also analyzed. The majority of students showed generally positive attitudes towards entrepreneurship at all six universities. Overall there was a significant difference between negative and positive attitudes (negative mean 184, positive mean 284. There was also some impact of demographic variables, such as university, parental income and profession. Both genders exhibited similar attitudes at most of the sample institutions. The implications for practice and policy are discussed.

  6. Attitudes, social representations and social attitudes

    OpenAIRE

    Farr, Robert, M.

    1994-01-01

    This paper plays the role of the devil's advocate in relation to Colin Fraser's paper "attitudes, social representations and widespread beliefs". It argues for the alternative perspective which Colin identifies that social representations and social attitudes are epistemologically incompatible theories.

  7. The Influence of Science Process Skills, Logical Thinking Abilities, Attitudes towards Science, and Locus of Control on Science Achievement among Form 4 Students in the Interior Division of Sabah, Malaysia

    Science.gov (United States)

    Fah, Lay Yoon

    2008-01-01

    The purpose of this study was to examine the direct and indirect effects of science process skills, logical thinking abilities, attitudes towards science, and locus of control on science achievement among Form 4 students in the Interior Division of Sabah, Malaysia. Research findings showed that there were low to moderate, positive but significant…

  8. The Beliefs, Attitudes and Views of University Students about Anger and the Effects of Cognitive Behavioral Therapy-Oriented Anger Control and Anxiety Management Programs on Their Anger Management Skill Levels

    Science.gov (United States)

    Karahan, T. Fikret; Yalçin, B. Murat; Erbas, Melda M.

    2014-01-01

    This study was designed as a qualitative focus group using a randomized controlled trail with a mixed methodology. The study has dual aims. First we searched the beliefs, attitudes and views of 176 university students on how to deal with anger using eight focus discussion groups. The anxiety and anger levels of these students were investigated…

  9. Attitude Control of Small Quad-rotor Based on Active Disturbance Rejection Control Theory%基于自抗扰理论的小型四旋翼飞行器姿态控制

    Institute of Scientific and Technical Information of China (English)

    张广昱; 袁昌盛

    2014-01-01

    To solve the attitude control problem of small quad-rotor according to its complex coupling ,non-linear and serious internal/external disturbance feature ,a control scheme based on active disturbance rejection control technique is proposed .The dynamic model is established with Newton-Euler equations ,and the uncertainty , coupling and parameter perturbation are considered as total disturbance .Extended state observer is used to esti-mate and compensate the total disturbance .The non-linear state error feedback is used to restrain the compen-sate error ,and did simulation experiment of attitude control for small quad-rotor .The result of the simulation shows that the extended state observer of the active disturbance rejection control technique can estimate/com-pensate disturbance well under circumstance of parameter perturbation and disturbance .The attitude controller based on active disturbance rejection control theory shows good dynamic quality ,steady-state accuracy and strong robustness .%针对四旋翼飞行器的强耦合性、非线性、易受外界干扰等控制难点,研究利用自抗扰控制器对四旋翼飞行器进行姿态控制的技术问题。通过牛顿-欧拉方程建立四旋翼飞行器动力学模型,将不确定性、耦合及参数摄动等干扰作为“总和干扰”,利用扩张状态观测器进行估计并动态反馈补偿,再利用非线性反馈抑制补偿残差,进行四旋翼飞行器姿态控制仿真实验。结果表明:在存在模型参数摄动和外界扰动的情况下,扩张状态观测器很好地实时估计和补偿了四旋翼飞行器的总和干扰,基于自抗扰的四旋翼飞行器姿态控制系统具有较好的动态品质、稳态精度以及较强的鲁棒性。

  10. Large angle attitude control of spacecraft based on on-off actuators%基于开关执行器的空间飞行器大角度姿态控制

    Institute of Scientific and Technical Information of China (English)

    周荻; 周成宝

    2014-01-01

    Considering the switching-type characteristic of attitude control actuators used in spacecraft three loop coupling attitude control systems,a large angle attitude maneuver control scheme of spacecraft is proposed.To avoid the singularity due to the use of Euler angle in large angle attitude maneuvers,the attitude kinematics of the spacecraft is described by quaternion.A variable structure controller with bounded inputs is designed by the method of Lyapunov and the stability of the system is proved.In order to avoid chattering,a boundary layer is used to replace the sign func-tion in the variable structure control law.The rest-to-rest attitude tracking control problem is simulated.Numerical simulation results show the effectiveness of the proposed attitude control method.%针对空间飞行器姿态控制系统采用开关式姿控发动机的特点,研究了空间飞行器大角度机动三通道耦合姿态控制问题。为克服大角度机动时使用欧拉角可能产生的奇异问题,采用四元数描述的空间飞行器姿态运动数学模型,应用 Lyapunov 方法设计了控制量受限情况下的基于误差四元数的大角度姿态运动变结构控制器,并给出了严格的数学证明。为了避免控制律中的颤动问题,用边界层来代替控制律中符号函数。给出了从一种静态到另外一种静态的姿态跟踪四元数指令确定方法。数值仿真结果说明了所提出的控制器的有效性。

  11. Chaotic Control with Finite Time of Spacecraft Attitude Dynamics%航天器姿态动力学有限时间的混沌控制

    Institute of Scientific and Technical Information of China (English)

    陈恒; 雷腾飞; 尹劲松

    2016-01-01

    针对一类航天器刚体姿态运动方程,首先对方程中的混沌特性进行了混沌动力学分析研究;其次提出了航天刚体姿态混沌运动的主动-有限时间控制,该控制器可以实现对时间的控制即通过调节终端吸引子的权数实现;最后,通过仿真验证了所提出的控制策略。仿真结果表明,设计的有限时间控制器比传统的控制器具有更强的鲁棒性和快速响应能力。%For a class of rigid spacecraft attitude motion equations,the chaotic dynamics characteristics were analyzed firstly,and then the initiative and finite time control was proposed which can be achieved by adj usting the rights of terminal promoters.The simulation results show that the designed finite-time con-troller has stronger robustness and faster response capacity than the traditional controller.

  12. Attitudes of Hungarian asthmatic and COPD patients affecting disease control: empirical research based on Health Belief Model

    Directory of Open Access Journals (Sweden)

    Judit eSimon

    2013-11-01

    Full Text Available Introduction: Patient non-adherence to treatment is a major problem across most chronic diseases. In COPD and asthma treatments it is a complex issue because people need to make behavioural and lifestyle changes while taking medications. Poor adherence results in increased rates of morbidity and mortality, more frequent hospitalisations, and ultimately higher healthcare expenditures. Material and methods: The objective of the study was to assess asthmatic and COPD patient’s attitudes toward adherence in Hungary. Health Belief Model was used to help explain reasons of non-adherence. The results of the study should provide additional support to understanding health-related behaviours and to developing health related programs enhancing adherence of asthmatic and COPD patients.145 diagnosed COPD patients and 161 diagnosed asthmatic patients were involved in 6 pulmonary centres. The questions were designed to measure Health Belief Model dimensions A 1-5 point verbal Likert scale was used. As a second stage, the answers were compared with the registered patient’s personal health data available in pulmonary centre’s documentation. The data was analysed using SPSS software.Results: More than 32% of patients are very interested in new asthma or COPD research results, but their main information source is physician. The trust toward the physician is very high. Patients accept treatments and rarely ask questions. Respondents are cooperative but sometimes fail to follow therapeutic recommendations. There is no willingness to join self-help groups or associations. Discussion: The paternalistic approach was generally accepted, moreover expected by the patients from the physicians. It is important to train patients, increase their self-efficacy, responsibility and involve them into self-management programs. Both physicians and patients should be trained how to communicate – this approach can lead to increased understanding and better adherence.

  13. Long Term Effect on Professionals' Knowledge, Practice and Attitudes towards User Involvement Four Years after Implementing an Organisational Development Plan: A Controlled Study.

    Directory of Open Access Journals (Sweden)

    Marit By Rise

    Full Text Available Health service organisations are increasingly implementing user involvement initiatives according to requirements from governments, such as user representation in administrational boards, better information to users, and more involvement of the users during treatment. Professionals are vital in all initiatives to enhance user involvement, and initiatives to increase involvement should influence the professionals' practice and attitudes. The implementation of a development plan intending to enhance user involvement in a mental health hospital in Central Norway had no effect on the professionals after 16 months. The objective was therefore to investigate the long term effect on the professionals' knowledge, practice and attitudes towards user involvement after four years.This was a non-randomized controlled study including professionals from three mental health hospitals in Central Norway. A development plan intended to enhance user participation was implemented in one of the hospitals, including establishing a patient education centre and a user office, purchasing of user expertise, appointing contact professionals for next of kin, and improving of the centre's information and the professional culture. The professionals at two other hospitals constituted the control group. All professionals were invited to answer the Consumer Participation Questionnaire (CPQ and additional questions, at a four year interval.A total of 399 professionals participated (43% response rate. Comparing the changes in the intervention group with the changes in the control group, the results showed that the plan had improved some aspects of the professionals' knowledge about the user involvement taking place in the hospital. In addition, some parts of the professionals' practice of providing information to the service users was improved, and the development plan might have raised their awareness about insufficient involvement of next of kin.This is the first controlled

  14. 高超声速飞行器自抗扰姿态控制器设计%Active disturbance rejection attitude control design for hypersonic vehicle

    Institute of Scientific and Technical Information of China (English)

    秦昌茂; 齐乃明; 朱凯

    2011-01-01

    针对高超声速飞行器无动力再入过程中具有强耦合、气动参数摄动及不确定性的非线性姿态模型,结合自抗扰控制中的扩张状态观测器(extended state observer,ESO)及非线性状态误差反馈律(nonlinear law state error feedback,NLSEF),分别设计了高超声速飞行器内环和外环自抗扰姿态控制器.将不确定性、耦合及参数摄动等干扰作为"总和干扰"利用扩张状态观测器进行估计并动态反馈补偿,再利用NLSEF抑制补偿残差.自抗扰控制器(active disturbance rejection control,ADRC)设计无需精确的飞行器被控模型,也无需精确的气动参数及摄动界限.仿真结果表明,控制系统能够克服干扰及气动参数大范围摄动的影响,在获取良好的动态品质和跟踪性能的同时,具有较强的鲁棒性.%For the hypersonic vehicle nonlinear attitude mode in re-entry process unpowered with a strong coupling, aerodynamic parameter perturbations and non-deterministic, combining extended state observer ( ESO) and nonlinear law state error feedback ( NLSEF) in the active disturbance rejection cotrol ( ADRC) , the hypersonic vehicle inner and outer ADRC attitude controller are designed respectively. Interferences, such as uncertainty, coupling and parameter perturbations, are regarded as "the sum of interference" , the extended state observer is used to estimate and implement dynamic feedback compensation, and then the NLSEF is used to inhibit the compensating residual. ADRC controller is designed without a precise model of vehicle, and without precise perturbation boundaries of aerodynamic parameters. Simulation results show that the control system can overcome the impact of large-scale perturbations of interference and aerodynamic parameters, which has good dynamic qualities, tracking capabilities, and strong robustness.

  15. Spacecraft Attitude Tracking and Maneuver Using Combined Magnetic Actuators

    Science.gov (United States)

    Zhou, Zhiqiang

    2012-01-01

    A paper describes attitude-control algorithms using the combination of magnetic actuators with reaction wheel assemblies (RWAs) or other types of actuators such as thrusters. The combination of magnetic actuators with one or two RWAs aligned with different body axis expands the two-dimensional control torque to three-dimensional. The algorithms can guarantee the spacecraft attitude and rates to track the commanded attitude precisely. A design example is presented for nadir-pointing, pitch, and yaw maneuvers. The results show that precise attitude tracking can be reached and the attitude- control accuracy is comparable with RWA-based attitude control. When there are only one or two workable RWAs due to RWA failures, the attitude-control system can switch to the control algorithms for the combined magnetic actuators with the RWAs without going to the safe mode, and the control accuracy can be maintained. The attitude-control algorithms of the combined actuators are derived, which can guarantee the spacecraft attitude and rates to track the commanded values precisely. Results show that precise attitude tracking can be reached, and the attitude-control accuracy is comparable with 3-axis wheel control.

  16. Investigation of Dynamic Aerodynamics and Control of Wind Turbine Sections Under Relevant Inflow/Blade Attitude Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Naughton, Jonathan W. [University of Wyoming

    2014-08-05

    The growth of wind turbines has led to highly variable loading on the blades. Coupled with the relative reduced stiffness of longer blades, the need to control loading on the blades has become important. One method of controlling loads and maximizing energy extraction is local control of the flow on the wind turbine blades. The goal of the present work was to better understand the sources of the unsteady loading and then to control them. This is accomplished through an experimental effort to characterize the unsteadiness and the effect of a Gurney flap on the flow, as well as an analytical effort to develop control approaches. It was planned to combine these two efforts to demonstrate control of a wind tunnel test model, but that final piece still remains to be accomplished.

  17. Attitudes regarding new enterprise risk and control regulations by the active population of the Geneva area: Cahier de recherche

    OpenAIRE

    Catenazzo, Giuseppe; Fragnière, Emmanuel

    2008-01-01

    Nowadays, professional bodies as well as public authorities are setting up new regulations and standards in order to deploy risk management approaches in the non-financial industries. For instance, Switzerland has recently introduced a new regulation on Internal control that forces most SMEs to implement an ICS (Internal Control System). However, introducing or dealing with new risk control regulations might not bring the desired effect to the organisation: logistical and psychological barrie...

  18. More is not always better: The pivotal role of desire for control in affecting service attitudes and behavior

    NARCIS (Netherlands)

    Joosten, H.W.M.; Bloemer, J.M.M.; Hillebrand, B.

    2013-01-01

    Many marketers and academics assume that customers always want control of the service experience and benefit (perceive value) from having more control (Namasivayam and Mount, 2006). However, empirical support for this assumption is limited. The study proposes that beneficial effects will occur if th

  19. Flexible Spacecraft Attitude stabilization Control Based on Direct Adaptive Algorithm%基于直接自适应的挠性航天器姿态稳定控制

    Institute of Scientific and Technical Information of China (English)

    刘敏; 徐世杰; 韩潮

    2012-01-01

    An adaptive control strategy based on backstepping control and direct adaptive control was proposed to resolve the flexible spacecraft attitude stabilization control problem.Firstly, the flexible spacecraft was divided into dynamics subsystem and kinematics subsystem, and an ideal reference model was designed.Secondly,under the assumption of small attitude angle, a direct adaptive intermediate control law was designed.Finally, the spacecraft attitude controller was designed by adopting the backstepping control method, and the stability of the close-loop control system was proved.Theoretical study and numerical simulation results validate the efficiency of the flexible spacecraft adaptive attitude stabilization controller.%针对挠性航天器姿态稳定控制,基于退步控制方法与直接自适应控制方法提出了一种自适应控制策略.首先将挠性航天器模型分解为运动学子系统和动力学子系统,并设计具有理想控制性能的参考模型;然后在姿态小角度的假设下,对满足近似严格正实性的姿态运动学子系统设计了直接自适应中间控制律;最后运用退步控制方法对航天器动力学子系统设计了姿态控制器,并证明了闭环系统的稳定性.理论分析和数值仿真结果表明该控制器对挠性航天器的姿态稳定控制是有效的.

  20. Active disturbance rejection control for spacecraft attitude maneuver and stability%航天器姿态机动及稳定的自抗扰控制

    Institute of Scientific and Technical Information of China (English)

    赖爱芳; 郭毓; 郑立君

    2012-01-01

    针对航天器动力学参数不确定性以及系统存在外部持续干扰的问题,提出了一种自抗扰姿态控制器的设计方法.在为期望姿态安排过渡过程的基础上,设计了扩张状态观测器,对参数不确定性和外部干扰进行估计,并实时补偿.为抑制跟踪误差,设计了非线性状态误差反馈律.仿真结果表明,该控制器不仅能很好地估计并补偿系统受到的持续干扰,而且对航天器动力学参数的不确定性具有较强的鲁棒性,满足航天器姿态快速机动和高稳定度的控制要求,性能指标明显优于PD控制.%For a spacecraft with dynamic parametric uncertainties and external persistent disturbances, we present an active disturbance rejection control (ADRC). After arranging the transient dynamics of the desired attitude, we design an extended state observer (ESO) to estimate the impact from parametric uncertainties and disturbances, and realize corre- sponding compensations online. A nonlinear state error feedback law is designed to reject the tracking error. Simulation results show that the designed controller not only accurately estimates and compensates the persistent disturbances, but also realizes the robustness to dynamic parametric uncertainties of the spacecraft. It meets the requirements on the spacecraft fast attitude maneuver and high stability. The performance indices are much superior to those of the PD controller.

  1. Design of Four Axis Spacecraft Attitude Control System%四轴飞行器姿态控制系统设计

    Institute of Scientific and Technical Information of China (English)

    常敏; 崔永进; 何蓓薇; 张学典; 钱研华; 王戈

    2015-01-01

    On the basis of the full study structural characteristics and dynamic characteristics of four axis spacecraft, this paper designed a flight control system with STM32F303 MCU and MPU6050 IMU sensor,the software running on the flight control system which is based on ChibiOS RTOS and the software running on handset which is based on Android OS. At the end of the paper,the designed flight control system has carried on the real machine test flights and debugging,the flight test show that the design of attitude control system for four axis spacecraft can control the unmanned aerial vehicles (UAV)flight smoothly.%文章在充分研究四轴飞行器的结构特点和动力学特性的基础上,设计并实现了以 STM32F303微控制器为核心,MPU6050为惯性测量单元的飞行控制系统硬件,基于 ChibiOS 实时操作系统的飞行控制软件,以及基于 Android 操作系统的手持端软件。最后对本文所设计的飞行器控制系统进行了真机飞行试验和调试,飞行试验表明,所设计的四轴飞行器姿态控制系统,能够很好的控制四轴飞行器实现半自主平稳飞行。

  2. Attitude Dynamics and Control of Spacecraft Filled with Liquid and Attached with a Flexible Appendage%带柔性附件的充液飞行器姿态动力学与控制

    Institute of Scientific and Technical Information of China (English)

    徐建国

    2008-01-01

    研究了流-刚-弹耦合飞行器系统的姿态动力学、稳定性与控制问题,给出了组成系统的每部分控制律,证明了在此控制律下系统可达到姿态定位和受控系统指数渐近稳定.%The attitude dynamics,stability and control of the spacecraft system coupled with fluid,rigid and elastic bodies are studied in this paper. The control laws are given respectively for every part of the system. It is proved that the control laws might lead the attitude of the system to the desired position and that the controlled system is exponentially asymptotically stable.

  3. Construction of attitude stability controller preferential evaluation system%姿态稳定控制器择优评价体系构建

    Institute of Scientific and Technical Information of China (English)

    殷春武; 侯明善; 李明翔

    2016-01-01

    An attitude controller preferential evaluation system based on group decision making is construc-ted to deal with the controller selection problem in the process of spacecraft overall design,and a reliability in-dex is defined to measure the reliability of the evaluation result.An evaluation index system is constructed, which includes the robustness of controller,controlling torque,sensitivity to parameter,complexity of control-ler and rate of convergence,determine the weights of indexes with the combination weighting method based on the OWA operator,and an interval group decision making method is provided to select the optimal controller,a quantitative description index of evaluation result’s reliability based on interval analysis is defined.The attitude stability controller preferential evaluation process in the process of spacecraft overall design is analyzed,the ef-fectiveness of the controller preferential evaluation system and the high reliability of the evaluation results are verified,which enriches the theory of decision-making,and enhance the policymakers’confidence.%针对航天器总体设计过程中姿态稳定控制器的选择问题,构建了一套基于群决策的姿态控制器择优评价体系,并给出度量评价结果可靠性的可靠度指标。构建了基于控制器鲁棒性、控制力矩、参数敏感性、控制器复杂度和收敛速度的姿态控制器择优评价指标体系,采用同时融合多种赋权法优势的有序加权(ordered weighted averaging,OWA)组合赋权法确定指标权重,给出一种群组专家参与的区间型姿态稳定控制器择优评价方法,并定义了基于区间分析的评价结果可靠度定量描述指标。实例分析了航天器总体设计过程中的姿态稳定控制器择优评价过程,验证了控制器择优评价体系的有效性和评价结果的高可靠度,丰富了决策理论,增强了决策者信心。

  4. Public attitudes and beliefs about genetics.

    Science.gov (United States)

    Condit, Celeste M

    2010-01-01

    The existing research base on public attitudes about genetics shows that people's attitudes vary according to the specific technologies and purposes to which genetic knowledge is applied. Genetic testing is viewed highly favorably, genetically modified food is viewed with ambivalence, and cloning is viewed negatively. Attitudes are favorable for uses that maintain a perceived natural order and unfavorable for uses that are perceived to change it. Public concerns about control of genetic information and eugenics are evident, but their strength and relevance to policy preference are unclear. The pattern of attitudes can be explained by theories of attitude formation, and the existing base of information can be deepened and given more explanatory and predictive power by integrating future research into the various traditions that theorize attitude formation.

  5. Sexual orientation differences in attitudes about sexuality, race, and gender.

    Science.gov (United States)

    Grollman, Eric Anthony

    2017-01-01

    Researchers have extensively documented sociodemographic predictors of race and gender attitudes, and the mechanisms through which such attitudes are formed and change. Despite its growing recognition as an important status characteristic, sexual orientation has received little attention as a predictor of Americans' race and gender attitudes. Using nationally representative data from the American National Election Survey 2012 Time Series Study, I compare heterosexuals' and lesbian, gay, and bisexual (LGB) people's attitudes about sexuality, race, and gender. For most attitudes, LGB people hold significantly more liberal attitudes about sexuality, race, and gender than do heterosexuals, even upon controlling for other powerful sociodemographic determinants of social attitudes. However, a substantial proportion of these sexual orientation gaps in attitudes - especially about race and gender - are explained by LGB people's relatively liberal political ideology. The findings provide evidence for the necessity of incorporating sexual orientation in future assessments of Americans' social and political attitudes.

  6. Farmers' Attitudes and Behavior toward Sustainable Agriculture.

    Science.gov (United States)

    Petrzelka, Peggy; Korsching, Peter F.; Malia, James E.

    1996-01-01

    A mail survey of Iowa farmers with membership in Practical Farmers of Iowa (PFI), a sustainable agriculture organization, was used to examine the attitude-behavior relationship of these farmers and the role social influences played in this relationship. Results indicate that when controlling explanatory factors, the attitude-behavior relationship…

  7. Fault Diagnosis Based on RO-NUIO/LMI for Flexible Satellite Attitude Control Systems during Orbit Control%基于RO-NUIO/LMI的挠性卫星轨控期间姿控系统故障诊断

    Institute of Scientific and Technical Information of China (English)

    侯倩; 程月华; 姜斌; 陆宁云

    2011-01-01

    During satellite orbit maneuver, the orbit control force causes disturbing torque and affects attitude of a satellite if the control force does not pass through the mass center of the satellite. In this paper, a set of reduced order nonlinear unknown input observers (RO-NUIO) are designed to detect and isolate faults. During the design process, the system is divided into three sub-systems to ensure that some states are not affected by the disturbance. Observers are designed by using the observable information. Meanwhile, some parameters of the observers can be obtained by using the LMI approach to reduce effects of nonlinear part on observers. The existence conditions of the observer proposed in this paper only depend on the inherent feature of the system. Combination of the reduced order idea and the LMI method make the structure of observers easy to be applied to nonlinear satellite attitude control systems. Numerical simulation is carried out to demonstrate the efficiency of the proposed fault diagnosis scheme for satellite attitude control systems.%卫星轨控期间,由于推力偏心,会产生较大的干扰力矩,直接影响卫星姿态.针对轨道控制期间的挠性卫星姿态控制系统,设计了干扰解耦的降阶非线性未知输入观测器(RO-NUIO),用于故障检测与故障隔离.在设计过程中,首先通过坐标变换,使得不可观的状态及部分可观状态不受干扰影响,然后针对不可观的子系统利用可观状态的信息设计观测器,观测器中的部分参数利用LMI方法获得,可以弱化非线性部分对观测器的影响.所设计观测器的存在条件仅依赖于系统本身特性,无需在线验证.观测器采用降阶设计,同时借助LMI思想,结构简单,适合于非线性卫星姿态控制系统.仿真结果验证了降阶非线性未知输入观测器实现卫星姿态控制故障诊断的可行性与有效性.

  8. Active vibration control and attitude maneuver of flexible spacecraft via direct adaptive control method%挠性航天器姿态机动直接自适应主动振动控制

    Institute of Scientific and Technical Information of China (English)

    刘敏; 徐世杰; 韩潮

    2013-01-01

    针对具有压电陶瓷自敏执行机构的挠性航天器,基于直接自适应控制方法,设计了姿态机动主动振动控制器.首先,验证了在执行机构与敏感器同位安装时,挠性航天器系统的近似严格正实性;然后,设计了挠性航天器的直接自适应姿态机动主动振动控制器,使得航天器输出渐近跟踪具有理想控制性能的参考模型输出;最后,在多组仿真条件下进行了挠性航天器直接自适应姿态机动控制数值仿真.理论分析与仿真结果表明,该方法对航天器惯量和挠性附件模态的不确定性具有强鲁棒性,能够实现对多阶模态的同时控制,对挠性航天器的姿态机动主动振动控制是有效的.%An attitude maneuver and active vibration control method was proposed for flexible spacecraft with piezoelectric material as flexible modes active suppression sensors and actuators. Firstly, the almost strict positive real ( ASPR) property of flexible spacecraft with collocated sensors and actuators was discussed. Then, the direct adaptive controller was designed to both the attitude maneuver and flexible appendix vibration. Finally, the controller was applied to a flexible spacecraft in different initial conditions. Theoretical anal-ysises and simulation results validate that the controller has strong robustness to spacecraft inertial and flexible model uncertainties, can suppress modes at the same time. Both the attitude maneuver and vibration suppression can be accomplished effectively.

  9. Exploring Attitudes and Beliefs towards Implementing Cattle Disease Prevention and Control Measures: A Qualitative Study with Dairy Farmers in Great Britain.

    Science.gov (United States)

    Brennan, Marnie L; Wright, Nick; Wapenaar, Wendela; Jarratt, Susanne; Hobson-West, Pru; Richens, Imogen F; Kaler, Jasmeet; Buchanan, Heather; Huxley, Jonathan N; O'Connor, Heather M

    2016-10-11

    Disease prevention and control practices are frequently highlighted as important to ensure the health and welfare of farmed animals, although little is known as to why not many practices are carried out. The aim of this study was to identify the motivators and barriers of dairy cattle farmers towards the use of biosecurity measures on dairy farms using a health psychology approach. Twenty-five farmers on 24 farms in Great Britain (GB) were interviewed using the Theory of Planned Behaviour framework. Results indicated that farmers perceived they had the ability to control what happened on their farms in terms of preventing and controlling disease, and described benefits from being proactive and vigilant. However, barriers were cited in relation to testing inaccuracies, effectiveness and time-efficiency of practices, and disease transmission route (e.g., airborne transmission). Farmers reported they were positively influenced by veterinarians and negatively influenced by the government (Department for Environment Food & Rural Affairs (DEFRA)) and the general public. Decisions to implement practices were influenced by the perceived severity of the disease in question, if disease was diagnosed on the farm already, or was occurring on other farms. Farmers described undertaking a form of personal risk assessment when deciding if practices were worth doing, which did not always involve building in disease specific factors or opinions from veterinarians or other advisors. These results indicate that further guidance about the intricacies of control and prevention principles in relation to specific animal diseases may be required, with an obvious role for veterinarians. There appears to be an opportunity for farm advisors and herd health professionals to further understand farmer beliefs behind certain attitudes and target communication and advice accordingly to further enhance dairy cattle health and welfare.

  10. The Diabetes Intention, Attitude, and Behavior Questionnaire: evaluation of a brief questionnaire to measure physical activity, dietary control, maintenance of a healthy weight, and psychological antecedents

    Directory of Open Access Journals (Sweden)

    Traina SB

    2016-02-01

    -related self-care activities. Most subjects in Stage II were male, Caucasian, and married. Mean age was 63 years. Factor analysis revealed six psychological constructs (Behavior, Planning, Intention, Perceived Behavioral Control, Attitude, and Subjective Norm. Test–retest reliability was acceptable (≥0.70 for all scales, except Perceived Behavioral Control. Construct validity was demonstrated based on correlations with diabetes-specific items/scales and the SF-36. Known-groups validity was confirmed for Behavior, Planning, and Intention when respondents were categorized into groups that differed based on body mass index, disease severity, and HbA1c. Item scores were transformed to a 100-point scale, and minimal clinically important change estimates ranged from 6–11 points, representing the change that would be considered important to a respondent. Conclusion: The DIAB-Q is a brief, psychometrically sound, patient-reported outcome that can be used among individuals with T2DM to evaluate intention to engage in self-care behaviors. Keywords: diabetes, Theory of Planned Behavior, DIAB-Q, attitude, intention, behavior, patient-reported outcome, questionnaire

  11. The Temporal Resolution of Flight Attitude Control in Dragonflies and Locusts: Lessons for the Design of Flapping-Wing MAVs

    Science.gov (United States)

    2007-12-04

    recording, at a frequency that equals the frequency difference. Images were digitized using the firewire capture software by Ultravision and could...1963): A stretch reflex controlling wingbeat frequency in grasshoppers . J. Exp. Biol. 40, 171-185 WILSON, D. M., WEIS-FOGH, T.(1962

  12. Project SUCCESS' Effects on Substance Use-Related Attitudes and Behaviors: A Randomized Controlled Trial in Alternative High Schools

    Science.gov (United States)

    Clark, Heddy Kovach; Ringwalt, Chris L.; Shamblen, Stephen R.; Hanley, Sean M.

    2011-01-01

    Using a randomized controlled effectiveness trial, we examined the effects of Project SUCCESS on a range of secondary outcomes, including the program's mediating variables. Project SUCCESS, which is based both on the Theory of Reasoned Action and on Cognitive Behavior Theory, is a school-based substance use prevention program that targets…

  13. Credit Card Misuse, Money Attitudes, and Compulsive Buying Behaviors: A Comparison of Internal and External Locus of Control (LOC) Consumers

    Science.gov (United States)

    Watson, Stevie

    2009-01-01

    This study examined attitudinal and behavioral differences between internal and external locus of control (LOC) consumers on credit card misuse, the importance of money, and compulsive buying. Using multiple analysis of variance and separate analyses of variance, internal LOC consumers were found to have lower scores on credit card misuse and…

  14. Predictive Attitude Maintenance For A Space Station

    Science.gov (United States)

    Hattis, Philip D.

    1989-01-01

    Paper provides mathematical basis for predictive management of angular momenta of control-moment gyroscopes (CMG's) to control attitude of orbiting space station. Numerical results presented for pitch control of proposed power-tower space station. Based on prior orbit history and mathematical model of density of atmosphere, predictions made of requirements on dumping and storage of angular momentum in relation to current loading state of CMG's and to acceptable attitude tolerances.

  15. Path planning and optimal control for attitude maneuver of flexible spacecraft%挠性航天器姿态机动路径设计及最优控制

    Institute of Scientific and Technical Information of China (English)

    黄颖; 韩帅帅; 王璐; 郭毓

    2015-01-01

    For the issue of attitude maneuver control of a flexible spacecraft,a novel attitude control maneuver scheme based on the linear quadratic regulator (LQR),the expended state observer(ESO) and path planning was proposed.The attitude dynamics state equation of a flexible spacecraft was es-tablished.To solve the problem that the attitude maneuver often leads to strong vibration of the flexi-ble appendages,the maneuvering path planning based on a curve of cosinusoidal angle speed change was given in which the initial velocity is not required to be zero.Based on LQR theory an attitude con-troller was designed for the flexible spacecraft.Furthermore,an extended state observer (ESO)for the flexible spacecraft was designed to estimate the attitude velocity,the modal velocity and the con-tinuous time-varying external disturbances.By combining the LQR controller with the ESO,active rejection of disturbances can be achieved in the proposed control scheme.Simulation results demon-strate the effectiveness of the proposed control strategy.%针对在轨挠性航天器姿态机动控制问题,提出了一种基于路径规划、线性二次型最优控制(LQR)和扩张状态观测器(ESO)新的姿态控制方法。在建立单轴挠性航天器姿态动力学系统状态方程的基础上,针对姿态机动易造成挠性附件大幅振动的问题,提出了一种余弦型角速度曲线的姿态机动路径规划方法,可应用于初速非零的情况。针对姿态角速度和挠性模态的变化率不易测得以及系统中受到持续时变干扰的问题,构建ESO 对系统状态量和干扰进行估计,并与 LQR 控制相结合,设计了具有自抗扰能力的姿态控制器。仿真结果验证了所提控制方法的有效性。

  16. 基于广义逆的欠驱动航天器姿态机动控制%Generalised Inversion Based Maneuver Attitude Control for Underactuated Spacecraft

    Institute of Scientific and Technical Information of China (English)

    黄静; 李传江; 马广富; 刘刚

    2013-01-01

    针对欠驱动刚体航天器机动控制问题,应用广义逆方法设计了姿态机动控制器.首先将三轴稳定欠驱动航天器动力学和运动学系统分解为三个子系统,应用微分几何理论将欠驱动航天器子系统转化为逐点线性形式,并设计了欠驱动航天器子系统渐近稳定控制器,进一步引入了动态尺度广义逆和摄动零控制向量,实现了对另外两轴的控制.设计的广义逆姿态控制器保证了整个系统的渐近稳定性,达到了控制要求.数值仿真实验结果表明了所设计控制律的有效性.%The methodology based on the concept of generalized inversion is investigated for asymptotic stabilization of underactuated rigid body dynamics under two degrees of actuation. Firstly, the underactuated kinematics and dynamics system is partitioned into three subsystems, and the underactuated subsystem is transformed as the point-wise linear form by differential geometry theory and achieves global realisability. Furthermore, with the introduction of dynamically scaled generalized inversion and perturbed null-control vector, a continuous feedback control law is designed to achieve the attitude stabilization of the underactuated spacecraft. Finally, the analytical and simulation results show that the proposed control methodology is effective.

  17. Explicit- and Implicit Bullying Attitudes in Relation to Bullying Behavior

    Science.gov (United States)

    van Goethem, Anne A. J.; Scholte, Ron H. J.; Wiers, Reinout W.

    2010-01-01

    The main aim of this study was to examine whether an assessment of implicit bullying attitudes could add to the prediction of bullying behavior after controlling for explicit bullying attitudes. Primary school children (112 boys and 125 girls, M age = 11 years, 5 months) completed two newly developed measures of implicit bullying attitudes (a…

  18. Impact of attitudes and beliefs regarding African American sexual behavior on STD prevention and control in African American communities: unintended consequences.

    Science.gov (United States)

    Valentine, Jo A

    2008-12-01

    Compared to whites, blacks experience significant health disparities for sexually transmitted diseases, particularly in the rates of chlamydia, gonorrhea, and syphilis. To develop more effective interventions to control and prevent STDs, public health practitioners should better understand and respond to factors that facilitate sexual risk-taking behaviors and impede access to STD health care and make use of factors that promote sexual health. Legacies of slavery, racism, and economic or class discrimination leave many blacks suspicious of interventions aimed at improving the welfare of their communities. Sexual behavior, in particular, has been used to justify social oppression of blacks in the United States. Although efforts to engage affected black communities in improving STD health care delivery have been undertaken, bias, prejudice, and stereotyping continue to contribute to negative experiences for many blacks across health care settings, including those involving STD care. Implementing more effective interventions to reduce the disparate burden of bacterial STDs in black communities requires accessible and acceptable STD health care. Understanding and addressing the potential impact of both provider and patient attitudes can improve these service delivery outcomes.

  19. Development and psychometric testing of the Attitudes, Subjective Norms, Perceived Behavioural Control, and Intention to Pursue a Career in Mental Health Nursing scale.

    Science.gov (United States)

    Wilbourn, Mark; Salamonson, Yenna; Ramjan, Lucie; Chang, Sungwon

    2017-01-19

    The aim of the present study was to develop and test the psychometric properties of the Attitudes, Subjective Norms, Perceived Behavioural Control, and Intention to Pursue a Career in Mental Health Nursing (ASPIRE) scale, an instrument to assess nursing students' intention to work in mental health nursing. Understanding the factors influencing undergraduate nursing students' career intentions might lead to improved recruitment strategies. However, there are no standardized tools to measure and assess students' intention to pursue a career in mental health nursing. The present study used a cross-sectional survey design undertaken at a large tertiary institution in Western Sydney (Australia) between May and August 2013. It comprised three distinct and sequential phases: (i) items were generated representing the four dimensions of the theory of planned behaviour; (ii) face and content validity were tested by a representative reference group and panel of experts; and (iii) survey data from 1109 first- and second-year and 619 third-year students were used in exploratory and confirmatory factor analyses to test the factorial validity of the scale. Internal consistency was measured using Cronbach's alpha. Items generated for the ASPIRE scale were subject to face and content validity testing. Results showed good factorial validity and reliability for the final 14-item scale. Principal axis factoring revealed a one-factor solution, the hypothesized model being supported by confirmatory factor analysis. The ASPIRE scale is a valid and reliable instrument for measuring intention to pursue a career in mental health nursing among Bachelor of Nursing students.

  20. 轮缘驱动式姿控飞轮电机设计%Design of rim-driven attitude control flywheel motor

    Institute of Scientific and Technical Information of China (English)

    王辉; 武俊峰; 吴一辉

    2012-01-01

    为了提高小卫星用姿控飞轮的转动惯量/质量比,实现飞轮调姿系统的轻量化,设计了一种飞轮用永磁无刷直流电机.根据电机磁路,推导了磁钢尺寸与最大磁能积的关系;采用有限元法分析了磁路参数对飞轮性能的影响;针对飞轮电机大气隙、大径长比的结构特点,给出了气隙磁通密度的计算方法;建立了绕组参数与电机额定数据间的关系;仿真分析了电机性能.通过对一台最高转速为6 000 r/min、角动量为5 Nms的飞轮电机样机进行实验验证,得出最大设计误差为6.5%,证明了设计方法的正确性.%To improve the inertia / mass ratio of attitude control flywheel used in small satellite and lighten the weight of flywheel attitude adjustment system,a brushless DC motor used in flywheel was designed. According to the motor magnetic circuit,the corresponding relationship between the size and maximum energy of magnet was derived. The influence of magnetic circuit parameters on the flywheel performance was analyzed by using the Finite Element Method (FEM). For the flywheel structure feature of large equivalent air-gap and large ratio of diameter to length, a method for calculating air-gap magnetic flux density was proposed. The relationship between winding parameters and the motor rated data was established. Simulation method was used to analyze the motor performances. Compared with a flywheel motor with the angular moment of 5 Nms at the highest speed of 6 000 r/min,the maximum error is 6. 5% .which proves the correctness of the design method.

  1. Towards an effective control programme of soil-transmitted helminth infections among Orang Asli in rural Malaysia. Part 2: Knowledge, attitude, and practices

    Directory of Open Access Journals (Sweden)

    Nasr Nabil A

    2013-01-01

    Full Text Available Abstract Background In the first part of this study, we investigated the prevalence and associated key factors of soil-transmitted helminth (STH infections among Orang Asli children in rural Malaysia; an alarming high prevalence and five key factors significantly associated with infections were reported. Part 2 of this study aims to evaluate the knowledge, attitude and practices (KAP on STH infections among Orang Asli in Peninsular Malaysia. Methods A cross-sectional study was carried out among 215 households from 13 villages in Lipis district, Pahang, Malaysia. Demographic and socioeconomic information of the participants and their KAP on STH were collected by using a pre-tested questionnaire. Results Overall, 61.4% of the participants had prior knowledge about intestinal helminths with a lack of knowledge on the transmission (28.8%, signs and symptoms (29.3% as well as the prevention (16.3%. Half of the respondents considered STH as harmful, while their practices to prevent infections were still inadequate. Significant associations between the KAP and age, gender, educational and employment status, family size, and household monthly income were reported. Moreover, significantly lower prevalence of STH infections was reported among children of respondents who wear shoes/slippers when outside the house (72.8%; 95% CI= 62.6, 80.5 vs 87.0%; 95% CI= 81.4, 91.1, wash their hands before eating (32.4%; 95% CI= 24.3, 42.2 vs 51.4%; 95% CI= 44.7, 60.1, and wash their hands after defecation (47.8%; 95% CI= 35.7, 57.1 vs 69.2%; 95% CI= 63.7, 78.7 as compared to their counterparts. Multiple logistic regression analysis indicated that the educational level of the respondents was the most important factor significantly associated with the KAP on STH among this population. Conclusion This study reveals inadequate knowledge, attitude and practices on STH infections among Orang Asli in rural Malaysia. Hence, there is a great need for a proper health education

  2. Modeling of spacecraft attitude systems with single gimbal control moment gyros and controllability analysis%具有单框架控制力矩陀螺航天器的建模及可控性分析

    Institute of Scientific and Technical Information of China (English)

    张佳为; 马克茂; 孟桂芝

    2012-01-01

    针对具有单框架控制力矩陀螺的航天器姿态控制问题,将航天器与控制力矩陀螺看作整体系统,应用Lagrangian方程与Hamiltonian方程建立系统在重力场中的数学模型.在考虑航天器短时间内大角度机动前提下,将系统在Lagrangian形式下的状态方程简化成仿射非线性形式,以控制力矩陀螺框架角速度为输入变量,回避控制力矩陀螺在奇异情况下对系统的影响.随后应用系统Hamiltonian形式的保体积性与非线性系统可控性定理证明该系统可控,且系统可控性不受单框架控制力矩陀螺群个数、构型、奇异问题的影响.系统在重力场中的数学模型与可控性结论为以后进一步研究航天器姿态控制方法,航天器系统稳定性问题提供了理论依据.%For a spacecraft using single gimbal control moment gyros (SGCMGs) as actuators, taking the spacecraft and SGCMGs as a whole system, the model of the attitude control system is constructed in the gravitational field by using Lagrangian and Hamilton equations. In the case of large-angle maneuvers of the spacecraft in short time, the state equation of the system in Lagrangian form is simplified as an affine nonlinear equation, with the angular velocity of SGCMG gimbals as an input variables, which avoids the singularity problem arising in conventional treatment. Finally, the controllability of the system is analyzed by using the preservation of the system volume in Hamiltonian form. The controllability property holds in spite of the number of the SGCMGs, their configuration and the presence of singularity. The model and the controllability of the attitude control system provide a theoretical basis of the further investigation on the control and stability analysis of the spacecraft system.

  3. Implicit attitudes in sexuality: gender differences.

    Science.gov (United States)

    Geer, James H; Robertson, Gloria G

    2005-12-01

    This study examined the role of gender in both implicit and explicit attitudes toward sexuality. Implicit attitudes are judgments or evaluations of social objects that are automatically activated, often without the individual's conscious awareness of the causation. In contrast, explicit attitudes are judgments or evaluations that are well established in awareness. As described in Oliver and Hyde's (1993) meta-analysis of self-report (explicit) data, women report greater negative attitudes toward sexuality than do men. In the current study, we used the Sexual Opinion Survey (SOS) developed by Fisher, Byrne, White, and Kelley (1988) to index explicit attitudes and the Implicit Association Test (IAT) developed by Greenwald, McGhee, and Schwartz (1998) to index implicit attitudes. Research has demonstrated that the IAT reveals attitudes that participants may be reluctant to express. Independent variables examined were participant gender, social acceptability of sexual words, and order of associated evaluations in the IAT (switching from positive to negative evaluations or the reverse). The IAT data revealed a significant Order x Gender interaction that showed that women had more negative implicit attitudes toward sexuality than did men. There was also a significant Order x Acceptability interaction, indicating that implicit attitudes were more strongly revealed when the sexual words used in the IAT were more socially unacceptable. As expected, on the SOS, women had more negative explicit attitudes toward sexuality. There was no significant correlation between explicit and implicit attitudes. These data suggest that at both automatic (implicit) and controlled (explicit) levels of attitudes, women harbor more negative feelings toward sex than do men.

  4. The influence of parents' martial dissolutions on children's attitudes toward family formation.

    Science.gov (United States)

    Axinn, W G; Thornton, A

    1996-02-01

    We investigate the influence of parents' martial dissolutions on their children's attitudes toward several dimensions of family formation. Hypotheses focus on the role of patients' attitudes as a mechanism linking parents' behavior to their children's attitudes. We test these hypotheses using intergenerational panel data that include measures of children's attitudes taken directly from children. Results demonstrate strong effects of parental divorce, remarriage, and widowhood on children's attitudes toward premarital sex, cohabitation, marriage, childbearing, and divorce. The results also show that parents' own attitudes link their behavior to their children's attitudes, although substantial effects of parental behavior remain after controlling for parents' attitudes.

  5. Cell Membrane Discharge Model Enlightened Robust Attitude Maneuvering Control for Flexible Spacecraft%受细胞膜放电模型启发的航天器姿态鲁棒控制

    Institute of Scientific and Technical Information of China (English)

    周端; 郭毓; 陈庆伟; 胡维礼

    2013-01-01

    研究了具有模型参数不确定和受空间环境干扰影响的挠性航天器姿态大角度快速机动快速稳定控制问题,设计了一种受细胞膜放电模型启发的鲁棒姿态控制器.综合考虑挠性航天器的强非线性和强耦合特性,设计了对模型参数和环境干扰具有鲁棒性的姿态机动控制器.为了减小机动中姿态突变激发的挠性附件振动,基于细胞膜放电的动力学模型设计了一种改进的鲁棒控制器.当参数不确定范围和干扰有界时,所提鲁棒控制器可使闭环系统的解最终一致有界.最后,分析了控制器参数对姿态控制性能及所需能量的影响.数值仿真验证了所提鲁棒控制器用于姿态机动控制可以得到良好的效果.%Under model parametric uncertainties and external disturbances in space, this study investigates attitude maneuvering control for large angle rapid maneuvering and fast stable of flexible spacecraft. A cell membrane discharge model enlightened robust attitude maneuvering control law is designed. To cope with the existing model parametric uncertainties and external disturbances, a robust attitude maneuvering controller is proposed based on the nonlinear and coupled characteristics of flexible spacecraft. The problem of jump of attitude which will excite the elastic vibration mode during large angle maneuver of flexible spacecraft is studied. By using dynamics model of cell membrane discharge, an improved robust attitude maneuvering controller is proposed. When the errors of model parametric uncertainties and external disturbances are bounded, it is proved that the closed-loop system is uniformly ultimately bounded. Finally, by using the control parameters properly, the control performance can be improved and the control energy can be reduced. The simulation results demonstrate the effectiveness of the proposed robust controller.

  6. Exploring Attitudes and Beliefs towards Implementing Cattle Disease Prevention and Control Measures: A Qualitative Study with Dairy Farmers in Great Britain

    Science.gov (United States)

    Brennan, Marnie L.; Wright, Nick; Wapenaar, Wendela; Jarratt, Susanne; Hobson-West, Pru; Richens, Imogen F.; Kaler, Jasmeet; Buchanan, Heather; Huxley, Jonathan N.; O’Connor, Heather M.

    2016-01-01

    disease was diagnosed on the farm already, or was occurring on other farms. Farmers described undertaking a form of personal risk assessment when deciding if practices were worth doing, which did not always involve building in disease specific factors or opinions from veterinarians or other advisors. These results indicate that further guidance about the intricacies of control and prevention principles in relation to specific animal diseases may be required, with an obvious role for veterinarians. There appears to be an opportunity for farm advisors and herd health professionals to further understand farmer beliefs behind certain attitudes and target communication and advice accordingly to further enhance dairy cattle health and welfare. PMID:27727168

  7. Weight self-regulation process in adolescence: the relationship between control weight attitudes, behaviors and body weight status

    Directory of Open Access Journals (Sweden)

    Jordi ePich

    2015-05-01

    Full Text Available Adolescents’ self-control weight behaviors were assessed (n= 1961; 12-17 years old; 2007-2008 in the Balearic Islands, Spain. The study analyzed the relationships between body weight status, body image and self-weight concern, and actual attempts to lose weight by restrained eating and/or increased exercising. In terms of regulatory focus theory (RFT, we considered that efforts to lose or to maintain weight (successful or failed would be motivated either by a promotion focus (to show an attractive body, a prevention focus (to avoid social rejection of fatness, or both. Results showed that 41% of overweight boys and 25% of obese boys stated that they had never made any attempt to lose weight, and 13% and 4% in females. Around half of overweight boys and around a quarter of obese boys stated that they were Not at all concerned about weight gain, and girls’ percentages decreased to 13% and 11% respectively. By contrast 57% of normal weight girls monitored their weight and stated that they had tried to slim at least once. Weight self-regulation in females attempted to combine diet and exercise, while boys relied almost exclusively on exercise. Apparent lack of consciousness of body weight status among overweight boys, and more important, subsequent absence of behaviors to reduce their weight clearly challenges efforts to prevent obesity. We argue that several causes may be involved in this outcome, including unconscious emotional (self-defense and cognitive (dissonance mechanisms driven by perceived social stigmatization of obesity. The active participation of social values of male and female body image (strong vs. pretty and the existence of social habituation to overweight are suggested. A better knowledge of psychosocial mechanisms underlying adolescent weight self-control may improve obesity epidemics.

  8. Weight Self-Regulation Process in Adolescence: The Relationship between Control Weight Attitudes, Behaviors, and Body Weight Status.

    Science.gov (United States)

    Pich, Jordi; Bibiloni, Maria Del Mar; Pons, Antoni; Tur, Josep A

    2015-01-01

    Adolescents' self-control weight behaviors were assessed (N = 1961; 12-17 years old; 2007-2008) in the Balearic Islands, Spain. The study analyzed the relationships between body weight status, body image, and self-weight concern, and actual attempts to lose weight by restrained eating and/or increased exercising. In terms of regulatory focus theory (RFT), we considered that efforts to lose or to maintain weight (successful or failed) would be motivated either by a "promotion focus" (to show an attractive body), or a "prevention focus" (to avoid social rejection of fatness), or both. Results showed that 41% of overweight boys and 25% of obese boys stated that they had never made any attempt to lose weight, and 13 and 4% in females. Around half of overweight boys and around a quarter of obese boys stated that they were "Not at all" concerned about weight gain, and girls' percentages decreased to 13 and 11%, respectively. By contrast, 57% of normal weight girls monitored their weight and stated that they had tried to become slim at least once. Weight self-regulation in females attempted to combine diet and exercise, while boys relied almost exclusively on exercise. Apparent lack of consciousness of body weight status among overweight boys, and more important, subsequent absence of behaviors to reduce their weight clearly challenges efforts to prevent obesity. We argue that several causes may be involved in this outcome, including unconscious, emotional (self-defense), and cognitive (dissonance) mechanisms driven by perceived social stigmatization of obesity. The active participation of social values of male and female body image (strong vs. pretty), and the existence of social habituation to overweight are suggested. A better knowledge of psychosocial mechanisms underlying adolescent weight self-control may improve obesity epidemics.

  9. A multi-component patient-handling intervention improves attitudes and behaviors for safe patient handling and reduces aggression experienced by nursing staff: A controlled before-after study

    DEFF Research Database (Denmark)

    Risør, Bettina Wulff; Casper, Svend Dalgas; Andersen, Lars Louis

    2017-01-01

    This study evaluated an intervention for patient-handling equipment aimed to improve nursing staffs' use of patient handling equipment and improve their general health, reduce musculoskeletal problems, aggressive episodes, days of absence and work-related accidents. As a controlled before......-after study, questionnaire data were collected at baseline and 12-month follow-up among nursing staff at intervention and control wards at two hospitals. At 12-month follow-up, the intervention group had more positive attitudes towards patient-handling equipment and increased use of specific patient-handling...... attitudes and behaviours for safe patient-handling and less physically aggressive episodes. However, this did not translate into improved health of the staff during the 12-month study period....

  10. On-the Fly Merging of Attitude Solutions

    DEFF Research Database (Denmark)

    Jørgensen, Peter Siegbjørn; Jørgensen, John Leif; Denver, Troelz

    2008-01-01

    Recent advances in autonomous attitude determination instrumentation enable even small satellites flying fully autonomous multi head star trackers providing full accurate and robust attitude information. Each sensor provides the full attitude information but for robustness and optimal usage...... of the available information, i.e. optimal accuracy, methods for merging such data should be investigated. The need for and desirability of attitude merging depends on the mission objective and available resources. To enable real-time attitude control and reduce requirements on download budget, on-board merging...... of attitude data will often be advantageous. This should be weighted against the need for post observation reconstruction of attitudes, especially needed when end products are sensitive to optimal attitude reconstruction. Instrument integrated merging algorithms will reduce the complexity of on-board AOCS...

  11. Visual attitude propagation for small satellites

    Science.gov (United States)

    Rawashdeh, Samir A.

    As electronics become smaller and more capable, it has become possible to conduct meaningful and sophisticated satellite missions in a small form factor. However, the capability of small satellites and the range of possible applications are limited by the capabilities of several technologies, including attitude determination and control systems. This dissertation evaluates the use of image-based visual attitude propagation as a compliment or alternative to other attitude determination technologies that are suitable for miniature satellites. The concept lies in using miniature cameras to track image features across frames and extracting the underlying rotation. The problem of visual attitude propagation as a small satellite attitude determination system is addressed from several aspects: related work, algorithm design, hardware and performance evaluation, possible applications, and on-orbit experimentation. These areas of consideration reflect the organization of this dissertation. A "stellar gyroscope" is developed, which is a visual star-based attitude propagator that uses relative motion of stars in an imager's field of view to infer the attitude changes. The device generates spacecraft relative attitude estimates in three degrees of freedom. Algorithms to perform the star detection, correspondence, and attitude propagation are presented. The Random Sample Consensus (RANSAC) approach is applied to the correspondence problem to successfully pair stars across frames while mitigating falsepositive and false-negative star detections. This approach provides tolerance to the noise levels expected in using miniature optics and no baffling, and the noise caused by radiation dose on orbit. The hardware design and algorithms are validated using test images of the night sky. The application of the stellar gyroscope as part of a CubeSat attitude determination and control system is described. The stellar gyroscope is used to augment a MEMS gyroscope attitude propagation

  12. 基于机械飞轮干扰补偿的小卫星自适应滑模变结构姿态控制%The Small Satellite Adaptive Sliding Mode Attitude Controller with Mechanical Flywheels Disturbance Compensation

    Institute of Scientific and Technical Information of China (English)

    杨宁宁; 杨照华; 余远金

    2013-01-01

    针对机械飞轮内干扰可能导致小卫星姿态控制系统性能下降问题,提出了一种加入机械飞轮干扰补偿的自适应滑模变结构姿态控制方法.本文针对基于机械飞轮的三轴稳定卫星姿态控制系统,首先建立系统详细的数学模型,包括基于机械飞轮的三轴稳定卫星姿态动力学方程和机械飞轮控制系统模型,然后针对此系统设计了一种基于机械飞轮干扰补偿的自适应滑模变结构控制器,其中通过设计一种状态观测器得到机械飞轮摩擦干扰的估计值,用于对机械飞轮摩擦干扰的补偿,并通过Lyapunov定理证明了此控制律能保证系统的渐近稳定性.最后仿真结果显示,此方法缩短了飞轮转速过零时间,降低了最大的姿态扰动量且提高了卫星姿态控制的精度和稳定度.%An adaptive sliding mode control law with disturbance compensation is proposed for small satellite attitude control system to overcome the deterioration of performance under mechanical flywheel disturbance. According to the small 3-axis stabilization satellite attitude control system with mechanical flywheels as actuators, the dynamic model of the system is firstly given, including attitude dynamic equations of a satellite with mechanical flywheels and the mechanical flywheels control system model. Secondly, an adaptive sliding mode control law which takes wheel disturbances into account is given and state observer is used to estimate wheels friction disturbance for compensation. The stability of the system is proven by using Lya- punov theorem. Finally, the simulation results show that this method shortens flywheel speed zero-crossing time, decreases the largest attitude disturbance value and effectively improves attitude control accuracy and stability.

  13. Evidence that attitude accessibility augments the relationship between speeding attitudes and speeding behavior: a test of the MODE model in the context of driving.

    Science.gov (United States)

    Elliott, Mark A; Lee, Emme; Robertson, Jamie S; Innes, Rhona

    2015-01-01

    According to the MODE model of attitude-to-behavior processes, attitude accessibility augments attitude-behavior correspondence, reflecting an automatic influence of attitudes on behavior. We therefore tested whether attitude accessibility moderates the attitude-behavior relationship in a context that is governed by characteristically automatic behavior, namely driving. In study 1 (correlational design), participants (N=130) completed online questionnaire measures of the valences and accessibilities of their attitudes towards speeding. Two weeks later, online questionnaire measures of subsequent speeding behavior were obtained. Attitude valence was a significantly better predictor of behavior at high (mean+1SD) versus low (mean-1SD) levels of attitude accessibility. In study 2 (experimental design), attitude accessibility was manipulated with a repeated attitude expression task. Immediately after the manipulation, participants (N=122) completed online questionnaire measures of attitude valence and accessibility, and two weeks later, subsequent speeding behavior. Increased attitude accessibility in the experimental (versus control) condition generated an increase in attitude-behavior correspondence. The findings are consistent with the MODE model's proposition that attitudes can exert an automatic influence on behavior. Interventions to reduce speeding could usefully increase the accessibility of anti-speeding attitudes and reduce the accessibility of pro-speeding attitudes.

  14. Instructional strategies to improve women's attitudes toward science

    Science.gov (United States)

    Newbill, Phyllis Leary

    Although negative attitudes toward science are common among women and men in undergraduate introductory science classes, women's attitudes toward science tend to be more negative than men's. The reasons for women's negative attitudes toward science include lack of self-confidence, fear of association with social outcasts, lack of women role models in science, and the fundamental differences between traditional scientific and feminist values. Attitudes are psychological constructs theorized to be composed of emotional, cognitive, and behavioral components. Attitudes serve functions, including social expressive, value expressive, utilitarian, and defensive functions, for the people who hold them. To change attitudes, the new attitudes must serve the same function as the old one, and all three components must be treated. Instructional designers can create instructional environments to effect attitude change. In designing instruction to improve women's attitudes toward science, instructional designers should (a) address the emotions that are associated with existing attitudes, (b) involve credible, attractive women role models, and (c) address the functions of the existing attitudes. Two experimental instructional modules were developed based on these recommendations, and two control modules were developed that were not based on these recommendations. The asynchronous, web-based modules were administered to 281 undergraduate geology and chemistry students at two universities. Attitude assessment revealed that attitudes toward scientists improved significantly more in the experimental group, although there was no significant difference in overall attitudes toward science. Women's attitudes improved significantly more than men's in both the experimental and control groups. Students whose attitudes changed wrote significantly more in journaling activities associated with the modules. Qualitative analysis of journals revealed that the guidelines worked exactly as predicted

  15. Patients' knowledge, attitudes, behaviour and health care experiences on the prevention, detection, management and control of hypertension in Colombia: a qualitative study.

    Directory of Open Access Journals (Sweden)

    Helena Legido-Quigley

    Full Text Available Hypertension is a leading cause of premature death worldwide and the most important modifiable risk factor for cardiovascular disease. Effective screening programs, communication with patients, regular monitoring, and adherence to treatment are essential to successful management but may be challenging in health systems facing resource constraints. This qualitative study explored patients' knowledge, attitudes, behaviour and health care seeking experiences in relation to detection, treatment and control of hypertension in Colombia. We conducted in-depth interviews and focus group discussions with 26 individuals with hypertension and 4 family members in two regions. Few participants were aware of ways to prevent high blood pressure. Once diagnosed, most reported taking medication but had little information about their condition and had a poor understanding of their treatment regime. The desire for good communication and a trusting relationship with the doctor emerged as key themes in promoting adherence to medication and regular attendance at medical appointments. Barriers to accessing treatment included co-payments for medication; costs of transport to health care facilities; unavailability of drugs; and poor access to specialist care. Some patients overcame these barriers with support from social networks, family members and neighbours. However, those who lacked such support, experienced loneliness and struggled to access health care services. The health insurance scheme was frequently described as administratively confusing and those accessing the state subsidized system believed that the treatment was inferior to that provided under the compulsory contributory system. Measures that should be addressed to improve hypertension management in Colombia include better communication between health care professionals and patients, measures to improve understanding of the importance of adherence to treatment, reduction of co-payments and transport

  16. Patients’ Knowledge, Attitudes, Behaviour and Health Care Experiences on the Prevention, Detection, Management and Control of Hypertension in Colombia: A Qualitative Study

    Science.gov (United States)

    Legido-Quigley, Helena; Camacho Lopez, Paul Anthony; Balabanova, Dina; Perel, Pablo; Lopez-Jaramillo, Patricio; Nieuwlaat, Robby; Schwalm, J-D; McCready, Tara; Yusuf, Salim; McKee, Martin

    2015-01-01

    Hypertension is a leading cause of premature death worldwide and the most important modifiable risk factor for cardiovascular disease. Effective screening programs, communication with patients, regular monitoring, and adherence to treatment are essential to successful management but may be challenging in health systems facing resource constraints. This qualitative study explored patients’ knowledge, attitudes, behaviour and health care seeking experiences in relation to detection, treatment and control of hypertension in Colombia. We conducted in-depth interviews and focus group discussions with 26 individuals with hypertension and 4 family members in two regions. Few participants were aware of ways to prevent high blood pressure. Once diagnosed, most reported taking medication but had little information about their condition and had a poor understanding of their treatment regime. The desire for good communication and a trusting relationship with the doctor emerged as key themes in promoting adherence to medication and regular attendance at medical appointments. Barriers to accessing treatment included co-payments for medication; costs of transport to health care facilities; unavailability of drugs; and poor access to specialist care. Some patients overcame these barriers with support from social networks, family members and neighbours. However, those who lacked such support, experienced loneliness and struggled to access health care services. The health insurance scheme was frequently described as administratively confusing and those accessing the state subsidized system believed that the treatment was inferior to that provided under the compulsory contributory system. Measures that should be addressed to improve hypertension management in Colombia include better communication between health care professionals and patients, measures to improve understanding of the importance of adherence to treatment, reduction of co-payments and transport costs, and easier

  17. Patients' knowledge, attitudes, behaviour and health care experiences on the prevention, detection, management and control of hypertension in Colombia: a qualitative study.

    Science.gov (United States)

    Legido-Quigley, Helena; Camacho Lopez, Paul Anthony; Balabanova, Dina; Perel, Pablo; Lopez-Jaramillo, Patricio; Nieuwlaat, Robby; Schwalm, J-D; McCready, Tara; Yusuf, Salim; McKee, Martin

    2015-01-01

    Hypertension is a leading cause of premature death worldwide and the most important modifiable risk factor for cardiovascular disease. Effective screening programs, communication with patients, regular monitoring, and adherence to treatment are essential to successful management but may be challenging in health systems facing resource constraints. This qualitative study explored patients' knowledge, attitudes, behaviour and health care seeking experiences in relation to detection, treatment and control of hypertension in Colombia. We conducted in-depth interviews and focus group discussions with 26 individuals with hypertension and 4 family members in two regions. Few participants were aware of ways to prevent high blood pressure. Once diagnosed, most reported taking medication but had little information about their condition and had a poor understanding of their treatment regime. The desire for good communication and a trusting relationship with the doctor emerged as key themes in promoting adherence to medication and regular attendance at medical appointments. Barriers to accessing treatment included co-payments for medication; costs of transport to health care facilities; unavailability of drugs; and poor access to specialist care. Some patients overcame these barriers with support from social networks, family members and neighbours. However, those who lacked such support, experienced loneliness and struggled to access health care services. The health insurance scheme was frequently described as administratively confusing and those accessing the state subsidized system believed that the treatment was inferior to that provided under the compulsory contributory system. Measures that should be addressed to improve hypertension management in Colombia include better communication between health care professionals and patients, measures to improve understanding of the importance of adherence to treatment, reduction of co-payments and transport costs, and easier access

  18. The Modeling and Fine Attitude Control for Aeroelastic Hypersonic Vehicle%弹性高超声速飞行器建模及精细姿态控制

    Institute of Scientific and Technical Information of China (English)

    孟中杰; 闫杰

    2011-01-01

    To ensure a good scramjet inlet environment, a hypersonic vehicle should be controlled as a fine attitude control. But the elastic vibration greatly influences the accuracy of attitude control. Taking the longitudinal channel of hypersonic vehicle for example, the impact of elastic problem on the flight control system is analyzed and a elastic aerodynamic model is established in this paper. Considering the large-scale perturbation of model parameters caused by body/engine coupling and aerodynamic heating, the fine attitude control system is designed base on robust H∞ theory and LQR theory under a active control strategy. Simulation results show that, under the condition of measurement noise, nonlinear actuator and large-scale perturbation of model parameters, the rigid body angle of attack is tracked exactly and the flexible angle of attack is well suppressed. The Control accuracy of local angle of attack of inlet is within ±0.4 degrees, and can meet the requirements for fine attitude control.%为保证超燃冲压发动机的良好进气,需要对高超声速飞行器进行精细姿态控制,但弹性振动问题极大影响其精细姿态控制精度.以高超声速飞行器的纵向通道为例,分析弹性振动问题对飞行控制系统的影响,建立面向控制的弹性高超声速飞行器数学模型,考虑气动参数和模态参数的大范围摄动,采用主动控制策略,基于鲁棒H∞理论和LQR理论设计精细姿态控制系统.大量仿真表明:在考虑测量噪声、舵机非线性、参数大范围摄动的情况下,控制系统能够很好地跟踪刚体攻角,抑制弹性攻角,并保证进气口当地攻角±0.4度的控制精度,满足高超声速飞行器精细姿态控制的要求.

  19. 基于扩张状态观测器的航天器自适应姿态控制%Adaptive Controller for Spacecraft Attitude Maneuver Based on Extended State Observer

    Institute of Scientific and Technical Information of China (English)

    袁国平; 史小平; 李隆

    2011-01-01

    针对航天器三轴姿态大角度机动时动力学特性耦合强烈的情况,同时考虑外界干扰及执行器的不确定性,根据扩张状态观测器的相关理论,提出了航天器姿态机动的一种自适应输出反馈控制策略.首先,采用动量矩定理和欧拉法建立了航天器的姿态动力学模型.然后,在此基础上,利用扩张状态观测器能够准确地获取航天器三轴间非线性耦合及其他未知的外界干扰信息的能力,设计了一种仅需要姿态角测量值的自适应输出反馈控制律,使航天器在大角度姿态机动的同时能够通过自适应律补偿控制力矩的输出偏差.仿真结果表明,在多种任务模式下,航天器都可以很好地完成姿态机动任务,从而验证了控制律的正确性和有效性.%To deal with spacecraft three-axis large attitude maneuver with the external disturbances and actuator uncertainties, a new adaptive output feedback controller was presented based on the extended state observer. Firstly, an attitude dynamic model by the Momentum theorem and Euler method was established. Secondly, based on the fact that the extended state observer could minimize the nonlinear coupling and external disturbances, the adaptive output feedback control strategy was developed only with the attitude angle output, which could compensate the control toque error during the large angle attitude maneuver. Finally, simulation results show that the precise attitude maneuver can be accomplished and the angles can converge to the desired states for different cases.

  20. 基于地面反力最优规划的双足机器人姿态控制%Attitude Control of Biped Robot Based on Optimal Reactive Force Distribution

    Institute of Scientific and Technical Information of China (English)

    田海英; 任志玲

    2001-01-01

    提出了一种基于地面反力最优规划的双足步行机器人上体姿态控制算法,以实现上体轨迹准确跟踪及为分级递阶控制结构中的地面反力/位混合控制提供参考输入。由于上体只安装了加速度器并未安装陀螺仪,文中采用线性观测器来重构沿偏转轴和俯仰轴的偏转速度,利用无源性理论控制器-观测器设计了保持上体姿态跟踪特性及系统为最终有界和局部指数稳定有界的地面反力期望值。%A new approach of designing attitude controller is developed based on the optimal reactive force distribution between the robot and environment. The function of the attitude controller is providing input for the force/position controller of the biped robot's Hierarchical Control System. Only get the angle of roll/pitch axis,passivity-based controller-observer is used for velocity of two axis. The idea external force input, which ensure the system of biped robot's body uniformly bounded and locally exponentially stability is get.

  1. Circumventing resistance: using values to indirectly change attitudes.

    Science.gov (United States)

    Blankenship, Kevin L; Wegener, Duane T; Murray, Renee A

    2012-10-01

    Most research on persuasion examines messages that directly address the attitude of interest. However, especially when message recipients are inclined to resist change, indirect methods might be more effective. Because values are rarely attacked and defended, value change could serve as a useful indirect route for attitude change. Attitudes toward affirmative action changed more when the value of equality was attacked (indirect change) than when affirmative action was directly attacked using the same message (Experiments 1-2). Changes in confidence in the value were responsible for the indirect change when the value was attacked (controlling for changes in favorability toward the value), whereas direct counterarguments to the message were responsible for the relative lack of change when the attitude was attacked directly (Experiment 2). Attacking the value of equality influenced attitudes toward policies related to the value but left policy attitudes unrelated to the value unchanged (Experiment 3). Finally, a manipulation of value confidence that left attitudes toward the value intact demonstrated similar confidence-based influences on policies related to the value of freedom (Experiment 4). Undermined value confidence also resulted in less confidence in the resulting policy attitudes controlling for the changes in the policy attitudes themselves (Experiments 3 and 4). Therefore, indirect change through value attacks presented a double threat--to both the policy attitudes and the confidence with which those policy attitudes were held (potentially leaving them open to additional influence).

  2. 挠性航天器混合H2/H∞输出反馈姿态控制%Mixed H2/H∞ Output Feedback Attitude Control for Flexible Spacecraft

    Institute of Scientific and Technical Information of China (English)

    刘华; 张玉民; 杨照华

    2012-01-01

    The H2/H∞ output feedback attitude control problem of the flexible spacecraft composed of a central rigid body and some attached appendages is researched in this paper.The attitude control problem of such flexible spacecrafts is always difficult because the vibration of the elastic appendages can affect the central rigid motion and the measurement of the vibration modes is not easy in practice.A dynamic output feedback H2/H∞ controller is designed here to perform attitude control in the presence of flexible vibration,model uncertainties and space environmental disturbances.The proposedalgorithm with H∞ output controller can implement the attitude control and the elastic mode stabilization at the same time.The system dynamics is also improved via the H2 design.Simulation shows the effectiveness of the presented algorithm.%研究一类带有挠性附件的航天器的H2H∞输出反馈姿态控制问题,所涉及的挠性航天器由刚性本体和挠性附件构成.由于挠性附件的振动和航天器本体姿态运动的耦合,再加之振动模态难以测量,对挠性航天器的姿态控制带来困难.针对该问题提出了基于H2/H∞理论的动态输出反馈控制器设计方法.动态输出反馈在模态变量不能测量的前提下也能有效控制航天器本体姿态,而H∞控制器具有很好的抗干扰能力,能有效抑制空间环境干扰力矩和模型不确定性对控制系统稳定性的影响.和纯H∞输出反馈控制算法相比,基于H2/H∞的设计同时提高系统的动态性能.数值仿真验证了所设计的控制方法对挠性航天器具有很好的姿态控制效果.

  3. Attributions and Attitudes of Mothers and Fathers in Jordan.

    Science.gov (United States)

    Al-Hassan, Suha; Takash, Hanan

    2011-07-01

    OBJECTIVE: The present study examined mean level similarities and differences as well as correlations between mothers' and fathers' attributions regarding successes and failures in caregiving situations and progressive versus authoritarian attitudes in Jordan. DESIGN: Interviews were conducted with both mothers and fathers in 112 families. RESULTS: There were no significant main effects of gender on any of the constructs of interest. Mothers and fathers reported similar levels of attributions regarding uncontrollable success, adult-controlled failure, and child-controlled failure in the same family. Regarding attitudes, mothers and fathers reported greater progressive attitudes than authoritarian attitudes. Large, significant correlations were found for concordance between parents in the same family on all seven attributions and attitudes examined; all remained significant after controlling for parents' age, education, and possible social desirability bias. Significant positive correlations were found for mothers' and fathers' attributions regarding uncontrollable success, adult-controlled failure, child-controlled failure, perceived control over failure, progressive attitudes, authoritarian attitudes, and modernity of attitudes. CONCLUSIONS: This study concluded that in Jordan mothers and fathers hold similar levels of attributions and attitudes.

  4. Attitude Maneuver Control for Flexible Spacecraft Based on a Multi-objective Joint-optimization Model%基于多目标联合优化的挠性航天器姿态机动控制

    Institute of Scientific and Technical Information of China (English)

    周端; 杨忠

    2015-01-01

    In order to implement the attitude maneuvering control of flexible spacecraft with so-lar array in the presence of external disturbances in space,the parameters optimization of atti-tude maneuver control for spacecraft has been studied.A multi-objective joint-optimization model of the attitude maneuver control for flexible spacecraft is constructed.Based on the multi-objective optimization elitist evolutionary algorithm,the profile and the controller pro-posed are optimized simultaneously.Considering the closed-loops stability,the contradiction between rapid maneuvering performance and high stabilization performance in maneuvering of flexible spacecraft is relieved.The semi-physical experiment results demonstrate that the meth-od proposed is effective.%针对受环境干扰的带有太阳能帆板的挠性航天器,研究了航天器姿态机动控制的参数优化问题。建立了挠性航天器姿态机动控制参数的联合优化模型,并采用一种基于精英机制的多目标优化算法,设计机动路径和控制器参数,在保证闭环系统稳定的前提下,以获得较好的机动快速性和较高的稳态精度。地面模拟实验验证了所提方法的有效性。

  5. Robust attitude maneuver and constrained control allocation for over-actuated rigid spacecraft with redundant reaction fly-wheels%轮控过驱动刚体航天器姿态机动与约束控制分配

    Institute of Scientific and Technical Information of China (English)

    霍星; 张爱华; 秦玉平

    2012-01-01

    Aimed at the uncertain inertia matrix of over-actuated spacecraft system and attitude maneuver control,this paper proposes robust adaptive backstepping control as a result of allowing for dynamic response characteristics of drive mechanism and describes an analysis of the system's stability using Lyapunov functions.The paper presents an algorithm based on the optimal unconstrained quadratic program to achieve a change from the desired instruction to the redundant flywheel instruction distribution and verifies control torque stability and energy optimization following the assignment by introducing a slack variable extension of optimal solution set.The numerical simulation of an attitude maneuver mission of a rigid spacecraft with redundant by using the MATLAB/Simulink software prove that the method allows a quicker and accurate control of over-actuated spacecraft attitude.%针对过驱动航天器系统转动惯量未知与姿态机动控制的问题,考虑执行机构的动态响应特性,设计了反步法的鲁棒自适应控制器。利用Lyapunov方法分析其系统的稳定性,提出基于约束最优二次规划的算法,实现期望指令到冗余飞轮的指令分配,引入一个松弛变量扩展优化解集,证明了分配后控制力矩的平稳性和能量的最优性。采用Simulink软件对某型轮控刚体航天器的姿态机动任务进行了仿真研究。结果表明,该方法能够实现快速和高精度控制过驱动航天器姿态。

  6. 挠性航天器姿态机动的变论域自整定模糊PID控制%Variable Universe Self-tuning Fuzzy PID Controller of Attitude Maneuver for Flexible Spacecraft

    Institute of Scientific and Technical Information of China (English)

    魏凤美; 赵育善; 师鹏

    2014-01-01

    建立了带有太阳翼的挠性航天器的姿态动力学模型,应用改进的罗德里格参数来描述姿态运动学模型。针对挠性航天器模型参数不确定性和环境干扰等问题,提出了变论域自整定模糊比例积分微分(PID)控制方案,构建了计算简单并且可以达到控制精度的伸缩因子。基于Matlab/Simulink进行了仿真验证,结果表明,变论域自整定模糊 PID 控制响应速度比传统PID控制、模糊PID控制快350 s,且无超调,不仅能够使航天器完成对目标姿态的机动,而且能够有效地抑制挠性太阳翼的振动。%The attitude dynamical equations of flexible spacecraft with solar panels were established, and the attitude kinematic equations were described by modified Rodrigues parameters (MRPs ) in order to prevent the singularity of the large angle maneuver. A variable universe self-tuning fuzzy PID controller was proposed for model uncertainties and environmental disturbances. A new shrinkable factor was designed, and it was easy to calculate and could achieve the accuracy. Numerical simulation based on Matlab/Simulink shows that the response of the variable universe self-tuning fuzzy PID controller are 350 s faster than that of the conventional PID and fuzzy PID controllers, and that it has no overshoot and can realize the effective control of attitude maneuver and effectively suppress the vibration of solar panels.

  7. Longitudinal Attitude control System Design and Simulation of Agricultural Unmanned Aerial Vehicle%农用无人机纵向姿态控制系统设计及仿真

    Institute of Scientific and Technical Information of China (English)

    刘超; 张长利; 王树文; 王润涛; 张伶鳦; 吕涛; 栾吉玲; 周雅楠

    2016-01-01

    针对农用无人机的作业特点和应用领域,设计了一种基于经典 PID 控制方法的纵向姿态控制系统。首先,利用MatLab 软件建立了无人机在配平点处的纵向运动数学模型,分析了无人机的纵向运动规律。在此基础上,采用经典PID理论对无人机纵向运动的俯仰角控制回路和高度控制回路进行设计。通过 Simulink 软件进行仿真实验,结果表明:该飞行姿态控制系统控制效果良好,可以满足农用无人机的技术要求。%This Longitudinal attitude control system is designed on the basis of Classic PID control method .It’ s also spe-cific to the character of how Agricultural unmanned aerial vehicle operates and its application field .The system firstly uses Matlab to build a Longitudinal motion mathematical model at the trim point of the vehicle ,which can analyze the Longitu-dinal motion of itself .Secondly , the system applies the Classic PID theory to the design of the Pitch and Height attitude control loop of the vehicle .The result shows that the attitude control system effects well during flight and can meet the technical requirement of Agricultural unmanned aerial vehicle .

  8. A Raspberry Pi-Based Attitude Sensor

    Science.gov (United States)

    Sreejith, A. G.; Mathew, Joice; Sarpotdar, Mayuresh; Mohan, Rekhesh; Nayak, Akshata; Safonova, Margarita; Murthy, Jayant

    We have developed a lightweight low-cost attitude sensor, based on a Raspberry Pi, built with readily available commercial components. It can be used in experiments where weight and power are constrained, such as in high-altitude lightweight balloon flights. This attitude sensor will be used as a major building block in a closed-loop control system with driver motors to stabilize and point cameras and telescopes for astronomical observations from a balloon-borne payload.

  9. A Raspberry Pi-Based Attitude Sensor

    CERN Document Server

    Sreejith, A G; Sarpotdar, Mayuresh; Mohan, Rekhesh; Nayak, Akshata; Safonova, Margarita; Murthy, Jayant

    2014-01-01

    We have developed a lightweight low-cost attitude sensor, based on a Raspberry Pi, built with readily available commercial components. It can be used in experiments where weight and power are constrained, such as in high- altitude lightweight balloon flights. This attitude sensor will be used as a major building block in a closed-loop control system with driver motors to stabilize and point cameras and telescopes for astronomical observations from a balloon-borne payload.

  10. Lateral Attitude Change.

    Science.gov (United States)

    Glaser, Tina; Dickel, Nina; Liersch, Benjamin; Rees, Jonas; Süssenbach, Philipp; Bohner, Gerd

    2015-08-01

    The authors propose a framework distinguishing two types of lateral attitude change (LAC): (a) generalization effects, where attitude change toward a focal object transfers to related objects, and (b) displacement effects, where only related attitudes change but the focal attitude does not change. They bring together examples of LAC from various domains of research, outline the conditions and underlying processes of each type of LAC, and develop a theoretical framework that enables researchers to study LAC more systematically in the future. Compared with established theories of attitude change, the LAC framework focuses on lateral instead of focal attitude change and encompasses both generalization and displacement. Novel predictions and designs for studying LAC are presented.

  11. Inertial Measurements Based Velocity-free Attitude Stabilization

    CERN Document Server

    Tayebi, A; Benallegue, A

    2012-01-01

    The existing attitude controllers (without angular velocity measurements) involve explicitly the orientation (\\textit{e.g.,} the unit-quaternion) in the feedback. Unfortunately, there does not exist any sensor that directly measures the orientation of a rigid body, and hence, the attitude must be reconstructed using a set of inertial vector measurements as well as the angular velocity (which is assumed to be unavailable in velocity-free control schemes). To overcome this \\textit{circular reasoning}-like problem, we propose a velocity-free attitude stabilization control scheme relying solely on inertial vector measurements. The originality of this control strategy stems from the fact that the reconstruction of the attitude as well as the angular velocity measurements are not required at all. Moreover, as a byproduct of our design approach, the proposed controller does not lead to the unwinding phenomenon encountered in unit-quaternion based attitude controllers.

  12. 基于路径规划和反推技术挠性航天器姿态控制%Attitude control of flexible spacecraft based on path planning and backstepping technique

    Institute of Scientific and Technical Information of China (English)

    赖爱芳; 郭毓; 周端; 魏国平

    2011-01-01

    In order to suppress appendages' vibration of a flexible spacecraft during attitude maneuver, an adaptive attitude control scheme was proposed based on path planning and backstepping technique. The maneuver path was planned to solve the conflict between swiftness and overshoot in traditional control as well as to suppress the vibration of flexible appendages. For flexible spacecraft dynamics and kinematics constituting a nonlinear cascaded system with uncertainties, an adaptive attitude controller was designed based on backstepping technique, in which only the output information was utilized. And the global uniform ultimate bounded stability of the system has been proved. For the system subject to inertia parameter uncertainties and bounded disturbances, the proposed controller in this paper can not only suppress the flexible appendages' vibration, but also realize fast maneuver and fast stability of spacecraft attitude. Simulation results show the effectiveness of the proposed adaptive controller.%为抑制航天器姿态机动过程中挠性附件的振动,提出了一种基于路径规划和反推技术的姿态自适应控制方案.对航天器姿态机动路径进行规划,以缓解传统控制中快速性和超调量之间的矛盾,并减小姿态机动引起的挠性附件振动.针对航天器姿态动力学和运动学构成的具有不确定性的非线性串级系统,基于反推技术设计了一种仅利用输出信息的自适应控制器,并证明了系统全局一致最终有界稳定.在系统具有惯量参数不确定及有界干扰力矩的情况下,设计的控制器能快速抑制挠性附件的振动,实现航天器姿态的快速机动和快速稳定.仿真结果验证了该挠性航天器自适应姿态控制算法的有效性.

  13. Cockpit management attitudes.

    Science.gov (United States)

    Helmreich, R L

    1984-10-01

    Distinctions are drawn between personality traits and attitudes. The stability of the personality and the malleability of attitudes are stressed. These concepts are related to pilot performance, especially in the areas of crew coordination and cockpit resource management. Airline pilots were administered a Cockpit Management Attitudes questionnaire; empirical data from that survey are reported and implications of the data for training in crew coordination are discussed.

  14. Attitude measurements and determination

    Science.gov (United States)

    Foliard, J.

    Satellite attitude determination using an inertial reference system is explained. The utility of being able to determine attitude is outlined. Construction of an attitude matrix from the Euler and Cardan angles of the satellite-Earth system is illustrated. Static and dynamic analysis methods are shown. The sensors employed when using the Sun, Earth's magnetic field, the Earth, and the stars as reference direction are described.

  15. Design of a novel sliding mode controller for the attitude control of reentry vehicle%基于新型滑模控制方法的再入飞行器姿态控制律设计

    Institute of Scientific and Technical Information of China (English)

    李宪强; 周军; 郭建国

    2015-01-01

    设计了一种新型滑模控制方法,该方法不但能对已有的控制律进行鲁棒性改进,而且能有效抑制抖振现象。在该方法的设计过程中,首先基于已有的控制律和标称系统,设计了一种新型的动态滑模面,然后对超扭曲算法进行改进,得出了一种快速、连续且有限时间收敛的算法,并首次将其作为新型趋近律,该趋近律与滑模面相结合能够大大增强现有控制律的鲁棒性,而且滑模的切换律是连续的,因此大大降低了系统的抖振。将以上方法应用于再入飞行器的姿态跟踪控制中,有效增强了已有控制律的鲁棒性,实现了大干扰情况下对姿态系统的稳定控制。通过仿真,验证了该方法在提高系统鲁棒性和降低抖振方面的有效性。%A novel sliding mode control method was proposed in this paper,which is not only capable of improving the robust⁃ness of the existing control law,but can also effectively attenuate chattering.In the design process,a novel dynamic sliding mode sur⁃face was designed firstly based on the nominal system and the existing control law.Then the super⁃twisted algorithm was improved.A fast continuous and finite time convergence algorithm was obtained,which was adopted as the novel reaching law for the first time. The reaching law combined with the sliding mode surface can greatly enhance the robustness of the existing control law.In addition, since the sliding mode switching law is continuous,the chattering was greatly attenuated. The proposed method was then applied to attitude tracking control of reentry vehicle and the robustness of the existing control law was effectively enhanced under large dis⁃turbance.Finally,the effectiveness of the method was demonstrated through simulation.

  16. 一种挠性航天器的对偶四元数姿轨耦合控制方法%A New Method for Orbit and Attitude Coupling Control Problem of Flexible Spacecraft Based on Dual Quaternions

    Institute of Scientific and Technical Information of China (English)

    杨一岱; 荆武兴; 张召

    2016-01-01

    为解决复杂的挠性航天器的姿轨控制问题,对于挠性航天器的姿轨耦合动力学建模与控制展开研究。基于对偶四元数原理,推导给出一套挠性航天器的姿轨一体化动力学模型。此种模型能够紧凑描述航天器的轨道和姿态,且能够自动引入航天器平动、转动与挠性附件振动三者之间的关联耦合作用。基于此模型设计了一种自适应位置姿态跟踪控制器,该控制器能够在航天器质量特性参数未知的情况下,对其位置和姿态进行轨迹跟踪控制,并使位置和姿态误差收敛。该自适应控制器还可对航天器上挠性附件对系统的耦合作用进行估计,进而在控制输出中对其进行补偿,提高卫星控制系统的稳定性。通过仿真对控制律进行校验,结果表明该控制律对挠性航天器控制效果良好,具有一定的工程应用参考价值。%In order to deal with the complicated problem of orbit and attitude control of a flexible spacecraft,a study of dynamic modeling and control of flexible spacecraft is conducted.A new dynamic model which can describe the orbit and attitude dynamics of flexible spacecraft at the same time is proposed,using the method of dual quaternions.The new dynamic model is able to describe the orbit and attitude of the spacecraft integrally,and to consider the coupling effect between the vibration of the flexible parts of the spacecraft and its translation and rotation automatically.An adaptive position and attitude-tracking controller which requires no information of the spacecraft′s inertial parameters is designed based on the model.The coupling effect of the flexible parts can be estimated using the adaptive controller,and thus the stability of the whole system during orbit and attitude maneuver process is improved.The simulation result demonstrates that the adaptive controller fits the problem of orbit and attitude control for flexible spacecraft well

  17. Tobacco self-efficacy and the influences on tobacco-control attitudes among college students%大学生控烟自我效能及对控烟态度的影响

    Institute of Scientific and Technical Information of China (English)

    尤华; 樊宏; 韦婷; 张峰; 陆慧; 吉华萍

    2012-01-01

    Objective To explore the tobacco self-efficacy (TSE) among college students, and to reveal the relationship between level of TSE and the collage students' attitudes on tobacco-control. Methods Self-designed questionnaires were applied to investigate the social-economic information, tobacco self-efficacy, and students' attitudes on major tobacco-control measures. Results Majority of the respondents were in a high level TSE. Specifically, 69.0% were in a high TSE group. Students generally assent those major tobacco-control measures, and their attitudes on tobacco-control measures were impacted by their TSE. Comparatively, many more students in high TSE group showed active attitude on the main measures than those in low TSE group. The data analysis results were as below, separately: to ban smoking in public places [OR = 1.61), to ban tobacco advertising(OR = 2.69) , Smoking-free campus(OR =2.33) and to prohibit students from smoking (OR=2.08). Conclusion College students' attitudes on tobacco-control are clearly influenced by their TSE level, hence, those comprehensive interventions should be strengthened to improve students' TSE, and thus to promote students' positive attitudes on tobacco-control policies and strategies.%目的 了解大学生控烟自我效能及其对控烟态度的影响,为进一步深入进行大学生控烟健康干预提供科学依据.方法 采用自行设计的问卷,对方便抽取的南京市2所高校大学生开展调查,内容包括个人一般情况、控烟自我效能及大学生对主要控烟措施的态度.结果 受访大学生的控烟自我效能普遍比较高(高分组占69.0%).大学生对控烟措施普遍持赞成态度.大学生控烟态度受控烟自我效能的影响.自我效能高的大学生中有更多人赞成公共场所禁烟( OR=1.61),禁止吸烟广告(OR=2.69),实施无烟校园政策(OR=2.33),禁止学生吸烟(OR=2.08).结论 大学生控烟态度受控烟自我效能的影响,应加强针对提高大

  18. Estonian and Russian Parental Attitudes to Childrearing and Play.

    Science.gov (United States)

    Saar, Aino; Niglas, Katrin

    2001-01-01

    Used Neukater and van der Kooji's parental attitude questionnaire to ask three groups of mothers (Estonian, non-Estonian in Estonia, Russians in Moscow) about their attitudes toward children's education and play. Found that Estonian mothers applied least control and that higher mother education resulted in less child control and instruction. (DLH)

  19. A randomised controlled trial to explore attitudes to routine scale and polish and compare manual versus ultrasonic scaling in the general dental service in Scotland [ISRCTN99609795

    Directory of Open Access Journals (Sweden)

    Smith Patricia A

    2005-06-01

    Full Text Available Abstract Background To investigate, within general dental practice, patients' and vocational dental practitioners' (VDP attitudes towards the benefits and costs of a simple scale and polish and to compare the experience of using manual versus ultrasonic instruments to scale teeth. Methods 28 VDPs and 420 patients participated. Patients were randomly allocated to either group. Patients' and VDPs' attitudes towards, and experience of, the scale and polish were elicited by means of self-administered questionnaires. Results The majority of patients (99% believed a scale and polish was beneficial. VDPs considered ultrasonic treatment to be appropriate on significantly more occasions than they did for manual scale and polish (P Conclusion Routine scaling and polishing is considered beneficial by both patients and vocational trainees. The majority of patients, regardless of treatment method, experience some degree of discomfort when undergoing a scale and polish. VDPs showed a preference for the ultrasonic treatment method.

  20. Effects of the implementation of the web-based patient support system on staff's attitudes towards computers and IT use: a randomised controlled trial.

    Science.gov (United States)

    Koivunen, Marita; Välimäki, Maritta; Patel, Anita; Knapp, Martin; Hätönen, Heli; Kuosmanen, Lauri; Pitkänen, Anneli; Anttila, Minna; Katajisto, Jouko

    2010-09-01

    Utilisation of information technology (IT) in the treatment of people with severe mental health problems is an unknown area in Europe. Use of IT and guiding patients to relevant sources of health information requires that nursing staff have positive attitudes toward computers and accept IT use as a part of daily practises. The aim of the study was to assess the effects of the implementation of a web-based patient support system on staff's attitudes towards computers and IT use on psychiatric wards. Hundred and forty-nine nurses in two psychiatric hospitals in Finland were randomised to two groups to deliver patient education for patients with schizophrenia and psychosis with a web-based system (n = 76) or leaflets (n = 73). After baseline nurses were followed-up for 18 months after the introduction of the system. The primary outcome was nurses' motivation to utilise computers, and the secondary outcomes were nurses' beliefs in and satisfaction with computers, and use of computer and internet. There were no statistically significant differences between study groups in attitudes towards computers (motivation p = 0.936, beliefs p = 0.270, satisfaction p = 0.462) and internet use (p = 0.276). However, nurses' general computer use (p = 0.029) increased more in the leaflet group than in the IT intervention group. We can conclude that IT has promise as an alternative method in patient education, as the implementation of the web-based patient support system in daily basis did not have a negative effect on nurses' attitudes towards IT.

  1. Attitude Control for Launchers Based on Robust State Observers%基于鲁棒状态观测器的运载火箭姿态控制系统设计

    Institute of Scientific and Technical Information of China (English)

    周军; 水尊师; 葛致磊

    2012-01-01

    考虑弹性振动和液体晃动,采用鲁棒观测器设计了运载火箭的姿态控制系统.将姿态角测量结果中弹性振动的影响视为外界干扰,利用状态观测器的低通滤波特性实现对高频弹性信号的衰减,同时状态观测器替代速率陀螺估计得到姿态角速度,以姿态角和角速度信号为输入,采用扭曲二阶滑模控制方法设计了姿态控制律,并从理论上对该控制律稳定液体晃动和弹性振动的原理进行了证明,对观测器变换矩阵的选择进行分析.数值仿真表明,在参数摄动和干扰的影响下,所提出的变结构控制律能够有效的跟踪控制指令,稳定系统姿态,具有较强的鲁棒性,同时鲁棒状态观测器能够准确的估计出角速度信息.%Regarding the bending and sloshing modes, the attitude control system of a launcher is designed by means of using robust state observers. The signal introduced by flexible modes is regarded as disturbance. On account of low pass characteristics of the state observer, the high frequency modes can be attenuated. The attitude rate is reconstructed by applying the state observer, and then the rate gyroscope is unnecessary. By using second-order super-twisting sliding mode control, the control system is built based on the attitude angle and angle rate. The stability of bending and sloshing modes is proved theoretically. The numerical simulation indicates that the commands can be tracked effectively in the flight control system and the attitude can be stabilized with fairly robust. Meanwhile, the observer can estimate the rate of angle exactly.

  2. Epistemics and attitudes

    Directory of Open Access Journals (Sweden)

    Pranav Anand

    2013-10-01

    Full Text Available This paper investigates the distribution of epistemic modals in attitude contexts in three Romance languages, as well as their potential interaction with mood selection. We show that epistemics can appear in complements of attitudes of acceptance (Stalnaker 1984, but not desideratives or directives; in addition, emotive doxastics (hope, fear and dubitatives (doubt permit epistemic possibility modals, but not their necessity counterparts. We argue that the embedding differences across attitudes indicate that epistemics are sensitive to the type of attitude an attitude predicate reports. We show that this sensitivity can be derived by adopting two types of proposals from the literature on epistemic modality and on attitude verbs: First, we assume that epistemics do not target knowledge uniformly, but rather quantify over an information state determined by the content of the embedding attitude (Hacquard 2006, 2010, Yalcin 2007. In turn, we adopt a fundamental split in the semantics of attitude verbs between ‘representational’ and ‘non-representational’ attitudes (Bolinger 1968: representational attitudes quantify over an information state (e.g., a set of beliefs for believe, which, we argue, epistemic modals can be anaphoric to. Non-representational attitudes do not quantify over an information state; instead, they combine with their complement via a comparison with contextually-provided alternatives using a logic of preference (cf. Bolinger 1968, Stalnaker 1984, Farkas 1985, Heim 1992, Villalta 2000, 2008. Finally, we argue that emotive doxastics and dubitatives have a hybrid semantics, which combines a representational component (responsible for licensing epistemic possibility modals, and a preference component (responsible for disallowing epistemic necessity modals. http://dx.doi.org/10.3765/sp.6.8 BibTeX info

  3. Swedish students' attitudes toward abortion.

    Science.gov (United States)

    Lindell, M E; Olsson, H M

    1993-01-01

    The Swedish abortion legislation of 1975 gave women the right to make a decision about abortion before the end of the 18th week of pregnancy. The number of abortions is rising in Sweden as a chosen method of birth control. The attitudes of students toward abortion were studied in 1986-1987. A questionnaire containing items on how sex education is taught, the anatomy and physiology of reproduction, contraceptives, sexually transmitted diseases, and legal abortion was answered by 421 high school students. Results pertaining to the students' attitudes toward abortion are reported. Two thirds of the students believed that the decision about an abortion should be made by the man and woman together. Nearly all respondents believed that abortion should not be considered a method of birth control. These results may be considered a guide for interventions to prevent the need for abortion. One fourth of all pregnancies in Sweden terminate in abortion. The students in the present study thought of abortion as a solution. Authors studying samples with different cultural backgrounds have reported similar attitudes.

  4. Individual Attitudes Towards Trade

    DEFF Research Database (Denmark)

    Jäkel, Ina Charlotte; Smolka, Marcel

    2013-01-01

    Using the 2007 wave of the Pew Global Attitudes Project, this paper finds statistically significant and economically large Stolper-Samuelson effects in individuals’ preference formation towards trade policy. High-skilled individuals are substantially more pro-trade than low-skilled individuals......-Ohlin model in shaping free trade attitudes, relative to existing literature....

  5. Language Learners' Acculturation Attitudes

    Science.gov (United States)

    Rafieyan, Vahid; Orang, Maryam; Bijami, Maryam; Nejad, Maryam Sharafi; Eng, Lin Siew

    2014-01-01

    Learning a language involves knowledge of both linguistic competence and cultural competence. Optimal development of linguistic competence and cultural competence, however, requires a high level of acculturation attitude toward the target language culture. To this end, the present study explored the acculturation attitudes of 70 Iranian…

  6. Asymmetrical international attitudes

    NARCIS (Netherlands)

    Van Oudenhoven, JP; Askevis-Leherpeux, F; Hannover, B; Jaarsma, R; Dardenne, B

    2002-01-01

    In general, attitudes towards nations have a fair amount of reciprocity: nations either like each other are relatively indifferent to each other or dislike each other Sometimes, however international attitudes are asymmetrical. In this study, we use social identity theory in order to explain asymmet

  7. 动能拦截器姿控固体小火箭点火算法设计%Ignition algorithm for attitude control solid-propellant nozzles in kinetic interceptor

    Institute of Scientific and Technical Information of China (English)

    李广华; 张洪波; 汤国建

    2015-01-01

    使用固体姿控小火箭是实现动能拦截器快响应和高精度姿态控制的最佳方案之一。针对一种新型动能拦截器姿控小火箭布局,提出了点火组合混合搜索算法。描述了动能拦截器姿控小火箭的配置方案,分析了弹体自旋需求。设计了一种结合目标排序法和区间搜索法的点火组合混合搜索算法:当可用小火箭个数较少时,采用目标排序法;当可用小火箭个数较多时,采用区间搜索法。指令力矩近似仿真结果及姿态控制数值仿真结果表明:该算法能够有效地近似指令力矩,实现快速高精度的姿态跟踪。%Using solid-propellant nozzles is one of the best schemes for kinetic interceptor to realize the fast response and high precision of attitude control.A mixed searching algorithm for ignition combination was presented for a novel attitude control solid-propellant nozzle in kinetic interceptor.Firstly,the configuration of solid-propellant nozzles was described and spin requirements of the kinetic interceptor were analyzed.Then the mixed searching algorithm was designed by a combination of sorting method and interval searching method.Sorting method is selected when the number of available nozzles is small and interval searching method is chosen on the contrary.Results of instruction torque approximation simulation and attitude control numerical simulation suggest that the algorithm can track the instruction torque effectively and achieve attitude tracking quickly and with a high precision.

  8. 基于滚动优化的模块航天器姿轨协同控制%Relative Cooperative Attitude and Position Control of Fractioned Spacecraft Based on Iterative Optimization

    Institute of Scientific and Technical Information of China (English)

    朱志斌; 李果; 何英姿; 魏春岭

    2011-01-01

    In short range guidance stage, eccentric low-level continuous vector thruster and transformed torque equipment were used to maintain the close approaching and circling of specific object, and complete simultaneously orbit control and light of sight (LOS) stabilization.Relative coupling attitude and orbit dynamic model was established based on T-H equation and error quaternion.Expected relative position gaits were designed respectively for close approaching phase and circling phase.Expected attitude was computed based on LOS angles.Traditional θ-D method can only linearize dynamic equation at start point which hold limited neighbor stable area that can not cover large alteration of relative states during the process.Piecewise linearized θ-D suboptimal controller was proposed based on iterative optimal theory and utilized in relative attitude and orbit control, in which vector part of error quaternion was directly used for state feedback.Decent dimension alternation was made for coupling attitude and position state equation.Simulation results demonstrate that this method are effective.%在近程导引段,采用偏心连续小推力矢量推进器和力矩输出装置,实现对特定目标的直线逼近、绕飞,同时完成轨道控制和视线姿态稳定.基于T-H方程和误差四元数建立相对姿轨耦合动力学模型,分别对直线逼近段和绕飞段设计相对位置期望轨线,期望姿态由视线方向计算得到.经典θ-D方法仅在起点处线性化动力学方程,稳定邻域范围有限,不能满足逼近和绕飞相对状态大范围变化的要求.因此基于滚动优化思想,提出分段线性化θ-D次优控制器设计方法,实现相对运动姿轨协同控制.其中姿态直接采用误差四元数矢量部分作状态反馈,降维处理姿轨耦合状态方程.仿真结果表明了该方法的有效性和实用性.

  9. 具有非凸约束的航天器姿态机动预测控制%A Predictive Control Algorithm for Spacecraft Attitude Maneuver with Nonconvex Geometric Constraint

    Institute of Scientific and Technical Information of China (English)

    程小军; 崔祜涛; 崔平远; 徐瑞

    2011-01-01

    针对航天器带有非凸几何约束以及输入有界的问题,提出了一种姿态机动预测控制算法.分析了姿态机动所受到的几何约束,并对非凸二次形式约束及其Hesse矩阵进行研究,证明了该约束的非凸性.通过对正定Hesse矩阵的构造,给出非凸约束凸化映射关系.最后给出姿态机动预测控制律,解决了由于姿态机动过程中非凸约束造成的全局解收敛困难以及路径安全性问题.数值仿真结果显示该算法不仅能在大范围内得到优化姿态路径,同时满足所有约束.%A predictive control algorithm is presented in this paper for spacecraft attitude maneuver with nonconvex geometric constraint and bounded inputs. The nonconvex property of the geometric constraint is proved based on the analysis of its Hessian matrix. Then the transformation from nonconvex constraint to convex one is presented by constructing positive definite Hessian matrix. Consequently, a predictive control algorithm for spacecraft attitude maneuver is presented, and it can readily obtain global solution , as well as to solve the safety problem. The simulation results show that the presented algorithm can achieve optimal attitude path and satisfy all constraints.

  10. Adaptive Robust Attitude Control of Spacecraft Based on Trajectory Tracking%基于轨迹跟踪的航天器姿态自适应鲁棒控制

    Institute of Scientific and Technical Information of China (English)

    周端; 郭毓; 陈庆伟; 胡维礼

    2013-01-01

    In order to implement the rapid attitude maneuvering control of flexible spacecrafts in large-angle mobility mode in the presence of inertia uncertainties and external disturbances in space, inspired by the model of cell membrane discharge, an adaptive robust attitude controller is proposed. In the investigation, first, the kinematics and dynamics of flexible spacecraft are analyzed. Then, an robust control law, which is based on the pre-planned attitude trajectory and is adaptive to uncertain inertia, is put forward to improve the rapid attitude maneuvering performance and suppress the vibration of flexible panels. Finally, to avoid the degradation of pointing accuracy and stability due to the attitude jump during the maneuvering, an improved adaptive robust controller is designed based on the dynamic model of cell membrane discharge. It is proved that the proposed controller guarantees the asymptotical stability of the closed-loop system. Moreover, under bounded inertia estimation errors, uniformly-ultimate bounded tracking errors can be obtained with the controller. Simulation results verify the effectiveness of the proposed controller.%针对存在不确定惯量和空间环境干扰的挠性航天器姿态大角度快速机动控制问题,提出了一种受细胞膜放电模型启发的自适应鲁棒姿态控制器设计方法.首先,为了快速完成姿态机动任务,并尽可能少激发挠性帆板振动,在挠性航天器运动学和动力学分析的基础上,提出了基于预先规划姿态运动轨迹且对不确定惯量具有自适应能力的自适应鲁棒控制器.在此基础上,为了改善机动过程中姿态跳变使系统指向精度和稳定度变差的问题,基于细胞膜放电的动力学模型设计了一种改进型自适应鲁棒控制器.所提出的控制器能够保证闭环系统渐进稳定;当惯量估计误差有界时,对于任意初始跟踪误差,该控制器可以保证姿态跟踪误差一致终值有界.仿真结

  11. Attitudes and persuasion.

    Science.gov (United States)

    Crano, William D; Prislin, Radmila

    2006-01-01

    Study of attitudes and persuasion remains a defining characteristic of contemporary social psychology. This review outlines recent advances, with emphasis on the relevance of today's work for perennial issues. We reiterate the distinction between attitude formation and change, and show its relevance for persuasion. Single- and dual-process models are discussed, as are current views on dissonance theory. Majority and minority influence are scrutinized, with special emphasis on integrative theoretical innovations. Attitude strength is considered, and its relevance to ambivalence and resistance documented. Affect, mood, and emotion effects are reviewed, especially as they pertain to fear arousal and (un)certainty. Finally, we discuss attitude-behavior consistency, perhaps the reason for our interest in attitudes in the first place, with emphasis on self-interest and the theory of planned behavior. Our review reflects the dynamism and the reach of the area, and suggests a sure and sometimes rapid accumulation of knowledge and understanding.

  12. Backstepping and dynamic control-allocation for attitude maneuver of spacecraft with redundant reaction fly-wheels%基于反步法与动态控制分配的航天器姿态机动控制

    Institute of Scientific and Technical Information of China (English)

    李波; 胡庆雷; 石忠; 马广富

    2012-01-01

    We develop a robust adaptive controller based on the backstepping method for the attitude maneuver of the spacecraft with unknown rotational inertia and unknown external disturbances. The stability of the closed-loop system is validated by using Lyapunov analysis. In considering the redundancy of the actuators-the reaction fly-wheels, we propose a dynamic allocation algorithm based on the constrained optimal quadratic programming for distributing the control command to the proper fly-wheel. This eliminates the physical restrictions on the fly-wheel characteristics and the limitation of the maximal torque, which are required in the conventional pseudo-inverse method. In addition, it also effectively suppresses the measurement noises and rejects the abnormal data from attitude sensors, improving the smoothness of the control torque. The proposed scheme has been applied to control the attitude maneuver of a wheel-control rigid spacecraft. Simulation results validate the efficacy of the proposed method.%针对存在未知转动惯量与外部干扰的航天器姿态机动控制问题,提出了一类基于反步法的鲁棒自适应控制器,并利用Lyapunov方法分析了系统的稳定性;考虑到作为执行机构的反作用飞轮存在冗余性,进一步提出了一种基于约束最优二次规划的动态控制分配算法来实现指令到期望飞轮的指令分配,克服传统伪逆法难以考虑飞轮动态特性、最大力矩等物理约束,并能有效的抑制姿态敏感器的测量噪声和测量异常值,实现控制力矩的平稳性.最后,将本文提出的控制方案应用于某型轮控刚体航天器的姿态机动任务中,仿真结果验证了本文提出方法的可行性、有效性.

  13. Hardware-in-the-loop Simulation for Spacecraft Attitude Control Based on Ad hoc Network%基于自组织网络的航天器姿态控制半实物仿真

    Institute of Scientific and Technical Information of China (English)

    胡敏; 吴锦杰; 曾国强

    2013-01-01

    To increase the effective load ratio of spacecraft,and to solve the wire connected problem of current attitude control system,a hardware-in-the-loop simulation system for rigid-body spacecraft attitude control based on the mono-axis air-bearing table and ad hoc wireless network was established,and the flexibility and reliability of the spacecraft design were greatly enhanced.Firstly,the constitution and scheme design were introduced in detail; the dual ARM redundant architecture was employed for the on-board computer,and the fiber gyro,on-board computer,reaction wheel and the dynamics simulation computer were connected via the ad hoc wireless network.Secondly,the attitude kinematic equation and dynamic equation were introduced and the control algorithms were proposed.Finally,the three-axis stable control for spacecraft was conducted in the simulation system.The simulation results show that the control precision is satisfied to meet the mission requirements and the correctness of the software and hardware interfaces are also verified.%为了提高航天器的有效载荷比,针对目前姿态控制系统中采用有线连接的问题,以单轴气浮台为仿真平台,基于无线自组织网络构建了一种刚体航天器姿态控制半实物仿真系统,提高航天器设计的灵活性和可靠性.首先详细介绍了该系统的总体构成和方案设计,星载计算机采用双ARM冗余的体系结构,光纤陀螺、星载计算机、反作用飞轮以及动力学仿真机之间可通过无线自组织网络节点互连.其次,介绍了姿态控制系统的数学模型及控制算法.最后,利用该系统对航天器三轴正常姿态稳定控制进行了半实物仿真.仿真结果表明,姿态控制精度能够满足任务需求,同时校验了仿真系统设计的合理性和正确性.

  14. Information and Attitudes toward Disability.

    Science.gov (United States)

    Hafer, Marilyn; Narcus, Margery

    1979-01-01

    Examined effects of two movies, Like Other People and The Music Box, on attitudes as measured by the Attitudes toward Disabled Persons scale. Results indicated more negative attitudes were induced in pretested participants by Like Other People at initial post-test; however, more favorable attitudes were exhibited by participants six weeks later.…

  15. Trying to trust: Brain activity during interpersonal social attitude change.

    Science.gov (United States)

    Filkowski, Megan M; Anderson, Ian W; Haas, Brian W

    2016-04-01

    Interpersonal trust and distrust are important components of human social interaction. Although several studies have shown that brain function is associated with either trusting or distrusting others, very little is known regarding brain function during the control of social attitudes, including trust and distrust. This study was designed to investigate the neural mechanisms involved when people attempt to control their attitudes of trust or distrust toward another person. We used a novel control-of-attitudes fMRI task, which involved explicit instructions to control attitudes of interpersonal trust and distrust. Control of trust or distrust was operationally defined as changes in trustworthiness evaluations of neutral faces before and after the control-of-attitudes fMRI task. Overall, participants (n = 60) evaluated faces paired with the distrust instruction as being less trustworthy than faces paired with the trust instruction following the control-of-distrust task. Within the brain, both the control-of-trust and control-of-distrust conditions were associated with increased temporoparietal junction, precuneus (PrC), inferior frontal gyrus (IFG), and medial prefrontal cortex activity. Individual differences in the control of trust were associated with PrC activity, and individual differences in the control of distrust were associated with IFG activity. Together, these findings identify a brain network involved in the explicit control of distrust and trust and indicate that the PrC and IFG may serve to consolidate interpersonal social attitudes.

  16. Simulation of 3-Axis Stable Satellite Attitude Control System Based on Modularization%基于模块化的三轴稳定卫星姿控系统仿真

    Institute of Scientific and Technical Information of China (English)

    梁骁俊

    2012-01-01

    研究卫星姿控系统快速建模问题,根据姿态控制原理以及控制系统的基本结构,遵循“开放性”、“集成性”和“模块化”等原则,提出建立了三轴稳定卫星姿态控制系统仿真通用模块库,并通过一个仿真算例验证了模块库的有效性.该库划分为执行机构、代数法姿态确定、常用模块、控制器、动力学与运动学、敏感器、空间环境和状态估计姿态确定等八大类功能模块,可嵌入到MATLAB平台中,使用方便,而且可以对模块库不断扩展改进,为三轴稳定卫星姿态控制系统设计与仿真验证提供了一个快速有效方法.%According to the principle and the structure of 3 梐xis stable satellite attitude control system, a unitized MATLAB/Simulink modules library for 3-axis stable satellite attitude control system was build to resolve the problem of fleetly modeling. It was designed following three rules: openness, integration and modularization, then its validity was proved by a simulation example. The library can be embedded into the platform of MATLAB/Simulink, which includes eight blocks; Actuators, Algebra AD Blocks, Commonly Used Blocks, Controllers, Dynamics and Kinematics, Sensor Models, Space Environment Blocks and State Estimation Blocks. So it is easy to use and can be serially improved. This method will be helpful for 3-axis stable satellite attitude control system design and simulation.

  17. Demand Characteristics in Classical Verbal Conditioning and Attitude Conditioning Studies.

    Science.gov (United States)

    McGinley, Hugh

    This paper is a draft for the American Psychological Association Symposium on the conditioning of verbal behavior and attitudes. The author presents the results of several studies he conducted in the classical conditioning of meaning and attitude. These studies attempt to control the measurement effects created by extraneous variables operating on…

  18. Explicit- and Implicit Bullying Attitudes in Relation to Bullying Behavior

    NARCIS (Netherlands)

    Goethem, A.A.J. van; Scholte, R.H.J.; Wiers, R.W.H.J.

    2010-01-01

    The main aim of this study was to examine whether an assessment of implicit bullying attitudes could add to the prediction of bullying behavior after controlling for explicit bullying attitudes. Primary school children (112 boys and 125 girls, M age = 11 years, 5 months) completed two newly develope

  19. Explicit- and implicit bullying attitudes in relation to bullying behavior

    NARCIS (Netherlands)

    van Goethem, A.A.J.; Scholte, R.H.J.; Wiers, R.W.

    2010-01-01

    The main aim of this study was to examine whether an assessment of implicit bullying attitudes could add to the prediction of bullying behavior after controlling for explicit bullying attitudes. Primary school children (112 boys and 125 girls, M age = 11 years, 5 months) completed two newly develope

  20. Does exposure to music videos predict adolescents’ sexual attitudes?

    NARCIS (Netherlands)

    Beentjes, J.W.J.; Konig, R.P.

    2013-01-01

    This study investigates whether exposure to music videos predicts adolescents' sexual attitudes when controlled for relevant characteristics of individuals and their social environment. Sexual attitudes are related to their music video use (i.e. exposure to music videos, peer group talk about music

  1. Does exposure to music videos predict adolescents' sexual attitudes?

    NARCIS (Netherlands)

    Beentjes, J.W.J.; Konig, R.P.

    2013-01-01

    This study investigates whether exposure to music videos predicts adolescents' sexual attitudes when controlled for relevant characteristics of individuals and their social environment. Sexual attitudes are related to their music video use (i.e. exposure to music videos, peer group talk about music

  2. Variable Attitude Test Stand

    Data.gov (United States)

    Federal Laboratory Consortium — The Variable Attitude Test Stand designed and built for testing of the V-22 tilt rotor aircraft propulsion system, is used to evaluate the effect of aircraft flight...

  3. Attitudes Towards Immigration

    DEFF Research Database (Denmark)

    Malchow-Møller, Nikolaj; Roland Munch, Jakob; Schroll, Sanne

    2006-01-01

    In this paper, we re-examine the role of economic self-interest in shaping people's attitudes towards immigration, using data from the European Social Survey 2002/2003. Compared to the existing literature, there are two main contributions of the present paper. First, we develop a more powerful test...... of the hypothesis that a positive relationship between education and attitudes towards immigration reflects economic self-interest in the labour market. Second, we develop an alternativeand more direct test of whether economic self-interest mattersfor people's attitudes towards immigration. We find that whilethe...... "original" relationship between education and attitudes found in the literature is unlikely to reflect economic self-interest, there is considerable evidence of economic self-interest when using the more directtest....

  4. Attitudes Towards Immigration

    DEFF Research Database (Denmark)

    Malchow-Møller, Nikolaj; Munch, Jakob Roland; Schroll, Sanne

    In this paper, we re-examine the role of economic self-interest in shaping people’s attitudes towards immigration, using data from the European Social Survey 2002/2003. Compared to the existing literature, there are two main contributions of the present paper. First, we develop a more powerful test...... of the hypothesis that a positive relationship between education and attitudes towards immigration reflects economic self-interest in the labour market. Second, we develop an alternative and more direct test of whether economic self-interest matters for people’s attitudes towards immigration. We find that while...... the "original" relationship between education and attitudes found in the literature is unlikely to reflect economic self-interest, there is considerable evidence of economic self-interest when using the more direct test...

  5. Spacecraft Attitude Determination

    DEFF Research Database (Denmark)

    Bak, Thomas

    This thesis describes the development of an attitude determination system for spacecraft based only on magnetic field measurements. The need for such system is motivated by the increased demands for inexpensive, lightweight solutions for small spacecraft. These spacecraft demands full attitude...... determination based on simple, reliable sensors. Meeting these objectives with a single vector magnetometer is difficult and requires temporal fusion of data in order to avoid local observability problems. In order to guaranteed globally nonsingular solutions, quaternions are generally the preferred attitude...... is a detailed study of the influence of approximations in the modeling of the system. The quantitative effects of errors in the process and noise statistics are discussed in detail. The third contribution is the introduction of these methods to the attitude determination on-board the Ørsted satellite...

  6. Research of solar array output for the minisatellite without attitude control%微小卫星无姿控下太阳电池阵输出功率研究

    Institute of Scientific and Technical Information of China (English)

    林君毅; 尹兴月

    2012-01-01

    The minisatellites operate in orbits of around 100 km to 1 000 km above the Earth's surface, powered by body mounted solar array. The output of the solar array was related to the minisatellite's attitude. For the minisatellite without attitude control, the output of the solar array was analyzed, and the law of change of output in梠rbit was also predicted, which was important to the power analysis for minisatellite.%微小卫星多采用体装式太阳电池阵,运行在100~1 000 km的轨道.卫星的飞行姿态对太阳电池阵的输出功率有重要影响.对于无姿态控制的微小卫星,分析了不同条件下太阳电池阵的功率输出.针对卫星在轨飞行,预计了太阳电池阵的输出功率及变化规律,为卫星功率计算提供了计算依据.

  7. 欠驱动航天器姿态稳定的分层滑模控制器设计%Hierarchical Sliding-Mode Control for Attitude Stabilization of an Underactuated Spacecraft

    Institute of Scientific and Technical Information of China (English)

    王冬霞; 贾英宏; 金磊; 周付根; 徐世杰

    2013-01-01

    For an underactuated spacecraft with two control actuators, an attitude controller is proposed based on hierarchical sliding-mode control. Firstly, attitude dynamics and kinematics models are introduced and analyzed. Secondly, the first-layer sliding surface is defined by the state variables of the underactuated system, and the equivalent controller is obtained by Filippov equivalent theorem. Then, the second-layer sliding surface and the third-layer sliding surface are constructed in sequence, and the switching controller is derived by using the sliding-mode control theory. Thus the total controller is deduced by the equivalent and switching controller. The global asymptotic stability of all sliding surfaces is proved by using Lyapunov stability theory and Barbalat theory. The simulation results illustrate the feasibility of the proposed control algorithm.%利用分层滑模控制方法,为带两个控制执行机构的欠驱动刚体航天器的姿态控制系统设计了一种三轴稳定控制器.首先,给出了基于两个推力器的欠驱动航天器的姿态动力学和运动学模型,分析了其模型特点.其次,将子系统的变量进行组合定义成第一层滑模面,利用Filippov等效定理求出等效控制律.然后依次构造出第二层滑模面及第三层滑模面,根据滑模控制原理求出切换控制律,进而得到总的控制量.利用Lyapunov稳定性理论和Barbalat引理及推论证明了各层滑模面的全局渐近稳定性.仿真实验验证了该控制方法的有效性.

  8. Attitudes towards documentary soundstracks

    DEFF Research Database (Denmark)

    Have, Iben

    2010-01-01

    . By listening to different voices - primarily from four focus group interviews - the article will discuss attitudes towards musical soundtracks in documentaries, attitudes being negotiated between emotional immersion and critical reflection, with the concept of manipulation as an underlying theme. In the end......, the article will argue for the need for an acoustemological approach (Feld, 1996) to study the epistemological potential of sound in audiovisual media....

  9. Attitudes towards immigration

    DEFF Research Database (Denmark)

    Malchow-Møller, Nikolaj; Munch, Jakob Roland; Skaksen, Jan Rose

    2008-01-01

    Using the European Social Survey 2002/3, we develop a new test of whether economic self-interest influences people's attitudes towards immigration, exploiting that people have widely different perceptions of the consequences of immigration......Using the European Social Survey 2002/3, we develop a new test of whether economic self-interest influences people's attitudes towards immigration, exploiting that people have widely different perceptions of the consequences of immigration...

  10. Study on dynamics modeling and attitude control of flexible solar sail spacecraft%柔性太阳帆航天器动力学建模与姿态控制

    Institute of Scientific and Technical Information of China (English)

    崔乃刚; 刘家夫; 荣思远

    2011-01-01

    For solar sail spacecraft with control vanes,solar sail attitude dynamics equations considering elastic vibration and vibration equations were deduced.The solutions of solar sail spacecraft dynamics equations were achieved by utilizing the concepts of unconstraint modes.The PD controller with Bang-Bang control strategies was designed considering the problems of yaw axis earth-pointing of solar sail on super-synchronous transfer orbit.Numerical simulation shows that the designed controller based on control vanes is capable of controlling the yaw axis earth-pointing fast and accurately.%对基于控制叶片的太阳帆航天器,推导考虑弹性振动的太阳帆姿态动力学方程和振动方程,利用非约束模态的概念给出了太阳帆航天器动力学方程的求解方法.结合超地球同步转移轨道太阳帆航天器偏航轴对地定向问题,设计了太阳帆俯仰轴的考虑Bang-Bang控制策略的PD控制器,数值仿真结果表明,所设计的基于控制叶片的控制器可以较快、较精确地实现偏航轴对地定向任务.

  11. Satisfying Stringent Requirements for Fine Attitude Control of Hypersonic Cruise Vehicle (HCV)%高超声速巡航飞行器振动建模及精细姿态控制

    Institute of Scientific and Technical Information of China (English)

    孟中杰; 黄攀峰; 闫杰

    2011-01-01

    Aim. The introduction of the full paper reviews a number of papers in the open literature and then out-lines the research in this paper, which is explained in sections 1, 2 and 3. Taking the longitudinal channel of a HCV for example, section 1 analyzes the impact of elastic vibration on its flight control system. Section 2 establishes the elastic aerodynamic model of the HCV by giving eqs. (9) and ( 11 ). The core of section 3 consists of:(t) we reduce the fine attitude control of HCV to the fine control of the inlet local angle of attack (AOA) of a scramjet; (2) considering that body/engine coupling and aerodynamic heating cause the large-scale perturbation of the aerodynamic parameters and model parameters, we design the fine attitude control system by using the H ∞ control theory, which is shown by the block diagram in Fig. 2; (3) we construct the generalized controlled object and solve the Riccati equation, thus obtaining the controller of the HCV; (4) we simulate the controller; the simulation results show preliminarily that: (a) with measurement noise, nonlinear actuator and large-scale perturbation of model parameters, the controller tracks the rigid AOA of HCV precisely and inhibits its flexible AOA well; (b) the ± 0. 6 degree control precision of inlet local angle of attack is guaranteed, thus meeting the stringent requirements for fine attitude control of HCV.%为保证超燃冲压发动机的良好进气环境,需要对高超声速巡航飞行器进行精细姿态控制,但弹性振动大大提高了精细姿态控制的设计难度.以高超声速巡航飞行器的纵向通道为例,文章分析弹性振动对飞行控制系统的影响,建立高超声速巡航飞行器的弹性模型,将精细姿态控制问题简化为超燃冲压发动机进气口当地攻角的精细控制问题,考虑机体/发动机耦合和气动热造成了气动参数和模态参数大范围摄动问题,基于H∞理论设计鲁棒控制系统.仿真表明,在考虑测量

  12. Roll stabilizer bars' design for solar-sail spacecraft attitude control%太阳帆航天器姿态控制滚转轴稳定机设计

    Institute of Scientific and Technical Information of China (English)

    马鑫; 杨萱; 杨辰; 钱航; 郑龙飞

    2014-01-01

    针对一种具体的由支撑臂支撑、方形帆面形式的太阳帆航天器,介绍了质心偏移类、帆面转动类两大类姿态控制机构,并分析了其优缺点,对其适用的姿态控制滚转轴稳定机进行了设计。在构型设计、材料强度、结构强度、质量优化、控制精度等设计约束条件下,围绕滚转轴稳定机转杆长度关键设计参数,通过分析长度角度制约关系、几何计算、帆面有限元非线性静态建模仿真验证、伸展臂弯曲受力有限元建模仿真验证给出了转杆长度值的优化设计结果为1.2 m,并以此为依据结合功率、转速公式计算选取了合理的极限转速取值为20.83(。)/s。给出了一种滚转轴稳定机转杆长度优化设计思路,为太阳帆航天器姿态控制方案设计提供了关键设计参数与设计约束条件,优化设计结果对实际工程应用具有一定参考价值。%Two kinds of solar-sail attitude control mechanism were described in this paper, one was the centroid offet class, the other was the sail plane rotating class. Advantages and disadvantages of these two kinds of attitude control mechanism were analyzed. An attitude control roll stabilizer barsis was designed which was suitable for a kind of square solar sail which had extension boom and square sail surface. The boom's length of roll stabilizer bars is the key parameter, it was optimized under some constraints such as: configuration design, material strength, structural strength, quality optimization and control accuracy, it was calculated and verified through geometry relations and nonlinear static finite element simulation. The simulation result wa s 1.2 m. The rotate speed limit was obtained by power and speed relation formula according to the result of the boom's length, which was 20.83 (.)/s. In this paper, an optimization design idea of roll stabilizer bars boom's length was given. The calculation and simulation results provide the

  13. 基于时频域分析的轮控航天器姿态控制规律参数整定%Parameter Tuning for the Attitude Control Algorithm of Wheel Controlled Spacecraft Based on Time and Frequency Domain Analysis

    Institute of Scientific and Technical Information of China (English)

    李传江; 郭延宁; 张永合; 马广富

    2011-01-01

    The problem of attitude control law design and parameter tuning for wheel controlled spacecraft is investigated. By using the xyz rotation sequence Euler angle to represent spacecraft attitude, the attitude dynamics and kinematics equations are given. A nonlinear decoupling control law is developed to ensure that the PID controller can be designed separately for each control loop. After that, taking roll loop for example, the relationship between PD control parameters and system bandwidth, cross frequency and phase margin are obtained, and can be used to design more effective controller to deal with vibration of flexible structure and time delay of the system. Then integral parameter selection rule and the integral saturation suppression strategy are proposed based on the characteristics of attitude control system. Besides, the efficiency of wheel and disturbing torques are also considered for control parameter tuning. Finally, a series of numerical simulations are performed to verify effectiveness and practicability of the proposed parameter tuning strategy.%研究了轮控航天器姿态控制规律的设计与参数整定问题.采用xyz转序欧拉角描述航天器姿态,建立了航天器动力学及运动学方程,并设计了非线性解耦控制律,使得各回路可独立设计PID控制器.以滚动回路为例,分析了PD控制参数与系统带宽、截止频率、相位裕度等多项频域指标的关系,从而设计有效的稳态控制器以应对挠性结构振动和系统时延等;接着根据姿态控制特性给出了积分参数选取及积分饱和处理策略;同时为快速完成姿态机动,结合时间最优控制特性分析了控制参数与机动角度的关系;此外,执行机构效率和系统干扰力矩等因素也被用于控制参数域的整定.最后利用整定策略设计了某型卫星的姿态控制器,并通过频域分析和数学仿真检验了该方法的有效性和实用性.

  14. Influencing Attitudes and Changing Behavior: A Basic Introduction to Relevant Methodology, Theory, and Applications. Revised Edition.

    Science.gov (United States)

    Zimbardo, Philip; Ebbesen, Ebbe B.

    In this introductory text to the field of attitude change, the emphasis is on one of the end products of research in social psychology--manipulation and control of attitudes and related behaviors. The text first defines the concept of attitude, then identifies ideas from the areas of history, literature, law, religion, and the social sciences that…

  15. 低精度传感器在动中通天线姿态控制中的设计应用%Design and Application of Low Precision Sensor in the Attitude Control of Seaborne Satelite Communication

    Institute of Scientific and Technical Information of China (English)

    蒋志遥

    2015-01-01

    In order tofi tting future marking require, we use the combination, which includes low precision sensor and stepping motor, to replace the common combination including inertial navigation unit and high precision sensor in the Seaborne Satellite Communication when the former combination can meet the required precision of antenna attitude control by using later combination meanwhile extremely reducing the whole components cost.%本文介绍了在船载"动中通"天线中利用低精度传感器和步进电机来替代常见的惯导单元或者高精度传感器,在达到不亚于使用后者的天线姿态控制的精度要求同时,极大地减小元件成本,更适应未来的市场需求.

  16. Attitudes of Children Established by Classical Conditioning.

    Science.gov (United States)

    Barnabei, Fred; And Others

    This study examined the attitudes of children established by classical conditioning. Subjects were 4th graders (26 males and 31 females). Each child was randomly assigned to either an experimental or a control group. A posttest-only design was used with positive and negative word associations presented to the experimental group, and neutral word…

  17. Participation in Adult Education: Attitudes and Barriers

    Science.gov (United States)

    Boeren, Ellen

    2011-01-01

    In this paper, we control the intention theory of Fishbein and Ajzen (1980) for the participation in an adult education course. Based on the Flemish Eurostat Adult Education Survey, we reveal that participants in adult education have a more positive attitude towards learning and that within the group of non-participants, those who formulate an…

  18. Scaling of Attitudes Toward Population Problems

    Science.gov (United States)

    Watkins, George A.

    1975-01-01

    This study related population problem attitudes and socioeconomic variables. Six items concerned with number of children, birth control, family, science, economic depression, and overpopulation were selected for a Guttman scalogram. Education, occupation, and number of children were correlated with population problems scale scores; marital status,…

  19. Improving Elderly Clients' Attitudes Through Photography

    Science.gov (United States)

    Aronson, David W.; Graziano, Anthony M.

    1976-01-01

    Ten older adults were involved in a photography activity once a week for six weeks, while five older adults were controls. Using pre- and post-program semantic differentials, it was found that the photography activity was associated with significant increases in positive attitudes. (Author)

  20. Death Education and Death-Related Attitudes.

    Science.gov (United States)

    Hoelter, Jon W.; Epley, Rita J.

    1979-01-01

    Assessed the impact of a death and dying course. Results showed no significant pre-test/post-test differences for the experimental or the control group, but indicated initial differences between the two groups, suggesting that students enrolling in a death and dying course have more favorable attitudes toward both suicide and abortion. (Author)