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Sample records for attitude control system

  1. 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.

  2. 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.

  3. 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.

  4. Dynamics and nonlinear attitude control of multibody space systems

    Science.gov (United States)

    Rui, Chunlei

    In this dissertation, we study dynamics and attitude control problems for a multibody system in space. The key feature of this work is the systematic use of shape changes as three dimensional attitude controls. Control models are identified for a general class of multibody space systems that are controlled by thrusters, reaction wheels, and/or joint actuators. The important role of shape change in attitude maneuvers for a multibody space system is identified and shape change is recognized as a means of attitude control. Formulas that quantify three dimensional attitude changes induced by periodic shape changes, rotation of reaction wheels and nonzero angular momentum are developed. The formulas prove fundamental for development of numerous attitude control algorithms. Explicit construction procedures are developed for shape changes that accomplish a desired three dimensional reconfiguration of a free-floating multibody space system with zero angular momentum with prescribed accuracy. The control computation involves evaluation of certain Lie brackets and solution of a simple system of algebraic equations. Explicit construction procedures are developed for shape changes that accomplish a desired three dimensional reorientation of a free-floating multibody space system with constant nonzero angular momentum with prescribed accuracy. Control algorithms are provided for reorientation of a multibody space system to one of its relative equilibria. Explicit control algorithms are developed for reaction wheel and shape changes that accomplish a desired three dimensional reorientation for a spacecraft system containing a single reaction wheel and a single movable appendage. Characterization of shape changes that enhance effectiveness of reaction wheels and joint actuators is given, and control algorithms are provided for effective simultaneous attitude changes and shape changes. Feedback attitude control laws are developed for three dimensional attitude maneuvers of a

  5. 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.

  6. 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.

  7. 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

  8. H∞ control option for a combined energy and attitude control system

    Science.gov (United States)

    Ban, Ying Siang; Varatharajoo, Renuganth

    2013-10-01

    A combined energy and attitude control system (CEACS) is a hybrid system that uses flywheels to store energy and provide a simultaneous attitude control in satellites. Previous work appeared in Advances in Space Research (ASR) employing the proportional-derivative (PD) control has proven that CEACS works well and achieves its mission requirement. However, the in-orbit system performance uncertainties present a challenge to the CEACS attitude pointing capability. Thus, this paper complements the previous mentioned work, and focuses on employing the H∞ optimal attitude control solution for the CEACS attitude control enhancement. The mathematical model and numerical treatments for the CEACS H∞ control architecture are presented. Numerical results show that a better attitude pointing accuracy at least up to 0.043° can be achieved with the H∞ control method.

  9. 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.

  10. 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.

  11. Stepping through versatile attitude control system design for stratospheric platforms

    OpenAIRE

    Boscaleri, A.; Baldi, M; F. CALONACI; Rissone, P.; Rotini, F.

    2005-01-01

    In addition to stepping through the typical hardware parts of an Attitude Control System borne for stratospheric platform, the paper describes some fast position sensors. The use of two axis magnetometers at high latitude, even though with a lower accuracy, is analyzed. A high-accuracy motorized sun tracker based on a Position Sensitive Detector photodiode capable of driving the gondola in pointing or scanning mode in any given arbitrary anti-sun direction is also presented. Lastly, as an imp...

  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. 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...

  14. 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

  15. Attitude Control System Design for Fast Rest-to-Rest Attitude Maneuver

    Science.gov (United States)

    Sakai, S.-I.; Bando, N.; Hashimoto, T.; Murata, Y.; Mochizuki, N.; Nakamura, T.; Kamiya, T.; Ogura, N.; Maeda, K.

    2009-08-01

    The VSOP-2 project is a new space VLBI (very long baseline interferometer) radio astronomy mission, proposed to inherit the fruitful success of the VSOP mission with the HALCA satellite. One of the most important advances of VSOP-2 is the use of higher observation frequency, which requires fast alternating observation of a target and calibrator in order to remove the phase changes caused by the atmosphere. Typically, both sources must be observed within 60 sec, and this switching must be carried out over many hours. ``ASTRO-G" is a satellite planned for this VSOP-2 project, and one of technical challenges is to achieve such fast rest-to-rest maneuvers, and the proper hardware must be selected to account for this fast attitude maneuver. The controlled momentum gyro (CMG) is an actuator that provides high torque with small power consumption, and the fiber optical gyro is a sensor able to measure the high angular velocity with excellent accuracy. This paper first describes these components for attitude control. Another challenge of the ASTRO-G's attitude control system is to design the switching for the flexible mode of the satellite structure, containing a large deployable reflector and a large solar panel. These produce resonances with fast switching and these must be attenuated. To achieve high agility in a flexible satellite, the controller design is crucial. One design feature is a novel robust input shaper named ``nil mode exciting profiler". Another feature is the feedback controller design. The paper describes these features and other potential problems with fast switching..

  16. 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.

  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. 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.

  19. 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...

  20. Attitude control study for a large flexible spacecraft using a Solar Electric Propulsion System (SEPS)

    Science.gov (United States)

    Tolivar, A. F.; Key, R. W.

    1980-01-01

    The attitude control performance of the solar electric propulsion system (SEPS) was evaluated. A thrust vector control system for powered flight control was examined along with a gas jet reaction control system, and a reaction wheel system, both of which have been proposed for nonpowered flight control. Comprehensive computer simulations of each control system were made and evaluated using a 30 mode spacecraft model. Results obtained indicate that thrust vector control and reaction wheel systems offer acceptable smooth proportional control. The gas jet control system is shown to be risky for a flexible structure such as SEPS, and is therefore, not recommended as a primary control method.

  1. 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.

  2. 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.

  3. Precision Integrated Power and Attitude Control System (IPACS) in the Presence of Dynamic Uncertainty

    Science.gov (United States)

    Kim, D.; MacKunis, W.; Fitz-Coy, N.; Dixon, W. E.

    2011-01-01

    An adaptive robust integrated power and attitude control system (IPACS) is presented for a variable speed control moment gyroscope (VSCMG)-actuated satellite. The developed IPACS method is capable of achieving precision attitude control while simultaneously achieving asymptotic power tracking for a rigid-body satellite in the presence of uncertain friction in the VSCMG gimbals and wheels. In addition, the developed controller compensates for the effects of uncertain, time-varying satellite inertia properties. Some challenges encountered in the control design are that the control input is premultiplied by a nonsquare, time-varying, nonlinear, uncertain matrix and is embedded in a discontinuous nonlinear. Globally uniformly ultimately bounded attitude tracking and asymptotic power tracking results are proven via Lyapunov stability analyses, and simulation results are provided to demonstrate the performance of the controller.

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

    International Nuclear Information System (INIS)

    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

  5. 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.

  6. Design and Integration of an All-Magnetic Attitude Control System for FASTSAT-HSV01's Multiple Pointing Objectives

    Science.gov (United States)

    DeKock, Brandon; Sanders, Devon; Vanzwieten, Tannen; Capo-Lugo, Pedro

    2011-01-01

    The FASTSAT-HSV01 spacecraft is a microsatellite with magnetic torque rods as it sole attitude control actuator. FASTSAT s multiple payloads and mission functions require the Attitude Control System (ACS) to maintain Local Vertical Local Horizontal (LVLH)-referenced attitudes without spin-stabilization, while the pointing errors for some attitudes be significantly smaller than the previous best-demonstrated for this type of control system. The mission requires the ACS to hold multiple stable, unstable, and non-equilibrium attitudes, as well as eject a 3U CubeSat from an onboard P-POD and recover from the ensuing tumble. This paper describes the Attitude Control System, the reasons for design choices, how the ACS integrates with the rest of the spacecraft, and gives recommendations for potential future applications of the work.

  7. 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. 

  8. Attitudes Toward Financial Control Systems in the United States and Japan†

    OpenAIRE

    Lane Daley; James Jiambalvo; Gary Sundem; Yasumasa Kondo

    1985-01-01

    Recently researchers have begun to investigate issues of differences in the use of managerial accounting tools across differing national environments. Much of this research is of the case study approach documenting actual practices for a small group of firms, or a distillation from numerous observations but using anecdotal evidence to support various conjectures.The study uses a survey of attitudes toward various aspects of budgeting and control systems to gain insight into the existence of d...

  9. 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.

  10. 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.

  11. Star Tracker Algorithms and a Low-Cost Attitude Determination and Control System for Space Missions

    OpenAIRE

    Delabie, Tjorven

    2016-01-01

    The attitude determination and control system determines and controls the orientation of the spacecraft. This system is crucial in the majority of space missions to e.g. point a camera to a star or direct an antenna to a ground station. Increasingly complex missions drive the need for higher accuracy, while the growing number of small spacecraft requires high robustness and low computational cost. This work focusses on the star tracker, a sensor that takes an image of the stars and compares i...

  12. 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...

  13. The Implementation of Satellite Attitude Control System Software Using Object Oriented Design

    Science.gov (United States)

    Reid, W. Mark; Hansell, William; Phillips, Tom; Anderson, Mark O.; Drury, Derek

    1998-01-01

    NASA established the Small Explorer (SNMX) program in 1988 to provide frequent opportunities for highly focused and relatively inexpensive space science missions. The SMEX program has produced five satellites, three of which have been successfully launched. The remaining two spacecraft are scheduled for launch within the coming year. NASA has recently developed a prototype for the next generation Small Explorer spacecraft (SMEX-Lite). This paper describes the object-oriented design (OOD) of the SMEX-Lite Attitude Control System (ACS) software. The SMEX-Lite ACS is three-axis controlled and is capable of performing sub-arc-minute pointing. This paper first describes high level requirements governing the SMEX-Lite ACS software architecture. Next, the context in which the software resides is explained. The paper describes the principles of encapsulation, inheritance, and polymorphism with respect to the implementation of an ACS software system. This paper will also discuss the design of several ACS software components. Specifically, object-oriented designs are presented for sensor data processing, attitude determination, attitude control, and failure detection. Finally, this paper will address the establishment of the ACS Foundation Class (AFC) Library. The AFC is a large software repository, requiring a minimal amount of code modifications to produce ACS software for future projects.

  14. Attitude tracking control for variable structure near space vehicles based on switched nonlinear systems

    Institute of Scientific and Technical Information of China (English)

    Wang Yufei; Jiang Changsheng; Wu Qingxian

    2013-01-01

    An adaptive robust attitude tracking control law based on switched nonlinear systems is presented for a variable structure near space vehicle (VSNSV) in the presence of uncertainties and disturbances.The adaptive fuzzy systems are employed for approximating unknown functions in the flight dynamic model and their parameters are updated online.To improve the flight robust performance,robust controllers with adaptive gains are designed to compensate for the approximation errors and thus they have less design conservation.Moreover,a systematic procedure is developed for the synthesis of adaptive fuzzy dynamic surface control (DSC) approach.According to the common Lyapunov function theory,it is proved that all signals of the closed-loop system are uniformly ultimately bounded by the continuous controller.The simulation results demonstrate the effectiveness and robustness of the proposed control scheme.

  15. Analytic investigation of the AEM-A/HCMM attitude control system performance. [Application Explorer Missions/Heat Capacity Mapping Mission

    Science.gov (United States)

    Lerner, G. M.; Huang, W.; Shuster, M. D.

    1977-01-01

    The Heat Capacity Mapping Mission (HCMM), scheduled for launch in 1978, will be three-axis stabilized relative to the earth in a 600-kilometer altitude, polar orbit. The autonomous attitude control system consists of three torquing coils and a momentum wheel driven in response to error signals computed from data received from an infrared horizon sensor and a magnetometer. This paper presents a simple model of the attitude dynamics and derives the equations that determine the stability of the system during both attitude acquisition (acquisition-mode) and mission operations (mission-mode). Modifications to the proposed mission-mode control laws which speed the system's response to transient attitude errors and reduce the steady-state attitude errors are suggested. Numerical simulations are performed to validate the results obtained with the simple model.

  16. Mission management, planning, and cost: PULSE Attitude And Control Systems (AACS)

    Science.gov (United States)

    1990-01-01

    The Pluto unmanned long-range scientific explorer (PULSE) is a probe that will do a flyby of Pluto. It is a low weight, relatively low costing vehicle which utilizes mostly off-the-shelf hardware, but not materials or techniques that will be available after 1999. A design, fabrication, and cost analysis is presented. PULSE will be launched within the first decade of the twenty-first century. The topics include: (1) scientific instrumentation; (2) mission management, planning, and costing; (3) power and propulsion systems; (4) structural subsystem; (5) command, control, and communication; and (6) attitude and articulation control.

  17. A robust momentum management and attitude control system for the space station

    Science.gov (United States)

    Speyer, J. L.; Rhee, Ihnseok

    1991-01-01

    A game theoretic controller is synthesized for momentum management and attitude control of the Space Station in the presence of uncertainties in the moments of inertia. Full state information is assumed since attitude rates are assumed to be very assurately measured. By an input-output decomposition of the uncertainty in the system matrices, the parameter uncertainties in the dynamic system are represented as an unknown gain associated with an internal feedback loop (IFL). The input and output matrices associated with the IFL form directions through which the uncertain parameters affect system response. If the quadratic form of the IFL output augments the cost criterion, then enhanced parameter robustness is anticipated. By considering the input and the input disturbance from the IFL as two noncooperative players, a linear-quadratic differential game is constructed. The solution in the form of a linear controller is used for synthesis. Inclusion of the external disturbance torques results in a dynamic feedback controller which consists of conventional PID (proportional integral derivative) control and cyclic disturbance rejection filters. It is shown that the game theoretic design allows large variations in the inertias in directions of importance.

  18. Attitude control system of the Delfi-n3Xt satellite

    NARCIS (Netherlands)

    Reijneveld, J.; Choukroun, D.

    2013-01-01

    This work is concerned with the development of the attitude control algorithms that will be implemented on board of the Delfi-n3xt nanosatellite, which is to be launched in 2013. One of the mission objectives is to demonstrate Sun pointing and three axis stabilization. The attitude control modes and

  19. Optimal magnetic attitude control

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Markley, F.L.

    1999-01-01

    Magnetic torquing is attractive as means of control for small satellites. The actuation principle is to use the interaction between the earth's magnetic field and a magnetic field generated by a coil set in the satellite. This control principle is inherently time-varying, and difficult to use...... 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...

  20. 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.

  1. A neural network approach to fault detection in spacecraft attitude determination and control systems

    Science.gov (United States)

    Schreiner, John N.

    This thesis proposes a method of performing fault detection and isolation in spacecraft attitude determination and control systems. The proposed method works by deploying a trained neural network to analyze a set of residuals that are defined such that they encompass the attitude control, guidance, and attitude determination subsystems. Eight neural networks were trained using either the resilient backpropagation, Levenberg-Marquardt, or Levenberg-Marquardt with Bayesian regularization training algorithms. The results of each of the neural networks were analyzed to determine the accuracy of the networks with respect to isolating the faulty component or faulty subsystem within the ADCS. The performance of the proposed neural network-based fault detection and isolation method was compared and contrasted with other ADCS FDI methods. The results obtained via simulation showed that the best neural networks employing this method successfully detected the presence of a fault 79% of the time. The faulty subsystem was successfully isolated 75% of the time and the faulty components within the faulty subsystem were isolated 37% of the time.

  2. 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.

  3. Model-Based Development and Evaluation of Control for Complex Multi-Domain Systems: Attitude Control for a Quadrotor UAV

    DEFF Research Database (Denmark)

    Grujic, Ivan; Nilsson, Rene

    Unmanned Aerial Vehicle (UAV) has been constructed and used to develop an attitude controller based on Model Predictive Control (MPC). The MPC controller has been compared to an existing open source Proportional Integral Derivative (PID) attitude controller. This thesis contributes to the discipline...

  4. The Software Design for the Wide-Field Infrared Explorer Attitude Control System

    Science.gov (United States)

    Anderson, Mark O.; Barnes, Kenneth C.; Melhorn, Charles M.; Phillips, Tom

    1998-01-01

    The Wide-Field Infrared Explorer (WIRE), currently scheduled for launch in September 1998, is the fifth of five spacecraft in the NASA/Goddard Small Explorer (SMEX) series. This paper presents the design of WIRE's Attitude Control System flight software (ACS FSW). WIRE is a momentum-biased, three-axis stabilized stellar pointer which provides high-accuracy pointing and autonomous acquisition for eight to ten stellar targets per orbit. WIRE's short mission life and limited cryogen supply motivate requirements for Sun and Earth avoidance constraints which are designed to prevent catastrophic instrument damage and to minimize the heat load on the cryostat. The FSW implements autonomous fault detection and handling (FDH) to enforce these instrument constraints and to perform several other checks which insure the safety of the spacecraft. The ACS FSW implements modules for sensor data processing, attitude determination, attitude control, guide star acquisition, actuator command generation, command/telemetry processing, and FDH. These software components are integrated with a hierarchical control mode managing module that dictates which software components are currently active. The lowest mode in the hierarchy is the 'safest' one, in the sense that it utilizes a minimal complement of sensors and actuators to keep the spacecraft in a stable configuration (power and pointing constraints are maintained). As higher modes in the hierarchy are achieved, the various software functions are activated by the mode manager, and an increasing level of attitude control accuracy is provided. If FDH detects a constraint violation or other anomaly, it triggers a safing transition to a lower control mode. The WIRE ACS FSW satisfies all target acquisition and pointing accuracy requirements, enforces all pointing constraints, provides the ground with a simple means for reconfiguring the system via table load, and meets all the demands of its real-time embedded environment (16 MHz Intel

  5. Structural control interaction for an LSS attitude control system using thrusters and reaction wheels

    Science.gov (United States)

    da Fonseca, Ijar M.; Bainum, Peter M.; da Silva, Adenilson R.

    2007-05-01

    This work provides some important information about control structure interaction (CSI) for a large space structure (LSS) attitude control subsystem (ACS) comprised of thrusters and reaction wheels. The LSS physical model is assumed as a rigid long tubular beam as the main bus with two attached long flexible solar panels. Two thrusters (one at each tip of the LSS) are used for large amplitude maneuvers and the reaction wheels for fine control. Lagrange's formulations for generalized and quasi-coordinates were used to derive the equations of motion. The gravity gradient, the solar pressure and the drag were included in the mathematical model as external perturbations. The assumed modes discretization method has been used to model the solar array elastic displacements so as to obtain a set of ordinary differential equations to describe the LSS motion. Different control strategies were implemented to analyze the CSI for two configurations, fine and coarse control. The MatLab/Simulink platform has been used for the computational simulations. The results are in agreement with the CSI theory in that thruster firings excite the solar panel vibrations and that the elastic vibration is an important issue to be taken into account for LSS ACS performance evaluation for both fine and coarse control. In spite of the CSI the maneuver objectives have been accomplished with results that meet the mission criteria.

  6. Transient Plume Model Testing Using LADEE Spacecraft Attitude Control System Operations

    Science.gov (United States)

    Woronowicz, Michael

    2011-01-01

    We have learned it is conceivable that the Neutral Mass Spectrometer on board the Lunarr Atmosphere Dust Environment Explorer (LADEE) could measure gases from surface-reflected Attitude Control System (ACS) thruster plume. At minimum altitude, the measurement would be maximized, and gravitational influence minimized ("short" time-of-flight (TOF) situation) Could use to verify aspects of thruster plume modeling Model the transient disturbance to NMS measurements due to ACS gases reflected from lunar surface Observe evolution of various model characteristics as measured by NMS Species magnitudes, TOF measurements, angular distribution, species separation effects

  7. Fault tolerant attitude control for small unmanned aircraft systems equipped with an airflow sensor array

    International Nuclear Information System (INIS)

    Inspired by sensing strategies observed in birds and bats, a new attitude control concept of directly using real-time pressure and shear stresses has recently been studied. It was shown that with an array of onboard airflow sensors, small unmanned aircraft systems can promptly respond to airflow changes and improve flight performances. In this paper, a mapping function is proposed to compute aerodynamic moments from the real-time pressure and shear data in a practical and computationally tractable formulation. Since many microscale airflow sensors are embedded on the small unmanned aircraft system surface, it is highly possible that certain sensors may fail. Here, an adaptive control system is developed that is robust to sensor failure as well as other numerical mismatches in calculating real-time aerodynamic moments. The advantages of the proposed method are shown in the following simulation cases: (i) feedback pressure and wall shear data from a distributed array of 45 airflow sensors; (ii) 50% failure of the symmetrically distributed airflow sensor array; and (iii) failure of all the airflow sensors on one wing. It is shown that even if 50% of the airflow sensors have failures, the aircraft is still stable and able to track the attitude commands. (paper)

  8. Fault tolerant attitude control for small unmanned aircraft systems equipped with an airflow sensor array.

    Science.gov (United States)

    Shen, H; Xu, Y; Dickinson, B T

    2014-01-01

    Inspired by sensing strategies observed in birds and bats, a new attitude control concept of directly using real-time pressure and shear stresses has recently been studied. It was shown that with an array of onboard airflow sensors, small unmanned aircraft systems can promptly respond to airflow changes and improve flight performances. In this paper, a mapping function is proposed to compute aerodynamic moments from the real-time pressure and shear data in a practical and computationally tractable formulation. Since many microscale airflow sensors are embedded on the small unmanned aircraft system surface, it is highly possible that certain sensors may fail. Here, an adaptive control system is developed that is robust to sensor failure as well as other numerical mismatches in calculating real-time aerodynamic moments. The advantages of the proposed method are shown in the following simulation cases: (i) feedback pressure and wall shear data from a distributed array of 45 airflow sensors; (ii) 50% failure of the symmetrically distributed airflow sensor array; and (iii) failure of all the airflow sensors on one wing. It is shown that even if 50% of the airflow sensors have failures, the aircraft is still stable and able to track the attitude commands. PMID:25405953

  9. Attitude control of a space platform/manipulator system using internal motion

    Science.gov (United States)

    Fernandes, Chris; Gurvits, Leonid; Li, Zexiang

    1994-08-01

    Attitude control of a space platform/manipulator system, using internal motion, is an example of a nonholonomic motion planning (NMP) problem arising from symmetry and conservation laws. Common to NMP problems are that an admissible configuration space path is constrained to a given nonholonomic distribution. We formulate the dynamic equations of a system consisting of a 3-DOF PUMA-like manipulator attached to a space platform (e.g., a space station or a satellite) as an NMP problem and discuss the cotrollability of the system. Then we describe the application of a simple algorithm for obtaining approximate optimal solutions. We conclude with a description of simulation software implementing the algorithm and simulation results for two experiments.

  10. Investigations of an integrated angular velocity measurement and attitude control system for spacecraft using magnetically suspended double-gimbal CMGs

    Science.gov (United States)

    Zheng, Shiqiang; Han, Bangcheng

    2013-06-01

    This paper presents an integrated angular velocity measurement and attitude control system of spacecraft using magnetically suspended double-gimbal control moment gyros (MSDGCMGs). The high speed rotor of MSDGCMG is alleviated by a five-degree-of-freedom permanent magnet biased AMB control system. With this special rotor supported manner, the MSDGCMG has the function of attitude rate sensing as well as attitude control. This characteristic provides a new approach to a compact light-weight spacecraft design, which can combine these two functions into a single device. This paper discusses the principles and implementations of AMB-based angular velocity measurement. Spacecraft dynamics with DGMSCMG actuators, including the dynamics of magnetically suspended high-speed rotor, the dynamics of inner gimbal and outer gimbal, as well as the determination method of spacecraft angular velocity are modeled, respectively. The effectiveness of the proposed integrated system is also validated numerically and experimentally.

  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

    how they lead to CMG singularities, are described. General ideas on control of the angular momentum of the spacecraft using changes in the momentum variables of a finite number of ASCMGs, are provided. Control schemes for agile and precise attitude maneuvers using ASCMG cluster in the absence of external torques and when the total angular momentum of the spacecraft is zero, is presented for both constant speed and variable speed modes. A Geometric Variational Integrator (GVI) that preserves the geometry of the state space and the conserved norm of the total angular momentum is constructed for numerical simulation and microcontroller implementation of the control scheme. The GVI is obtained by discretizing the Lagrangian of the rnultibody systems, in which the rigid body attitude is globally represented on the Lie group of rigid body rotations. Hardware and software architecture of a novel spacecraft Attitude Determination and Control System (ADCS) based on commercial smartphones and a bare minimum hardware prototype of an ASCMG using low cost COTS components is also described. A lightweight, dynamics model-free Variational Attitude Estimator (VAE) suitable for smartphone implementation is employed for attitude determination and the attitude control is performed by ASCMG actuators. The VAE scheme presented here is implemented and validated onboard an Unmanned Aerial Vehicle (UAV) platform and the real time performance is analyzed. On-board sensing, data acquisition, data uplink/downlink, state estimation and real-time feedback control objectives can be performed using this novel spacecraft ADCS. The mechatronics realization of the attitude determination through variational attitude estimation scheme and control implementation using ASCMG actuators are presented here. Experimental results of the attitude estimation (filtering) scheme using smartphone sensors as an Inertial Measurement Unit (IMU) on the Hardware In the Loop (HIL) simulator testbed are given. These

  12. Integrated Orbit, Attitude, and Structural Control System Design for Space Solar Power Satellites

    Science.gov (United States)

    Woods-Vedeler, Jessica (Technical Monitor); Moore, Chris (Technical Monitor); Wie, Bong; Roithmayr, Carlos

    2001-01-01

    The major objective of this study is to develop an integrated orbit, attitude, and structural control system 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 500 700 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 system 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 o.set 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.

  13. 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.

  14. Satellite Attitude Control System Design Taking into Account the Fuel Slosh and Flexible Dynamics

    Directory of Open Access Journals (Sweden)

    Alain G. de Souza

    2014-01-01

    Full Text Available The design of the spacecraft Attitude Control System (ACS becomes more complex when the spacecraft has different type of components like, flexible solar panels, antennas, mechanical manipulators and tanks with fuel. The interaction between the fuel slosh motion, the panel’s flexible motion and the satellite rigid motion during translational and/or rotational manoeuvre can change the spacecraft center of mass position damaging the ACS pointing accuracy. This type of problem can be considered as a Fluid-Structure Interaction (FSI where some movable or deformable structure interacts with an internal fluid. This paper develops a mathematical model for a rigid-flexible satellite with tank with fuel. The slosh dynamics is modelled using a common pendulum model and it is considered to be unactuated. The control inputs are defined by a transverse body fixed force and a moment about the centre of mass. A comparative investigation designing the satellite ACS by the Linear Quadratic Regulator (LQR and Linear Quadratic Gaussian (LQG methods is done. One has obtained a significant improvement in the satellite ACS performance and robustness of what has been done previously, since it controls the rigid-flexible satellite and the fuel slosh motion, simultaneously.

  15. 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

  16. Scout fourth stage attitude and velocity control (AVC) system feasibility study

    Science.gov (United States)

    Byars, L. B.

    1975-01-01

    The feasibility of incorporating a guidance system in the Scout fourth stage to achieve a significant improvement in expected payload delivery accuracy is studied. The technical investigations included the determination of the AVC equipment performance requirements, establishment of qualification and acceptance test levels, generation of layouts illustrating design approaches for the upper D and payload transition sections to incorporate the hardware, and the preparation of a vendor bid package. Correction concepts, utilizing inertial velocity and attitude, were identified and evaluated. Fourth stage attitude adjustments as determined from inertial velocity variation through the first three stages and a final velocity correction based upon the measured in-plane component errors at injection were employed. Results show radical reductions in apogee-perigee deviations.

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

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek proposes to develop and deliver a complete engineering model colloid thruster system, capable of thrust levels and lifetimes required for spacecraft...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Attitude control and stabilization technology discipline

    Science.gov (United States)

    Sunkel, John W.

    1990-01-01

    Viewgraphs on attitude control and stabilization technology discipline for the Space Station Freedom are presented. Topics covered include: attitude control technologies for multi-user accommodation; flexible dynamics and control; computational control techniques; and automatic proximity operations.

  3. 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...

  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...

  5. 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.

  6. 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....

  7. 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.

  8. 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.

  9. Local Vertical/Local Horizontal Attitude Control for Spartan Spacecraft

    OpenAIRE

    Morrissey, James; Olney, David

    1996-01-01

    A Spartan spacecraft attitude control system was reconfigured to provide attitude pointing with respect to a Local Vertical/Local Horizontal reference frame even though the baseline system uses only an initial start attitude, sun sensors, and star tracker/gyros for defining the spacecraft attitude. No earth sensors of any kind are used. Deployed from the orbiter for two days, usually for solar and stellar inertial pointing, Spartan missions use pointing programs that must be written months pr...

  10. 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.

  11. 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.

  12. 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.

  13. Chaotic attitude control of satellite using impulsive control

    International Nuclear Information System (INIS)

    Nowadays, attitude control systems of satellites demand better performance, resulting in the application of new advanced nonlinear control theory. In this paper, impulsive control is applied to a six-dimensional system which describes the attitude dynamics of a satellite subjected to deterministic external perturbations which induce chaotic motion when no control is affected. Several theorems on the stability of impulsive control systems are presented. These theorems are then used to find the conditions under which the chaotic systems can be asymptotically controlled to the origin by using impulsive control. Given the parameters of the chaotic system and the impulsive control law, an estimation of the upper bound of the impulse interval is given. Finally, we give some simulations results to visualize the effectiveness and feasibility of the proposed method.

  14. Attitude control system design and on-orbit performance analysis of nano-satellite—“Tian Tuo 1”

    Directory of Open Access Journals (Sweden)

    Ran Dechao

    2014-06-01

    Full Text Available “Tian Tuo 1” (TT-1 nano-satellite is the first single-board nano-satellite that was successfully 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 feasibility 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.

  15. Models of complex attitude systems

    DEFF Research Database (Denmark)

    Sørensen, Bjarne Taulo

    production systems was modelled. The analysis was based on data from a cross-cultural survey involving 1931 participants from Belgium, Denmark, Germany and Poland. The survey questionnaire contained measures of personal value orientations and attitudes towards environment and nature, industrial food...... search algorithms and structural equation models. The results suggest that evaluative judgments of the importance of production system attributes are generated in a schematic manner, driven by personal value orientations. The effect of personal value orientations was strong and largely unmediated......, understanding them as embedded into a wider attitude system that consists of attitudes towards objects of different abstraction levels, ranging from personal value orientations over general socio-political attitudes to evaluations of specific characteristics of agricultural production systems. It is assumed...

  16. Attitude Determination and Control System (ADCS) and Maintenance and Diagnostic System (MDS): A maintenance and diagnostic system for Space Station Freedom

    Science.gov (United States)

    Toms, David; Hadden, George D.; Harrington, Jim

    1990-01-01

    The Maintenance and Diagnostic System (MDS) that is being developed at Honeywell to enhance the Fault Detection Isolation and Recovery system (FDIR) for the Attitude Determination and Control System on Space Station Freedom is described. The MDS demonstrates ways that AI-based techniques can be used to improve the maintainability and safety of the Station by helping to resolve fault anomalies that cannot be fully determined by built-in-test, by providing predictive maintenance capabilities, and by providing expert maintenance assistance. The MDS will address the problems associated with reasoning about dynamic, continuous information versus only about static data, the concerns of porting software based on AI techniques to embedded targets, and the difficulties associated with real-time response. An initial prototype was built of the MDS. The prototype executes on Sun and IBM PS/2 hardware and is implemented in the Common Lisp; further work will evaluate its functionality and develop mechanisms to port the code to Ada.

  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. Angular rate estimation for multi-body spacecraft attitude control

    OpenAIRE

    Palermo, William J.

    2001-01-01

    Spacecraft with high performance attitude control systems requirements have traditionally relied on imperfect mechanical gyroscopes for primary attitude determination. Gyro bias errors are corrected with a Kalman filter algorithm that uses updates from precise attitude sensors like star trackers. Gyroscopes, however, have a tendency to degrade or fail on orbit, becoming a life limiting factor for many satellites. When errors become erratic, pointing accuracy may be lost during short star gaps...

  19. The Submillimeter Wave Astronomy Satellite Attitude Control Software Design

    OpenAIRE

    Anderson, Mark; Wennersten, Miriam; Bonnett, Joseph; Hill, Adrian

    1995-01-01

    The Submilimeter Wave Astronomy Satellite (SWAS) was selected for flight by NASA in 1989 as a part of the Small Explorer (SMEX) program. SWAS's primary science objective is to conduct high spectral resolution surveys of galactic molecular clouds. The SWAS Attitude Control System (ACS) is three-axis controlled, zero momentum stabilized, and is capable of performing subarcminute pointing. This paper will discuss the design of the software components which comprise the Attitude Control System So...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. The Attitude Control System Concept for the Joint Australian Engineering Micro-Satellite (JAESat)

    OpenAIRE

    Dando, Aaron

    2005-01-01

    JAESat is a joint micro-satellite project between Queensland University of Technology (QUT), Australian Space Research Institute (ASRI) and other national and international partners including the Australian Cooperative Research Centre for Satellite Systems (CRCSS), Kayser-Threde GmbH, Aerospace Concepts and Auspace who will contribute to this project. The JAESat micro-satellite project is an educational and GNSS technology demonstration mission. The main objectives of the JAESat mission are t...

  5. Geometric Tracking Control of the Attitude Dynamics of a Rigid Body on SO(3)

    OpenAIRE

    Lee, Taeyoung

    2010-01-01

    This paper provides new results for a 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 selecting an attitude error function carefully, we show that the proposed control system guarantees a desirable tracking performance uniformly for nontrivial...

  6. 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.

  7. The development and demonstration of hybrid programmable attitude control electronics

    Science.gov (United States)

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

    1973-01-01

    In the course of extended life attitude control system (ELACS) research sponsored by NASA a hybrid programable attitude control electronics (HYPACE) concept was developed and demonstrated. The wide variety of future planetary missions demanded a new control approach to accommodate the automatic fault tolerance and long the life requirements of such missions. HYPACE provides an adaptable, analog/digital design approach that permits preflight and in-flight accommodation of mission changes, component performance variations, and spacecraft changes, through programing. This enabled broad multimission flexibility of application in a cost effective manner. Previously, flight control computers have not been not flown on planetary missions because of weight and power problems. These problems were resolved in the design of HYPACE. 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.

  8. Study of tethered satellite active attitude control

    Science.gov (United States)

    Colombo, G.

    1982-01-01

    Existing software was adapted for the study of tethered subsatellite rotational dynamics, an analytic solution for a stable configuration of a tethered subsatellite was developed, the analytic and numerical integrator (computer) solutions for this "test case' was compared in a two mass tether model program (DUMBEL), the existing multiple mass tether model (SKYHOOK) was modified to include subsatellite rotational dynamics, the analytic "test case,' was verified, and the use of the SKYHOOK rotational dynamics capability with a computer run showing the effect of a single off axis thruster on the behavior of the subsatellite was demonstrated. Subroutines for specific attitude control systems are developed and applied to the study of the behavior of the tethered subsatellite under realistic on orbit conditions. The effect of all tether "inputs,' including pendular oscillations, air drag, and electrodynamic interactions, on the dynamic behavior of the tether are included.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. System and method for correcting attitude estimation

    Science.gov (United States)

    Josselson, Robert H. (Inventor)

    2010-01-01

    A system includes an angular rate sensor disposed in a vehicle for providing angular rates of the vehicle, and an instrument disposed in the vehicle for providing line-of-sight control with respect to a line-of-sight reference. The instrument includes an integrator which is configured to integrate the angular rates of the vehicle to form non-compensated attitudes. Also included is a compensator coupled across the integrator, in a feed-forward loop, for receiving the angular rates of the vehicle and outputting compensated angular rates of the vehicle. A summer combines the non-compensated attitudes and the compensated angular rates of the to vehicle to form estimated vehicle attitudes for controlling the instrument with respect to the line-of-sight reference. The compensator is configured to provide error compensation to the instrument free-of any feedback loop that uses an error signal. The compensator may include a transfer function providing a fixed gain to the received angular rates of the vehicle. The compensator may, alternatively, include a is transfer function providing a variable gain as a function of frequency to operate on the received angular rates of the vehicle.

  14. A novel single thruster control strategy for spacecraft attitude stabilization

    Science.gov (United States)

    Godard; Kumar, Krishna Dev; Zou, An-Min

    2013-05-01

    Feasibility of achieving three axis attitude stabilization using a single thruster is explored in this paper. Torques are generated using a thruster orientation mechanism with which the thrust vector can be tilted on a two axis gimbal. A robust nonlinear control scheme is developed based on the nonlinear kinematic and dynamic equations of motion of a rigid body spacecraft in the presence of gravity gradient torque and external disturbances. The spacecraft, controlled using the proposed concept, constitutes an underactuated system (a system with fewer independent control inputs than degrees of freedom) with nonlinear dynamics. Moreover, using thruster gimbal angles as control inputs make the system non-affine (control terms appear nonlinearly in the state equation). This necessitates the control algorithms to be developed based on nonlinear control theory since linear control methods are not directly applicable. The stability conditions for the spacecraft attitude motion for robustness against uncertainties and disturbances are derived to establish the regions of asymptotic 3-axis attitude stabilization. Several numerical simulations are presented to demonstrate the efficacy of the proposed controller and validate the theoretical results. The control algorithm is shown to compensate for time-varying external disturbances including solar radiation pressure, aerodynamic forces, and magnetic disturbances; and uncertainties in the spacecraft inertia parameters. The numerical results also establish the robustness of the proposed control scheme to negate disturbances caused by orbit eccentricity.

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. Attitude Estimation in Fractionated Spacecraft Cluster Systems

    Science.gov (United States)

    Hadaegh, Fred Y.; Blackmore, James C.

    2011-01-01

    An attitude estimation was examined in fractioned free-flying spacecraft. Instead of a single, monolithic spacecraft, a fractionated free-flying spacecraft uses multiple spacecraft modules. These modules are connected only through wireless communication links and, potentially, wireless power links. The key advantage of this concept is the ability to respond to uncertainty. For example, if a single spacecraft module in the cluster fails, a new one can be launched at a lower cost and risk than would be incurred with onorbit servicing or replacement of the monolithic spacecraft. In order to create such a system, however, it is essential to know what the navigation capabilities of the fractionated system are as a function of the capabilities of the individual modules, and to have an algorithm that can perform estimation of the attitudes and relative positions of the modules with fractionated sensing capabilities. Looking specifically at fractionated attitude estimation with startrackers and optical relative attitude sensors, a set of mathematical tools has been developed that specify the set of sensors necessary to ensure that the attitude of the entire cluster ( cluster attitude ) can be observed. Also developed was a navigation filter that can estimate the cluster attitude if these conditions are satisfied. Each module in the cluster may have either a startracker, a relative attitude sensor, or both. An extended Kalman filter can be used to estimate the attitude of all modules. A range of estimation performances can be achieved depending on the sensors used and the topology of the sensing network.

  20. Uniaxial aerodynamic attitude control of artificial satellites

    Science.gov (United States)

    Sazonov, V. V.

    1983-01-01

    Within the context of a simple mechanical model the paper examines the movement of a satellite with respect to the center of masses under conditions of uniaxial aerodynamic attitude control. The equations of motion of the satellite take account of the gravitational and restorative aerodynamic moments. It is presumed that the aerodynamic moment is much larger than the gravitational, and the motion equations contain a large parameter. A two-parameter integrated surface of these equations is constructed in the form of formal series in terms of negative powers of the large parameter, describing the oscillations and rotations of the satellite about its lengthwise axis, approximately oriented along the orbital tangent. It is proposed to treat such movements as nominal undisturbed motions of the satellite under conditions of aerodynamic attitude control. A numerical investigation is made for the above integrated surface.

  1. Observing Mode Attitude Controller for the Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Calhoun, Philip C.; Garrick, Joseph C.

    2007-01-01

    The Lunar Reconnaissance Orbiter (LRO) mission is the first of a series of lunar robotic spacecraft scheduled for launch in Fall 2008. LRO will spend at least one year in a low altitude polar orbit around the Moon, collecting lunar environment science and mapping data to enable future human exploration. The LRO employs a 3-axis stabilized attitude control system (ACS) whose primary control mode, the "Observing mode", provides Lunar Nadir, off-Nadir, and Inertial fine pointing for the science data collection and instrument calibration. The controller combines the capability of fine pointing with that of on-demand large angle full-sky attitude reorientation into a single ACS mode, providing simplicity of spacecraft operation as well as maximum flexibility for science data collection. A conventional suite of ACS components is employed in this mode to meet the pointing and control objectives. This paper describes the design and analysis of the primary LRO fine pointing and attitude re-orientation controller function, known as the "Observing mode" of the ACS subsystem. The control design utilizes quaternion feedback, augmented with a unique algorithm that ensures accurate Nadir tracking during large angle yaw maneuvers in the presence of high system momentum and/or maneuver rates. Results of system stability analysis and Monte Carlo simulations demonstrate that the observing mode controller can meet fine pointing and maneuver performance requirements.

  2. 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.

  3. 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.

  4. 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.

  5. The use of real-time, hardware-in-the-loop simulation in the design and development of the new Hughes HS601 spacecraft attitude control system

    Science.gov (United States)

    Slafer, Loren I.

    1989-01-01

    Realtime simulation and hardware-in-the-loop testing is being used extensively in all phases of the design, development, and testing of the attitude control system (ACS) for the new Hughes HS601 satellite bus. Realtime, hardware-in-the-loop simulation, integrated with traditional analysis and pure simulation activities is shown to provide a highly efficient and productive overall development program. Implementation of high fidelity simulations of the satellite dynamics and control system algorithms, capable of real-time execution (using applied Dynamics International's System 100), provides a tool which is capable of being integrated with the critical flight microprocessor to create a mixed simulation test (MST). The MST creates a highly accurate, detailed simulated on-orbit test environment, capable of open and closed loop ACS testing, in which the ACS design can be validated. The MST is shown to provide a valuable extension of traditional test methods. A description of the MST configuration is presented, including the spacecraft dynamics simulation model, sensor and actuator emulators, and the test support system. Overall system performance parameters are presented. MST applications are discussed; supporting ACS design, developing on-orbit system performance predictions, flight software development and qualification testing (augmenting the traditional software-based testing), mission planning, and a cost-effective subsystem-level acceptance test. The MST is shown to provide an ideal tool in which the ACS designer can fly the spacecraft on the ground.

  6. Motion control of the satellite mounted robot arm which assures satellite attitude stability

    Science.gov (United States)

    Mitsushige, Oda

    When a robot arm is mounted on a satellite to perform some tasks, the satellite's attitude must be stabilized to retain the communication link and to generate electrical power from solar panels. It is not realistic to control the total system as one dynamic system, since the number of degrees of freedom becomes too large to be handled by state-of-the-art satellite mounted computers. This paper proposes a coordinated control between the satellite's attitude control system and the robot-arm control system. The robot-arm control system estimates the angular momentum of the planned robot-arm's motion. The satellite's attitude control system will compensate for the reaction by using feed-forward control. The robot-arm controller also manages the motion plan of the robot arm in order not to disturb the satellite's attitude stability.

  7. Preliminary Attitude Control Studies for the ASTER Mission

    International Nuclear Information System (INIS)

    This work discusses an attitude control study for the ASTER mission, the first Brazilian mission to the deep space. The study is part of a larger scenario that is the development of optimal trajectories to navigate in the 2001 SN263 asteroid system, together with the generation of orbit and attitude controllers for autonomous operation. The spacecraft attitude is defined from the orientation of the body reference system to the Local Vertical Local Horizontal (LVLH) of a circular orbit around the Alpha asteroid. The rotational equations of motion involve the dynamic equations, where the three angular speeds are generated from a set of three reaction wheels and the gravitational torque. The rotational kinematics is represented in the Euler angles format. The controller is developed via the linear quadratic regulator approach with output feedback. It involves the generation of a stability augmentation (SAS) loop and a tracking outer loop, with a compensator of desired structure. It was chosen the feedback of the p, q and r angular speeds in the SAS, one for each reaction wheel. In the outer loop, it was chosen a proportional integral compensator. The parameters are tuned using a numerical minimization that represents a linear quadratic cost, with weightings in the tracking error and controls. Simulations are performed with the nonlinear model. For small angle manoeuvres, the linear results with reaction wheels or thrusters are reasonable, but, for larger manoeuvres, nonlinear control techniques shall be applied, for example, the sliding mode control

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

    OpenAIRE

    Jian Fu; Liangming Wang; Mou Chen; Sijiang Chang

    2015-01-01

    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 ...

  9. 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.

  10. Attitude Analysis and Robust Adaptive Backstepping Sliding Mode Control of Spacecrafts Orbiting Irregular Asteroids

    Directory of Open Access Journals (Sweden)

    Chunhui Liang

    2014-01-01

    Full Text Available Attitude stability analysis and robust control algorithms for spacecrafts orbiting irregular asteroids are investigated in the presence of model uncertainties and external disturbances. Rigid spacecraft nonlinear attitude models are considered and detailed attitude stability analysis of spacecraft subjected to the gravity gradient torque in an irregular central gravity field is included in retrograde orbits and direct orbits using linearized system model. The robust adaptive backstepping sliding mode control laws are designed to make the attitude of the spacecrafts stabilized and responded accurately to the expectation in the presence of disturbances and parametric uncertainties. Numerical simulations are included to illustrate the spacecraft performance obtained using the proposed control laws.

  11. 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.

  12. Attitude Controller-Observer Design for the NTNU Test Satellite

    OpenAIRE

    Alvenes, Fredrik

    2013-01-01

    This report presents the results from the development and design of an Attitude Controller-Observer for the NTNU Test Satellite (NUTS). It gives an insight to mathematical modeling of satellite attitude dynamics for 3 degrees of freedom. By the different limitations of how the NUTS operates, these models are adjusted accordingly.A strategy for controlling the attitude is presented. Through an explanation of the magnetic actuators, the control laws are also adapted to work with the NUTS satell...

  13. Rover Attitude and Pointing System Simulation Testbed

    Science.gov (United States)

    Vanelli, Charles A.; Grinblat, Jonathan F.; Sirlin, Samuel W.; Pfister, Sam

    2009-01-01

    The MER (Mars Exploration Rover) Attitude and Pointing System Simulation Testbed Environment (RAPSSTER) provides a simulation platform used for the development and test of GNC (guidance, navigation, and control) flight algorithm designs for the Mars rovers, which was specifically tailored to the MERs, but has since been used in the development of rover algorithms for the Mars Science Laboratory (MSL) as well. The software provides an integrated simulation and software testbed environment for the development of Mars rover attitude and pointing flight software. It provides an environment that is able to run the MER GNC flight software directly (as opposed to running an algorithmic model of the MER GNC flight code). This improves simulation fidelity and confidence in the results. Further more, the simulation environment allows the user to single step through its execution, pausing, and restarting at will. The system also provides for the introduction of simulated faults specific to Mars rover environments that cannot be replicated in other testbed platforms, to stress test the GNC flight algorithms under examination. The software provides facilities to do these stress tests in ways that cannot be done in the real-time flight system testbeds, such as time-jumping (both forwards and backwards), and introduction of simulated actuator faults that would be difficult, expensive, and/or destructive to implement in the real-time testbeds. Actual flight-quality codes can be incorporated back into the development-test suite of GNC developers, closing the loop between the GNC developers and the flight software developers. The software provides fully automated scripting, allowing multiple tests to be run with varying parameters, without human supervision.

  14. 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。

  15. MODEL OF CENTRIFUGAL EFFECT AND ATTITUDE MANEUVER STABILITY OF A COUPLED RIGID-FLEXIBLE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-bin; WANG Zhao-lin; WANG Tian-shu; LIU Ning

    2005-01-01

    The influences of nonlinear centrifugal force to large overall attitude motion of coupled rigid-flexible system was investigated. First the nonlinear model of the coupled rigidflexible system was deduced from the idea of "cenlrifugal potential field", and then the dynamic effects of the nonlinear centrifugal force to system attitude motion were analyzed by approximate calculation; At last, the Lyapunov function based on energy norm was selected,in the condition that only the measured values of attitude and attitude speed are available,and it is proved that the PD feedback control law can ensure the attitude stability during large angle maneuver.

  16. 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.

  17. 基于RVM回归的姿控系统多故障检测%Multi-fault detection for attitude control system based on RVM regression

    Institute of Scientific and Technical Information of China (English)

    胡迪; 董云峰

    2011-01-01

    针对卫星姿控系统故障具有并发性和多发性的特点,敏感器和执行机构均可能发生故障,依据相关向量机(RVM)回归理论,采用基于模型辩识,残差评价的方法实现姿控系统多故障检测.通过对太阳敏感器、陀螺和反作用轮的历史输入输出数据建立RVM回归模型,考虑到建模精确度直接影响到检测精确度,对比分析最小二乘支持向量机回归( LSSVR)的回归模型,并给出了二者辩识精确度对比结果.对比结果表明,RVM较LSSVR具有较好的建模精确度.将RVM回归模型应用于太阳敏感器、陀螺和反作用轮的单一故障和多故障检测过程中,仿真结果表明,RVM回归能有效实现姿控系统的多故障检测.%As satellite attitude control system ( ACS) failures have concurrent and multiple features, both the sensors and actuators may occur faults. Model identification and residual evaluation were applied to ACS fault detection based on relevance vector machine ( RVM) theory. RVM regression was utilized to perform offline regression modeling for the satellite's sun sensor, gyro and reaction wheel, and obtain the regression modeling through analyzing input/output history data stream. As a result, the accuracy of modeling identification was affected by regression model. A comparison between least square support vector regression (LSSVR) and RVM regression was analyzed. The simulation result shows that the RVM is much better than LSSVR. Different scenarios with sun sensor, gyro and reaction wheel to realize concurrent and multiple fault detection were simulated. The result shows that the RVM regression is convenient to the attitude control system.

  18. Consumer attitudes to different pig production systems

    DEFF Research Database (Denmark)

    de Barcellos, Marcia Dutra; Grunert, Klaus G.; Zhou, Y.;

    2013-01-01

    pig breeds are raised, over large-scale and small family farms. Farms with maximum attention to food safety, which furthermore can provide lean meat with consistent quality, are also preferred. Imported pig breeds and tasty but variable meat were rejected. A 3-cluster solution found that consumers......In many countries consumers have shown an increasing interest to the way in which food products are being produced. This study investigates Chinese consumers’ attitudes towards different pig production systems by means of a conjoint analysis. While there has been a range of studies on Western...... consumers’ attitudes to various forms of food production, little is known about the level of Chinese consumers’ attitudes. A cross-sectional survey was carried out with 472 participants in 6 Chinese cities. Results indicate that Chinese consumers prefer industrial pig production systems, where traditional...

  19. Spacecraft methods and structures with enhanced attitude control that facilitates gyroscope substitutions

    Science.gov (United States)

    Li, Rongsheng (Inventor); Kurland, Jeffrey A. (Inventor); Dawson, Alec M. (Inventor); Wu, Yeong-Wei A. (Inventor); Uetrecht, David S. (Inventor)

    2004-01-01

    Methods and structures are provided that enhance attitude control during gyroscope substitutions by insuring that a spacecraft's attitude control system does not drive its absolute-attitude sensors out of their capture ranges. In a method embodiment, an operational process-noise covariance Q of a Kalman filter is temporarily replaced with a substantially greater interim process-noise covariance Q. This replacement increases the weight given to the most recent attitude measurements and hastens the reduction of attitude errors and gyroscope bias errors. The error effect of the substituted gyroscopes is reduced and the absolute-attitude sensors are not driven out of their capture range. In another method embodiment, this replacement is preceded by the temporary replacement of an operational measurement-noise variance R with a substantially larger interim measurement-noise variance R to reduce transients during the gyroscope substitutions.

  20. 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.

  1. 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.

  2. 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...

  3. Integrated Method - the Optimum Way to Improve the Quality of Frequency Response Characteristics of the Space Vehicle Attitude Control System

    Science.gov (United States)

    Britova, Yu.; Dmitriev, V.; Kostyuchenko, T.

    2016-06-01

    The integrated method applied to the design of technical systems is a process in which various project, calculation and verification procedures are interconnected and interrelated. The results of procedures are used in a certain sequence, thus ensuring maximum reachable optimality of the system being designed.

  4. 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.

  5. 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....

  6. Pushing the Limits of Cubesat Attitude Control: A Ground Demonstration

    Science.gov (United States)

    Sanders, Devon S.; Heater, Daniel L.; Peeples, Steven R.; Sules. James K.; Huang, Po-Hao Adam

    2013-01-01

    A cubesat attitude control system (ACS) was designed at the NASA Marshall Space Flight Center (MSFC) to provide sub-degree pointing capabilities using low cost, COTS attitude sensors, COTS miniature reaction wheels, and a developmental micro-propulsion system. The ACS sensors and actuators were integrated onto a 3D-printed plastic 3U cubesat breadboard (10 cm x 10 cm x 30 cm) with a custom designed instrument board and typical cubesat COTS hardware for the electrical, power, and data handling and processing systems. In addition to the cubesat development, a low-cost air bearing was designed and 3D printed in order to float the cubesat in the test environment. Systems integration and verification were performed at the MSFC Small Projects Rapid Integration & Test Environment laboratory. Using a combination of both the miniature reaction wheels and the micro-propulsion system, the open and closed loop control capabilities of the ACS were tested in the Flight Robotics Laboratory. The testing demonstrated the desired sub-degree pointing capability of the ACS and also revealed the challenges of creating a relevant environment for development testin

  7. Attitude and Vibration Control of Flexible Spacecraft Using Singular Perturbation Approach

    OpenAIRE

    Morteza Shahravi; Milad Azimi

    2014-01-01

    This paper addresses a composite two-time-scale control system for simultaneous three-axis attitude maneuvering and elastic mode stabilization of flexible spacecraft. By choosing an appropriate time coordinates transformation system, the spacecraft dynamics can be divided into double time-scale subsystems using singular perturbation theory (SPT). Attitude and vibration control laws are successively designed by considering a time bandwidths separation between the oscillatory flexible parts mot...

  8. Consumer Attitudes Towards Domestic Solar Power Systems

    OpenAIRE

    Faiers, Adam; Neame, Charles

    2006-01-01

    The success of the UK policy to reduce carbon emissions is partly dependent on the ability to persuade householders to become more energy efficient, and to encourage installation of domestic solar systems. Solar power is an innovation in the UK but the current policy of stimulating the market with grants is not resulting in widespread adoption. This case study, using householders in central England, investigates householder attitudes towards characteristics of solar systems and identifies som...

  9. Satellite Attitude Control Using Only Electromagnetic Actuation

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    The primary purpose of this work was to develop control laws for three axis stabilization of a magnetic actuated satellite. This was achieved by a combination of linear and nonlinear system theory. In order to reach this goal new theoretical results were produced in both fields. The focus...... was that interaction between the Earth's magnetic field and a magnetic field generated by a set of coils in the satellite can be used for actuation. Magnetic torquing was found attractive for generation of control torques on small satellites, since magnetic control systems are relatively lightweight, require low power...... part of the thesis. Its design was based on sliding mode control theory. The essence of the sliding control presented in the thesis was to split the controller design into two steps: a sliding manifold design and a sliding condition design. The emphasis was on the sliding condition design, which...

  10. Space station dynamics, attitude control and momentum management

    Science.gov (United States)

    Sunkel, John W.; Singh, Ramen P.; Vengopal, Ravi

    1989-01-01

    The Space Station Attitude Control System software test-bed provides a rigorous environment for the design, development and functional verification of GN and C algorithms and software. The approach taken for the simulation of the vehicle dynamics and environmental models using a computationally efficient algorithm is discussed. The simulation includes capabilities for docking/berthing dynamics, prescribed motion dynamics associated with the Mobile Remote Manipulator System (MRMS) and microgravity disturbances. The vehicle dynamics module interfaces with the test-bed through the central Communicator facility which is in turn driven by the Station Control Simulator (SCS) Executive. The Communicator addresses issues such as the interface between the discrete flight software and the continuous vehicle dynamics, and multi-programming aspects such as the complex flow of control in real-time programs. Combined with the flight software and redundancy management modules, the facility provides a flexible, user-oriented simulation platform.

  11. Estimating Friction Parameters in Reaction Wheels for Attitude Control

    Directory of Open Access Journals (Sweden)

    Valdemir Carrara

    2013-01-01

    Full Text Available The ever-increasing use of artificial satellites in both the study of terrestrial and space phenomena demands a search for increasingly accurate and reliable pointing systems. It is common nowadays to employ reaction wheels for attitude control that provide wide range of torque magnitude, high reliability, and little power consumption. However, the bearing friction causes the response of wheel to be nonlinear, which may compromise the stability and precision of the control system as a whole. This work presents a characterization of a typical reaction wheel of 0.65 Nms maximum angular momentum storage, in order to estimate their friction parameters. It used a friction model that takes into account the Coulomb friction, viscous friction, and static friction, according to the Stribeck formulation. The parameters were estimated by means of a nonlinear batch least squares procedure, from data raised experimentally. The results have shown wide agreement with the experimental data and were also close to a deterministic model, previously obtained for this wheel. This model was then employed in a Dynamic Model Compensator (DMC control, which successfully reduced the attitude steady state error of an instrumented one-axis air-bearing table.

  12. 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...

  13. 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...

  14. Satellite Attitude Control Using Only Electromagnetic Actuation

    OpenAIRE

    Wisniewski, Rafal

    1997-01-01

    The primary purpose of this work was to develop control laws for three axis stabilization of a magnetic actuated satellite. This was achieved by a combination of linear and nonlinear system theory. In order to reach this goal new theoretical results were produced in both fields. The focus of the work was on the class of periodic systems reflecting orbital motion of the satellite. In addition to a theoretical treatment, the thesis contains a large portion of application considerations. The con...

  15. 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.

  16. Star tracker based attitude determination system for nanosatellites

    OpenAIRE

    Jané Abad, Jaume

    2015-01-01

    The aim of this project is to conceive, design, implement, test, qualify, operate, and validate a new high accuracy sensor based on a star sensor for the ADCS subsystem of the 3Cat-2 Mission. This system will implement the necessary algorithms for the star identification and attitude determination in a highly constrained in time, size, mass and power embedded environment. Test and qualification campaign shall be done both in controlled environment and field test. [ANGLÈS] Access to space i...

  17. 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, o......, over a period of only 18 months. This paper emphasises on the trade-offs required to build an operational ADCS system within such a rapidly developing project....

  18. 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, o......, over a period of only 18 months. This paper emphasises on the trade-offs required to build an operational ADCS system within such a rapidly developing project....

  19. 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.

  20. 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.

  1. Spacecraft momentum control systems

    CERN Document Server

    Leve, Frederick A; Peck, Mason A

    2015-01-01

    The goal of this book is to serve both as a practical technical reference and a resource for gaining a fuller understanding of the state of the art of spacecraft momentum control systems, specifically looking at control moment gyroscopes (CMGs). As a result, the subject matter includes theory, technology, and systems engineering. The authors combine material on system-level architecture of spacecraft that feature momentum-control systems with material about the momentum-control hardware and software. This also encompasses material on the theoretical and algorithmic approaches to the control of space vehicles with CMGs. In essence, CMGs are the attitude-control actuators that make contemporary highly agile spacecraft possible. The rise of commercial Earth imaging, the advances in privately built spacecraft (including small satellites), and the growing popularity of the subject matter in academic circles over the past decade argues that now is the time for an in-depth treatment of the topic. CMGs are augmented ...

  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. Consumer attitudes towards domestic solar power systems

    International Nuclear Information System (INIS)

    The success of the UK policy to reduce carbon emissions is partly dependent on the ability to persuade householders to become more energy efficient, and to encourage installation of domestic solar systems. Solar power is an innovation in the UK but the current policy of stimulating the market with grants is not resulting in widespread adoption. This case study, using householders in central England, investigates householder attitudes towards characteristics of solar systems and identifies some of the barriers to adoption. The study utilises Diffusion of Innovations theory to identify attitudes towards system attributes, and isolates the characteristics that are preventing a pragmatic 'early majority' from adopting the technology. A group of 'early adopters', and a group of assumed 'early majority' adopters of solar power were surveyed and the results show that overall, although the 'early majority' demonstrate a positive perception of the environmental characteristics of solar power, its financial, economic and aesthetic characteristics are limiting adoption. Differences exist between the two groups showing support for the concept of a 'chasm' between adopter categories after Moore (Crossing the Chasm: Marketing and Selling High-tech Products to Mainstream Customers, second ed. Harper Perennial, New York). However, if consumers cannot identify the relative advantage of solar power over their current sources of power, which is supplied readily and cheaply through a mains system, it is unlikely that adoption will follow. Recommendations concerning the marketing and development of solar products are identified

  4. Attitude control/momentum management and payload pointing in advanced space vehicles

    Science.gov (United States)

    Parlos, Alexander G.; Jayasuriya, Suhada

    1990-01-01

    The design and evaluation of an attitude control/momentum management system for highly asymmetric spacecraft configurations are presented. The preliminary development and application of a nonlinear control system design methodology for tracking control of uncertain systems, such as spacecraft payload pointing systems are also presented. Control issues relevant to both linear and nonlinear rigid-body spacecraft dynamics are addressed, whereas any structural flexibilities are not taken into consideration. Results from the first task indicate that certain commonly used simplifications in the equations of motions result in unstable attitude control systems, when used for highly asymmetric spacecraft configurations. An approach is suggested circumventing this problem. Additionally, even though preliminary results from the second task are encouraging, the proposed nonlinear control system design method requires further investigation prior to its application and use as an effective payload pointing system design technique.

  5. Micro Sun Sensor with CMOS Imager for Small Satellite Attitude Control

    OpenAIRE

    Yoshihara, Keisuke; Hashimoto, Hidekazu; Yamamoto, Toru; Saito, Hirobumi; HIROKAWA, Eiji; Mita, Makoto; Magoshi, Kota

    2005-01-01

    A new type of Micro Sun Sensor (MSS) was started development for use on JAXA’s small satellites and space exploring spacecraft as attitude sensor. In recent years, small satellites are used for various missions, such as the Earth observation and science observation, and high functional attitude control system for small satellite is also required. Therefore, the sun sensor for small satellite is required to be good balance of its dimension, mass, power consumption and performance. The detector...

  6. 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)

  7. Attitude control/momentum management of the Space Station Freedom for large angle torque-equilibrium-attitude configurations

    Science.gov (United States)

    Parlos, Alexander G.; Sunkel, John W.

    1990-01-01

    An attitude-control and momentum-management (ACMM) system for the Space Station in a large-angle torque-equilibrium-attitude (TEA) configuration is developed analytically and demonstrated by means of numerical simulations. The equations of motion for a rigid-body Space Station model are outlined; linearized equations for an arbitrary TEA (resulting from misalignment of control and body axes) are derived; the general requirements for an ACMM are summarized; and a pole-placement linear-quadratic regulator solution based on scheduled gains is proposed. Results are presented in graphs for (1) simulations based on configuration MB3 (showing the importance of accounting for the cross-inertia terms in the TEA estimate) and (2) simulations of a stepwise change from configuration MB3 to the 'assembly complete' stage over 130 orbits (indicating that the present ACCM scheme maintains sufficient control over slowly varying Space Station dynamics).

  8. Global Observer-based Attitude Controller Using Direct Inertial Measurements

    Directory of Open Access Journals (Sweden)

    Saâdi Bouhired

    2014-04-01

    Full Text Available In this work, we address the problem of global attitude control using direct inertial measurements. When using direct inertial measurement to observe the rigid body attitude, it is shown that due to a geometrical obstruction, it is impossible to achieve global asymptotic stability. In fact, for a particular initial condition the tracking error quaternion converges to a pure imaginary quaternion formed by an eigenvector of a characteristic matrix related to the inertial constant and known vectors. Our proposition consists of adding a dynamic signal to force the rigid body to escape from such a situation. The proposed observer-based controller is synthesized based on a single Lyapunov function and a stability analysis shows that the controller stabilizes globally and asymptotically the rigid body attitude at the desired one. The effectiveness of the proposed observer-based controller is confirmed by simulation results.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Prospects of Relative Attitude Control Using Coulomb Actuation

    Science.gov (United States)

    Schaub, Hanspeter; Stevenson, Daan

    2013-12-01

    The relative attitude is studied between two charge controlled spacecraft being held at a fixed separation distance. While one body has a spherical shape, the 2nd body is assumed to be non-spherical and tumbling. The attitude control goal is to arrest the rotation of the 2nd body. While prior work has identified the existence of torques between charged bodies, this is the first analytical study on a charged feedback attitude control. Using the recently developed multi-sphere method to provide a simplified electrostatic force and torque model between non-spherical shapes, Lyapunov theory is used to develop a stabilizing attitude control using spacecraft potential as the control variable. Zero and non-zero equilibrium potentials are considered, with the later suitable for the electrostatic tug concept. With a pulling configuration, the cylinder will come to rest with the long axis aligned with the inter-vehicle axis in a stable configuration. For a pusher, the cylinder will settle 90 degrees rotated from this axis. Numerical simulations illustrate the control performance.

  15. 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.

  16. 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…

  17. 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.

  18. 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.

  19. A Nonlinear Attitude Estimator for Attitude and Heading Reference Systems Based on MEMS Sensors

    DEFF Research Database (Denmark)

    Wang, Yunlong; Soltani, Mohsen; Hussain, Dil muhammed Akbar

    2016-01-01

    In this paper, a nonlinear attitude estimator is designed for an Attitude Heading and Reference System (AHRS) based on Micro Electro-Mechanical Systems (MEMS) sensors. The design process of the attitude estimator is stated with detail, and the equilibrium point of the estimator error model...... is proved to be asymptotically stable using LaSalle's invariance set theorem through limitation of the range of scalar element of quaternion without affecting practical use. Also, a new Lyapunov candidate function, satisfying continuously differentiable positive definite requirement, is presented to avoid...

  20. Near minimum-time feedback attitude control with multiple saturation constraints for agile satellites

    Institute of Scientific and Technical Information of China (English)

    Liu Xiangdong; Xin Xing; Li Zhen; Chen Zhen; Sheng Yongzhi

    2016-01-01

    Agile satellites are of importance in modern aerospace applications, but high mobility of the satellites may cause them vulnerable to saturation during attitude maneuvers due to limited rating of actuators. This paper proposes a near minimum-time feedback control law for the agile satellite attitude control system. The feedback controller is formed by specially designed cascaded sub-units. The rapid dynamic response of the modified Bang–Bang control logic achieves the near optimal property and ensures the non-saturation properties on three-axis. To improve the dynamic performance, a model reference control strategy is proposed, in which the on-line near optimal attitude maneuver path is generated by the cascade controller and is then tracked by a nonlinear back-stepping controller. Furthermore, the accuracy and the robustness of the control system are achieved by momentum-based on-line inertial identification. The rapid attitude maneuvering can be applied for tasks including the move to move case. Numerical simulations are conducted to verify the effectiveness of the proposed control strategy in terms of the saturation-free property and rapidness.

  1. Active Vibration Control of Satellite Flexible Structures during Attitude Maneuvers

    OpenAIRE

    Saeed Hemmati; Morteza Shahravi; Keramat Malekzadeh

    2013-01-01

    The purpose of this study is controlling active vibration of satellite flexible structures during attitude maneuvers. A smart structure is a structure which is able to sense and control active reaction to any external factors and stimulation. As it comes from the definition of smart structures, development of this knowledge depends on the materials science development, theories and strategies for control. In materials science, smart materials are developed in such a way that they are able to ...

  2. Attitude control of a space structure using a 3-R rigid manipulator

    Science.gov (United States)

    Mukherjee, Ranjan; Zurowski, Mary

    The attitude control of space structures is an important problem. There has been considerable research in this area that has focussed on the use of momentum exchange devices. In this paper, we propose to control the attitude of space structures using a serial three-link PUMA-type manipulator that can be mounted on the space structure. This unconventional method of attitude control exploits the nonholonomic nature of the constraints that arise due to the conservation of angular momentum. We adopt a surface integral approach for the motion planning of the manipulator that will reorient the space structure in any desired way. The salient features of our algorithm are: (a) it is possible to mathematically prove the controllability of the system; (b) The motion of the manipulator can be planned amidst additional constraints like joint limits of the manipulator; and (c) the algorithm can be easily extended for application to flexible space structures.

  3. 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.

  4. 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.

  5. 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.

  6. 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 ...

  7. Attitude Determination System for a Phased Array Beamformer

    OpenAIRE

    Garrucho Moras, Lidia

    2015-01-01

    The project aims to design and build a control system for a new GNSS reflectometer. The instrument has two antenna arrays and it is needed to electronically steer the beams of these arrays (each array has two frequency bands and two beams per band) to point some satellites and the ground point where the transmitted signals from these satellites reflect. To achieve this, the instrument needs to determine the position and attitude of the sensor using GNSS receivers and IMUs and then it will cal...

  8. 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.

  9. High precision and convenient extension simulation platform for satellite attitude and orbit system

    Science.gov (United States)

    Cui, Hongzheng; Han, Chao; Chen, Pei; Luo, Qinqin

    2012-01-01

    In this paper, a high precision and convenient extension simulation platform for satellite attitude and orbit system is developed, to demonstrate the satellite attitude and orbit system for given space mission, and test the new underdeveloped algorithms for attitude/orbit dynamics, attitude determination, orbit navigation, and attitude/orbit control. The simulation platform is based on Matlab/Simulink software, using the technique of Simulink modeling, importing C/Fortran code in Matlab/Simulink, and embedded Matlab function, with beautiful reusability, inheritability and expansibility. The paper orderly presents the background behind the development of the platform, the platform design architecture and capability, the validity of the platform, the inheritability and expansibility of the platform, the platform implementation example for Chinese weather satellite (FY-3), and the future development for the platform.

  10. Design and analysis of a moment control unit for agile satellite with high attitude stability requirement

    Science.gov (United States)

    Zhang, Yao; Li, Mou; Song, Zhuoyue; Shan, Jinjun; Guan, Xin; Tang, Liang

    2016-05-01

    A moment control unit is developed and verified by numerical simulation. This moment control unit is employed as an actuator for the satellite attitude control. It contains four control moment gyroscopes (CMGs) to realize the rapid attitude maneuver and a vibration isolation system for each CMG. This unit can not only reduce the required electronics for each CMG and thus the weight, but also improve the stability of the satellite attitude. The design of the structure is presented first. This structure not only holds and protects the CMGs, but also isolates the vibrations caused by each CMG. Then, a dynamic model of a single CMG with a vibration isolation system is formulated, and the time- and frequency-domain characteristics of this dynamic model are discussed. Numerical simulations of a satellite attitude control example are then used to evaluate the system. The new moment control unit occupies less volume than previous designs, and the results show that the new design improves satellite pointing performance because of the vibration isolation.

  11. Spacecraft Hybrid (Mixed-Actuator) Attitude Control Experiences on NASA Science Missions

    Science.gov (United States)

    Dennehy, Cornelius J.

    2014-01-01

    There is a heightened interest within NASA for the design, development, and flight implementation of mixed-actuator hybrid attitude control systems for science spacecraft that have less than three functional reaction wheel actuators. This interest is driven by a number of recent reaction wheel failures on aging, but what could be still scientifically productive, NASA spacecraft if a successful hybrid attitude control mode can be implemented. Over the years, hybrid (mixed-actuator) control has been employed for contingency attitude control purposes on several NASA science mission spacecraft. This paper provides a historical perspective of NASA's previous engineering work on spacecraft mixed-actuator hybrid control approaches. An update of the current situation will also be provided emphasizing why NASA is now so interested in hybrid control. The results of the NASA Spacecraft Hybrid Attitude Control Workshop, held in April of 2013, will be highlighted. In particular, the lessons learned captured from that workshop will be shared in this paper. An update on the most recent experiences with hybrid control on the Kepler spacecraft will also be provided. This paper will close with some future considerations for hybrid spacecraft control.

  12. 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.

  13. 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.

  14. Multivariable control theory applied to hierarchial attitude control for planetary spacecraft

    Science.gov (United States)

    Boland, J. S., III; Russell, D. W.

    1972-01-01

    Multivariable control theory is applied to the design of a hierarchial attitude control system for the CARD space vehicle. The system selected uses reaction control jets (RCJ) and control moment gyros (CMG). The RCJ system uses linear signal mixing and a no-fire region similar to that used on the Skylab program; the y-axis and z-axis systems which are coupled use a sum and difference feedback scheme. The CMG system uses the optimum steering law and the same feedback signals as the RCJ system. When both systems are active the design is such that the torques from each system are never in opposition. A state-space analysis was made of the CMG system to determine the general structure of the input matrices (steering law) and feedback matrices that will decouple the axes. It is shown that the optimum steering law and proportional-plus-rate feedback are special cases. A derivation of the disturbing torques on the space vehicle due to the motion of the on-board television camera is presented. A procedure for computing an upper bound on these torques (given the system parameters) is included.

  15. Wheel speed management control system for spacecraft

    Science.gov (United States)

    Goodzeit, Neil E. (Inventor); Linder, David M. (Inventor)

    1991-01-01

    A spacecraft attitude control system uses at least four reaction wheels. In order to minimize reaction wheel speed and therefore power, a wheel speed management system is provided. The management system monitors the wheel speeds and generates a wheel speed error vector. The error vector is integrated, and the error vector and its integral are combined to form a correction vector. The correction vector is summed with the attitude control torque command signals for driving the reaction wheels.

  16. 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.

  17. Development of miniaturised low cost attitude determination system for sounding rockets

    Science.gov (United States)

    Bekkeng, Jan Kenneth; Booij, Wilfred; Moen, J.

    2005-08-01

    Spacecraft attitude (orientation) information is needed in order to transform scientific vector measurements in the reference frame of the rocket into a more meaningful Earth-fixed reference frame. By fusing data from a 3-axial magnetometer, a sun sensor and three rate gyros the rockets attitude can be determined (reconstructed). Since the system does not need to determine the attitude in real time (the attitude data is not used to control the rocket orientation), all data from the attitude sensors can be transmitted back to ground, where they are fused to estimate an absolute orientation of the rocket. A prototype inertial measurement unit and a miniature high accuracy lens-less sun sensor for spinning rocket is under development. A test version of both instruments will be launched on a single stage Hotel Payload sounding rocket from Andøya Rocket Range in July 2005.

  18. Systems of attitudes towards production in the pork industry

    DEFF Research Database (Denmark)

    Sørensen, Bjarne Taulo; Dutra de Barcellos, Marcia; Veflen Olsen, Nina;

    2012-01-01

    , understanding them as embedded into a wider attitude system that consists of attitudes towards objects of different abstraction levels, ranging from personal value orientations over general socio-political attitudes to evaluations of specific characteristics of agricultural production systems. It is assumed...... that evaluative affect propagates through the system in such a way that the system becomes evaluatively consistent and operates as a schema for the generation of evaluative judgments. In the empirical part of the paper, the causal structure of an attitude system from which people derive their evaluations of pork...... production, food and the environment, technological progress, animal welfare, local employment and local economy. In addition, the survey included a conjoint task by which participants’ evaluations of the importance of production system attributes were measured. The data were analysed by means of causal...

  19. Method and apparatus for rate integration supplement for attitude referencing with quaternion differencing

    Science.gov (United States)

    Rodden, John James (Inventor); Price, Xenophon (Inventor); Carrou, Stephane (Inventor); Stevens, Homer Darling (Inventor)

    2002-01-01

    A control system for providing attitude control in spacecraft. The control system comprising a primary attitude reference system, a secondary attitude reference system, and a hyper-complex number differencing system. The hyper-complex number differencing system is connectable to the primary attitude reference system and the secondary attitude reference system.

  20. 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.

  1. 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.

  2. Entry Attitude Controller for the Mars Science Laboratory

    Science.gov (United States)

    Brugarolas, Paul B.; SanMartin, A. Miguel; Wong, Edward C.

    2007-01-01

    This paper describes the preliminary concept for the RCS 3-axis attitude controller for the exo-atmospheric and guided entry phases of the Mars Science Laboratory Entry, Descend and Landing. 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. 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 structure with deadbands that minimizes fuel usage. The performance of this design is demonstrated via simulation.

  3. Hierarchical structured robust adaptive attitude controller design for reusable launch vehicles

    Institute of Scientific and Technical Information of China (English)

    Guangxue Yu; Huifeng Li

    2015-01-01

    Reentry attitude control for reusable launch vehicles (RLVs) is chal enging due to the characters of fast nonlinear dy-namics and large flight envelop. A hierarchical structured attitude control system for an RLV is proposed and an unpowered RLV con-trol model is developed. Then, the hierarchical structured control frame consisting of attitude control er, compound control strategy and control al ocation is presented. At the core of the design is a robust adaptive control (RAC) law based on dual loop time-scale separation. A radial basis function neural network (RBFNN) is implemented for compensation of uncertain model dynamics and external disturbances in the inner loop. And then the robust op-timization is applied in the outer loop to guarantee performance robustness. The overal control design frame retains the simplicity in design while simultaneously assuring the adaptive and robust performance. The hierarchical structured robust adaptive con-trol er (HSRAC) incorporates flexibility into the design with regard to control er versatility to various reentry mission requirements. Simulation results show that the improved tracking performance is achieved by means of RAC.

  4. 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.

  5. 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. PMID:24534327

  6. Magnetospheric Multiscale (MMS) Mission Attitude Ground System Design

    Science.gov (United States)

    Sedlak, Joseph E.; Superfin, Emil; Raymond, Juan C.

    2011-01-01

    This paper presents an overview of the attitude ground system (AGS) currently under development for the Magnetospheric Multiscale (MMS) mission. The primary responsibilities for the MMS AGS are definitive attitude determination, validation of the onboard attitude filter, and computation of certain parameters needed to improve maneuver performance. For these purposes, the ground support utilities include attitude and rate estimation for validation of the onboard estimates, sensor calibration, inertia tensor calibration, accelerometer bias estimation, center of mass estimation, and production of a definitive attitude history for use by the science teams. Much of the AGS functionality already exists in utilities used at NASA's Goddard Space Flight Center with support heritage from many other missions, but new utilities are being created specifically for the MMS mission, such as for the inertia tensor, accelerometer bias, and center of mass estimation. Algorithms and test results for all the major AGS subsystems are presented here.

  7. 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.

  8. Public attitudes towards nuclear power and alternative energy systems

    International Nuclear Information System (INIS)

    Phase I of this study analyzed attitudes and beliefs of respondents drawn from Metro-Manila. The second phase utilized a sample drawn from residents near a geothermal power plant site in Southern Philippines. Four dimensions of beliefs (psychological/environmental risks, technological benefits/development, economic benefits/implications and socio-political implications/benefits) were identified through factor analysis of belief items on nuclear energy and refined empirically to determine perceptions of respondents about all energy systems. Identification of the relationships between dimensions provided insight into the shared perceptions about each energy system held by the various groups of respondents. The overall attitude of the respondents towards energy systems (nuclear, solar, hydro, geothermal and oil) was determined using three attitude measures: Fishbein model, Osgood's semantic differential technique, and direct response to unfavorability/favorability scale. The belief dimensions were correlated with the attitude measures to determine the degree of contribution of each dimension to attitude. A comparative analysis was made to differentiate attitudes and beliefs held by the PRO and CON nuclear groups, and by the subsamples: university students, science teachers and barangay leaders of the Metro-Manila sample. Attitudes and beliefs relating to the demographic variables were also examined for the two samples. (author)

  9. 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.

  10. 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.

  11. Backstepping-Based Inverse Optimal Attitude Control of Quadrotor

    Directory of Open Access Journals (Sweden)

    An Honglei

    2013-05-01

    Full Text Available Input saturation must be taken into account for applying rapid reorientation in the large angle manoeuvre of a quadrotor. In this paper, a backstepping‐based inverse optimal attitude controller (BIOAC is derived which has the property of a maximum convergence rate in the sense of a control Lyapunov function (CLF under input torque limitation. In the controller, a backstepping technique is used for handling the complexity introducing by the unit quaternion representation of the attitude of a quadrotor with four parameters. Moreover, the inverse optimal approach is employed to circumvent the difficulty of solving the Hamilton‐Jacobi‐Bellman (HJB equation. The performance of BIOAC is compared with a PD controller in which the input torque limitation is not considered under the same unit quaternion representation using numerical simulation while the results show that BIOAC gains faster convergence with less control effort. Next, BIOAC is realized on a test bed and the effectiveness of the control law is verified by experimental studies.

  12. Multimode attitude and orbit control for the Atmosphere Explorer spacecraft

    Science.gov (United States)

    Stewart, B.

    1975-01-01

    The orbit profile for the Atmosphere Explorer requires a velocity adjust capability of 2000 ft/sec/sec and individual maneuvers of up to 24 ft/sec in magnitude. This requirement is met by a monopropellant hydrazine propulsion subsystem which also provides, by virtue of the tank arrangement, a means of adjusting the spacecraft center of mass in orbit, thereby minimizing external disturbance torques. The attitude control subsystem is of the momentum bias type. A large internal flywheel furnishes gyroscopic stiffness and permits rapid changes in operating mode (despun to spinning mode) by controlled interchange of momentum between the flywheel and the spacecraft main body.

  13. 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

  14. 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

  15. Chinese consumers' attitude towards different pig production systems

    DEFF Research Database (Denmark)

    de Barcellos, Marcia Dutra; Grunert, Klaus G.; Yanfeng, Z.;

    2008-01-01

    This study investigates Chinese consumers' attitude towards different pig production systems by means of a conjoint analysis. While there has been a range of studies on western consumers' attitudes to various forms of food production, little is known about such attitudes in other cultural context...... to food safety which furthermore can provide lean meat with consistent quality are also preferred compared to farms that have less focus on food safety. Chinese consumers also rejected imported pig breeds and tasty but variable meat.......This study investigates Chinese consumers' attitude towards different pig production systems by means of a conjoint analysis. While there has been a range of studies on western consumers' attitudes to various forms of food production, little is known about such attitudes in other cultural contexts....... A cross-sectional survey was carried out in six Chinese cities and 473 valid questionnaires were obtained. Results indicate that Chinese consumers prefer industrial pig production systems, where traditional pig breeds are raised, over large-scale and small family farms. Farms with maximum attention...

  16. Delay Depending Decentralized Adaptive Attitude Synchronization Tracking Control of Spacecraft Formation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jiakang; MA Guangfu; HU Qinglei

    2012-01-01

    This paper deals with the problem of cooperative attitude tracking with time-varying communication delays as well as the delays between inter-synchronization control parts and self-tracking control parts in the spacecraft formation flying.First,we present the attitude synchronization tracking control algorithms and analyze the sufficient delay-dependent stability condition with the choice of a Lyapunov function when the angular velocity can be measured.More specifically,a class of linear filters is developed to derive an output feedback control law without having direct information of the angular velocity,which is significant for practical applications with low-cost configurations of spacecraft.Using a well-chosen Lyapunov-Krasovskii function,it is proven that the presented control law can make the spacecraft formation attitude tracking system synchronous and achieve exponential stability,in the face of model uncertainties,as well as non-uniform time-varying delays in communication links and different control parts.Finally,simulation results are presented to demonstrate the effectiveness of the proposed control schemes.

  17. Controlled comparison of attitudes of psychiatrists, general practitioners, homosexual doctors and homosexual men to male homosexuality.

    OpenAIRE

    Bhugra, D.; King, M

    1989-01-01

    A controlled analysis of the attitudes of doctors and homosexual men to male homosexuality is reported. Not surprisingly the homosexual men held the most liberal attitudes which served as a yard-stick against which the doctors' attitudes could be assessed. The implications of these data, collected before the AIDS era, are discussed in terms of the current needs of homosexual patients.

  18. 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.

  19. An Attitude Control of Flexible Spacecraft Using Fuzzy-PID Controller

    Science.gov (United States)

    Park, Jong-Oh; Im, Young-Do

    This primary objective of this study is to demonstrate simulation and ground-based experiment for the attitude control of flexible spacecraft. A typical spacecraft structure consists of the rigid body and flexible appendages which are large flexible solar panels, parabolic antennas built from light materials in order to reduce their weight. Therefore the attitude control has a big problem because these appendages induce structural vibration under the excitation of external forces. A single-axis rotational simulator with a flexible arm is constructed with on-off air thrusters and reaction wheel as actuation. The simulator is also equipped with payload pointing capability by simultaneous thruster and DC servo motor actuation. The experiment of flexible spacecraft attitude control is performed using only the reaction wheel. Using the reaction wheel the performance of the fuzzy-PID controller is illustrated by simulation and experimental results for a single-axis rotational simulator.

  20. A Dynamic Attitude Measurement System Based on LINS

    Directory of Open Access Journals (Sweden)

    Hanzhou Li

    2014-08-01

    Full Text Available A dynamic attitude measurement system (DAMS is developed based on a laser inertial navigation system (LINS. Three factors of the dynamic attitude measurement error using LINS are analyzed: dynamic error, time synchronization and phase lag. An optimal coning errors compensation algorithm is used to reduce coning errors, and two-axis wobbling verification experiments are presented in the paper. The tests indicate that the attitude accuracy is improved 2-fold by the algorithm. In order to decrease coning errors further, the attitude updating frequency is improved from 200 Hz to 2000 Hz. At the same time, a novel finite impulse response (FIR filter with three notches is designed to filter the dither frequency of the ring laser gyro (RLG. The comparison tests suggest that the new filter is five times more effective than the old one. The paper indicates that phase-frequency characteristics of FIR filter and first-order holder of navigation computer constitute the main sources of phase lag in LINS. A formula to calculate the LINS attitude phase lag is introduced in the paper. The expressions of dynamic attitude errors induced by phase lag are derived. The paper proposes a novel synchronization mechanism that is able to simultaneously solve the problems of dynamic test synchronization and phase compensation. A single-axis turntable and a laser interferometer are applied to verify the synchronization mechanism. The experiments results show that the theoretically calculated values of phase lag and attitude error induced by phase lag can both match perfectly with testing data. The block diagram of DAMS and physical photos are presented in the paper. The final experiments demonstrate that the real-time attitude measurement accuracy of DAMS can reach up to 20″ (1σ and the synchronization error is less than 0.2 ms on the condition of three axes wobbling for 10 min.

  1. Attitudes and practices adopted by hypertensive workers on the disease’s control

    OpenAIRE

    Zélia Maria de Sousa Araújo Santos; Helder Pádua Lima

    2005-01-01

    Systemic arterial hypertension (HAS) consists of a major public health problem, with a prevalence of 20 to 25% in the population above 18 years old. In the professional practice, the lack of treatment adhesion is frequently observed, being manifested not only by the medicamental treatment’s suspension or irregularity, but also by the adoption of inadequate life style. This work had the aim of identifying the attitudes and practices of hypertensive workers on the diseases’ control. The researc...

  2. A study of attitude control concepts for precision-pointing non-rigid spacecraft

    Science.gov (United States)

    Likins, P. W.

    1975-01-01

    Attitude control concepts for use onboard structurally nonrigid spacecraft that must be pointed with great precision are examined. The task of determining the eigenproperties of a system of linear time-invariant equations (in terms of hybrid coordinates) representing the attitude motion of a flexible spacecraft is discussed. Literal characteristics are developed for the associated eigenvalues and eigenvectors of the system. A method is presented for determining the poles and zeros of the transfer function describing the attitude dynamics of a flexible spacecraft characterized by hybrid coordinate equations. Alterations are made to linear regulator and observer theory to accommodate modeling errors. The results show that a model error vector, which evolves from an error system, can be added to a reduced system model, estimated by an observer, and used by the control law to render the system less sensitive to uncertain magnitudes and phase relations of truncated modes and external disturbance effects. A hybrid coordinate formulation using the provided assumed mode shapes, rather than incorporating the usual finite element approach is provided.

  3. Spacecraft attitude control using neuro-fuzzy approximation of the optimal controllers

    Science.gov (United States)

    Kim, Sung-Woo; Park, Sang-Young; Park, Chandeok

    2016-01-01

    In this study, a neuro-fuzzy controller (NFC) was developed for spacecraft attitude control to mitigate large computational load of the state-dependent Riccati equation (SDRE) controller. The NFC was developed by training a neuro-fuzzy network to approximate the SDRE controller. The stability of the NFC was numerically verified using a Lyapunov-based method, and the performance of the controller was analyzed in terms of approximation ability, steady-state error, cost, and execution time. The simulations and test results indicate that the developed NFC efficiently approximates the SDRE controller, with asymptotic stability in a bounded region of angular velocity encompassing the operational range of rapid-attitude maneuvers. In addition, it was shown that an approximated optimal feedback controller can be designed successfully through neuro-fuzzy approximation of the optimal open-loop controller.

  4. A STUDY OF ATTITUDE OF UNIVERSITY STUDENTS TOWARDS SEMESTER SYSTEM

    OpenAIRE

    Jagbir Singh

    2015-01-01

    Semester System at university stage is not only an examination system rather an education system whose primary concern is learning instead of centred instead teaching centre. This study is aimed to examine the attitude of university students towards Semester System and study the problems faced by students in new semester system along with the analysis of the curriculum of University stage. The investigator randomly selected a total number of 11 Departments for the study that included Arts, ...

  5. 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.

  6. 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. PMID:22435844

  7. 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.

  8. Attitudes of European citizens towards pig production systems

    DEFF Research Database (Denmark)

    Krystallis, Athanasios; de Barcellos, Marcia Dutra; Kügler, Jens Oliver;

    2009-01-01

    The objective of the study is to map citizen attitudes towards pigmeat production systems, and to investigate whether these attitudes associate with pork and pork product consumption. A conjoint experimentwas carried out with empirical data collected from 1931 individuals in four European countries...... pork with specific fat content, and finally the preferred quality characteristics of the pork end-product. The results of the conjoint analysis were used for a subsequent cluster analysis in order to identify European citizen clusters. Respondents' socio-demographic profile, attitudes towards issues...... that are expected to influence the way people evaluate pig meat production systems, and consumption frequency of various pork products are used as background information to identify segment profiles. Pork appears to play a substantial role as a part of the diet for most respondents in the four countries...

  9. Tethered satellite system dynamics and control

    Science.gov (United States)

    Musetti, B.; Cibrario, B.; Bussolino, L.; Bodley, C. S.; Flanders, H. A.; Mowery, D. K.; Tomlin, D. D.

    1990-01-01

    The first tethered satellite system, scheduled for launch in May 1991, is reviewed. The system dynamics, dynamics control, and dynamics simulations are discussed. Particular attention is given to in-plane and out-of-plane librations; tether oscillation modes; orbiter and sub-satellite dynamics; deployer control system; the sub-satellite attitude measurement and control system; the Aeritalia Dynamics Model; the Martin-Marietta and NASA-MSFC Dynamics Model; and simulation results.

  10. Deploying process modeling and attitude control of a satellite with a large deployable antenna

    OpenAIRE

    Zhigang Xing; Gangtie Zheng

    2014-01-01

    Modeling and attitude control methods for a satellite with a large deployable antenna are studied in the present paper. Firstly, for reducing the model dimension, three dynamic models for the deploying process are developed, which are built with the methods of multi-rigid-body dynamics, hybrid coordinate and substructure. Then an attitude control method suitable for the deploying process is proposed, which can keep stability under any dynamical parameter variation. Subsequently, this attitude...

  11. Exploring Individual Differences in Attitudes toward Audience Response Systems

    Science.gov (United States)

    Kay, Robin H.; Knaack, Liesel

    2009-01-01

    The purpose of this study was to examine individual differences in attitudes toward Audience Response Systems (ARSs) in secondary school classrooms. Specifically, the impact of gender, grade, subject area, computer comfort level, participation level, and type of use were examined in 659 students. Males had significantly more positive attitudes…

  12. Attitude Control Algorithm for Reusable Launch Vehicle in Reentry Flight Phase

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jun; JI Peng-fei; HU Wei-jun

    2009-01-01

    An attitude control algorithm for reusable launch vehicle (RLV) in reentry phase is proposed based on sliding mode variable structure control technique. The aerodynamic characteristics of RLV vary rapidly, and the serious uncertainties and nonlinearities exist in the reentry flight phase. As an example, American X-34 technology demonstrator is investigated. The chattering brought by the variable structure control technique is eliminated efficiently by choosing a suitable reaching law and a sign function. A control mode of reaction control system is presented based on the RCS scheme of X-34 vehicle. As two different attitude control effectors, aerosurfaces and RCS, are employed in the reentry flight phase, a composite control strategy based on the dynamic pressure variety is presented. Also, an actuator model and a RCS thruster model are built. Analysis and nonlinear simulation results show that the sliding mode variable structure controller achieves better performance, the overshoot and steady-state error are only 0.7% and 0.04° respectively.

  13. 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...

  14. 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.

  15. Youth attitudes towards tobacco control: a preliminary assessment.

    Science.gov (United States)

    Waller, Bronwen J; Cohen, Joanna E; Ashley, Mary Jane

    2004-01-01

    The attitudes of Ontario youth toward the sale and price of cigarettes, making smoking against the law, and tobacco company truthfulness were assessed in 2001 and compared to adult attitudes in 2000 and youth attitudes in 2003. Youth were more supportive of restricting cigarette sales and raising prices than adults, and more likely to agree that the government should make smoking against the law, but they were less distrustful of tobacco companies. In 2003, youth were more supportive of sales restrictions and making smoking illegal, and more distrustful of tobacco companies, than in 2001. More comprehensive assessments and continued monitoring of youth attitudes are needed. PMID:15841850

  16. Nitrous Oxide Liquid Injection Thrust Vector Control System Testing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A Nitrous Oxide-fed Liquid Thrust Vector Control system is proposed as an efficient method for vehicle attitude control during powered flight. Pulled from a N2O...

  17. Finite-time output feedback attitude coordination control for formation flying spacecraft without unwinding

    Science.gov (United States)

    Guo, Yong; Song, Shen-Min; Li, Xue-Hui

    2016-05-01

    In this paper, two finite-time attitude coordinated controllers for formation flying spacecraft are investigated based on rotation matrix. Because rotation matrix can represent the set of attitudes both globally and uniquely, the two controllers can deal with unwinding that can result in extra fuel consumption. To address the lack of angular velocity measurement, the second attitude coordinated controller is given by using a novel filter. Through homogeneous method and Lyapunov theories, it is shown that the proposed controllers can achieve the finite-time stability. Numerical simulations also demonstrate that the proposed control schemes are effective.

  18. Precision Attitude Determination System (PADS) design and analysis. Two-axis gimbal star tracker

    Science.gov (United States)

    1973-01-01

    Development of the Precision Attitude Determination System (PADS) focused chiefly on the two-axis gimballed star tracker and electronics design improved from that of Precision Pointing Control System (PPCS), and application of the improved tracker for PADS at geosynchronous altitude. System design, system analysis, software design, and hardware design activities are reported. The system design encompasses the PADS configuration, system performance characteristics, component design summaries, and interface considerations. The PADS design and performance analysis includes error analysis, performance analysis via attitude determination simulation, and star tracker servo design analysis. The design of the star tracker and electronics are discussed. Sensor electronics schematics are included. A detailed characterization of the application software algorithms and computer requirements is provided.

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

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    The objective of this paper is to develop a control scheme for stabilization of a hamiltonian system. The method generalizes the results available in the literature on motion control in the Euclidean space to an arbitrary differrential manifol equipped with a metric. This modification is essencial...... for global stabilization of a rotary motion. Along with a model of the system formulated in the Hamilton's canonical from the algorithm uses information about a required potential energy and a dissipation term. The control action is the sum of the gradient of the potential energy and the dissipation force....... It is shown that this control law makes the system uniformly asymptotically stable to the desired reference point. The concepet is very straightforward in the Euclidean space however a global rotation control cannot be tackled.An additional modification is made to address a system which flow lies...

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

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2001-01-01

    The objective of this paper is to develop a control scheme for stabilization of a hamiltonian system. The method generalizes the results available in the literature on motion control in the Euclidean space to an arbitrary differrential manifol equipped with a metric. This modification is essencial...... for global stabilization of a rotary motion. Along with a model of the system formulated in the Hamilton's canonical from the algorithm uses information about a required potential energy and a dissipation term. The control action is the sum of the gradient of the potential energy and the dissipation force....... It is shown that this control law makes the system uniformly asymptotically stable to the desired reference point. The concepet is very straightforward in the Euclidean space however a global rotation control cannot be tackled.An additional modification is made to address a system which flow lies...

  1. Decentralized sliding-mode control for spacecraft attitude synchronization under actuator failures

    Science.gov (United States)

    Wu, Baolin; Wang, Danwei; Poh, Eng Kee

    2014-12-01

    This paper examines attitude synchronization and tracking problems with model uncertainties, external disturbances, actuator failures and control torque saturation. Two decentralized sliding mode control laws are proposed and analyzed based on algebraic graph theory. Using Barbalat's Lemma, it is shown that the control laws guarantee each spacecraft approaches the desired time-varying attitude and angular velocity while maintaining attitude synchronization among the other spacecraft in the formation. The first controller is designed in the presence of model uncertainties, external disturbances, and actuator failures. The results are extended to the case with control input saturation in the second controller. Both control laws do not require online identification of failures. Numerical simulations are presented to show the effectiveness of the proposed attitude synchronization and tracking approaches.

  2. Changing Student Attitudes using Andes, An Intelligent Homework System

    Science.gov (United States)

    van de Sande, Brett; Vanlehn, Kurt; Treacy, Don; Shelby, Bob; Wintersgill, Mary

    2007-03-01

    The size of introductory physics lectures often inhibits personal homework assistance and timely corrective feedback. Andes, an intelligent homework help system designed for two semesters of introductory physics, can fill this need by encouraging students to use sound problem solving techniques and providing immediate feedback on each step of a solution. On request, Andes provides principles-based hints based on previous student actions. A multi-year study at the U.S. Naval Academy demonstrates that students using Andes perform better than students working the same problems as graded pencil and paper homeworks. In addition, student attitude surveys show that Andes is preferred over other homework systems. These findings have implications for student attitudes toward, and mastery of, physics. See http://www.andes.pitt.edu for more information.

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

    International Nuclear Information System (INIS)

    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. (research papers)

  4. 76 FR 50810 - Seventh Meeting: RTCA Special Committee 219: Attitude and Heading Reference System

    Science.gov (United States)

    2011-08-16

    ... Committee 219 meeting: Attitude and Heading Reference System. SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 219: Attitude and Heading Reference System... Federal Aviation Administration Seventh Meeting: RTCA Special Committee 219: Attitude and...

  5. Maternal and Paternal Psychological Control as Moderators of the Link between Peer Attitudes and Adolescents' Risky Sexual Behavior

    Science.gov (United States)

    Oudekerk, Barbara A.; Allen, Joseph P.; Hafen, Christopher A.; Hessel, Elenda T.; Szwedo, David E.; Spilker, Ann

    2014-01-01

    Maternal and paternal psychological control, peer attitudes, and the interaction of psychological control and peer attitudes at age 13 were examined as predictors of risky sexual behavior before age 16 in a community sample of 181 youth followed from age 13 to 16. Maternal psychological control moderated the link between peer attitudes and sexual…

  6. Structural dynamics and attitude control study of early manned capability space station configurations

    Science.gov (United States)

    Ayers, J. Kirk; Cirillo, William M.; Giesy, Daniel P.; Hitchcock, Jay C.; Kaszubowski, Martin J.; Raney, J. Philip

    1987-01-01

    A study was performed to determine the vibration and attitude control characteristics of critical space station configurations featuring early manned capability during buildup from initial user support through the operations capability reference station. Five configurations were selected and were examined thus determining the changes that are likely to occur in the characteristics of the system as the station progresses from a single boom structure to a mature, dual keel, operations capability reference station. Both 9 foot and 5 meter truss bay sizes were investigated. All configurations analyzed were stable; however, the 5 meter truss bay size structure exhibited superior stability characteristics.

  7. IMU/GPS System Provides Position and Attitude Data

    Science.gov (United States)

    Lin, Ching Fang

    2006-01-01

    A special navigation system is being developed to provide high-quality information on the position and attitude of a moving platform (an aircraft or spacecraft), for use in pointing and stabilization of a hyperspectral remote-sensing system carried aboard the platform. The system also serves to enable synchronization and interpretation of readouts of all onboard sensors. The heart of the system is a commercially available unit, small enough to be held in one hand, that contains an integral combination of an inertial measurement unit (IMU) of the microelectromechanical systems (MEMS) type, Global Positioning System (GPS) receivers, a differential GPS subsystem, and ancillary data-processing subsystems. The system utilizes GPS carrier-phase measurements to generate time data plus highly accurate and continuous data on the position, attitude, rotation, and acceleration of the platform. Relative to prior navigation systems based on IMU and GPS subsystems, this system is smaller, is less expensive, and performs better. Optionally, the system can easily be connected to a laptop computer for demonstration and evaluation. In addition to airborne and spaceborne remote-sensing applications, there are numerous potential terrestrial sensing, measurement, and navigation applications in diverse endeavors that include forestry, environmental monitoring, agriculture, mining, and robotics.

  8. Measuring Public Attitudes Toward Natural Resource Issues: Coyote Control

    OpenAIRE

    Arthur, Louise M.

    1981-01-01

    A method to obtain quantitative information on public attitudes toward natural resource issues is described.1 The quantification depends on the structure of the entire survey instrument as well as on individual items in the survey. Items are designed and organized to facilitate (1) the summarizing of measured attitudes toward very complex resource issues, and (2) meaningful comparisons of the summary attitudinal measures to other quantified impacts --economic and physical --for policy analysi...

  9. 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.

  10. 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.

  11. 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.

  12. 75 FR 49550 - Fifth Meeting: RTCA Special Committee 219: Attitude and Heading Reference System (AHRS)

    Science.gov (United States)

    2010-08-13

    ...: Notice of RTCA Special Committee 219: Attitude and Heading Reference System (AHRS). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of ] RTCA Special Committee 219: Attitude and... Federal Aviation Administration Fifth Meeting: RTCA Special Committee 219: Attitude and Heading...

  13. A spectral identification technique for adaptive attitude control and pointing of the Space Telescope

    Science.gov (United States)

    Teuber, D. L.

    1976-01-01

    The Space Telescope is a 2.4 m class aperture optical telescope having near-diffraction-limited performance. It will be placed into earth orbit by 1980 via the Space Shuttle. The problem considered is how to achieve negligible degradation of the astronomy imaging capability (to 0.005 arc second) due to smearing by pointing motions during observations. Initially, pointing instability sources were identified and a linear stability was used to assess the magnitude of elastic body modes and to design control system compensation regions necessary for subsequent adaptive control. A spectral identification technique for this adaptive attitude control and pointing has been investigated that will alleviate requirements for comprehensive dynamic ground testing. Typical all-digital simulation results describing motions of the telescope line of sight are presented.

  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. 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.

  16. Design and Implementation of Attitude Control for 3-axes Magnetic Coil Stabilization of a Spacecraft

    OpenAIRE

    Tudor, Zdenko

    2011-01-01

    Spacecrafts, especially satellites, play an ever greater rolein our daily lives as we increasingly depend on the services they provide,which in turn, more often than not, critically depend on maintainingcorrect payload attitude. As smaller educational satellites pavethe way for organization, group and privately owned pico-satellites, weexplore the possibilities of attitude control through magnetic coil actuation.We approach the whole problem, from control theory developmentto first prototype ...

  17. Attitude Ground System (AGS) For The Magnetospheric Multi-Scale (MMS) Mission

    Science.gov (United States)

    Raymond, Juan C.; Sedlak, Joseph E.; Vint, Babak

    2015-01-01

    The Magnetospheric Multiscale (MMS) mission is a Solar-Terrestrial Probe mission consisting of four identically instrumented spin-stabilized spacecraft flying in an adjustable pyramid-like formation around the Earth. The formation of the MMS spacecraft allows for three-dimensional study of the phenomenon of magnetic reconnection, which is the primary objective of the mission. The MMS spacecraft were launched early on March 13, 2015 GMT. Due to the challenging and very constricted attitude and orbit requirements for performing the science, as well as the need to maintain the spacecraft formation, multiple ground functionalities were designed to support the mission. These functionalities were incorporated into a ground system known as the Attitude Ground System (AGS). Various AGS configurations have been used widely to support a variety of three-axis-stabilized and spin-stabilized spacecraft missions within the NASA Goddard Space Flight Center (GSFC). The original MMS operational concept required the AGS to perform highly accurate predictions of the effects of environmental disturbances on the spacecraft orientation and to plan the attitude maneuvers necessary to stay within the science attitude tolerance. The orbit adjustment requirements for formation control drove the need also to perform calibrations that have never been done before in support of NASA GSFC missions. The MMS mission required support analysts to provide fast and accurately calibrated values of the inertia tensor, center of mass, and accelerometer bias for each MMS spacecraft. During early design of the AGS functionalities, a Kalman filter for estimating the attitude, body rates, center of mass, and accelerometer bias, using only star tracker and accelerometer measurements, was heavily analyzed. A set of six distinct filters was evaluated and considered for estimating the spacecraft attitude and body rates using star tracker data only. Four of the six filters are closely related and were compared

  18. An Estimator for Attitude and Heading Reference Systems Based on Virtual Horizontal Reference

    DEFF Research Database (Denmark)

    Wang, Yunlong; Soltani, Mohsen; Hussain, Dil muhammed Akbar

    2016-01-01

    The output of the attitude determination systems suffers from large errors in case of accelerometer malfunctions. In this paper, an attitude estimator, based on Virtual Horizontal Reference (VHR), is designed for an Attitude Heading and Reference System (AHRS) to cope with this problem. The VHR...... makes it possible to correct the output of roll and pitch of the attitude estimator in the situations without accelerometer measurements, which cannot be achieved by the conventional nonlinear attitude estimator. The performance of VHR is tested both in simulation and hardware environment to validate...

  19. Student Compliance and Attitude: A Function of Classroom Control Technique.

    Science.gov (United States)

    Houser, Betsy B.

    This paper examines the effects of a teacher's classroom utilization of certain means of social influence or bases of social power (reward, coercive, referent, legitimate, and informational) upon: (1) level of student compliance, and (2) attitude of the student toward the teacher. A total of 588 white, middle-class fourth, fifth, and sixth grade…

  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. Control system design method

    Science.gov (United States)

    Wilson, David G.; Robinett, III, Rush D.

    2012-02-21

    A control system design method and concomitant control system comprising representing a physical apparatus to be controlled as a Hamiltonian system, determining elements of the Hamiltonian system representation which are power generators, power dissipators, and power storage devices, analyzing stability and performance of the Hamiltonian system based on the results of the determining step and determining necessary and sufficient conditions for stability of the Hamiltonian system, creating a stable control system based on the results of the analyzing step, and employing the resulting control system to control the physical apparatus.

  3. Development of helicopter attitude axes controlled hover flight without pilot assistance and vehicle crashes

    Science.gov (United States)

    Simon, Miguel

    In this work, we show how to computerize a helicopter to fly attitude axes controlled hover flight without the assistance of a pilot and without ever crashing. We start by developing a helicopter research test bed system including all hardware, software, and means for testing and training the helicopter to fly by computer. We select a Remote Controlled helicopter with a 5 ft. diameter rotor and 2.2 hp engine. We equip the helicopter with a payload of sensors, computers, navigation and telemetry equipment, and batteries. We develop a differential GPS system with cm accuracy and a ground computerized navigation system for six degrees of freedom (6-DoF) free flight while tracking navigation commands. We design feedback control loops with yet-to-be-determined gains for the five control "knobs" available to a flying radio-controlled (RC) miniature helicopter: engine throttle, main rotor collective pitch, longitudinal cyclic pitch, lateral cyclic pitch, and tail rotor collective pitch. We develop helicopter flight equations using fundamental dynamics, helicopter momentum theory and blade element theory. The helicopter flight equations include helicopter rotor equations of motions, helicopter rotor forces and moments, helicopter trim equations, helicopter stability derivatives, and a coupled fuselage-rotor helicopter 6-DoF model. The helicopter simulation also includes helicopter engine control equations, a helicopter aerodynamic model, and finally helicopter stability and control equations. The derivation of a set of non-linear equations of motion for the main rotor is a contribution of this thesis work. We design and build two special test stands for training and testing the helicopter to fly attitude axes controlled hover flight, starting with one axis at a time and progressing to multiple axes. The first test stand is built for teaching and testing controlled flight of elevation and yaw (i.e., directional control). The second test stand is built for teaching and

  4. GCFR plant control system

    International Nuclear Information System (INIS)

    A plant control system is being designed for a gas-cooled fast breeder reactor (GCFR) demonstration plant. Control analysis is being performed as an integral part of the plant design process to ensure that control requirements are satisfied as the plant design evolves. The load control portion of the plant control system provides stable automatic (closed-loop) control of the plant over the 25% to 100% load range. Simulation results are presented to demonstrate load control system performance. The results show that the plant is controllable at full load with the control system structure selected, but gain scheduling is required to achieve desired performance over the load range

  5. 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.

  6. 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.

  7. Attitudes of Brazilian citizens towards pig production systems

    DEFF Research Database (Denmark)

    de Barcellos, Marcia Dutra; Kügler, Jens Oliver; Saab, Maria Stella Melo;

    were identified as "average", "environmental conscious" and "tradition and animal welfare-oriented" citizens. Although attitudes towards environment and nature were indeed related to citizens' specific attitudes towards pig farming at the cluster level, the relationship between citizenship...

  8. A comparison of dysfunctional attitudes in substance abusers and control group and its psychological outcome

    OpenAIRE

    2008-01-01

    Objectives: Addiction researchers find that addictive processes are influenced by patient beliefs and attitudes. This research was carried out to assess the role of dysfunctional attitudes, outcomes of psychology in substance abuse behaviors of subject were referred to addiction treatment center in the city of Bandar Abbas, and to compare the with the control group. Methods: This is a retrospective study in which 100 subject substance abusers were compared with 100 subject s of c...

  9. Programmable scan/read circuitry for charge coupled device imaging detectors. [spcecraft attitude control and star trackers

    Science.gov (United States)

    Salomon, P. M.; Smilowitz, K.

    1984-01-01

    A circuit for scanning and outputting the induced charges in a solid state charge coupled device (CCD) image detector is disclosed in an image detection system for use in a spacecraft attitude control system. The image detection system includes timing control circuitry for selectively controlling the output of the CCD detector so that video outputs are provided only with respect to induced charges corresponding to predetermined sensing element lines of the CCD detector. The timing control circuit and the analog to digital converter are controlled by a programmed microprocessor which defines the video outputs to be converted and further controls the timing control circuit so that no video outputs are provided during the delay associated with analog to digital conversion.

  10. 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.

  11. 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.

  12. On Controlled P Systems

    OpenAIRE

    Krithivasan, Kamala; Paun, Gheorghe; Ramanujan, Ajeesh; Research Group on Natural Computing (Universidad de Sevilla) (Coordinador)

    2013-01-01

    We introduce and brie y investigate P systems with controlled computations. First, P systems with label restricted transitions are considered (in each step, all rules used have either the same label, or, possibly, the empty label, ), then P systems with the computations controlled by languages (as in context-free controlled grammars). The relationships between the families of sets of numbers computed by the various classes of controlled P systems are investigated, also comp...

  13. New optimal control laws for attitude of a rigid body motion without angular velocity measurements

    Energy Technology Data Exchange (ETDEWEB)

    El-Gohary, Awad [Department of Statistics and Operational Research, Faculty of Science King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)] e-mail: aigohary@ksu.edu.sa

    2005-08-01

    In this paper we shall use the passive properties of Euler dynamic equations as well as the structural properties of kinematic equations in terms of Cayley-Rodrigues and Modified Rodrigues parameters to derive optimal control laws without any information about the angular velocity of the rigid body. The interesting difference in the current study is the assumption that only the kinematics attitude parameters are available for the control process. The optimal control laws ensure the optimal asymptotic stability of the rigid body motion and minimize a selecting performance are obtained in terms of the kinematics attitude parameters and their estimates. Numerical examples are presented to demonstrate the theoretical results.

  14. An Estimator for Attitude and Heading Reference Systems Based on Virtual Horizontal Reference

    DEFF Research Database (Denmark)

    Wang, Yunlong; Soltani, Mohsen; Hussain, Dil muhammed Akbar

    2016-01-01

    The output of the attitude determination systems suffers from large errors in case of accelerometer malfunctions. In this paper, an attitude estimator, based on Virtual Horizontal Reference (VHR), is designed for an Attitude Heading and Reference System (AHRS) to cope with this problem. The VHR...... makes it possible to correct the output of roll and pitch of the attitude estimator in the situations without accelerometer measurements, which cannot be achieved by the conventional nonlinear attitude estimator. The performance of VHR is tested both in simulation and hardware environment to validate...... their estimation performance. Moreover, the hardware test results are compared with that of a high-precision commercial AHRS to verify the estimation results. The implemented algorithm has shown high accuracy of attitude estimation that makes the system suitable for many applications....

  15. Maternal and Paternal Psychological Control as Moderators of the Link between Peer Attitudes and Adolescents’ Risky Sexual Behavior

    OpenAIRE

    Oudekerk, Barbara A.; Allen, Joseph P.; Hafen, Christopher A.; Hessel, Elenda T.; Szwedo, David E.; Spilker, Ann

    2013-01-01

    Maternal and paternal psychological control, peer attitudes, and the interaction of psychological control and peer attitudes at age 13 were examined as predictors of risky sexual behavior before age 16 in a community sample of 181 youth followed from age 13 to 16. Maternal psychological control moderated the link between peer attitudes and sexual behavior. Peer acceptance of early sex predicted greater risky sexual behaviors, but only for teens whose mothers engaged in high levels of psycholo...

  16. Weight Control Beliefs, Body Shape Attitudes, and Physical Activity among Adolescents

    Science.gov (United States)

    Martin, Scott B.; Rhea, Deborah J.; Greenleaf, Christy A.; Judd, Doryce E.; Chambliss, Heather O.

    2011-01-01

    Background: Relatively little is known about how perceived weight controllability influences important psychological health factors among adolescents. Thus, the purpose of this study is to explore adolescents' weight controllability beliefs and how those beliefs influence weight-related attitudes and behaviors. Methods: Adolescents (N = 369, mean…

  17. Methods for attitude guidance and precise robust gyromoment control of large-scale agile observation spacecraft

    Science.gov (United States)

    Somov, Sergey; Butyrin, Sergey; Somov, Yevgeny

    2012-11-01

    Problems on guidance and robust gyromoment attitude control of agile information satellite for remote sensing the Earth surface are considered. Elaborated methods for dynamic research of the spacecraft programmed angular motion at principle modes under external and parametric disturbances, partial discrete measurement of the state and digital control of the gyro moment cluster by the excessive gyrodine schemes, are presented.

  18. 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.

  19. Vision-Based Attitude and Formation Determination System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To determine pointing and position vectors in both local and inertial coordinate frames, multi-spacecraft missions typically utilize separate attitude determination...

  20. 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.

  1. Nurses' Attitudes Toward the Use of the Bar-coding Medication Administration System

    NARCIS (Netherlands)

    S.D. Marini; A. Hasman; H.A.S. Huijer; H. Dimassi

    2010-01-01

    This study determines nurses' attitudes toward bar-coding medication administration system use. Some of the factors underlying the successful use of bar-coding medication administration systems that are viewed as a connotative indicator of users' attitudes were used to gather data that describe the

  2. Discrete Control Systems

    CERN Document Server

    Lee, Taeyoung; McClamroch, N Harris

    2007-01-01

    Discrete control systems, as considered here, refer to the control theory of discrete-time Lagrangian or Hamiltonian systems. These discrete-time models are based on a discrete variational principle, and are part of the broader field of geometric integration. Geometric integrators are numerical integration methods that preserve geometric properties of continuous systems, such as conservation of the symplectic form, momentum, and energy. They also guarantee that the discrete flow remains on the manifold on which the continuous system evolves, an important property in the case of rigid-body dynamics. In nonlinear control, one typically relies on differential geometric and dynamical systems techniques to prove properties such as stability, controllability, and optimality. More generally, the geometric structure of such systems plays a critical role in the nonlinear analysis of the corresponding control problems. Despite the critical role of geometry and mechanics in the analysis of nonlinear control systems, non...

  3. ALFA Detector Control System

    CERN Document Server

    Oleiro Seabra, Luis Filipe; The ATLAS collaboration

    2015-01-01

    ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS (A Toroidal LHC Apparatus). The ALFA system is composed by four stations installed in the LHC tunnel 240 m away from the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronics for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.

  4. ALFA Detector Control System

    CERN Document Server

    Oleiro Seabra, Luis Filipe; The ATLAS collaboration

    2015-01-01

    ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS/LHC. The ALFA system is composed by two stations installed in the LHC tunnel 240 m away from each side of the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronic for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.

  5. A modular control system

    International Nuclear Information System (INIS)

    The main objective of the modular control system is to provide the requirements to most of the processes supervision and control applications within the industrial automatization area. The design is based on distribution, modulation and expansion concepts. (Author)

  6. Motion control systems

    CERN Document Server

    Sabanovic, Asif

    2011-01-01

    "Presents a unified approach to the fundamental issues in motion control, starting from the basics and moving through single degree of freedom and multi-degree of freedom systems In Motion Control Systems, Šabanovic and Ohnishi present a unified approach to very diverse issues covered in motion control systems, offering know-how accumulated through work on very diverse problems into a comprehensive, integrated approach suitable for application in high demanding high-tech products. It covers material from single degree of freedom systems to complex multi-body non-redundant and redundant systems. The discussion of the main subject is based on original research results and will give treatment of the issues in motion control in the framework of the acceleration control method with disturbance rejection technique. This allows consistent unification of different issues in motion control ranging from simple trajectory tracking to topics related to haptics and bilateral control without and with delay in the measure...

  7. Applied Control Systems Design

    CERN Document Server

    Mahmoud, Magdi S

    2012-01-01

    Applied Control System Design examines several methods for building up systems models based on real experimental data from typical industrial processes and incorporating system identification techniques. The text takes a comparative approach to the models derived in this way judging their suitability for use in different systems and under different operational circumstances. A broad spectrum of control methods including various forms of filtering, feedback and feedforward control is applied to the models and the guidelines derived from the closed-loop responses are then composed into a concrete self-tested recipe to serve as a check-list for industrial engineers or control designers. System identification and control design are given equal weight in model derivation and testing to reflect their equality of importance in the proper design and optimization of high-performance control systems. Readers’ assimilation of the material discussed is assisted by the provision of problems and examples. Most of these e...

  8. 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.

  9. Step Motor Control System

    Institute of Scientific and Technical Information of China (English)

    ZhangShuochengt; WangDan; QiaoWeimin; JingLan

    2003-01-01

    All kinds of step motors and servomotors are widely used in CSR control system, such as many vacuum valves control that set on the HIRFL-CSR; all kinds of electric switches and knobs of ECR Ion Source; equipment of CSR Beam Diagnostics and a lot of large equipment like Inside Gun Toroid and Collector Toroid of HIRFL. A typical control system include up to 32 16-I/O Control boards, and each 16-I/O Control board can control 4 motors at the same time (including 8 Limit Switches).

  10. Attitude control of geostationary satellites with double gimballed momentum wheels

    Science.gov (United States)

    Schulz, G.; Lange, T.

    1981-11-01

    Conventional control methods are generalized using state vector feedback design procedures. Alternatively, a decoupled control method using a nondiagonal inertia tensor was derived. These are confronted to modern control theory design method with observer, where especially the insensitivity with respect to variants of the moments of inertia was demonstrated.

  11. Attitude Control of a Small Coaxial Helicopter with a Bell Type Stabilizer Bar

    Science.gov (United States)

    Sunada, Shigeru; Hirosue, Wataru; Kawashima, Kenta

    We analyzed the small coaxial helicopter recently developed for entertainment. The upper rotor is connected with a stabilizer bar alone and the lower rotor is not connected with it. The cyclic pitch of the upper rotor is controlled by this stabilizer bar, and that of the lower rotor is controlled by servo motors. We investigated how this stabilizer bar varies the cyclic pitch of the upper rotor and how it contributes to attitude control of a fuselage.

  12. Bounded attitude control of rigid bodies: Real-time experimentation to a quadrotor mini-helicopter

    OpenAIRE

    Guerrero-Castellanos, Fermi; Marchand, Nicolas; Hably, Ahmad; Lesecq, Suzanne; Delamare, Jérôme

    2011-01-01

    A quaternion-based feedback is developed for the attitude stabilization of rigid bodies. The control design takes into account a priori input bounds and is based on nested saturation approach. It results in a very simple controller suitable for an embedded use with low computational resources available. The proposed method is generic not restricted to symmetric rigid bodies and does not require the knowledge of the inertia matrix of the body. The control law can be tuned to force closed-loop ...

  13. 随钻井下姿态测量系统%Attitude measurement system Downhole drilling

    Institute of Scientific and Technical Information of China (English)

    贾衡天; 张程光; 高文凯; 管康; 范锦辉; 彭浩; 邓乐

    2015-01-01

    In drilling oil drilling it′s important to accurately understand the attitude information of drilling tool. By measuring the attitude information accurately it can grasp the orientation parameters of borehole.With the development of petroleum industry in recent years, it need to use precise trajectory control technology for oil drilling technology to adapt to directional wells, horizontal wells and large displacement well application.This paper designs a downhole attitude measurement system which can work in drilling conditions. By measuring the signal of three axis gyroscope, accelerometer and magnetic sensor. and doing corresponding algorithm, it can get the attitude information of underground drilling.%在随钻石油钻探时需要准确地了解钻具的姿态信息,通过对姿态信息的测量可以准确地掌握井眼的方位参数。随着近年来石油工业的发展,要求石油钻井技术采用精确的轨迹控制技术,适应定向井、水平井和大位移井等应用的需要。设计一种井下姿态测量系统,可以工作在随钻条件下,通过测量三轴陀螺仪、加速度计和磁阻传感器的信号并进行相应的算法处理,得到钻具在井下的姿态信息。

  14. Discrete control systems

    CERN Document Server

    Okuyama, Yoshifumi

    2014-01-01

    Discrete Control Systems establishes a basis for the analysis and design of discretized/quantized control systemsfor continuous physical systems. Beginning with the necessary mathematical foundations and system-model descriptions, the text moves on to derive a robust stability condition. To keep a practical perspective on the uncertain physical systems considered, most of the methods treated are carried out in the frequency domain. As part of the design procedure, modified Nyquist–Hall and Nichols diagrams are presented and discretized proportional–integral–derivative control schemes are reconsidered. Schemes for model-reference feedback and discrete-type observers are proposed. Although single-loop feedback systems form the core of the text, some consideration is given to multiple loops and nonlinearities. The robust control performance and stability of interval systems (with multiple uncertainties) are outlined. Finally, the monograph describes the relationship between feedback-control and discrete ev...

  15. The role of peer arrests on the development of youths' attitudes towards the justice system.

    Science.gov (United States)

    Fine, Adam; Cavanagh, Caitlin; Donley, Sachiko; Steinberg, Laurence; Frick, Paul J; Cauffman, Elizabeth

    2016-04-01

    During adolescence, youths develop attitudes about the justice system. Although there is consistent evidence that personal experiences with legal actors contribute to attitudes toward the justice system, adolescents' attitudes may also be influenced vicariously through their friends' experiences with the justice system. Using data from a sample of 1,216 first-time male adolescent offenders, the present study examines how attitudes toward the justice system develop over 24 months following the adolescent's first arrest. Even after accounting for personal justice system experiences, including self-reported offending, time on the streets, and contacts with the police, results indicate that adolescents with friends who were arrested report more negative attitudes toward the justice system than those without friends who were arrested. Further, experiencing a friend's arrest has a larger impact on the attitudes of youths who are experiencing it for the first time. We provide evidence that attitudes toward the justice system are a product of accumulated social experiences-both personal and vicarious-with the justice system. (PsycINFO Database Record PMID:26595702

  16. 76 FR 80447 - Eighth Meeting: RTCA Special Committee 219: Attitude and Heading Reference Systems (AHRS)

    Science.gov (United States)

    2011-12-23

    ... Federal Aviation Administration Eighth Meeting: RTCA Special Committee 219: Attitude and Heading Reference...). ACTION: Notice of RTCA Special Committee 219: Attitude and Heading Reference Systems (AHRS). SUMMARY: The FAA is issuing this notice to advise the public of the eighth meeting of RTCA Special Committee...

  17. Technology Use in Rwandan Secondary Schools: An Assessment of Teachers' Attitudes towards Geographic Information Systems (GIS)

    Science.gov (United States)

    Akinyemi, Felicia O.

    2016-01-01

    Technology use is evident in all spheres of human endeavour. Focusing on technology use in education, this paper examines teachers' attitudes towards geographic information system (GIS). An assessment was made of GIS teachers in Rwandan secondary schools. Key areas covered include how GIS is implemented in schools, teachers' attitudes and…

  18. 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.

  19. The Attitudes & Beliefs on Classroom Control Inventory-Revised and Revisited: A Continuation of Construct Validation

    Science.gov (United States)

    Martin, Nancy K.; Yin, Zenong; Mayall, Hayley

    2008-01-01

    The purpose of this study was to report the psychometric properties of the revised Attitudes and Beliefs of Classroom Control Inventory (ABCC-R). Data were collected from 489 participants via the ABCC-R, Teacher Efficacy Scale, Problems in School Questionnaire, and a demographic questionnaire. Results were in keeping with the construct. The…

  20. Tobacco Control Policy Advocacy Attitudes and Self-Efficacy among Ethnically Diverse High School Students

    Science.gov (United States)

    Ramirez, Amelie G.; Velez, Luis F.; Chalela, Patricia; Grussendorf, Jeannie; McAlister, Alfred L.

    2006-01-01

    This study applied self-efficacy theory to assess empowerment to advocate on behalf of tobacco control policies. The Youth Tobacco Survey with added policy advocacy self-efficacy, attitudes, and outcome expectations scales was given to 9,177 high school students in Texas. Asians showed the lowest prevalence of experimentation and current smoking,…

  1. 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.

  2. 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...

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

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    , nevertheless, a solution of the riccati equation gives an excellent frame for investigations provided in this paper. An observation that geomagnetic field changes approximately periodically when satellite is on a near polar orbit is used throughout this paper. Three types of attitude controllers are proposed...

  4. 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.

  5. A comparison of dysfunctional attitudes in substance abusers and control group and its psychological outcome

    Directory of Open Access Journals (Sweden)

    2008-11-01

    This research was carried out to assess the role of dysfunctional attitudes, outcomes of psychology in substance abuse behaviors of subject were referred to addiction treatment center in the city of Bandar Abbas, and to compare the with the control group. Methods: This is a retrospective study in which 100 subject substance abusers were compared with 100 subject s of control group who were selected using convenience sampling and were also demographically matched. Data were gathered using a demographic questionnaire, clinical interview, dysfunctional attitudes scale (DAS, Depression Anxiety Stress Scale (DASS. The data were analyzed via descriptive statistic method, T- Test and chi-square and variance analysis. Findings: Findings indicated that in comparison with control group, subject of substance abusers had experienced more stress, anxiety, depression, had shown a cognitively more percent of them dysfunctional attitudes in comparison with control group. Results: The results suggested that the dysfunctional attitudes could be as a Vulnerability Factor that increase abuse of substance consequently use of cognitive therapy could be helpful and effective in prevention and treatment of the addicts.

  6. Control system design guide

    Energy Technology Data Exchange (ETDEWEB)

    Sellers, David; Friedman, Hannah; Haasl, Tudi; Bourassa, Norman; Piette, Mary Ann

    2003-05-01

    The ''Control System Design Guide'' (Design Guide) provides methods and recommendations for the control system design process and control point selection and installation. Control systems are often the most problematic system in a building. A good design process that takes into account maintenance, operation, and commissioning can lead to a smoothly operating and efficient building. To this end, the Design Guide provides a toolbox of templates for improving control system design and specification. HVAC designers are the primary audience for the Design Guide. The control design process it presents will help produce well-designed control systems that achieve efficient and robust operation. The spreadsheet examples for control valve schedules, damper schedules, and points lists can streamline the use of the control system design concepts set forth in the Design Guide by providing convenient starting points from which designers can build. Although each reader brings their own unique questions to the text, the Design Guide contains information that designers, commissioning providers, operators, and owners will find useful.

  7. Solar-sail attitude control based on moving masses and roll stabilizer bars%采用滑块和RSB的太阳帆姿态控制

    Institute of Scientific and Technical Information of China (English)

    罗超; 郑建华

    2011-01-01

    本文研究以滑块和滚转轴稳定条RSB(Roll Stabilizer Bars)作为执行机构的太阳帆航天器的姿态控制,分析了姿态控制机构的物理模型,利用欧拉方程建立了太阳帆的姿态动力学模型.针对此类模型,设计了太阳帆航天器三轴姿态控制系统,通过数值仿真研究了三轴姿态控制的短期响应特性.最后以中科院空间中心提出的SPORT(Solar Polar Orbit Radio Telescope)任务为背景,研究了在轨道转移过程中太阳帆的姿态控制效果.仿真结果表明,基于滑块和滚转轴稳定条控制的太阳帆能够满足大角度快速的姿态机动要求,从而实现任务要求的目标轨道.%In this paper, solar-sail attitude control system which employed moving masses for pitch/yaw trim control and roll stabilizer bars for roll control was studied. Physical model of solar-sail attitude control system had been analyzed, and the dynamical model was establishe d using Euler' s attitude dynamical equations. According to the model, a nonlinear PID controller was found to control the three-axis attitudes. Finally, a series of simulations, including the Solar Polar Orbit Radio Telescope misson' s trajectory transfer, were run to determine the effectiveness of the attitude controller and characterize the behavior of attitude control method using moving masses and RSB.

  8. NPSAT1 attitude control subsystem hardware-in-the-loop simulation

    OpenAIRE

    Schmidt, Alexander

    2003-01-01

    NPSAT1 is a three-axis stabilized spacecraft. Its Attitude Control Subsystem (ACS) uses a magnetic control approach that will be used for the first time. The Magnetic control approach is verified with an ACS SIMULINK model of NPSAT1. The correct SIMULINK implementation of the magnetic control algorithm will be verified with an ACS air bearing SIMULINK model and a hardware-embedded ACS control algorithm SIMULINK model that controls the test platform on a spherical air bearing table. This is a ...

  9. Mead photovoltaic system controller

    Energy Technology Data Exchange (ETDEWEB)

    Millner, A.R.

    1979-01-31

    A system controller has been designed, built, tested, and in operation for one year at MIT/Lincoln Laboratory's 25-kW-peak Solar Photovoltaic Power System located at Mead, Nebraska. The controller allows the site to operate without human intervention, and has brought to light some of the problems of charge-control algorithms in a deep-discharge environment.

  10. 控制分配在平流层飞艇姿态控制中的应用%Control allocation approach for stratospheric airship attitude control

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    针对平流层飞艇一般采用多控制机构的特点,将广义逆控制分配方法应用到飞艇姿态控制系统中,并根据飞艇控制机构特性采用了加权伪逆控制分配算法。飞艇姿态控制仿真结果表明:设计的控制分配方法可以有效实现多控制机构的协调操纵,对姿态角控制效果良好,避免了单一操纵舵面过早进入饱和状态的情况;合理调整控制分配权值可减少能量损耗,增强实时性,便于工程实现。%The stratospheric airships generally act with the redundant control effectors,thus a control allocation approach based on generalized inverse was applied to the airship attitude control system and the weighted pseudo-inverse control allocation method was adopted on the basis of characteristics of airship control effectors.The simulation results of a stratospheric airship attitude control show that:the designed control allocation approach can realize the coordinated operation of redundant control effectors effectively and its control effect on attitude angle is good,which avoids the premature saturation of control surface when using single effector;the reasonable adjustment of control allocation weights can reduce energy consumption,enhance instantaneity and provide convenience in engineering.

  11. Control allocation approach for stratospheric airship attitude control%控制分配在平流层飞艇姿态控制中的应用

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    针对平流层飞艇一般采用多控制机构的特点,将广义逆控制分配方法应用到飞艇姿态控制系统中,并根据飞艇控制机构特性采用了加权伪逆控制分配算法。飞艇姿态控制仿真结果表明:设计的控制分配方法可以有效实现多控制机构的协调操纵,对姿态角控制效果良好,避免了单一操纵舵面过早进入饱和状态的情况;合理调整控制分配权值可减少能量损耗,增强实时性,便于工程实现。%The stratospheric airships generally act with the redundant control effectors,thus a control allocation approach based on generalized inverse was applied to the airship attitude control system and the weighted pseudo-inverse control allocation method was adopted on the basis of characteristics of airship control effectors.The simulation results of a stratospheric airship attitude control show that:the designed control allocation approach can realize the coordinated operation of redundant control effectors effectively and its control effect on attitude angle is good,which avoids the premature saturation of control surface when using single effector;the reasonable adjustment of control allocation weights can reduce energy consumption,enhance instantaneity and provide convenience in engineering.

  12. Active control of the attitude motion and structural vibration of a flexible satellite by jet thrusters

    Science.gov (United States)

    Lee, Mokin

    A Lagrangian formulation is used to obtain the equations of motion of a flexible satellite in a tree-type geometry. The flexible satellite model is the geosynchronous INSAT-II type satellite with a flexible balance beam and a flexible solar panel attached to the rigid main body. In deriving the equations of motion, the orbital motion, the librational motion, and the structural motion of flexible bodies are involved. The assumed-modes method is used to express the deflections of the flexible structures in the form of a finite series of space-dependent admissible functions multiplied by time-dependent amplitudes. The kinetic energy, potential energy, strain energy, and virtual work of the flexible satellite are evaluated as functions of time in terms of the generalized coordinates. Then, by substituting them into Lagrange's equations for discrete systems, the governing equations of motion of the flexible satellite are obtained as a set of second-order nonlinear ordinary differential equations. The attitude motion and the structural motion of the flexible satellite are coupled motions with one another. Uncontrolled dynamics show that the librational and structural motions are oscillatory and undamped motions. The stability and performance of the flexible satellite needs to be improved by designing control systems. A control objective is proposed to improve the stability and performance for pointing accuracy maneuver by controlling the librational motions and flexible modes simultaneously. For the control objective, a control system is synthesized, using feedback linearization control, thrust determination, thrust management, and pulse-width pulse-frequency modulation. Feedback linearization for second-order nonlinear systems is used to obtain a stable feedback control system for the pointing-accuracy control. A stable feedback control system is obtained by adjusting the diagonal matrices of the linear second-order system. Jet thrusters are used as the primary

  13. A Practical Method for Implementing an Attitude and Heading Reference System

    Directory of Open Access Journals (Sweden)

    Rodrigo Munguía

    2014-04-01

    Full Text Available This paper describes a practical and reliable algorithm for implementing an Attitude and Heading Reference System (AHRS. This kind of system is essential for real time vehicle navigation, guidance and control applications. When low cost sensors are used, efficient and robust algorithms are required for performance to be acceptable. The proposed method is based on an Extended Kalman Filter (EKF in a direct configuration. In this case, the filter is explicitly derived from both the kinematic and error models. The selection of this kind of EKF configuration can help in ensuring a tight integration of the method for its use in filter-based localization and mapping systems in autonomous vehicles. Experiments with real data show that the proposed method is able to maintain an accurate and drift-free attitude and heading estimation. An additional result is to show that there is no ostensible reason for preferring that the filter have an indirect configuration over a direct configuration for implementing an AHRS system.

  14. Integrated inertial stellar attitude sensor

    Science.gov (United States)

    Brady, Tye M. (Inventor); Kourepenis, Anthony S. (Inventor); Wyman, Jr., William F. (Inventor)

    2007-01-01

    An integrated inertial stellar attitude sensor for an aerospace vehicle includes a star camera system, a gyroscope system, a controller system for synchronously integrating an output of said star camera system and an output of said gyroscope system into a stream of data, and a flight computer responsive to said stream of data for determining from the star camera system output and the gyroscope system output the attitude of the aerospace vehicle.

  15. Common Control System Vulnerability

    Energy Technology Data Exchange (ETDEWEB)

    Trent Nelson

    2005-12-01

    The Control Systems Security Program and other programs within the Idaho National Laboratory have discovered a vulnerability common to control systems in all sectors that allows an attacker to penetrate most control systems, spoof the operator, and gain full control of targeted system elements. This vulnerability has been identified on several systems that have been evaluated at INL, and in each case a 100% success rate of completing the attack paths that lead to full system compromise was observed. Since these systems are employed in multiple critical infrastructure sectors, this vulnerability is deemed common to control systems in all sectors. Modern control systems architectures can be considered analogous to today's information networks, and as such are usually approached by attackers using a common attack methodology to penetrate deeper and deeper into the network. This approach often is composed of several phases, including gaining access to the control network, reconnaissance, profiling of vulnerabilities, launching attacks, escalating privilege, maintaining access, and obscuring or removing information that indicates that an intruder was on the system. With irrefutable proof that an external attack can lead to a compromise of a computing resource on the organization's business local area network (LAN), access to the control network is usually considered the first phase in the attack plan. Once the attacker gains access to the control network through direct connections and/or the business LAN, the second phase of reconnaissance begins with traffic analysis within the control domain. Thus, the communications between the workstations and the field device controllers can be monitored and evaluated, allowing an attacker to capture, analyze, and evaluate the commands sent among the control equipment. Through manipulation of the communication protocols of control systems (a process generally referred to as ''reverse engineering''), an

  16. Drone Control System

    Science.gov (United States)

    1983-01-01

    Drones, subscale vehicles like the Firebees, and full scale retired military aircraft are used to test air defense missile systems. The DFCS (Drone Formation Control System) computer, developed by IBM (International Business Machines) Federal Systems Division, can track ten drones at once. A program called ORACLS is used to generate software to track and control Drones. It was originally developed by Langley and supplied by COSMIC (Computer Software Management and Information Center). The program saved the company both time and money.

  17. Magnetic spectrometer control system

    International Nuclear Information System (INIS)

    The design and implementation of a new computerized control system for the several devices of the magnetic spectrometer at TANDAR Laboratory is described. This system, as a main difference from the preexisting one, is compatible with almost any operating systems of wide spread use available in PC. This allows on-line measurement and control of all signals from any terminal of a computer network. (author)

  18. 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.

  19. Load Control System Reliability

    Energy Technology Data Exchange (ETDEWEB)

    Trudnowski, Daniel [Montana Tech of the Univ. of Montana, Butte, MT (United States)

    2015-04-03

    This report summarizes the results of the Load Control System Reliability project (DOE Award DE-FC26-06NT42750). The original grant was awarded to Montana Tech April 2006. Follow-on DOE awards and expansions to the project scope occurred August 2007, January 2009, April 2011, and April 2013. In addition to the DOE monies, the project also consisted of matching funds from the states of Montana and Wyoming. Project participants included Montana Tech; the University of Wyoming; Montana State University; NorthWestern Energy, Inc., and MSE. Research focused on two areas: real-time power-system load control methodologies; and, power-system measurement-based stability-assessment operation and control tools. The majority of effort was focused on area 2. Results from the research includes: development of fundamental power-system dynamic concepts, control schemes, and signal-processing algorithms; many papers (including two prize papers) in leading journals and conferences and leadership of IEEE activities; one patent; participation in major actual-system testing in the western North American power system; prototype power-system operation and control software installed and tested at three major North American control centers; and, the incubation of a new commercial-grade operation and control software tool. Work under this grant certainly supported the DOE-OE goals in the area of “Real Time Grid Reliability Management.”

  20. ISTTOK control system upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Ivo S., E-mail: ivoc@ipfn.ist.utl.pt; Duarte, Paulo; Fernandes, Horácio; Valcárcel, Daniel F.; Carvalho, Pedro J.; Silva, Carlos; Duarte, André S.; Neto, André; Sousa, Jorge; Batista, António J.N.; Carvalho, Bernardo B.

    2013-10-15

    Highlights: •ISTTOK fast controller. •All real-time diagnostic and actuators were integrated in the control platform. •100 μs control cycle under the MARTe framework. •The ISTTOK control system upgrade provides reliable operation with an improved operational space. -- Abstract: The ISTTOK tokamak (Ip = 4 kA, BT = 0.5 T, R = 0.46 m, a = 0.085 m) is one of the few tokamaks with regular alternate plasma current (AC) discharges scientific programme. In order to improve the discharge stability and to increase the number of AC discharge cycles a novel control system was developed. The controller acquires data from 50 analog-to-digital converter (ADC) channels of real-time diagnostics and measurements: tomography, Mirnov coils, interferometer, electric probes, sine and cosine probes, bolometer, current delivered by the power supplies, loop voltage and plasma current. The system has a control cycle of 100 μs during which it reads all the diagnostics connected to the advanced telecommunications computing architecture (ATCA) digitizers and sends the control reference to ISTTOK actuators. The controller algorithms are executed on an Intel{sup ®} Q8200 chip with 4 cores running at 2.33 GHz and connected to the I/O interfaces through an ATCA based environment. The real-time control system was programmed in C++ on top of the Multi-threaded Application Real-Time executor (MARTe). To extend the duration of the AC discharges and the plasma stability a new magnetising field power supply was commissioned and the horizontal and vertical field power supplies were also upgraded. The new system also features a user-friendly interface based on HyperText Markup Language (HTML) and Javascript to configure the controller parameters. This paper presents the ISTTOK control system and the consequent update of real-time diagnostics and actuators.

  1. Dynamics and control of multibody tethered systems

    Science.gov (United States)

    Kalantzis, S.; Modi, V. J.; Pradhan, S.; Misra, A. K.

    The equations of motion for a multibody tethered satellite system in a three dimensional Keplerian orbit are derived. The model considers a multi-satellite system connected in series by flexible tethers. Both tethers and subsatellites are free to undergo three dimensional attitude motion, together with longitudinal and transverse vibration for the tether. The elastic deformations of the tethers are discretized using the assumed-mode method. In addition, the tether attachment points to the subsatellites are kept arbitrary and time varying, with deployment and retrieval degrees of freedom. The governing equations of motion are derived using an Order ( N) Lagrangian formulation. Next, two independent controllers, i.e. an attitude and vibration controller, are designed to regulate the rigid and flexible motion present in the system, excited from various maneuvres performed during the course of a mission. The former controller utilizes the thrusters and momentum-wheels located on the rigid satellites with a control algorithm based on the feedback linearization technique. On the other hand, the latter is designed using the robust linear quadratic Gaussian-loop transfer recovery method actuating the variable tether attachment point, or offset position. Both controllers are successful in suppressing unwanted disturbances in the system in a acceptable amount of time.

  2. Systems of attitudes towards production in the pork industry. A cross-national study.

    Science.gov (United States)

    Sørensen, Bjarne Taulo; Barcellos, Marcia Dutra de; Olsen, Nina Veflen; Verbeke, Wim; Scholderer, Joachim

    2012-12-01

    Existing research on public attitudes towards agricultural production systems is largely descriptive, abstracting from the processes through which members of the general public generate their evaluations of such systems. The present paper adopts a systems perspective on such evaluations, understanding them as embedded into a wider attitude system that consists of attitudes towards objects of different abstraction levels, ranging from personal value orientations over general socio-political attitudes to evaluations of specific characteristics of agricultural production systems. It is assumed that evaluative affect propagates through the system in such a way that the system becomes evaluatively consistent and operates as a schema for the generation of evaluative judgments. In the empirical part of the paper, the causal structure of an attitude system from which people derive their evaluations of pork production systems was modelled. The analysis was based on data from a cross-national survey involving 1931 participants from Belgium, Denmark, Germany and Poland. The survey questionnaire contained measures of personal value orientations and attitudes towards environment and nature, industrial food production, food and the environment, technological progress, animal welfare, local employment and local economy. In addition, the survey included a conjoint task by which participants' evaluations of the importance of production system attributes were measured. The data were analysed by means of causal search algorithms and structural equation models. The results suggest that evaluative judgments of the importance of pork production system attributes are generated in a schematic manner, driven by personal value orientations. The effect of personal value orientations was strong and largely unmediated by attitudes of an intermediate level of generality, suggesting that the dependent variables in the particular attitude system that was modelled here can be understood as value

  3. ROV Motion Control Systems

    OpenAIRE

    Dukan, Fredrik

    2014-01-01

    This thesis is about automatic motion control systems for remotely operated vehicles (ROV). The work has focused on topics within guidance and navigation. In addition, a motion control system has been developed, implemented, tested and used on two ROVs in sea trials.The main motivation for the work has been the need to automate ROV tasks in order to make the ROV a more efficient tool for exploring the ocean space. Many parts of a motion control system for a ROV is similar to that of surface v...

  4. Control system integration

    CERN Document Server

    Shea, T J

    2008-01-01

    This lecture begins with a definition of an accelerator control system, and then reviews the control system architectures that have been deployed at the larger accelerator facilities. This discussion naturally leads to identification of the major subsystems and their interfaces. We shall explore general strategies for integrating intelligent devices and signal processing subsystems based on gate arrays and programmable DSPs. The following topics will also be covered: physical packaging; timing and synchronization; local and global communication technologies; interfacing to machine protection systems; remote debugging; configuration management and source code control; and integration of commercial software tools. Several practical realizations will be presented.

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

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    1997-01-01

    systems is limited, nevertheless, a solution of the Riccati equation gives an excellent frame for investigations provided in this paper. An observation that geomagnetic field changes approximately periodically when a satellite is on a near polar orbit is used throughout this paper. Three types of attitude...

  6. BeppoSAX attitude operations for GRB follow up

    International Nuclear Information System (INIS)

    This poster describes the attitude dynamics software, Attitude and Orbit Control Ground Support System (AOCGSS), which was developed by TELESPAZIO and integrated in the Operations Control Centre (OCC), in order to support the on ground operations of the Attitude and Orbit Control Subsystem (AOCS). In particular its involvement during the operations performed to carry out the Gamma Ray Burst (GRB) Follow Up is described

  7. 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.

  8. 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.

  9. Design and application of single-antenna GPS/accelerometers attitude determination system

    Institute of Scientific and Technical Information of China (English)

    He Jie; Huang Xianlin; Wang Guofeng

    2008-01-01

    In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system is of large volume, high cost, and complex structure, this approach is presented to determine the attitude based on vector space with single-antenna GPS and accelerometers in the micro inertial measurement unit (MIMU).It can provide real-time and accurate attitude information. Subsequently, the single-antenna GPS/SINS integrated navigation system is designed based on the combination of position, velocity, and attitude. Finally the semi-physical simulations of single-antenna GPS attitude determination system and single-antenna GPS/SINS integrated navigation system are carried out. The simulation results, based on measured data, show that the single-antenna GPS/SINS system can provide more accurate navigation information compared to the GPS/SINS system, based on the combination of position and velocity. Furthermore, the single-antenna GPS/SINS system is characteristic of lower cost and simpler structure. It provides the basis for the application of a single-antenna GPS/SINS integrated navigation system in a micro aerial vehicle (MAV).

  10. The Controllable Lifestyle Factor and Students' Attitudes about Specialty Selection.

    Science.gov (United States)

    Schwartz, Richard W.; And Others

    1990-01-01

    Students were asked to state their selected specialty and to rank the importance that each of 25 influences listed on a questionnaire had in making their specialty choice. Selected specialties were classified into three groups: noncontrollable lifestyle, controllable lifestyle, and surgery. (MLW)

  11. 姿态控制中的散开现象%Unwinding phenomenon in attitude control

    Institute of Scientific and Technical Information of China (English)

    何朕; 王广雄

    2015-01-01

    对散开现象提出了一种新的解释,并对姿态控制提出了一种新的PD型控制。实际应用中常用四元数来表示一刚体运动的姿态。可是四元数的状态空间S3对姿态集合SO(3)是双重覆叠的,即每一个姿态对应两个不同的四元数向量。这样,当采用四元数来进行反馈控制时,四元数的非唯一性会在q∈S3和-q∈S3的邻域分别形成一个吸引域和一个排斥域,从而导致了姿态控制的散开现象。文中用一个姿态控制的实例来说明这个不稳定现象。为了避免出现散开现象,提出了一个PD型的非线性控制器。这种控制器还有一个特点是能够以最小转角来回归平衡状态。%A new exposition of the unwinding phenomenon was presented and a new type of PD controller for attitude control was proposed. The quaternions are often used in practical applications to represent rig-id-body attitude. However, the quaternion state space S3 double covers the set of attitudes SO(3) in the sense that each attitude corresponds to two different quaternion vectors. Thus, in the case of feedback control using quaternions, this nonunique representation can give rise to regions of attraction and repul-sion in the neighborhood of q∈S3 and-q∈S3 , respectively, and cause the unwinding phenomenon of at-titude control. A practical attitude control example was presented to illustrate this unstable behavior. A PD-type nonlinear controller was proposed to avoid the unwinding phenomenon. This controller also has an advantage of retuning to the equilibrium state with minimum angle of rotation.

  12. Control systems under attack?

    CERN Document Server

    Lüders, Stefan

    2005-01-01

    The enormous growth of the Internet during the last decade offers new means to share and distribute both information and data. In Industry, this results in a rapprochement of the production facilities, i.e. their Process Control and Automation Systems, and the data warehouses. At CERN, the Internet opens the possibility to monitor and even control (parts of) the LHC and its four experiments remotely from anywhere in the world. However, the adoption of standard IT technologies to Distributed Process Control and Automation Systems exposes inherent vulnerabilities to the world. The Teststand On Control System Security at CERN (TOCSSiC) is dedicated to explore the vulnerabilities of arbitrary Commercial-Of-The-Shelf hardware devices connected to standard Ethernet. As such, TOCSSiC should discover their vulnerabilities, point out areas of lack of security, and address areas of improvement which can then be confidentially communicated to manufacturers. This paper points out risks of accessing the Control and Automa...

  13. An Application of UAV Attitude Estimation Using a Low-Cost Inertial Navigation System

    Science.gov (United States)

    Eure, Kenneth W.; Quach, Cuong Chi; Vazquez, Sixto L.; Hogge, Edward F.; Hill, Boyd L.

    2013-01-01

    Unmanned Aerial Vehicles (UAV) are playing an increasing role in aviation. Various methods exist for the computation of UAV attitude based on low cost microelectromechanical systems (MEMS) and Global Positioning System (GPS) receivers. There has been a recent increase in UAV autonomy as sensors are becoming more compact and onboard processing power has increased significantly. Correct UAV attitude estimation will play a critical role in navigation and separation assurance as UAVs share airspace with civil air traffic. This paper describes attitude estimation derived by post-processing data from a small low cost Inertial Navigation System (INS) recorded during the flight of a subscale commercial off the shelf (COTS) UAV. Two discrete time attitude estimation schemes are presented here in detail. The first is an adaptation of the Kalman Filter to accommodate nonlinear systems, the Extended Kalman Filter (EKF). The EKF returns quaternion estimates of the UAV attitude based on MEMS gyro, magnetometer, accelerometer, and pitot tube inputs. The second scheme is the complementary filter which is a simpler algorithm that splits the sensor frequency spectrum based on noise characteristics. The necessity to correct both filters for gravity measurement errors during turning maneuvers is demonstrated. It is shown that the proposed algorithms may be used to estimate UAV attitude. The effects of vibration on sensor measurements are discussed. Heuristic tuning comments pertaining to sensor filtering and gain selection to achieve acceptable performance during flight are given. Comparisons of attitude estimation performance are made between the EKF and the complementary filter.

  14. Control and Information Systems

    Directory of Open Access Journals (Sweden)

    Jiri Zahradnik

    2003-01-01

    Full Text Available The article deals with main tends of scientific research activities of Department of Control and Information Systems at the Faculty of Electrical Engineering of University of Zilina and its perspectives in this area.

  15. Fault Tolerant Control Systems

    DEFF Research Database (Denmark)

    Bøgh, S.A.

    requirements for a dedicated software environment for fault tolerant control systems design. The second detailed study addressed the detection of a fault event and determination of the failed component. A variety of algorithms were compared, based on two fault scenarios in the speed governor actuator setup......This thesis considered the development of fault tolerant control systems. The focus was on the category of automated processes that do not necessarily comprise a high number of identical sensors and actuators to maintain safe operation, but still have a potential for improving immunity to component...... failures. It is often feasible to increase availability for these control loops by designing the control system to perform on-line detection and reconfiguration in case of faults before the safety system makes a close-down of the process. A general development methodology is given in the thesis...

  16. Reset Control Systems

    CERN Document Server

    Baños, Alfonso

    2012-01-01

    Reset Control Systems addresses the analysis for reset control treating both its basic form which requires only that the state of the controller be reinitialized to zero (the reset action) each time the tracking error crosses zero (the reset condition), and some useful variations of the reset action (partial reset with fixed or variable reset percentage) and of the reset condition (fixed or variable reset band and anticipative reset). The issues regarding reset control – concepts and motivation; analysis tools; and the application of design methodologies to real-world examples – are given comprehensive coverage. The text opens with an historical perspective which moves from the seminal work of the Clegg integrator and Horowitz FORE to more recent approaches based on impulsive/hybrid control systems and explains the motivation for reset compensation. Preliminary material dealing with notation, basic definitions and results, and with the definition of the control problem under study is also included. The fo...

  17. Tautological control systems

    CERN Document Server

    Lewis, Andrew D

    2014-01-01

    This brief presents a description of a new modelling framework for nonlinear/geometric control theory. The framework is intended to be—and shown to be—feedback-invariant. As such, Tautological Control Systems provides a platform for understanding fundamental structural problems in geometric control theory. Part of the novelty of the text stems from the variety of regularity classes, e.g., Lipschitz, finitely differentiable, smooth, real analytic, with which it deals in a comprehensive and unified manner. The treatment of the important real analytic class especially reflects recent work on real analytic topologies by the author. Applied mathematicians interested in nonlinear and geometric control theory will find this brief of interest as a starting point for work in which feedback invariance is important. Graduate students working in control theory may also find Tautological Control Systems to be a stimulating starting point for their research.

  18. Compassionate attitude towards others' suffering activates the mesolimbic neural system.

    Science.gov (United States)

    Kim, Ji-Woong; Kim, Sung-Eun; Kim, Jae-Jin; Jeong, Bumseok; Park, Chang-Hyun; Son, Ae Ree; Song, Ji Eun; Ki, Seon Wan

    2009-08-01

    Compassion is one of the essential components which enable individuals to enter into and maintain relationships of caring. Compassion tends to motivate us to help people who are emotionally suffering. It is also known that a feeling of intrinsic reward may occur as a result of experiencing compassion for others. We conducted this study to understand the neural nature of compassion for other people's emotional state. Twenty-one healthy normal volunteers participated in this study. We used a 2 x 2 factorial design in which each subject was asked to assume a compassionate attitude or passive attitude while viewing the sad or neutral facial affective pictures during functional magnetic imaging. The main effect of a compassionate attitude was observed in the medial frontal cortex, the subgenual frontal cortex, the inferior frontal cortex and the midbrain regions. A test of the interaction between a compassionate attitude and sad facial affect revealed significant activations in the midbrain-ventral striatum/septal network region. The results of this study suggest that taking a compassionate attitude towards other people's sad expressions modulate the activities of the midbrain-ventral striatum/septal region network, which is known to play a role in the prosocial/social approach motivation and its accompanied rewarding feeling. PMID:19428038

  19. System and method for generating attitude determinations using GPS

    Science.gov (United States)

    Cohen, Clark E. (Inventor)

    1996-01-01

    A GPS attitude receiver for determining the attitude of a moving vehicle in conjunction with a first, a second, a third, and a fourth antenna mounted to the moving vehicle. Each of the antennas receives a plurality of GPS signals that each include a carrier component. For each of the carrier components of the received GPS signals there is an integer ambiguity associated with the first and fourth antennas, an integer ambiguity associated with second and fourth antennas, and an integer ambiguity associated with the third and fourth antennas. The GPS attitude receiver measures phase values for the carrier components of the GPS signals received from each of the antennas at a plurality of measurement epochs during an initialization period and at a measurement epoch after the initialization period. In response to the phase values measured at the measurement epochs during the initialization period, the GPS attitude receiver computes integer ambiguity resolution values representing resolution of the integer ambiguities. Then, in response to the computed integer ambiguity resolution values and the phase value measured at the measurement epoch after the initialization period, it computes values defining the attitude of the moving vehicle at the measurement epoch after the initialization period.

  20. [Attitude and perceived control of the elderly towards the consumption of anxiolytic, sedative and hypnotic medications].

    Science.gov (United States)

    Guindon, Marilyn; Cappeliez, Philippe

    2011-03-01

    This study examines the importance of variables from the Theory of Planned Behaviour (i.e., attitudes toward behaviour, subjective norms, and perceived control) for the prediction of consumption of anxiolytic and sedative-hypnotic (ASH) medications in a sample of older persons, aged 69 years on average, 62 consumers and 92 non-consumers. A favourable attitude toward ASH and a sense of having less control regarding these drugs predict both current usage and intention to continue. Perceived control predicts intention to start consumption of ASH in current non-consumers. This study underlines the importance of considering the role of the older person's decisional power in the consumption of these medications. PMID:21470438

  1. Design of Attitude Stability System for Prolate Dual-spin Satellite in Its Inclined Elliptical Orbit

    CERN Document Server

    Muliadi, J; Budiyono, A

    2008-01-01

    In general, most of communication satellites were designed to be operated in geostationary orbit. And many of them were designed in prolate dual-spin configuration. As a prolate dual-spin vehicle, they have to be stabilized against their internal energy dissipation effect. Several countries that located in southern hemisphere, has shown interest to use communication satellite. Because of those countries southern latitude, an idea emerged to incline the communication satellite (due to its prolate dualspin configuration) in elliptical orbit. This work is focused on designing Attitude Stability System for prolate dual-spin satellite in the effect of perturbed field of gravity due to the inclination of its elliptical orbit. DANDE (De-spin Active Nutation Damping Electronics) provides primary stabilization method for the satellite in its orbit. Classical Control Approach is used for the iteration of DANDE parameters. The control performance is evaluated based on time response analysis.

  2. Adaptive Inflow Control System

    CERN Document Server

    Volkov, Vasily Y; Zhuravlev, Oleg N; Nukhaev, Marat T; Shchelushkin, Roman V

    2014-01-01

    This article presents the idea and realization for the unique Adaptive Inflow Control System being a part of well completion, able to adjust to the changing in time production conditions. This system allows to limit the flow rate from each interval at a certain level, which solves the problem of water and gas breakthroughs. We present the results of laboratory tests and numerical calculations obtaining the characteristics of the experimental setup with dual-in-position valves as parts of adaptive inflow control system, depending on the operating conditions. The flow distribution in the system was also studied with the help of three-dimensional computer model. The control ranges dependences are determined, an influence of the individual elements on the entire system is revealed.

  3. Attitude toward the Patient Safety Culture in healthcare systems

    Directory of Open Access Journals (Sweden)

    Fereydoon Laal

    2016-04-01

    Full Text Available Introduction: Patient Safety Culture (PSC involves a harmonious pattern of individual and organization behaviors based on common beliefs and values. This study aimed to evaluate the attitude of healthcare providers toward PSC in the hospitals and clinics of Zabol city, Iran. Materials and Methods: This descriptive cross-sectional study was conducted in 2015. Sample population consisted of the physicians, nurses, and paraclinical staff (radiologists and laboratory experts engaged in different healthcare centers of Zabol city, Iran. Data were collected using the Hospital Survey on Patient Safety Culture (HSOPSC questionnaire. Data analysis was performed in SPSS V.22 at the significance level of 0.05. Results: In total, 231 healthcare practitioners were enrolled in this study. Participants were divided into three groups of physicians, nurses, and paraclinical staff (n=77, 33.33%. Mean of age and clinical experience was 29.94 and 6.23 years, respectively. Among the main aspects of PSC, “general understanding of patient safety” had the highest mean score (13.53, and the lowest mean score was achieved in “non-punitive response to error” (8.89. In the aspect of “manager expectations and actions promoting safety”, a significant difference was observed in the mean scores of the study groups (P=0.030. Moreover, our results showed a significant difference between the mean scores of physicians and nurses in the aspect of “openness and honesty in communication” (P=0.023. Conclusion: According to the results of this study, improvement of PSC is necessary for the efficient management of hospitals and clinics. This is attainable through collaborative and instructive workshops, developing educational programs, and designing incident reporting systems.

  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. The ISOLDE control system

    Science.gov (United States)

    Deloose, I.; Pace, A.

    1994-12-01

    The two CERN isotope separators named ISOLDE have been running on the new Personal Computer (PC) based control system since April 1992. The new architecture that makes heavy use of the commercial software and hardware of the PC market has been implemented on the 1700 geographically distributed control channels of the two separators and their experimental area. Eleven MSDOS Intel-based PCs with approximately 80 acquisition and control boards are used to access the equipment and are controlled from three PCs running Microsoft Windows used as consoles through a Novell Local Area Network. This paper describes the interesting solutions found and discusses the reduced programming workload and costs that have been obtained.

  6. FMIT facility control system

    International Nuclear Information System (INIS)

    The control system for the Fusion Materials Irradiation Test (FMIT) Facility, under construction at Richland, Washington, uses current techniques in distributed processing to achieve responsiveness, maintainability and reliability. Developmental experience with the system on the FMIT Prototype Accelerator (FPA) being designed at the Los Alamos National Laboratory is described as a function of the system's design goals and details. The functional requirements of the FMIT control system dictated the use of a highly operator-responsive, display-oriented structure, using state-of-the-art console devices for man-machine communications. Further, current technology has allowed the movement of device-dependent tasks into the area traditionally occupied by remote input-output equipment; the system's dual central process computers communicate with remote communications nodes containing microcomputers that are architecturally similar to the top-level machines. The system has been designed to take advantage of commercially available hardware and software

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

    International Nuclear Information System (INIS)

    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 (Fnet) 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. (paper)

  8. CNEOST Control Software System

    Science.gov (United States)

    Wang, Xin; Zhao, Hai-bin; Xia, Yan; Lu, Hao; Li, Bin

    2016-01-01

    In 2013, CNEOST (China Near Earth Object Survey Telescope) adapted its hardware system for the new CCD camera. Based on the new system architecture, the control software is re-designed and implemented. The software system adopts the messaging mechanism based on the WebSocket protocol, and possesses good flexibility and expansibility. The user interface based on the responsive web design has realized the remote observations under both desktop and mobile devices. The stable operation of the software system has greatly enhanced the operation efficiency while reducing the complexity, and has also made a successful attempt for the future system design of telescope and telescope cloud.

  9. Attitudes towards smoking and tobacco control among pre-clinical medical students in Malaysia.

    Science.gov (United States)

    Tee, G H; Hairi, N N; Hairi, F

    2012-08-01

    Physicians should play a leading role in combatting smoking; information on attitudes of future physicians towards tobacco control measures in a middle-income developing country is limited. Of 310 future physicians surveyed in a medical school in Malaysia, 50% disagreed that it was a doctor's duty to advise smokers to stop smoking; 76.8% agreed that physicians should not smoke before advising others not to smoke; and 75% agreed to the ideas of restricting the sale of cigarettes to minors, making all public places smoke-free and banning advertising of tobacco-related merchandise. Future physicians had positive attitudes towards tobacco regulations but had not grasped their responsibilities in tobacco control measures. PMID:22668450

  10. 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.

  11. Attitudes, norms and perceived behavioural control: explaining fertility intentions in Bulgaria

    OpenAIRE

    Billari, Francesco C.; Philipov, Dimiter; Testa, Maria Rita

    2009-01-01

    Abstract In this article, we study fertility decision-making through timing parity-progression intentions. The theoretical framework builds on Ajzen?s social-psychological ?Theory of Planned Behavior?: intentions are seen as directly dependent on three components: attitudes, norms and perceived behavioural control. We study the case of Bulgaria, a ?lowest-low? fertility country. In 2002, a sample survey containing a specially designed module was conducted. This module included an i...

  12. Neural Flight Control System

    Science.gov (United States)

    Gundy-Burlet, Karen

    2003-01-01

    The Neural Flight Control System (NFCS) was developed to address the need for control systems that can be produced and tested at lower cost, easily adapted to prototype vehicles and for flight systems that can accommodate damaged control surfaces or changes to aircraft stability and control characteristics resulting from failures or accidents. NFCS utilizes on a neural network-based flight control algorithm which automatically compensates for a broad spectrum of unanticipated damage or failures of an aircraft in flight. Pilot stick and rudder pedal inputs are fed into a reference model which produces pitch, roll and yaw rate commands. The reference model frequencies and gains can be set to provide handling quality characteristics suitable for the aircraft of interest. The rate commands are used in conjunction with estimates of the aircraft s stability and control (S&C) derivatives by a simplified Dynamic Inverse controller to produce virtual elevator, aileron and rudder commands. These virtual surface deflection commands are optimally distributed across the aircraft s available control surfaces using linear programming theory. Sensor data is compared with the reference model rate commands to produce an error signal. A Proportional/Integral (PI) error controller "winds up" on the error signal and adds an augmented command to the reference model output with the effect of zeroing the error signal. In order to provide more consistent handling qualities for the pilot, neural networks learn the behavior of the error controller and add in the augmented command before the integrator winds up. In the case of damage sufficient to affect the handling qualities of the aircraft, an Adaptive Critic is utilized to reduce the reference model frequencies and gains to stay within a flyable envelope of the aircraft.

  13. 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.

  14. 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.

  15. 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.

  16. Control Systems with Friction

    OpenAIRE

    Olsson, Henrik

    1996-01-01

    Friction-related problems are frequently encountered in control systems. This thesis treats three aspects of such problems: modeling, analysis, and friction compensation. A new dynamic friction model is presented and investigated. The model is described by a first order nonlinear differential equation with a reasonable number of parameters, yet it captures most of the experimentally observed friction phenomena. The model is suitable both for simulation purposes and control design. Analysis of...

  17. Design and validation of inverse optimisation software for the attitude control of microsatellites

    Science.gov (United States)

    Horri, N. M.; Palmer, P.; Roberts, M.

    2011-12-01

    The capabilities of microsatellite attitude control hardware have considerably evolved during the last two decades. However, three axis attitude control software is still predominantly based on the conservative use of standard flight proven PD type controllers, which are known to be limited in terms of rapidity for a prescribed level of energy consumption. Microsatellites are therefore typically not as agile as they could be. This conservatism is due to the complexity of implementing global numerical optimisation techniques to satellite attitude control. In this paper, we consider the model of a low earth orbiting microsatellite with a four wheel configuration, where the speed of one of the wheels is kept constant to provide a momentum bias and guarantee gyroscopic stiffness to disturbances. A geometric optimal control approach is presented, which circumvents the tedious tasks of numerically solving online the nonlinear optimisation problem. The approach is based on the design of suboptimal phase space trajectories. The phase space trajectory of a standard linear controller, typically a PD law with gyro-compensation, is used as a benchmark. The proposed inverse optimal control technique is then used to enforce higher convergence rate constraints than the benchmark law, without increasing the total energy consumption. The convergence rate of a Lyapunov function under the effect of the optimal controller outperforms the convergence rate of the same function under PD control and keeps increasing until a design settling time limit is reached. Guidelines are given for the tuning of the controller. The optimal attitude control algorithms are validated on a microsatellite software simulator in collaboration with the space company Surrey Satellite Technology Limited (SSTL). The software simulator incorporates a precise model of the effects of estimation errors, noise, external disturbances, sampling and actuator dynamics. The software is similar to the flight software of

  18. Nurses' Perceptions and Attitudes Toward Use of Oral Patient-Controlled Analgesia.

    Science.gov (United States)

    Riemondy, Susan; Gonzalez, Lorie; Gosik, Kirk; Ricords, Amy; Schirm, Victoria

    2016-04-01

    Patient-controlled analgesia (PCA) administered intravenously is a generally well-accepted therapy by nurses and patients. PCA devices are now available for oral medications, allowing patients to self-administer pain pills without requesting them from the nurse. Successful introduction of new pain medication delivery devices can depend on nurses' knowledge and attitudes. The aim of this institutional review board approved project was to evaluate nurses' perceptions and attitudes toward using an oral PCA device for patients' pain. A 4-week study was designed and conducted at an academic medical center on an orthopedic unit and a women's health unit. Nurse participants received education on using the oral PCA device and were invited to complete a pre- and poststudy knowledge and attitude survey regarding pain management. Nurses and patients also completed a questionnaire about perceptions related to using the oral PCA device. Findings showed that nurses' attitudes toward using the oral PCA device were less favorable than those of patients, suggesting that nurses may require additional education for acceptance of this device. Results from 37 nurses showed improvement in overall knowledge and attitudes, from 70.8% pretest to 74.2% post-test. Although improvement was not statistically significant (p = .1637), two items showed significant improvement. Knowledge about the effectiveness of NSAIDS was 27.5% pretest compared with 60.0% post-test (p = .0028); and understanding about use of opioids in patients with a history of substance abuse was 50% pretest compared with 70% post-test (p = .0531). Helping nurses overcome the perceived barriers to use of an oral PCA device has potential implications for better pain management as well as enhanced patient satisfaction. PMID:27091584

  19. neural control system

    International Nuclear Information System (INIS)

    Automatic power stabilization control is the desired objective for any reactor operation , especially, nuclear power plants. A major problem in this area is inevitable gap between a real plant ant the theory of conventional analysis and the synthesis of linear time invariant systems. in particular, the trajectory tracking control of a nonlinear plant is a class of problems in which the classical linear transfer function methods break down because no transfer function can represent the system over the entire operating region . there is a considerable amount of research on the model-inverse approach using feedback linearization technique. however, this method requires a prices plant model to implement the exact linearizing feedback, for nuclear reactor systems, this approach is not an easy task because of the uncertainty in the plant parameters and un-measurable state variables . therefore, artificial neural network (ANN) is used either in self-tuning control or in improving the conventional rule-based exper system.the main objective of this thesis is to suggest an ANN, based self-learning controller structure . this method is capable of on-line reinforcement learning and control for a nuclear reactor with a totally unknown dynamics model. previously, researches are based on back- propagation algorithm . back -propagation (BP), fast back -propagation (FBP), and levenberg-marquardt (LM), algorithms are discussed and compared for reinforcement learning. it is found that, LM algorithm is quite superior

  20. Aerojet - Attitude Control Engines. Chapter 3, Appendix E

    Science.gov (United States)

    Pfeifer, Gerald R.

    2009-01-01

    All the engines were both qualification and acceptance tested at Marquardt s facilities. After we won the Apollo Program contract, we went off and built two vacuum test facilities, which simulated altitude continuous firing for as long as we wanted to run an engine. They would run days and days with the same capability we had on steam ejection. We did all of the testing in both for the qualification and the acceptance test. One of them was a large ball, which was an eighteen-foot diameter sphere, evacuated again with a big steam ejector system that could be used for system testing; that s where we did the Lunar Excursion Module testing. We put the whole cluster in there and tested the entire cluster at the simulated altitude conditions. The lowest altitude we tested at - typically an acceptance test - was 105,000 feet simulated altitude. The big ball - because people were interested in what they called goop formation, which is an unburned hydrazine product migrating to cold surfaces on different parts of spacecraft - was built to address those kinds of issues. We ran long-life tests in a simulated space environment with the entire inside of the test cell around the test article, liquid nitrogen cooled, so it could act as getter for any of the exhaust products. That particular facility could pull down to about 350,000 feet (atmosphere) equivalent altitude, which was pushing pretty close to the thermodynamic triple point of the MMH. It was a good test facility. Those facilities are no longer there. When the guys at Marquardt sold the company to what eventually became part of Aerojet, all those test facilities were cut off at the roots. I think they have a movie studio there at this point. That part of it is truly not recoverable, but it did some excellent high-altitude, space-equivalent testing at the time. Surprisingly, we had very few problems while testing in the San Fernando Valley. In the early 1960s, nobody had ever seen dinitrogen tetroxide (N2O4), so that

  1. Tobacco control education, attitudes and beliefs of Nigerian health profession students

    Directory of Open Access Journals (Sweden)

    Oluwatunmise Awojobi

    2012-08-01

    Full Text Available Objectives: The purpose of this study is to explore tobacco control-related education of health profession students and demonstrate variations according to course of study. Methods: This was a cross-sectional survey of 154 of third year nursing, pharmacy, medical and dental students in a tertiary institution in Lagos, Nigeria. The validated Global Health Professional Students survey questionnaire was used to collect data on recall of tobacco-related training, attitudes to tobacco control and beliefs about the role of health professionals in tobacco control. This was voluntary and anonymous. Descriptive and univariate analysis were conducted. Results: Only 11.8(n=18 of all respondents recalled being trained on all possible items of formal tobacco-related training. Pharmacy students had significantly low levels of training recall (χ[sup]2[/sup][sub](3[/sub]=9.88; p=0.02. Nursing students were reported to have the most positive attitudes to tobacco control with the highest mean score of 4.27 (95= 3.88-4.66. However, there was no significant difference in attitudes to tobacco control. Compared to other students, Nursing students were significantly less likely to believe that as health professionals they had a role in tobacco-control (χ[sup]2[/sup][sub](3[/sub] = 8.06; p=0.045. Conclusions: Many respondents believed they have a role in providing cessation interventions and that specific training should be part of the education they receive. However, fewer respondents report receiving such training. The education and training of these samples of health profession students needs to place more emphasis on their role in tobacco control if they are to effectively function as health promoting health professionals in preventing tobacco-related diseases.

  2. Precision Pointing Control System (PPCS) system design and analysis. [for gimbaled experiment platforms

    Science.gov (United States)

    Frew, A. M.; Eisenhut, D. F.; Farrenkopf, R. L.; Gates, R. F.; Iwens, R. P.; Kirby, D. K.; Mann, R. J.; Spencer, D. J.; Tsou, H. S.; Zaremba, J. G.

    1972-01-01

    The precision pointing control system (PPCS) is an integrated system for precision attitude determination and orientation of gimbaled experiment platforms. The PPCS concept configures the system to perform orientation of up to six independent gimbaled experiment platforms to design goal accuracy of 0.001 degrees, and to operate in conjunction with a three-axis stabilized earth-oriented spacecraft in orbits ranging from low altitude (200-2500 n.m., sun synchronous) to 24 hour geosynchronous, with a design goal life of 3 to 5 years. The system comprises two complementary functions: (1) attitude determination where the attitude of a defined set of body-fixed reference axes is determined relative to a known set of reference axes fixed in inertial space; and (2) pointing control where gimbal orientation is controlled, open-loop (without use of payload error/feedback) with respect to a defined set of body-fixed reference axes to produce pointing to a desired target.

  3. Control of complex systems

    CERN Document Server

    Albertos, Pedro; Blanke, Mogens; Isidori, Alberto; Schaufelberger, Walter; Sanz, Ricardo

    2001-01-01

    The world of artificial systems is reaching complexity levels that es­ cape human understanding. Surface traffic, electricity distribution, air­ planes, mobile communications, etc. , are examples that demonstrate that we are running into problems that are beyond classical scientific or engi­ neering knowledge. There is an ongoing world-wide effort to understand these systems and develop models that can capture its behavior. The reason for this work is clear, if our lack of understanding deepens, we will lose our capability to control these systems and make they behave as we want. Researchers from many different fields are trying to understand and develop theories for complex man-made systems. This book presents re­ search from the perspective of control and systems theory. The book has grown out of activities in the research program Control of Complex Systems (COSY). The program has been sponsored by the Eu­ ropean Science Foundation (ESF) which for 25 years has been one of the leading players in stimula...

  4. The Relationship between Justice and Attitudes: An Examination of Justice Effects on Event and System-Related Attitudes

    Science.gov (United States)

    Ambrose, Maureen; Hess, Ronald L.; Ganesan, Shankar

    2007-01-01

    Research in organizational justice has always been interested in the relationship between justice and attitudes. This research often examines how different types of justice affect different attitudes, with distributive justice predicted to affect attitudes about specific events (e.g., performance evaluation) and procedural justice predicted to…

  5. Electric turbocompound control system

    Energy Technology Data Exchange (ETDEWEB)

    Algrain, Marcelo C. (Dunlap, IL)

    2007-02-13

    Turbocompound systems can be used to affect engine operation using the energy in exhaust gas that is driving the available turbocharger. A first electrical device acts as a generator in response to turbocharger rotation. A second electrical device acts as a motor to put mechanical power into the engine, typically at the crankshaft. Apparatus, systems, steps, and methods are described to control the generator and motor operations to control the amount of power being recovered. This can control engine operation closer to desirable parameters for given engine-related operating conditions compared to actual. The electrical devices can also operate in "reverse," going between motor and generator functions. This permits the electrical device associated with the crankshaft to drive the electrical device associated with the turbocharger as a motor, overcoming deficient engine operating conditions such as associated with turbocharger lag.

  6. 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.

  7. 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.

  8. The roles of users personal characteristics and organisational support in the attitude towards using ERP systems in a Spanish public hospital.

    Science.gov (United States)

    Escobar-Rodriguez, Tomas; Bartual-Sopena, Lourdes

    2013-01-01

    Enterprise resources planning (ERP) systems enable central and integrative control over all processes throughout an organisation by ensuring one data entry point and the use of a common database. T his paper analyses the attitude of healthcare personnel towards the use of an ERP system in a Spanish public hospital, identifying influencing factors. This research is based on a regression analysis of latent variables using the optimisation technique of partial least squares. We propose a research model including possible relationships among different constructs using the technology acceptance model. Our results show that the personal characteristics of potential users are key factors in explaining attitude towards using ERP systems.

  9. The method of testing of the attitude reference systems with optoelectronic sensors

    Science.gov (United States)

    Szelmanowski, Andrzej; Michalak, Slawomir

    2003-09-01

    What the paper deals with is the method of testing of the attitude reference systems with the coning excitation/motion applied. A theoretical description of the excitation at issue has been given and followed with a comparative analysis of the excitation generated in the UPG-48 station with a tilting platform. Experimental data of testing of the attitude and heading reference system AHRS LCR-92 system for the non-holonomical excitation/motion have been compared with results effected by some simulation-based tests of numerical models of the attitude and heading reference systems with the optoelectronic sensors. On the grounds of some numerical-simulation-effected findings gained with the AutoCAD packet, a concept of a coning-excitation-generating measuring station has been developed at the Air Force Institute of Technology and presented in this paper.

  10. 基于Simulink/Stateflow的小卫星姿态控制模块设计一仿研究%Simulink/Stateflow Based Attitude Control Block Design and Sinulation of Small Satellite

    Institute of Scientific and Technical Information of China (English)

    吕波; 曾国强; 姚红; 胡敏

    2011-01-01

    According to demands of autonomous operation of small satellite on orbit, the design and simulation of attitude control block was researched on, satellite attitude motion and builded attitude control law were described by modified rodrigues parameters, six kinds of attitude control mode and it' s transform logic were designed using stateflow, and attitude control simulation system was alse constructed using simulink. Attitude control simulation analysis was carried on time sequence commands of nadir pointing mode, target pointing mode and idle mode, and the attitude convergence result was achieved, which indicated that the design of attitude control law and transform logic among attitude control modes was correct.%针对小卫星在轨自主运行的需要,对其姿态控制模块进行设计与仿真研究,其中使用修正罗德里格参数描述卫星姿态运动并进行姿态控制律设计,使用Stateflow设计了六种姿态控制模式及其转换逻辑并结合Simulink搭建了姿态控制仿真系统.根据对地定向模式、目标指向模式、闲置模式的时序指令进行了姿态控制仿真分析,三种模式下姿态均收敛,说明了姿态控制律设计和姿态控制模式之间转换逻辑设计的正确性.

  11. Design of Four Rotor Attitude Controller Based on ARM%基于AR M的四旋翼姿态控制器设计

    Institute of Scientific and Technical Information of China (English)

    吴承建; 沈捷; 陈乾坤

    2016-01-01

    四旋翼姿态控制器采用集成了加速度计和陀螺仪的惯性测量单元,实时采集姿态数据,传输给Cortex-M4内核的处理芯片,利用四元数姿态解算方法,对加速度和角速度数据融合解算处理;采用位置式PID控制算法,控制4个无刷电机的转速,实现控制四旋翼飞行器的飞行姿态;建立万向云台调试系统,通过实践调试验证该控制器能实现控制四旋翼姿态的稳定性;稳定飞行时,姿态角的平均振荡范围为5°。%Four rotor attitude controller adopts the inertial measurement unit which integrated accelerometer with gyro,gather attitude data real-time,then transferred to the Cortex-M4 core processing chips,Using the attitude of quaternion calculation method,the data in-tegration of acceleration and angular velocity is calculated.And use positional PID control algorithm to control four brushless motor speed to achieve controlled four-rotor aircraft flight attitude.Establish universal platform debug system,through the practice of testing to verify controller can achieve the stability control of four rotor profile.The stable flight attitude average oscillation angle range is 5 degree.

  12. Incoherent control of locally controllable quantum systems

    International Nuclear Information System (INIS)

    An incoherent control scheme for state control of locally controllable quantum systems is proposed. This scheme includes three steps: (1) amplitude amplification of the initial state by a suitable unitary transformation, (2) projective measurement of the amplified state, and (3) final optimization by a unitary controlled transformation. The first step increases the amplitudes of some desired eigenstates and the corresponding probability of observing these eigenstates, the second step projects, with high probability, the amplified state into a desired eigenstate, and the last step steers this eigenstate into the target state. Within this scheme, two control algorithms are presented for two classes of quantum systems. As an example, the incoherent control scheme is applied to the control of a hydrogen atom by an external field. The results support the suggestion that projective measurements can serve as an effective control and local controllability information can be used to design control laws for quantum systems. Thus, this scheme establishes a subtle connection between control design and controllability analysis of quantum systems and provides an effective engineering approach in controlling quantum systems with partial controllability information.

  13. Modular thyristor controlled series capacitor control system

    Energy Technology Data Exchange (ETDEWEB)

    Clark, K.; Larsen, E.V.; Wegner, C.A.; Piwko, R.J.

    1995-06-13

    A modular thyristor controlled series capacitor (TCSC) system, including a method and apparatus, uses phase controlled firing based on monitored capacitor voltage and line current. For vernier operation, the TCSC system predicts an upcoming firing angle for switching a thyristor controlled commutating circuit to bypass line current around a series capacitor. Each bypass current pulse changes the capacitor voltage proportionally to the integrated value of the current pulse. The TCSC system promptly responds to an offset command from a higher-level controller to control bypass thyristor duty to minimize thyristor damage, and to prevent capacitor voltage drift during line current disturbances. In a multi-module TCSC system, the higher level controller accommodates competing objectives of various system demands, including minimizing losses in scheduling control, stabilizing transients, damping subsynchronous resonance (SSR) oscillations, damping direct current (DC) offset, and damping power-swings. 67 figs.

  14. Telerobotic virtual control system

    Science.gov (United States)

    Zhai, Shumin; Milgram, Paul

    1992-03-01

    A project to develop a telerobotic `virtual control' capability, currently underway at the University of Toronto, is described. The project centers on a new mode of interactive telerobotic control based on the technology of combining computer generated stereographic images with remotely transmitted stereoscopic video images. A virtual measurement technique, in conjunction with a basic level of digital image processing, comprising zooming, parallax adjustment, edge enhancement, and edge detection has been developed to assist the human operator in visualization of the remote environment and in spatial reasoning. The aim is to maintain target recognition, tactical planning, and high-level control functions in the hands of the human operator with the computer performing low-level computation and control. Control commands initiated by the operator are implemented through manipulation of a virtual image of the robot system, merged with a live video image of the remote scene. This paper discusses the philosophy and objectives of the project, with emphasis on the underlying human factor considerations in the design, and reports the progress made to date in this effort.

  15. Control rod drive system

    International Nuclear Information System (INIS)

    The present invention concerns an electromotive driving-type control rod driving system of a BWR type reactor, for which sliding resistance (friction) test can be performed of a movable portion of the control rod driving mechanisms. Namely, a hydraulic pressure control unit has following constitutions in addition to a conventional constitution as a sliding resistance test performing function. (1) A restricting valve is disposed downstream of the scram valve of scram pipelines to control flow rate and pressure of pressurized water flown in the pipelines. (2) A pressure gauge detects a pressure between the scram valve and the restricting valve. (3) A flow meter detects the flow rate of pipelines controlled by the restricting valve. (4) A recording pressure detector detects the pressure at the downstream of the restricting valve. (5) The recording device is attached when the sliding resistant test is performed for tracing the pressure measured by the pressure detection device. Further, the scram valve sends electric signals to a central operation chamber when it is fully closed. The central operation chamber has a function of fully opening the restricting valve by way of the electric signals. (I.S.)

  16. Controlled Quantum Open Systems

    CERN Document Server

    Alicki, R

    2003-01-01

    The theory of controlled quantum open systems describes quantum systems interacting with quantum environments and influenced by external forces varying according to given algorithms. It is aimed, for instance, to model quantum devices which can find applications in the future technology based on quantum information processing. One of the main problems making difficult the practical implementations of quantum information theory is the fragility of quantum states under external perturbations. The aim of this note is to present the relevant results concerning ergodic properties of open quantum systems which are useful for the optimization of quantum devices and noise (errors) reduction. In particular we present mathematical characterization of the so-called "decoherence-free subspaces" for discrete and continuous-time quantum dynamical semigroups in terms of $C^*$-algebras and group representations. We analyze the non-Markovian models also, presenting the formulas for errors in the Born approximation. The obtain...

  17. Crawling the Control System

    Energy Technology Data Exchange (ETDEWEB)

    Theodore Larrieu

    2009-10-01

    Information about accelerator operations and the control system resides in various formats in a variety of places on the lab network. There are operating procedures, technical notes, engineering drawings, and other formal controlled documents. There are programmer references and API documentation generated by tools such as doxygen and javadoc. There are the thousands of electronic records generated by and stored in databases and applications such as electronic logbooks, training materials, wikis, and bulletin boards and the contents of text-based configuration files and log files that can also be valuable sources of information. The obvious way to aggregate all these sources is to index them with a search engine that users can then query from a web browser. Toward this end, the Google "mini" search appliance was selected and implemented because of its low cost and its simple web-based configuration and management. In addition to crawling and indexing electronic documents, the appliance provides an API that has been used to supplement search results with live control system data such as current values of EPICS process variables and graphs of recent data from the archiver.

  18. MIRADAS control system

    Science.gov (United States)

    Rosich Minguell, Josefina; Garzón Lopez, Francisco

    2012-09-01

    The Mid-resolution InfRAreD Astronomical Spectrograph (MIRADAS, a near-infrared multi-object echelle spectrograph operating at spectral resolution R=20,000 over the 1-2.5μm bandpass) was selected in 2010 by the Gran Telescopio Canarias (GTC) partnership as the next-generation near-infrared spectrograph for the world's largest optical/infrared telescope, and is being developed by an international consortium. The MIRADAS consortium includes the University of Florida, Universidad de Barcelona, Universidad Complutense de Madrid, Instituto de Astrofísica de Canarias, Institut de Física d'Altes Energies, Institut d'Estudis Espacials de Catalunya and Universidad Nacional Autónoma de México. This paper shows an overview of the MIRADAS control software, which follows the standards defined by the telescope to permit the integration of this software on the GTC Control System (GCS). The MIRADAS Control System is based on a distributed architecture according to a component model where every subsystem is selfcontained. The GCS is a distributed environment written in object oriented C++, which runs components in different computers, using CORBA middleware for communications. Each MIRADAS observing mode, including engineering, monitoring and calibration modes, will have its own predefined sequence, which are executed in the GCS Sequencer. These sequences will have the ability of communicating with other telescope subsystems.

  19. 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.

  20. Robust H∞ control for networked control systems

    Institute of Scientific and Technical Information of China (English)

    Ma Weiguo; Shao Cheng

    2008-01-01

    The robust H∞ control for networked control systems with both stochastic network-induced delay and data packet dropout is studied.When data are transmitted over network,the stochastic data packet dropout process can be described by a two-state Markov chain.The networked control systems with stochastic network-induced delay and data packet dropout are modeled as a discrete time Markov jump linear system with two operation modes.The sufficient condition of robust H∞ control for networked control systems stabilized by state feedback controller is presented in terms of linear matrix inequality.The state feedback controller can be constructed via the solution of a set of linear matrix inequalities.An example is given to verify the effectiveness of the method proposed.

  1. Farmer attitudes and livestock disease: exploring citizenship behaviour and peer monitoring across two BVD control schemes in the UK

    OpenAIRE

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

    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 colle...

  2. Farmer attitudes and livestock disease:Exploring citizenship behaviour and peer monitoring across two BVD control schemes in the UK

    OpenAIRE

    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 colle...

  3. Angular Velocity Observer on the Special Orthogonal Group for Velocity-Free Rigid-Body Attitude Tracking Control

    OpenAIRE

    Wu, Tse-Huai; Lee, Taeyoung

    2015-01-01

    This paper studies a rigid body attitude tracking control problem with attitude measurements only, when angular velocity measurements are not available. An angular velocity observer is constructed such that the estimated angular velocity is guaranteed to converge to the true angular velocity asymptotically from almost all initial estimates. As it is developed directly on the special orthogonal group, it completely avoids singularities, complexities, or discontinuities caused by minimal attitu...

  4. 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. PMID:23775132

  5. Evaluation of the Geomagnetic Field Models based on Magnetometer Measurements for Satellite's Attitude Determination System

    Science.gov (United States)

    Cilden, Demet; Kaymaz, Zerefsan; Hajiyev, Chingiz

    2016-07-01

    Magnetometers are common attitude determination sensors for small satellites at low Earth orbit; therefore, magnetic field model of the Earth is necessary to estimate the satellite's attitude angles. Difference in the components of the magnetic field vectors -mostly used as unit vector. Therefore the angle between them (model and measurement data) affects the estimation accuracy of the satellite's attitude. In this study, geomagnetic field models are compared with satellite magnetic field observations in order to evaluate the models using the magnetometer results with high accuracy. For attitude determination system, IGRF model is used in most of the cases but the difference between the sensor and model increases when the geomagnetic activity occurs. Hence, several models including the empirical ones using the external variations in the Earth's geomagnetic field resulting from the solar wind and interplanetary magnetic field are of great importance in determination of the satellite's attitude correctly. IGRF model describes the internal-part of the geomagnetic field, on the other hand candidate models to IGRF, such as recently developed POMME-6 model based on Champ data, CHAOS-5 (CHAmp, Oersted, Swarm), T89 (Tsyganenko's model), include simple parameterizations of external fields of magnetospheric sources in addition to the internal field especially for low Earth orbiting satellites. Those models can be evaluated to see noticeable difference on extraterrestrial field effects on satellite's attitude determination system changing with its height. The comparisons are made between the models and observations and between the models under various magnetospheric activities. In this study, we will present our preliminary results from the comparisons and discuss their implications from the satellite attitude perspective.

  6. 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.

  7. BLTC control system software

    Energy Technology Data Exchange (ETDEWEB)

    Logan, J.B., Fluor Daniel Hanford

    1997-02-10

    This is a direct revision to Rev. 0 of the BLTC Control System Software. The entire document is being revised and released as HNF-SD-FF-CSWD-025, Rev 1. The changes incorporated by this revision include addition of a feature to automate the sodium drain when removing assemblies from sodium wetted facilities. Other changes eliminate locked in alarms during cold operation and improve the function of the Oxygen Analyzer. See FCN-620498 for further details regarding these changes. Note the change in the document number prefix, in accordance with HNF-MD-003.

  8. Matlab control systems engineering

    CERN Document Server

    Lopez, Cesar

    2014-01-01

    MATLAB is a high-level language and environment for numerical computation, visualization, and programming. Using MATLAB, you can analyze data, develop algorithms, and create models and applications. The language, tools, and built-in math functions enable you to explore multiple approaches and reach a solution faster than with spreadsheets or traditional programming languages, such as C/C++ or Java. MATLAB Control Systems Engineering introduces you to the MATLAB language with practical hands-on instructions and results, allowing you to quickly achieve your goals. In addition to giving an in

  9. 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.

  10. Distributed event-triggered cooperative attitude control of multiple rigid bodies with leader-follower architecture

    Science.gov (United States)

    Weng, Shengxuan; Yue, Dong

    2016-02-01

    In this note, the distributed event-triggered cooperative attitude control of multiple rigid bodies with leader-follower architecture is investigated, where both the cases of static and dynamic leaders are all considered. Two distributed triggering procedures are first introduced for the followers and leaders, and then the distributed cooperative controllers are designed under the proposed triggering schemes. Under the designed controllers with the event-triggered strategies, it is shown that the orientations of followers converge to the convex hull formed by the desired leaders' orientations with zero angular velocities. Moreover, the communication pressure in network is reduced and the energy of each agent is saved. Simulation results show the effectiveness of the proposed method.

  11. 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.

  12. 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.

  13. Attitude Ground System (AGS) for the Magnetospheric Multi-Scale (MMS) Mission

    Science.gov (United States)

    Raymond, Juan C.; Sedlak, Joseph E.; Vint, Babak

    2015-01-01

    MMS Overview Recall from Conrads presentation earlier today MMS launch: March 13, 2015 on an Atlas V from Space Launch Complex 40, Cape Canaveral, Florida MMS Observatory Separation: five minute intervals spinning at 3 rpm approximately 1.5 hours after launch MMS Science Goals: study magnetospheric plasma physics and understand the processes that cause power grids, communication disruptions and Aurora formation Mission: 4 identical spacecraft in tetrahedral formation with variable size1.2 x 12 RE in Phase 1, with apogee on dayside to observe bow shock1.2 x 25 RE in Phase 2, with apogee on night side to observe magneto tail Challenges Tight attitude control box, orbit and formation maintenance requirements Maneuvers on thrusters every two weeks Delta-H Spin axis direction and spin rate maintenance Delta-V Orbit and Formation maintenance Mission phase transitions AGS support Smart targeting prediction of Spin-Axis attitude in the presence of environmental torques to stay within the science attitude Determination of the spacecraft attitude and spin rate (sensitive to knowledge of inertia tensor)Calibrations to improve attitude determination results and improve orbit maneuvers Mass properties (Center of Mass, and inertia tensor for nutation and coning) Accelerometer bias (sensitive to the accuracy of the rate estimates) Sensor alignments.

  14. Dynamics of a variable mass system applied to spacecraft rocket attitude theory

    Science.gov (United States)

    Mudge, Jason Dominic

    This research project is a study of the dynamics of a variable mass system. The scope of this research project is to gain understanding as to how a variable mass system will behave. The intent is to bring the level of understanding of variable mass dynamics higher and closer to the level of constant mass dynamics in the area of spacecrafts in particular. A main contribution is the finding of a set of criteria to minimize or eliminate the deviation of the nutation angle (or cone angle or angle of attack) of spacecraft rockets passively, i.e. without active control. The motivation for this research project is the Star 48 anomaly. The Star 48 is a solid rocket motor which has propelled (boosted) communication satellites from lower earth orbit to a higher one during the 1980's. The anomaly is that when the spacecraft rocket is being propelled, the nutation angle may deviate excessively which is considered undesirable. In the first part of this research project, a variable mass system is described and defined and the governing equations are derived. The type of governing equations derived are those that are most useful for analyzing the motion of a spacecraft rocket. The method of derivation makes use of Leibnitz Theorem, Divergence Theorem and Newton's Second Law of Motion. Next, the governing equations are specialized with several assumptions which are generally accepted assumptions applied in the analysis of spacecraft rockets. With these assumptions, the form governing equations is discussed and then the equations are solved analytically for the system's angular velocity. Having solved for the angular velocity of the system, the attitude of the system is obtained using a unique method which circumvents the nonlinearities that exist using Euler Angles and their kinematical equations. The attitude is approximately found analytically and a set of criteria is discussed which will minimize or eliminate the deviation of the nutation angle of a spacecraft rocket. Finally

  15. 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.

  16. Performance analysis of an integrated GPS/inertial attitude determination system. M.S. Thesis - MIT

    Science.gov (United States)

    Sullivan, Wendy I.

    1994-01-01

    The performance of an integrated GPS/inertial attitude determination system is investigated using a linear covariance analysis. The principles of GPS interferometry are reviewed, and the major error sources of both interferometers and gyroscopes are discussed and modeled. A new figure of merit, attitude dilution of precision (ADOP), is defined for two possible GPS attitude determination methods, namely single difference and double difference interferometry. Based on this figure of merit, a satellite selection scheme is proposed. The performance of the integrated GPS/inertial attitude determination system is determined using a linear covariance analysis. Based on this analysis, it is concluded that the baseline errors (i.e., knowledge of the GPS interferometer baseline relative to the vehicle coordinate system) are the limiting factor in system performance. By reducing baseline errors, it should be possible to use lower quality gyroscopes without significantly reducing performance. For the cases considered, single difference interferometry is only marginally better than double difference interferometry. Finally, the performance of the system is found to be relatively insensitive to the satellite selection technique.

  17. Analysis of state-of-the-art single-thruster attitude control techniques for spinning penetrator

    Science.gov (United States)

    Raus, Robin; Gao, Yang; Wu, Yunhua; Watt, Mark

    2012-07-01

    The attitude dynamics and manoeuvre survey in this paper is performed for a mission scenario involving a penetrator-type spacecraft: an axisymmetric prolate spacecraft spinning around its minor axis of inertia performing a 90° spin axis reorientation manoeuvre. In contrast to most existing spacecraft only one attitude control thruster is available, providing a control torque perpendicular to the spin axis. Having only one attitude thruster on a spinning spacecraft could be preferred for spacecraft simplicity (lower mass, lower power consumption etc.), or it could be imposed in the context of redundancy/contingency operations. This constraint does yield restrictions on the thruster timings, depending on the ratio of minor to major moments of inertia among other parameters. The Japanese Lunar-A penetrator spacecraft proposal is a good example of such a single-thruster spin-stabilised prolate spacecraft. The attitude dynamics of a spinning rigid body are first investigated analytically, then expanded for the specific case of a prolate and axisymmetric rigid body and finally a cursory exploration of non-rigid body dynamics is made. Next two well-known techniques for manoeuvring a spin-stabilised spacecraft, the Half-cone/Multiple Half-cone and the Rhumb line slew, are compared with two new techniques, the Sector-Arc Slew developed by Astrium Satellites and the Dual-cone developed at Surrey Space Centre. Each technique is introduced and characterised by means of simulation results and illustrations based on the penetrator mission scenario and a brief robustness analysis is performed against errors in moments of inertia and spin rate. Also, the relative benefits of each slew algorithm are discussed in terms of slew accuracy, energy (propellant) efficiency and time efficiency. For example, a sequence of half-cone manoeuvres (a Multi-half-cone manoeuvre) tends to be more energy-efficient than one half-cone for the same final slew angle, but more time-consuming. As another

  18. Guaranteed cost control for networked control systems

    Institute of Scientific and Technical Information of China (English)

    Linbo XIE; Huajing FANG; Ying ZHENG

    2004-01-01

    The guaranteed cost control problem for networked control systems (NCSs) is addressed under communication constraints and varying sampling rate. First of all, a simple information-scheduling scheme is presented to describe the scheduling approach of system signals in NCSs. Then, based on such a scheme and given sampling method, the design procedure in dynamic output feedback manner is also derived which renders the closed loop system to be asymptotically stable and guarantees an upper bound of the LQ performance cost function.

  19. 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.

  20. Space station structural dynamics/reaction control system interaction study

    Science.gov (United States)

    Pinnamaneni, M.; Murray, J.

    1987-01-01

    The performance of the Reaction Control System is impacted by the extreme flexibility of the space station structure. The method used to analyze the periodic thrust profile of a simple form of phase plane logic is presented. The results illustrate the effect on flexible body response of the type of phase plane logic utilized and the choice of control parameters: cycle period and attitude deadband.

  1. Optically controlled welding system

    Science.gov (United States)

    Gordon, Stephen S. (Inventor)

    1989-01-01

    An optically controlled welding system (10) wherein a welding torch (12) having through-the-torch viewing capabilities is provided with an optical beam splitter (56) to create a transmitted view and a reflective view of a welding operation. These views are converted to digital signals which are then processed and utilized by a computerized robotic welder (15) to make the welding torch responsive thereto. Other features includes an actively cooled electrode holder (26) which minimizes a blocked portion of the view by virtue of being constructed of a single spoke or arm (28) and a weld pool contour detector (14) comprising a laser beam directed onto the weld pool with the position of specular radiation reflected therefrom being characteristic of a penetrated or unpenetrated condition of the weld pool.

  2. Factors Related to Faculty Members' Attitude and Adoption of a Learning Management System

    Science.gov (United States)

    Wichadee, Saovapa

    2015-01-01

    Learning Management Systems (LMS) play a crucial role in organizing the course contents. However, some instructors use LMS in their classes while some do not. This study aimed to discover the factors in relation to the instructors' attitude toward LMS and adoption of LMS in their course. A survey was administered to 62 instructors to follow up the…

  3. Attitudes of Saudi Universities Faculty Members towards Using Learning Management System (JUSUR)

    Science.gov (United States)

    Hussein, Hisham Barakat

    2011-01-01

    The research aims to identify the Attitudes of faculty members at Saudi Universities towards using E-learning Management System JUSUR, which follows the National Center for E-learning. A descriptive analysis was used as a research methodology. Ninety participants in this research were asked to complete a 5-point Likert scale questionnaire, which…

  4. Use and Attitude towards Learning Management Systems (LMS) in Saudi Arabian Universities

    Science.gov (United States)

    Alghamdi, Saleh Ramadhan; Bayaga, Anass

    2016-01-01

    This paper was designed to establish the relationships between faculty members' use and attitude towards Learning Management Systems (LMSs). LMSs have been adopted in various educational institutions due to their numerous applications and functionalities to improve pedagogy. As a result, faculty members are urged to utilise them for enhancing…

  5. Gender Differences in Attitudes toward Computers and Performance in the Accounting Information Systems Class

    Science.gov (United States)

    Lenard, Mary Jane; Wessels, Susan; Khanlarian, Cindi

    2010-01-01

    Using a model developed by Young (2000), this paper explores the relationship between performance in the Accounting Information Systems course, self-assessed computer skills, and attitudes toward computers. Results show that after taking the AIS course, students experience a change in perception about their use of computers. Females'…

  6. Attitudes of Deaf Adults Regarding Preferred Sign Language Systems Used in the Classroom with Deaf Students.

    Science.gov (United States)

    Kautzky-Bowden, Sally M.; Gonzales, B. Robert

    1987-01-01

    A questionnaire survey assessing attitudes of 50 deaf adults toward sign language systems used in schools found the majority supported American Sign Language and Manually Coded English-Pidgin with some reservations. Respondents were also concerned about needs of individual deaf children and deaf adult involvement in educational decision making for…

  7. Explaining attitudes towards the justice system in the UK and Europe

    NARCIS (Netherlands)

    S.G.J. Van de Walle (Steven); J.W. Raine (John)

    2008-01-01

    markdownabstract__Summary__ _Objectives_ The main objective of this study was to analyse citizens’ attitudes towards the justice system and their determinants, both in the UK and internationally. Based on a literature review and an analysis of existing opinion data, it maps common reasons for di

  8. Nonlinear control for dual quaternion systems

    Science.gov (United States)

    Price, William D.

    addressed via coordinate transformation. It is shown that driftless nonlinear systems that do not meet Brockett's conditions for coordinate transformation can be augmented such that they can be transformed into the Brockett's canonical form, which is nonholonomic. It is also shown that the kinematics for quaternion systems can be represented by a nonholonomic integrator. Then, a discontinuous controller designed for nonholonomic systems is applied. Examples of various applications for dual quaternion systems are given including spacecraft attitude and position control and robotics.

  9. 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.

  10. Psychological and Psychophysiological Research of the Attitude System of Students for Technical and Humanitarian Specialities

    Directory of Open Access Journals (Sweden)

    Natalia GORDIENKO

    2015-06-01

    Full Text Available Currently the problem of students’ professional development and the formation of their future work readiness with account for their psychological peculiarities is very actual. Our reference to the point is determined by several factors: 1 contemporary students have difficulties in their professional identity formation, and in curriculum learning; 2 the new specialities are appear; 3 technical progress influences the human potential demands changes and specialities learning; existing psychograms grow obsolete; 4 the attitude system of different educational profiles students’ is not studied sufficiently, and there not enough computer based psychodiagnostic research methods (techniques. Relevant personality attitude’s system research is still carried out introspectively, or else with the help of socio-psychological methods that significantly limit the research perspectives. The aim of this article is to analyse the results of psychological and psychophysiological research of the contents and extent of the humanitarian and technical profiles students’ attitude system. We have organized an experimental research in two stages: St-Petersburg universities students’ questionnaire; and laboratory research on the base of psychophysiological testing laboratory. We have worked out and tested psychological computer methods for different profiles students’ attitude system research: associative experiment version and the technology “Psychomotor differential”. We present here the results of the different profiles students’ attitude system research: their needs, instincts, psychological defence influencing profession learning. Besides, we have analysed differences in the temperament and students’ common and non-verbal intelligence level. With the help of authentic versions of the instrumental- computer methods we have received objective differences of the needs system and psychophysiological parameters of the motivation and emotional component

  11. 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

  12. Coordination control of distributed systems

    CERN Document Server

    Villa, Tiziano

    2015-01-01

    This book describes how control of distributed systems can be advanced by an integration of control, communication, and computation. The global control objectives are met by judicious combinations of local and nonlocal observations taking advantage of various forms of communication exchanges between distributed controllers. Control architectures are considered according to  increasing degrees of cooperation of local controllers:  fully distributed or decentralized controlcontrol with communication between controllers,  coordination control, and multilevel control.  The book covers also topics bridging computer science, communication, and control, like communication for control of networks, average consensus for distributed systems, and modeling and verification of discrete and of hybrid systems. Examples and case studies are introduced in the first part of the text and developed throughout the book. They include: control of underwater vehicles, automated-guided vehicles on a container terminal, contro...

  13. Concept and System of Personification Control System

    Institute of Scientific and Technical Information of China (English)

    Bai,Fengshuang; Yin,Yixin; Tu,Xuyan; Zhang,Ying

    2006-01-01

    This paper provides the system and conception of the Personification Control System (PCS) on the basis of Intelligent Control System based on Artificial life (ICS/AL), Artificial Emotion, Humanoid Control, and Intelligent Control System based on Field bus. According to system science and deciding of organize of biology, the Pyramid System of PCS are created. Then Pyramid System of PCS which is made up of PCS1/H, PCS1/S, PCS1/O, PCS1/C and PCS1/G is described.

  14. Thermal control system technology discipline

    Science.gov (United States)

    Ellis, Wilbert E.

    1990-01-01

    Viewgraphs on thermal control systems technology discipline for Space Station Freedom are presented. Topics covered include: heat rejection; heat acquisition and transport; monitoring and control; passive thermal control; and analysis and test verification.

  15. 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

  16. Control system for HIMAC injector

    International Nuclear Information System (INIS)

    A control system for HIMAC injector has been designed. The system consists of three mini-computers and many intelligent device controllers. The device controller is a single-board computer with a real time monitor and is installed in each device. Almost man-machine interactions for an operation of the injector system are performed by touch panels and rotary encoders. (author)

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

    International Nuclear Information System (INIS)

    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.

  18. 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.

  19. Star trackers, star catalogs, and attitude determination - Probabilistic aspects of system design

    Science.gov (United States)

    Vedder, John D.

    1992-01-01

    Optimizing spacecraft attitude determination systems that use onboard star trackers requires analysis and evaluation of some probabilistic aspects of system design. This paper discusses methods of constructing or compiling optimum star catalogs, which are defined as uniform distributions on a sphere. Both local and global measures of uniformity on a sphere are defined. Application of these methods and measures to a specific problem is also discussed. In addition, Poisson models of star tracker acquisition probabilities are formulated to provide a useful analytical basis for designing and optimizing attitude determination systems. These analytical models and methods lead to rapid and realistic quantitative results, and should therefore facilitate making system performance trades. Use of such methods should also reduce the need for performing tedious computer simulations to obtain analogous results.

  20. Adaptive filter for a miniature MEMS based attitude and heading reference system

    Institute of Scientific and Technical Information of China (English)

    WANG Mei; WANG Yong-quan; ZHANG Yan-hua

    2006-01-01

    An extended Kalman filter with adaptive gain was used to build a miniature attitude and heading reference system based on a stochastic model. The adaptive filter has six states with a time variable transition matrix. When the system is in the non-acceleration mode, the accelerometer measurements of the gravity and the compass measurements of the heading have observability and yield good estimates of the states. When the system is in the high dynamic mode and the bias has converged to an accurate estimate, the attitude calculation will be maintained for a long interval of time. The adaptive filter tunes its gain automatically based on the system dynamics sensed by the accelerometers to yield optimal performance.

  1. 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.

  2. ATTITUDE TOWARDS THE USE OF LEARNING MANAGEMENT SYSTEM AMONG UNIVERSITY STUDENTS: A Case Study

    Directory of Open Access Journals (Sweden)

    Fuad A. A.TRAYEK

    2013-07-01

    Full Text Available Learning management system (LMS is a learning platform for both full time and distant learning students at the International Islamic University in Malaysia (IIUM. LMS becomes a tool for IIUM to disseminate information and learning resources to the students. The objectives of this study were to Ø investigate students' attitudes toward the use of LMS, Ø to verify the impact of perceived usefulness and perceived ease of use on attitude towards use of learning management system, Ø to examine the differences in attitudes toward the use of LMS between distance learning and full time students. There were 120 (70 full time and 50 distance learning students at the Institute of Education responded for the study. The collected data was analysed using descriptive statistics, t-test and Multiple Regression Analysis (MRA. The results of the study showed that perceived ease of use and perceived usefulness determine students' attitudes toward the use of LMS. However, this study did not find any significant differences between distance learning and full time students. According to the findings the study recommended that the University should continue using LMS because it is useful for both distance learning and full time students. Further suggestions are made to customize and upgrade the LMS suitable for innovative teaching and learning.

  3. SPS : the control system

    CERN Multimedia

    CERN Neyrac Films

    1975-01-01

    English version. Part of the series of films produced by CERN about the SPS. "More than 10.000 things to control, 7,00 things to measure and 30,000 ? to survey, distributed over more than 10 square km. That was the problem which faced the controls group." Comments: images of control room, computer screens, and computer centre rather dark

  4. Networked control of microgrid system of systems

    Science.gov (United States)

    Mahmoud, Magdi S.; Rahman, Mohamed Saif Ur; AL-Sunni, Fouad M.

    2016-08-01

    The microgrid has made its mark in distributed generation and has attracted widespread research. However, microgrid is a complex system which needs to be viewed from an intelligent system of systems perspective. In this paper, a network control system of systems is designed for the islanded microgrid system consisting of three distributed generation units as three subsystems supplying a load. The controller stabilises the microgrid system in the presence of communication infractions such as packet dropouts and delays. Simulation results are included to elucidate the effectiveness of the proposed control strategy.

  5. 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...

  6. Control of large spaceborne antenna systems with flexible booms by mechanical decoupling

    Science.gov (United States)

    Wang, P. K. C.

    1983-01-01

    A simple practical method for designing antenna-feed attitude control systems for large deployable spaceborne antenna systems with long flexible booms is proposed. The basic idea is to mechanically decouple the antenna-feed from the boom so that the feed-attitude control system can be designed without taking the boom dynamics into consideration, thus avoiding a complex control problem involving an infinite-dimensional distributed parameter system. The validity of the proposed method is substantiated by analytical and numerical studies using a mathematical model for the flexible boom which could undergo both bending and torsional vibrations. This approach leads to simple antenna-feed attitude control systems which are amenable to physical implementation.

  7. The design of image stabilization control system

    Science.gov (United States)

    Lin, Zhe; Wu, Chunnan; Yu, Fei; Kang, Xiaojun

    2012-09-01

    For high resolution satellite remote sensing cameras, the line of sight (LOS) moving during the image exposure period will cause the modulation transfer function (MTF) degradation and image blurring. Image stabilization component is used to improve image quality by actively removing the apparent motion induced by vibration, tracking error and attitude instability. In this paper, the image stabilization component is considered as a kind of closed loop servo control system, and the image stabilization effect is converted into servo control performance for research. Firstly, the image stabilization servo loop scheme and transfer function model are constructed and the LOS jitter is considered as the output of a stochastic system derived by white-Gaussian noise. Based on the proposed model, the demand boundary of jitter rejection function is described, and the design criterion to be satisfied is obtained according to the requirement of image stabilization performance. And then, a discrete Kalman estimation algorithm is introduced into image stabilization servo loop to filter out the noise caused by pixel-shift sensor (PSS) and compensate for the delay due to the PSS measurement. Based on the given design criterion, the control law is designed by using the output of Kalman filter. The computer simulation is achieved to show that the proposed control strategy can significantly improve the image stabilization performance.

  8. Predictors of attitude and intention to use knowledge management system among Korean nurses.

    Science.gov (United States)

    Yun, Eun Kyoung

    2013-12-01

    Knowledge sharing using Knowledge Management (KM) systems helps nurses to understand and acquire appropriate knowledge that influences the quality of healthcare service. The purpose of this study was to identify organizational and individual factors influencing attitude and intention to use KM systems among Korean nurses. A cross-sectional survey design was used to study a sample of 245 nurses employed at five hospitals in Seoul. A multiple hierarchical regression was used to examine predictors of nurses' attitude and intention to use. From an individual perspective, nurse's informatics competency was identified as a significant factor influencing attitudes toward knowledge management usage within adhocracy and clan cultures. However, from an organizational perspective, level of hospital information system was identified as a significant factor influencing KM system usage within adhocracy cultures. The findings of this study will be helpful in better understanding and assessing the impact of the factors affecting the implementation of nursing knowledge management systems and in further developing successful managerial strategies using knowledge resources in healthcare settings. PMID:23806194

  9. Development and Testing of a High-Precision Position and Attitude Measuring System for a Space Mechanism

    Science.gov (United States)

    Khanenya, Nikolay; Paciotti, Gabriel; Forzani, Eugenio; Blecha, Luc

    2016-01-01

    This paper describes a high-precision optical metrology system - a unique ground test equipment which was designed and implemented for simultaneous precise contactless measurements of 6 degrees-of-freedom (3 translational + 3 rotational) of a space mechanism end-effector [1] in a thermally controlled ISO 5 clean environment. The developed contactless method reconstructs both position and attitude of the specimen from three cross-sections measured by 2D distance sensors [2]. The cleanliness is preserved by the hermetic test chamber filled with high purity nitrogen. The specimen's temperature is controlled by the thermostat [7]. The developed method excludes errors caused by the thermal deformations and manufacturing inaccuracies of the test jig. Tests and simulations show that the measurement accuracy of an object absolute position is of 20 micron in in-plane measurement (XY) and about 50 micron out of plane (Z). The typical absolute attitude is determined with an accuracy better than 3 arcmin in rotation around X and Y and better than 10 arcmin in Z. The metrology system is able to determine relative position and movement with an accuracy one order of magnitude lower than the absolute accuracy. Typical relative displacement measurement accuracies are better than 1 micron in X and Y and about 2 micron in Z. Finally, the relative rotation can be measured with accuracy better than 20 arcsec in any direction.

  10. Optical tools and techniques for aligning solar payloads with the SPARCS control system. [Solar Pointing Aerobee Rocket Control System

    Science.gov (United States)

    Thomas, N. L.; Chisel, D. M.

    1976-01-01

    The success of a rocket-borne experiment depends not only on the pointing of the attitude control system, but on the alignment of the attitude control system to the payload. To ensure proper alignment, special optical tools and alignment techniques are required. Those that were used in the SPARCS program are described and discussed herein. These tools include theodolites, autocollimators, a 38-cm diameter solar simulator, a high-performance 1-m heliostat to provide a stable solar source during the integration of the rocket payload, a portable 75-cm sun tracker for use at the launch site, and an innovation called the Solar Alignment Prism. Using the real sun as the primary reference under field conditions, the Solar Alignment Prism facilitates the coalignment of the attitude sun sensor with the payload. The alignment techniques were developed to ensure the precise alignment of the solar payloads to the SPARCS attitude sensors during payload integration and to verify the required alignment under field conditions just prior to launch.

  11. A Confirmatory Factor Analysis of Preservice Teachers' Responses to the Attitudes and Beliefs on Classroom Control Inventory.

    Science.gov (United States)

    Henson, Robin K.; Roberts, J. Kyle

    This study examined the factorial invariance of scores from the Attitudes and Beliefs on Classroom Control Inventory (ABCC) (Martin and others, 1998) for 243 undergraduate preservice teachers. Although the original ABCC was developed with inservice teachers, use of the instrument to study the classroom beliefs of preservice teachers had not been…

  12. Predicting Participation in Group Parenting Education in an Australian Sample: The Role of Attitudes, Norms, and Control Factors

    Science.gov (United States)

    White, Katherine M.; Wellington, Larne

    2009-01-01

    We examined the theory of planned behavior (TPB) in predicting intentions to participate in group parenting education. One hundred and seventy-six parents (138 mothers and 38 fathers) with a child under 12 years completed TPB items assessing attitude, subjective norms, perceived behavioral control (PBC), and two additional social influence…

  13. Control integral systems; Sistemas integrales de control

    Energy Technology Data Exchange (ETDEWEB)

    Burgos, Estrella [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1998-12-31

    Almost two third of the electric power generation in Mexico are obtained from hydrocarbons, for that reasons Comision Federal de Electricidad (CFE) dedicated special commitment in modernizing the operation of fossil fuel central stations. In attaining this objective the control systems play a fundamental roll, from them depend a good share of the reliability and the efficiency of the electric power generation process, as well as the extension of the equipment useful life. Since 1984 the Instituto de Investigaciones Electricas (IIE) has been working, upon the request of CFE, on the development of digital control systems. To date it has designed and implemented a logic control system for gas burners, which controls 32 burners of the Unit 4 boiler of the Generation Central of Valle de Mexico and two systems for distributed control for two combined cycle central stations, which are: Dos Bocas, Veracruz Combined cycle central, and Gomez Palacio, Durango combined cycle central. With these two developments the IIE enters the World tendency of implementing distributed control systems for the fossil fuel power central update [Espanol] Casi las dos terceras partes de la generacion electrica en Mexico se obtienen a partir de hidrocarburos, es por eso que la Comision Federal de Electricidad (CFE) puso especial empeno en modernizar la operacion de las centrales termoelectricas de combustibles fosiles. En el logro de este objetivo los sistemas de control desempenan un papel fundamental, de ellos depende una buena parte la confiabilidad y la eficiencia en el proceso de generacion de energia electrica, asi como la prolongacion de la vida util de los equipos. Desde 1984 el Instituto de Investigaciones Electricas (IIE) ha trabajado, a solicitud de la CFE, en el desarrollo de sistemas digitales de control. A la fecha se han disenado e implantado un sistema de control logico de quemadores de gas, el cual controla 32 quemadores de la caldera de la unidad 4 de la central de generacion

  14. Real Time Mode Sensing and Attitude Control of Flexible Launch Vehicle with Fiber Bragg Grating Sensor Array

    Science.gov (United States)

    Jiang, Hao

    Missiles and launch vehicles are typically slender in shape to reduce aerodynamic drag. Bending vibration occurs when a flying object with a large slenderness ratio performs pitch or yaw commands. The Inertial Measurement Unit (IMU) onboard measures the attitude and angular velocities of the deflected body as well as the rigid body motion, and in turn feeds these signals back into the control loop. Feedback of vibrating information degrades the control system stability and in the worst cases makes the system unstable. These effects become more significant as the slenderness ratio of the rocket increases. Another important challenge in launch vehicle control is created by the time-varying mass and inertia, as well as the consequent changes in modal frequencies and modal shapes of the structure as propellant is exhausted. This dissertation presents a method to correct the IMU sensors measurements with real time vibrating deflection measured by FBG sensors which have negligible mass penalty. Compared to notch filters and observers, unexpected errors induced by frequency variations, mode truncations, and un-modeled aerodynamics induced by deformation are avoided by using FBG corrected measurements. To deal with the time varying modal properties, a novel approach for the real-time estimation of mode shapes on a variable mass structure using FBG sensors is also presented in this dissertation. The method is validated by comparing estimated modal shapes to both numerical predictions and experiments on a vertical cantilever beam in which a step change in mass is introduced. The results show that the first three mode shapes of the beam can be estimated in real time using strain measurements from a FBG sensor array sampled at 1 kHz. A trajectory control system of a vertical cantilever beam is used in this dissertation to validate the method based on real-time mode sensing and FBG correction on IMU sensors. The flexible rocket dynamics and the prospective applications of this

  15. 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.

  16. Framework for control system development

    International Nuclear Information System (INIS)

    Control systems being developed for the present generation of accelerators will need to adapt to changing machine and operating state conditions. Such systems must also be capable of evolving over the life of the accelerator operation. In this paper we present a framework for the development of adaptive control systems

  17. Delays and networked control systems

    CERN Document Server

    Hetel, Laurentiu; Daafouz, Jamal; Johansson, Karl

    2016-01-01

    This edited monograph includes state-of-the-art contributions on continuous time dynamical networks with delays. The book is divided into four parts. The first part presents tools and methods for the analysis of time-delay systems with a particular attention on control problems of large scale or infinite-dimensional systems with delays. The second part of the book is dedicated to the use of time-delay models for the analysis and design of Networked Control Systems. The third part of the book focuses on the analysis and design of systems with asynchronous sampling intervals which occur in Networked Control Systems. The last part of the book exposes several contributions dealing with the design of cooperative control and observation laws for networked control systems. The target audience primarily comprises researchers and experts in the field of control theory, but the book may also be beneficial for graduate students. .

  18. Asynchronous control for networked systems

    CERN Document Server

    Rubio, Francisco; Bencomo, Sebastián

    2015-01-01

    This book sheds light on networked control systems; it describes different techniques for asynchronous control, moving away from the periodic actions of classical control, replacing them with state-based decisions and reducing the frequency with which communication between subsystems is required. The text focuses specially on event-based control. Split into two parts, Asynchronous Control for Networked Systems begins by addressing the problems of single-loop networked control systems, laying out various solutions which include two alternative model-based control schemes (anticipatory and predictive) and the use of H2/H∞ robust control to deal with network delays and packet losses. Results on self-triggering and send-on-delta sampling are presented to reduce the need for feedback in the loop. In Part II, the authors present solutions for distributed estimation and control. They deal first with reliable networks and then extend their results to scenarios in which delays and packet losses may occur. The novel ...

  19. Honesty and Management Control System Design: An Experimental Study

    OpenAIRE

    Maria J. Sanchez-Exposito; David Naranjo-Gil

    2012-01-01

    The manipulation of performance measures is a central theme in management accounting research. Individuals have private information that can be used for their own benefit; and thus they can falsify their performance reporting. Psychology literature asserts that the attitude of individuals to maximize their own interests or common benefits depends on their cognitive orientation. Accounting literature argues that management control systems can motivate individuals to act for the organization be...

  20. ON COMPLEX DYNAMIC CONTROL SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    CHENG Daizhan

    2003-01-01

    This paper presents some recent works on the control of dynamic systems, which have certain complex properties caused by singularity of the nonlinear structures, structure-varyings, or evolution process etc. First, we consider the structure singularity of nonlinear control systems. It was revealed that the focus of researches on nonlinear control theory is shifting from regular systems to singular systems. The singularity of nonlinear systems causes certain complexity. Secondly, the switched systems are considered. For such systems the complexity is caused by the structure varying. We show that the switched systems have significant characteristics of complex systems. Finally, we investigate the evolution systems. The evolution structure makes complexity, and itself is a proper model for complex systems.

  1. Performance analysis of a GPS Interferometric attitude determination system for a gravity gradient stabilized spacecraft. M.S. Thesis

    Science.gov (United States)

    Stoll, John C.

    1995-01-01

    The performance of an unaided attitude determination system based on GPS interferometry is examined using linear covariance analysis. The modelled system includes four GPS antennae onboard a gravity gradient stabilized spacecraft, specifically the Air Force's RADCAL satellite. The principal error sources are identified and modelled. The optimal system's sensitivities to these error sources are examined through an error budget and by varying system parameters. The effects of two satellite selection algorithms, Geometric and Attitude Dilution of Precision (GDOP and ADOP, respectively) are examined. The attitude performance of two optimal-suboptimal filters is also presented. Based on this analysis, the limiting factors in attitude accuracy are the knowledge of the relative antenna locations, the electrical path lengths from the antennae to the receiver, and the multipath environment. The performance of the system is found to be fairly insensitive to torque errors, orbital inclination, and the two satellite geometry figures-of-merit tested.

  2. UAV Flight Control System Based on an Intelligent BEL Algorithm

    Directory of Open Access Journals (Sweden)

    Huangzhong Pu

    2013-02-01

    Full Text Available A novel intelligent control strategy based on a brain emotional learning (BEL algorithm is investigated in the application of the attitude control of a small unmanned aerial vehicle (UAV in this study. The BEL model imitates the emotional learning process in the amygdala‐ orbitofrontal (A‐O system of mammalian brains. Here it is used to develop the flight control system of the UAV. The control laws of elevator, aileron and rudder manipulators adopt the forms of traditional flight control laws, and three BEL models are used in above three control loops, to on‐ line regulate the control gains of each controller. Obviously, a BEL intelligent control system is self‐learning and self‐adaptive, which is important for UAVs when flight conditions change, while traditional flight control systems remain unchanged after design. In simulation, the UAV is on a flat flight and suddenly a wind disturbs it making it depart from the equilibrium state. In order to make the UAV recover to the original equilibrium state, the BEL intelligent control system is adopted. The simulation results illustrate that the BEL‐based intelligent flight control system has characteristics of better adaptability and stronger robustness, when compared with the traditional flight control system.

  3. Attitude Control of Micro Spacecraft Without Angular Velocity Measurement%微小型航天器无角速度测量姿态控制

    Institute of Scientific and Technical Information of China (English)

    龚宜; 刘莹莹; 周军

    2013-01-01

    研究微小型航天器姿态跟踪在角速度不可测量以及控制力矩受限情况下的的控制方法.首先基于无源性原理,仅依赖姿态测量,建立一个类似PD控制的方法.为了让初始状态和角度误差始终在合理的控制范围内,对误差函数加入跳变规则,从而获得一种混合控制方法;然后利用Lyapunov原理证明了闭环系统的全局渐进稳定性;最后通过仿真与已有方法进行比较研究,验证了控制方法的有效性,即使初始速度估计误差和初始角度误差很大,依然可以控制.%The paper mainly dealt with the problem of attitude control of a micro rigid spacecraft without angular velocity measurement and under control torque constraint through a hybrid tracking controller.Based on passivity approach using only attitude measurements,a control law similar to the PD law was established; then in order to limit the inertial states and the attitude error to an appropriate bound,a switching rule was added to the error functions,so that a hybrid control law was gained.A Lyapunov approach was used to prove the global asymptotic stability of the closed loop system.The simulation results were presented to corroborate the effectiveness of this controller in contrast to another existing controller,even when the initial estimated angular velocity error and the initial angular error are large.

  4. A position and attitude vision measurement system for wind tunnel slender model

    Science.gov (United States)

    Cheng, Lei; Yang, Yinong; Xue, Bindang; Zhou, Fugen; Bai, Xiangzhi

    2014-11-01

    A position and attitude vision measurement system for drop test slender model in wind tunnel is designed and developed. The system used two high speed cameras, one is put to the side of the model and another is put to the position where the camera can look up the model. Simple symbols are set on the model. The main idea of the system is based on image matching technique between the 3D-digital model projection image and the image captured by the camera. At first, we evaluate the pitch angles, the roll angles and the position of the centroid of a model through recognizing symbols in the images captured by the side camera. And then, based on the evaluated attitude info, giving a series of yaw angles, a series of projection images of the 3D-digital model are obtained. Finally, these projection images are matched with the image which captured by the looking up camera, and the best match's projection images corresponds to the yaw angle is the very yaw angle of the model. Simulation experiments are conducted and the results show that the maximal error of attitude measurement is less than 0.05°, which can meet the demand of test in wind tunnel.

  5. Public Attitudes to Housing Systems for Pregnant Pigs.

    Directory of Open Access Journals (Sweden)

    E B Ryan

    Full Text Available Understanding concerns about the welfare of farm animals is important for the development of socially sustainable production practices. This study used an online survey to test how views on group versus stall housing for pregnant sows varied when Canadian and US participants were provided information about these systems, including access to scientific papers, YouTube videos, Google images, and a frequently-asked-questions page (S1 Appendix. Initial responses and changes in responses after accessing the information were analyzed from Likert scores of 242 participants and from their written comments. Participants were less willing to accept the use of gestation stalls after viewing information on sow housing. For example, initially 30.4% of respondents indicated that they supported the use of gestation stalls; this declined to 17.8% after participants were provided additional information. Qualitative analysis of comments showed that supporters of gestation stalls expressed concern about the spread of disease and aggression between animals in less confined systems, whereas supporters of group housing placed more emphasis on the sow's ability to interact socially and perform natural behaviors. These results point to public opposition to the use of gestation stalls, and indicate that the more that the public learns about gestation stalls the less willing they will be to accept their use.

  6. Ground Control System Description Document

    Energy Technology Data Exchange (ETDEWEB)

    Eric Loros

    2001-07-31

    The Ground Control System contributes to the safe construction and operation of the subsurface facility, including accesses and waste emplacement drifts, by maintaining the configuration and stability of the openings during construction, development, emplacement, and caretaker modes for the duration of preclosure repository life. The Ground Control System consists of ground support structures installed within the subsurface excavated openings, any reinforcement made to the rock surrounding the opening, and inverts if designed as an integral part of the system. The Ground Control System maintains stability for the range of geologic conditions expected at the repository and for all expected loading conditions, including in situ rock, construction, operation, thermal, and seismic loads. The system maintains the size and geometry of operating envelopes for all openings, including alcoves, accesses, and emplacement drifts. The system provides for the installation and operation of sensors and equipment for any required inspection and monitoring. In addition, the Ground Control System provides protection against rockfall for all subsurface personnel, equipment, and the engineered barrier system, including the waste package during the preclosure period. The Ground Control System uses materials that are sufficiently maintainable and that retain the necessary engineering properties for the anticipated conditions of the preclosure service life. These materials are also compatible with postclosure waste isolation performance requirements of the repository. The Ground Control System interfaces with the Subsurface Facility System for operating envelopes, drift orientation, and excavated opening dimensions, Emplacement Drift System for material compatibility, Monitored Geologic Repository Operations Monitoring and Control System for ground control instrument readings, Waste Emplacement/Retrieval System to support waste emplacement operations, and the Subsurface Excavation System

  7. 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.

  8. The CARMA Control System

    Science.gov (United States)

    Gwon, C.; Beard, A. D.; Daniel, P.; Hobbs, R.; Scott, S. L.; Kraybill, J. C.; Leitch, E.; Mehringer, D. M.; Plante, R.; Amarnath, N. S.; Pound, M. W.; Rauch, K. P.; Teuben, P. J.

    2004-07-01

    The Combined Array for Research in Millimeter-wave Astronomy (CARMA) will be the combination of the BIMA, OVRO, and SZA millimeter arrays. With first light scheduled for 2005, CARMA will be the first heterogeneous millimeter array, combining antennas varying from 3.5 m to 10.4 m in diameter. The controls for CARMA involve creating a uniform interface for all antennas. The antennas are grouped into five independently-controlled sub-arrays, which will be used for scientific observations, engineering, or maintenance. The sub-arrays are controlled by two components: the Sub-array Command Processor (SCP) and the Sub-array Tracker (SAT). While each sub-array has a dedicated SCP for handling command processing, a single SAT computes and distributes slowly varying parameters to the necessary sub-arrays. The sub-array interface uses CORBA distributed objects to physically separate the user interface from the array. This allows for stability in the core engine controlling the array while enabling flexibility in the user interface implementation.

  9. Electrochemically controlled supramolecular systems

    NARCIS (Netherlands)

    Nijhuis, Christian A.; Ravoo, Bart Jan; Huskens, Jurriaan; Reinhoudt, David N.

    2007-01-01

    Large and complex molecular structures can be assembled by supramolecular chemistry and self-organization. For practical purposes it is required that the assembly and disassembly of supramolecular complexes and materials can be directed and controlled by external stimuli in order to build, for insta

  10. The APS control system network

    International Nuclear Information System (INIS)

    The APS accelerator control system is a distributed system consisting of operator interfaces, a network, and computer-controlled interfaces to hardware. This implementation of a control system has come to be called the open-quotes Standard Model.close quotes The operator interface is a UNDC-based workstation with an X-windows graphical user interface. The workstation may be located at any point on the facility network and maintain full functionality. The function of the network is to provide a generalized communication path between the host computers, operator workstations, input/output crates, and other hardware that comprise the control system. The crate or input/output controller (IOC) provides direct control and input/output interfaces for each accelerator subsystem. The network is an integral part of all modem control systems and network performance will determine many characteristics of a control system. This paper will describe the overall APS network and examine the APS control system network in detail. Metrics are provided on the performance of the system under various conditions

  11. 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.

  12. CONTROLE MULTI-AGENTS D’ATTITUDE D’UN SATELLITE PAR GYROSCOPES

    OpenAIRE

    BRAHAMI, Mustapha Anwar

    2013-01-01

    Ce mémoire de magistère porte sur le contrôle d’attitude des micro-satellites. Après avoir montré l’importance et la nécessité du contrôle d’attitude ainsi que les différents dispositifs utilisées pour la détermination et la commande d’attitude, nous présenterons les notions et les outils mathématiques essentiels à la modélisation d’attitude d’un micro-satellite. La seconde partie concerne la simulation d’attitude du premier satellite Algérien Alsat-1, il s’agira dans un pre...

  13. Intelligent house control system

    OpenAIRE

    Stražišar, Rok

    2008-01-01

    The thesis describes a smart house and the system that empowers it with intelligence. The goal of the thesis is to present the hardware and software involved and debate about the usability, pros and cons of such a system. The work addresses the smart house from several viewpoints: safety, comfort, economy, accessibility for people with special needs and affordability. Using smart house makes every day´s life more secure and comfortable, while it also enables independency to the people with sp...

  14. Hyperbaric Pressure Control System

    OpenAIRE

    Berg, Brian; Skjørten, Anders; Nicolaysen, Jonas; Skarseth, Thor Ove; Carlstedt, Jonas

    2015-01-01

    The requirement specification for the project where changed from delivery of a fully working product to contain only the design of this system due to long lead times on some of the high-pressure hydraulic parts. Three of the students where already working for FMC before project start, where two of them had experience with hydraulic Subsea Systems. Our project model where changed during the project. We started out with a Waterfall model and ended up with an Evolutionary model

  15. Changes in Eating Attitudes, Body Esteem and Weight Control Behaviours during Adolescence in a South African Cohort

    OpenAIRE

    Tabither M Gitau; Micklesfield, Lisa K.; Pettifor, John. M.; Norris, Shane A

    2014-01-01

    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...

  16. 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.

  17. Assessment of the Effects of Student Response Systems on Student Learning and Attitudes over a Broad Range of Biology Courses

    OpenAIRE

    Preszler, Ralph W.; Dawe, Angus; Shuster, Charles B.; Shuster, Michèle

    2007-01-01

    With the advent of wireless technology, new tools are available that are intended to enhance students' learning and attitudes. To assess the effectiveness of wireless student response systems in the biology curriculum at New Mexico State University, a combined study of student attitudes and performance was undertaken. A survey of students in six biology courses showed that strong majorities of students had favorable overall impressions of the use of student response systems and also thought t...

  18. Controlling systems of cogeneration blocks

    International Nuclear Information System (INIS)

    In this article the main parts of cogeneration unit control system are described. Article is aimed on electric power measurement with electricity protection as with temperature system regulation. In conclusion of the article, the control algorithm with perspective of cogeneration solve is indicated. (authors)

  19. Classifications of Linear Controlled Systems

    OpenAIRE

    Li, Jing

    2008-01-01

    This paper is devoted to a study of linear, differential and topological classifications for linear controlled systems governed by ordinary differential equations. The necessary and sufficient conditions for the linear and topological equivalence are given. It is also shown that the differential equivalence is the same as the linear equivalence for the linear controlled systems.

  20. Control systems on Lie groups.

    Science.gov (United States)

    Jurdjevic, V.; Sussmann, H. J.

    1972-01-01

    The controllability properties of systems which are described by an evolution equation in a Lie group are studied. The revelant Lie algebras induced by a right invariant system are singled out, and the basic properties of attainable sets are derived. The homogeneous case and the general case are studied, and results are interpreted in terms of controllability. Five examples are given.

  1. Evaluating the Handling Qualities of Flight Control Systems Including Nonlinear Aircraft and System Dynamics

    Science.gov (United States)

    Lin, Raymond Chao

    The handling qualities evaluation of nonlinear aircraft systems is an area of concern in loss-of-control (LOC) prevention. The Get Transfer Function (GetTF) method was demonstrated for evaluating the handling qualities of flight control systems and aircraft containing nonlinearities. NASA's Generic Transport Model (GTM), a nonlinear model of a civilian jet transport aircraft, was evaluated. Using classical techniques, the stability, control, and augmentation (SCAS) systems were designed to control pitch rate, roll rate, and airspeed. Hess's structural pilot model was used to model pilot dynamics in pitch and roll-attitude tracking. The simulated task was simultaneous tracking of, both, pitch and roll attitudes. Eight cases were evaluated: 1) gain increase of pitch-attitude command signal, 2) gain increase of roll-attitude command signal, 3) gain reduction of elevator command signal, 4) backlash in elevator actuator, 5) combination 3 and 4 in elevator actuator, 6) gain reduction of aileron command signal, 7) backlash in aileron actuator, and 8) combination of 6 and 7 in aileron actuator. The GetTF method was used to estimate the transfer function approximating a linear relationship between the proprioceptive signal of the pilot model and the command input. The transfer function was then used to predict the handling qualities ratings (HQR) and pilot-induced oscillation ratings (PIOR). The HQR is based on the Cooper-Harper rating scale. In pitch-attitude tracking, the nominal aircraft is predicted to have Level 2* HQRpitch and 2 pitch tracking exercise was also conducted to validate the structural pilot model.

  2. Optimal Control of Mechanical Systems

    Directory of Open Access Journals (Sweden)

    Vadim Azhmyakov

    2007-01-01

    Full Text Available In the present work, we consider a class of nonlinear optimal control problems, which can be called “optimal control problems in mechanics.” We deal with control systems whose dynamics can be described by a system of Euler-Lagrange or Hamilton equations. Using the variational structure of the solution of the corresponding boundary-value problems, we reduce the initial optimal control problem to an auxiliary problem of multiobjective programming. This technique makes it possible to apply some consistent numerical approximations of a multiobjective optimization problem to the initial optimal control problem. For solving the auxiliary problem, we propose an implementable numerical algorithm.

  3. Performance of Networked Control Systems

    Directory of Open Access Journals (Sweden)

    Yingwei Zhang

    2013-01-01

    Full Text Available Data packet dropout is a special kind of time delay problem. In this paper, predictive controllers for networked control systems (NCSs with dual-network are designed by model predictive control method. The contributions are as follows. (1 The predictive control problem of the dual-network is considered. (2 The predictive performance of the dual-network is evaluated. (3 Compared to the popular networked control systems, the optimal controller of the new NCSs with data packets dropout is designed, which can minimize infinite performance index at each sampling time and guarantee the closed-loop system stability. Finally, the simulation results show the feasibility and effectiveness of the controllers designed.

  4. Linear CCD attitude measurement system based on the identification of the auxiliary array CCD

    Science.gov (United States)

    Hu, Yinghui; Yuan, Feng; Li, Kai; Wang, Yan

    2015-10-01

    Object to the high precision flying target attitude measurement issues of a large space and large field of view, comparing existing measurement methods, the idea is proposed of using two array CCD to assist in identifying the three linear CCD with multi-cooperative target attitude measurement system, and to address the existing nonlinear system errors and calibration parameters and more problems with nine linear CCD spectroscopic test system of too complicated constraints among camera position caused by excessive. The mathematical model of binocular vision and three linear CCD test system are established, co-spot composition triangle utilize three red LED position light, three points' coordinates are given in advance by Cooperate Measuring Machine, the red LED in the composition of the three sides of a triangle adds three blue LED light points as an auxiliary, so that array CCD is easier to identify three red LED light points, and linear CCD camera is installed of a red filter to filter out the blue LED light points while reducing stray light. Using array CCD to measure the spot, identifying and calculating the spatial coordinates solutions of red LED light points, while utilizing linear CCD to measure three red LED spot for solving linear CCD test system, which can be drawn from 27 solution. Measured with array CCD coordinates auxiliary linear CCD has achieved spot identification, and has solved the difficult problems of multi-objective linear CCD identification. Unique combination of linear CCD imaging features, linear CCD special cylindrical lens system is developed using telecentric optical design, the energy center of the spot position in the depth range of convergence in the direction is perpendicular to the optical axis of the small changes ensuring highprecision image quality, and the entire test system improves spatial object attitude measurement speed and precision.

  5. Neural networks based three-axis satellite attitude control using only magnetic torquers

    International Nuclear Information System (INIS)

    Full text: Magnetic control is a favorable way to stabilize small satellites. Often, the hardware is simple and lightweight, and does not degrade or change mass over time. However, a magnetic control system does have some disadvantages and limitations. The control, which is in the form of magnetic moment, can only be applied perpendicular to the local magnetic field. In addition, there is uncertainty in the Earth magnetic field models due to the complicated dynamic nature of the field. Also, the magnetic hardware and the spacecraft can interact, causing both to behave in undesirable ways. To overcome these limitations some intelligence is incorporated in the controller. In this paper, control laws are developed to stabilize spacecraft on Three axes. The motivation for this project is ANUSAT, which is a micro-satellite under development at Anna University in collaboration with ISRO. This control could be carried out solely with satellite's magnetometer measurements and its position in orbit. The magnetic dipole moment for control is: M = Kp (Bo - Br) + Kd (dBo/dt - dBr/dt) Where Bo is the measured magnetic field, Br is the reference magnetic field, and Kp and Kd are the control position and rate gains respectively. The value of the controller gains are selected by the Intelligent Neural Network System in the feedback path. Control laws are numerically tested to show that the magnetic control system works within resolution limits

  6. Generalized H2 Control Synthesis for Periodic Systems

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Stoustrup, Jakob

    2001-01-01

    solvability of $H_2$ suboptimal control are stated. An algorithm for state feedback control synthesis is provided. The findings are applied for the attitude control of a satellite equipped with electro-magnetic coils, which comprises a very attractive means of attitude corrections for small low...

  7. Full quaternion based finite-time cascade attitude control approach via pulse modulation synthesis for a spacecraft.

    Science.gov (United States)

    Mazinan, A H; Pasand, M; Soltani, B

    2015-09-01

    In the aspect of further development of investigations in the area of spacecraft modeling and analysis of the control scheme, a new hybrid finite-time robust three-axis cascade attitude control approach is proposed via pulse modulation synthesis. The full quaternion based control approach proposed here is organized in association with both the inner and the outer closed loops. It is shown that the inner closed loop, which consists of the sliding mode finite-time control approach, the pulse width pulse frequency modulator, the control allocation and finally the dynamics of the spacecraft is realized to track the three-axis referenced commands of the angular velocities. The pulse width pulse frequency modulators are in fact employed in the inner closed loop to accommodate the control signals to a number of on-off thrusters, while the control allocation algorithm provides the commanded firing times for the reaction control thrusters in the overactuated spacecraft. Hereinafter, the outer closed loop, which consists of the proportional linear control approach and the kinematics of the spacecraft is correspondingly designed to deal with the attitude angles that are presented by quaternion vector. It should be noted that the main motivation of the present research is to realize a hybrid control method by using linear and nonlinear terms and to provide a reliable and robust control structure, which is able to track time varying three-axis referenced commands. Subsequently, a stability analysis is presented to verify the performance of the overall proposed cascade attitude control approach. To prove the effectiveness of the presented approach, a thorough investigation is presented compared to a number of recent corresponding benchmarks. PMID:26142216

  8. Entry Vehicle Control System Design for the Mars Smart Lander

    Science.gov (United States)

    Calhoun, Philip C.; Queen, Eric M.

    2002-01-01

    The NASA Langley Research Center, in cooperation with the Jet Propulsion Laboratory, participated in a preliminary design study of the Entry, Descent and Landing phase for the Mars Smart Lander Project. This concept utilizes advances in Guidance, Navigation and Control technology to significantly reduce uncertainty in the vehicle landed location on the Mars surface. A candidate entry vehicle controller based on the Reaction Control System controller for the Apollo Lunar Excursion Module digital autopilot is proposed for use in the entry vehicle attitude control. A slight modification to the phase plane controller is used to reduce jet-firing chattering while maintaining good control response for the Martian entry probe application. The controller performance is demonstrated in a six-degree-of-freedom simulation with representative aerodynamics.

  9. Control principles of complex systems

    Science.gov (United States)

    Liu, Yang-Yu; Barabási, Albert-László

    2016-07-01

    A reflection of our ultimate understanding of a complex system is our ability to control its behavior. Typically, control has multiple prerequisites: it requires an accurate map of the network that governs the interactions between the system's components, a quantitative description of the dynamical laws that govern the temporal behavior of each component, and an ability to influence the state and temporal behavior of a selected subset of the components. With deep roots in dynamical systems and control theory, notions of control and controllability have taken a new life recently in the study of complex networks, inspiring several fundamental questions: What are the control principles of complex systems? How do networks organize themselves to balance control with functionality? To address these questions here recent advances on the controllability and the control of complex networks are reviewed, exploring the intricate interplay between the network topology and dynamical laws. The pertinent mathematical results are matched with empirical findings and applications. Uncovering the control principles of complex systems can help us explore and ultimately understand the fundamental laws that govern their behavior.

  10. Integrated control system for LEHIPA

    International Nuclear Information System (INIS)

    The Low Energy High Intensity Proton Accelerator (LEHIPA) is a 20 MeV 30 mA proton accelerator which will be achieved in multiple stages. LEHIPA consists of several sub systems/devices located at different positions of the beam path which includes ION source, RF Power, RF Protection Interlock System, Low Conductivity Water plant, Low Level RF Control Systems, Vacuum System, Beam Diagnostics and Beam Line Devices. All these subsystems have their own local control systems (LCS) which will coordinate the operation of the corresponding subsystem. The control system for LEHIPA is thus being designed as a Distributed Control System with different teams developing each LCS. The control system will assist the operator to achieve a beam of desired characteristics by interacting with various sub systems of the accelerator in a seamless manner, protect the various parts of machine by generating the necessary interlocks, keep track of various parameters monitored periodically by suitably archiving them, alarms annunciation and trouble shoot from the control room. This paper describes approach to system design of ICS. (author)

  11. Mobile robot control system

    OpenAIRE

    Jiruška, Jiří

    2015-01-01

    This thesis deals with differential drive wheeled mobile robot which is running under a real-time operating system. Introductory part is focused on theoretical description of robot and its original firmware. Practical part deals with creating software and implementation several methods that allow following the line by robot using reflectance sensor array. Significant part of this thesis is focused on design and implementation of communication protocol, based on IEEE 802.15.4 which provides co...

  12. A novel testability model for health management of heading attitude system

    Institute of Scientific and Technical Information of China (English)

    Liu Guanjun; Yang Shuming; Qiu Jing; Yang Peng

    2013-01-01

    Prognostics and health management (PHM) is very important to guarantee the reliability and safety of aerospace systems,and sensing and test are the precondition of PHM.Integrating design for testability into early design stage of system early design stage is deemed as a fundamental way to improve PHM performance,and testability model is the base of testability analysis and design.This paper discusses a hierarchical model-based approach to testability modeling and analysis for heading attitude system health management.Quantified directed graph,of which the nodes represent components and tests and the directed edges represent fault propagation paths,is used to describe fault-test dependency,and quantitative testability information is assigned to nodes and directed edges.The fault dependencies between nodes can be obtained by functional fault analysis methodology that captures the physical architecture and material flows such as energy,heat,data,and so on.By incorporating physics of failure models into component,the dynamic process of a failing or degrading component can be projected onto system behavior,i.e.,system symptoms.Then,the analysis of extended failure modes,mechanisms and effects is utilized to construct fault evolution-test dependency.Using this integrated model,the designers and system analysts can assess the test suite's fault detectability,fault isolability and fault predictability.And heading attitude system application results show that the proposed model can support testability analysis and design for PHM very well.

  13. 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.

  14. Microprocessor control of photovoltaic systems

    Science.gov (United States)

    Millner, A. R.; Kaufman, D. L.

    1984-01-01

    The present low power CMOS microprocessor controller for photovoltaic power systems possesses three programs, which are respectively intended for (1) conventional battery-charging systems with state-of-charge estimation and sequential shedding of subarrays and loads, (2) maximum power-controlled battery-charging systems, and (3) variable speed dc motor drives. Attention is presently given to the development of this terrestrial equipment for spacecraft use.

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

    Directory of Open Access Journals (Sweden)

    Zhuoli Tao

    2015-12-01

    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.

  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. 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).

  18. JT-60 plasma control system

    International Nuclear Information System (INIS)

    JT-60 plasma control can be performed by the supervisory controller, the measurement system and actuators such as the poloidal field coil power supplies, gas injectors, neutral beam injection (NBI) heating system and radio frequency (RF) heating system. One of the most important characteristics of this system is a perfect digital control one composed of mini-computers, fast array processors and CAMAC modules, and it has large flexibility and few troubles to adjust the system. This system started to be operated in April 1985, after the six-year-long design, construction and testing, and have been operated and improved many times for two years. In this paper, the final system specification and its performance are presented aiming at the technological aspect of hardware and software. In addition, and experienced troubles are also presented. (author)

  19. Study on GPS/INS System Using Novel Filtering Methods for Vessel Attitude Determination

    Directory of Open Access Journals (Sweden)

    Xiyuan Chen

    2013-01-01

    Full Text Available Any vehicle such as vessel has three attitude parameters, which are mostly defined as pitch, roll, and heading from true north. In hydrographic surveying, determination of these parameters by using GPS or INS technologies is essential for the requirements of vehicle measurements. Recently, integration of GPS/INS by using data fusion algorithm became more and more popular. Therefore, the data fusion algorithm plays an important role in vehicle attitude determination. To improve attitude determination accuracy and efficiency, two improved data fusion algorithms are presented, which are extended Kalman particle filter (EKPF and genetic particle filter (GPF. EKPF algorithm combines particle filter (PF with the extended Kalman filter (EKF to avoid sample impoverishment during the resampling process. GPF is based on genetic algorithm and PF; several genetic operators such as selection, crossover, and mutation are adopted to optimize the resampling process of PF, which can not only reduce the particle impoverishment but also improve the computation efficiency. The performances of the system based on the two proposed algorithms are analyzed and compared with traditional KF. Simulation results show that, comprehensively considering the determination accuracy and consumption cost, the performance of the proposed GPF is better than EKPF and traditional KF.

  20. Control of Solar Energy Systems

    CERN Document Server

    Camacho, Eduardo F; Rubio, Francisco R; Martínez, Diego

    2012-01-01

    Control of Solar Energy Systems details the main solar energy systems, problems involved with their control, and how control systems can help in increasing their efficiency.  After a brief introduction to the fundamental concepts associated with the use of solar energy in both photovoltaic and thermal plants, specific issues related to control of solar systems are embarked upon. Thermal energy systems are then explored in depth, as well as  other solar energy applications such as solar furnaces and solar refrigeration systems. Problems of variable generation profile and of the contribution of many solar plants to the same grid system are considered with the necessary integrated and supervisory control solutions being discussed. The text includes material on: ·         A comparison of basic and advanced control methods for parabolic troughs from PID to nonlinear model-based control; ·         solar towers and solar tracking; ·         heliostat calibration, characterization and off...

  1. Emission control system

    Science.gov (United States)

    Parrish, Clyde F. (Inventor); Chung, J. Landy (Inventor)

    2009-01-01

    Methods and apparatus utilizing hydrogen peroxide are useful to reduce SOx and mercury (or other heavy metal) emissions from combustion flue gas streams. The methods and apparatus may further be modified to reduce NOx emissions. Continuous concentration of hydrogen peroxide to levels approaching or exceeding propellant-grade hydrogen peroxide facilitates increased system efficiency. In this manner, combustion flue gas streams can be treated for the removal of SOx and heavy metals, while isolating useful by-products streams of sulfuric acid as well as solids for the recovery of the heavy metals. Where removal of NOx emissions is included, nitric acid may also be isolated for use in fertilizer or other industrial applications.

  2. Traction Control System for Motorcycles

    Directory of Open Access Journals (Sweden)

    Cardinale Pascal

    2009-01-01

    Full Text Available Traction control is a widely used control system to increase stability and safety of four wheel vehicles. Automatic stability control is used in the BMW K1200R motorcycle and in motoGP competition, but not in other motorcycles. This paper presents an algorithm and a low-cost real-time hardware implementation for motorcycles. A prototype has been developed, applied on a commercial motorcycle, and tested in a real track. The control system that can be tuned by the driver during the race has been appreciated by the test driver.

  3. Structural interaction with control systems

    Science.gov (United States)

    Noll, R. B.; Zvara, J.

    1971-01-01

    A monograph which assesses the state of the art of space vehicle design and development is presented. The monograph presents criteria and recommended practices for determining the structural data and a mathematical structural model of the vehicle needed for accurate prediction of structure and control-system interaction; for design to minimize undesirable interactions between the structure and the control system; and for determining techniques to achieve the maximum desirable interactions and associated structural design benefits. All space vehicles are treated, including launch vehicles, spacecraft, and entry vehicles. Important structural characteristics which affect the structural model used for structural and control-system interaction analysis are given.

  4. MULTIPLE ECH LAUNCHER CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    GREEN,M.T; PONCE,D; GRUNLOH,H.J; ELLIS,R.A; GROSNICKLE,W.H; HUMPHREY,R.L

    2003-10-01

    OAK-B135 The addition of new, high power gyrotrons to the heating and current drive arsenal at DIII-D, required a system upgrade for control of fully steerable ECH Launchers. Each launcher contains two pointing mirrors with two degrees of mechanical freedom. The two flavors of motion are called facet and tilt. Therefore up to four channels of motion per launcher need to be controlled. The system utilizes absolute encoders to indicate mirror position and therefore direction of the microwave beam. The launcher movement is primarily controlled by PLC, but future iterations of design, may require this control to be accomplished by a CPU on fast bus such as Compact PCI. This will be necessary to accomplish real time position control. Safety of equipment and personnel is of primary importance when controlling a system of moving parts. Therefore multiple interlocks and fault status enunciators have been implemented. This paper addresses the design of a Multiple ECH Launcher Control System, and characterizes the flexibility needed to upgrade to a real time position control system in the future.

  5. Linux in Industrial Control Systems

    CERN Document Server

    Riesco, T

    2001-01-01

    Today the Linux operating system has become a real alternative for industrial control systems. Linux supports all layers in control systems starting with Real-Time or embedded systems for data acquisition, following with treatment, storage, communication and data adaptation, and finally, with supervision and user interfaces. In the last years the Linux development has grown being incorporated in several industrial systems demonstrating high performance, availability and stability for complex processes in chemical, automobile or petrol industries. In many of these industries Linux architectures have been tested and validated successfully. The new CERN policy supporting Linux, as well as the emergence of cheap and robust Linux solutions, motivates its implementation in our safety control and supervision systems in the near future.

  6. The Analysis of ATTITUDE on Speech in The Joy Luck Club--From the Perspective of APPRAISAL Systems

    Institute of Scientific and Technical Information of China (English)

    Zhao Ling

    2015-01-01

    This thesis takes advantage of the sub-category- ATTITUDE in APPRAISAL Systems to track the high- light of The Joy Luck Club written by American-Chinese novelist Amy Tan,focusing on one theme: June' s recollection on the colfflict she and her mother used to have. It mainly analyzes the interpersonal meaning of the selected speech, and different modes of speech concerning the expression of attitude.

  7. Programming a real-time operating system for satellite control applications Satellite Control Applications

    International Nuclear Information System (INIS)

    With the realization of ideas like formation flights and multi-body space vehicles the demands on an attitude control system have become increasingly complex. Even in its most simplified form, the control system for a typical geostationary satellite has to run various supervisory functions along with determination and control algorithms side by side. Within each algorithm it has to employ multiple actuation and sensing mechanisms and service real time interrupts, for example, in the case of actuator saturation and sensor data fusion. This entails the idea of thread scheduling and program synchronization, tasks specifically meant for a real time OS. This paper explores the embedding of attitude determination and control loop within the framework of a real time operating system provided for TI's DSP C6xxx series. The paper details out the much functionality provided within the scaleable real time kernel and the analysis and configuration tools available, It goes on to describe a layered implementation stack associated with a typical control for Geo Stationary satellites. An application for control is then presented in which state of the art analysis tools are employed to view program threads, synchronization semaphores, hardware interrupts and data exchange pipes operating in real time. (author)

  8. Hybrid systems controller design methodology

    OpenAIRE

    Pluska, Michal; Sinclair, David

    2010-01-01

    peer-reviewed Around ninety percent of vehicle innovations are driven mainly by electronics. The software implementing control algorithms combines the sensor values and calculates some meaningful actuator signals. On the other hand software in the vehicle can be seen as a part of a hybrid system. The hybrid system is a dynamic system that can have both continuous and discrete dynamic behaviour, its mean a system is described by both a differential equation and a difference equation. Moreov...

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

    OpenAIRE

    Maryam Amin; Pawan Nyachhyon; Maryam Elyasi; Muhammed Al-Nuaimi

    2014-01-01

    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 evalua...

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

    OpenAIRE

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

    2014-01-01

    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 expe...

  11. Dressage, Control, and Enterprise Systems

    DEFF Research Database (Denmark)

    Gal, Uri; Berente, Nicholas; Yoo, Youngjin

    2010-01-01

    that the ideal of complete enterprise control remains unattainable, as aspects of demonstrative control are inevitably implicated within broader enterprise-wide control systems within contemporary organizations. We conclude with implications for research and practice.......In 2004, National Aeronautics and Space Administration (NASA) implemented Full Cost, an activity-based accounting program through an agency-wide enterprise resource planning (ERP) implementation. We apply Foucault's notion of 'dressage' to highlight aspects of demonstrative control associated...... with this implementation effort and to outline the different dimensions along which control was distributed. We suggest that some elements of Full Cost and the ERP system were geared toward satisfying disciplinary requirements without necessarily contributing to productive activity. We term these elements dressage-as-control...

  12. Controller design and performance of the Spacelab instrument pointing system

    Science.gov (United States)

    Woelker, A.

    The Spacelab instrument pointing system (IPS) is designed for high-precision pointing of space experiments. The IPS demonstrated its performance during the maiden flight on the Shuttle in July 1985. The control system provides three-axis pointing and stabilization in the arcsec range for a variety of experiments. The envisaged pointing accuracy as well as the structural flexibility of the plant and disturbances imposed challenging requirements on the controller design. The control system comprises a feedback loop with attenuation filters and PID control as well as feed-forward compensation of external disturbances. Based on optical sensor and gyro measurements the attitude is determined via a special version of the Kalman filter.

  13. Robust power system frequency control

    CERN Document Server

    Bevrani, Hassan

    2014-01-01

    This updated edition of the industry standard reference on power system frequency control provides practical, systematic and flexible algorithms for regulating load frequency, offering new solutions to the technical challenges introduced by the escalating role of distributed generation and renewable energy sources in smart electric grids. The author emphasizes the physical constraints and practical engineering issues related to frequency in a deregulated environment, while fostering a conceptual understanding of frequency regulation and robust control techniques. The resulting control strategi

  14. NPL superconducting Linac control system

    International Nuclear Information System (INIS)

    The control system for the NPL Linac is based on a Microvax II host computer connected in a star network with 9 satellite computers. These satellites use single board varsions of DEC's PDP 11 processor. The operator's console uses high performance graphics and touch screen technology to display the current linac status and as the means for interactively controlling the operation of the accelerator

  15. Contamination Control: a systems approach

    NARCIS (Netherlands)

    Donck, J.C.J. van der

    2010-01-01

    Contamination influences a wide variety of industrial processes. For complex systems, contamination control, the collective effort to control contamination to such a level that it guarantees or even improves process or product functionality, offers a way for finding workable solutions. Central in th

  16. Analysis of response delay of the attitude in a single-axis rotation INS/GPS system

    Science.gov (United States)

    Zhu, Jing; Wang, Xingshu; Wang, Jun; Dai, Dongkai; Xiong, Hao

    2016-01-01

    Deflections of the vertical (DOV) are normally ignored in the gravity compensation procedure, which become one of the primary error sources in inertial navigation. In a single-axis rotation INS/GPS system, bias of the gyro and the accelerometer can be ignored, the attitude error is mainly affected by DOV. In this paper, the ideal system assumption is abandoned and the influence of DOV on the attitude is comprehensively discussed, which can be divided into two parts i.e. the direct influence and the indirect influence. The attitude error tracks the DOV along the trajectory belongs to the former. A relatively fixed delay between the attitude error and the DOV belongs to the latter. The delay is essentially induced by the weak observability of the system to the violent DOV. Factors which affect the delay are carefully analyzed. The simulation results show that the delay is mainly affected by accuracies of the inertial sensors and the GPS. It decreases with the GPS accuracy increasing, but increases with the inertial sensor accuracy increasing. The process noise covariance matrix Q plays an important role. With analysis of the characteristics of the delay, influence of the DOV on attitude is studied further, which is necessary for the attitude correction in future.

  17. 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.

  18. The ATLAS Detector Control System

    CERN Document Server

    Schlenker, S; Kersten, S; Hirschbuehl, D; Braun, H; Poblaguev, A; Oliveira Damazio, D; Talyshev, A; Zimmermann, S; Franz, S; Gutzwiller, O; Hartert, J; Mindur, B; Tsarouchas, CA; Caforio, D; Sbarra, C; Olszowska, J; Hajduk, Z; Banas, E; Wynne, B; Robichaud-Veronneau, A; Nemecek, S; Thompson, PD; Mandic, I; Deliyergiyev, M; Polini, A; Kovalenko, S; Khomutnikov, V; Filimonov, V; Bindi, M; Stanecka, E; Martin, T; Lantzsch, K; Hoffmann, D; Huber, J; Mountricha, E; Santos, HF; Ribeiro, G; Barillari, T; Habring, J; Arabidze, G; Boterenbrood, H; Hart, R; Marques Vinagre, F; Lafarguette, P; Tartarelli, GF; Nagai, K; D'Auria, S; Chekulaev, S; Phillips, P; Ertel, E; Brenner, R; Leontsinis, S; Mitrevski, J; Grassi, V; Karakostas, K; Iakovidis, G.; Marchese, F; Aielli, G

    2011-01-01

    The ATLAS experiment is one of the multi-purpose experiments at the Large Hadron Collider (LHC), constructed to study elementary particle interactions in collisions of high-energy proton beams. Twelve different sub-detectors as well as the common experimental infrastructure are supervised by the Detector Control System (DCS). The DCS enables equipment supervision of all ATLAS sub-detectors by using a system of >130 server machines running the industrial SCADA product PVSS. This highly distributed system reads, processes and archives of the order of 106 operational parameters. Higher level control system layers allow for automatic control procedures, efficient error recognition and handling, and manage the communication with external systems such as the LHC. This contribution firstly describes the status of the ATLAS DCS and the experience gained during the LHC commissioning and the first physics data taking operation period. Secondly, the future evolution and maintenance constraints for the coming years an...

  19. A Wireless Swing Angle Measurement Scheme Using Attitude Heading Reference System Sensing Units Based on Microelectromechanical Devices

    Directory of Open Access Journals (Sweden)

    Bingtuan Gao

    2014-11-01

    Full Text Available Feasible real-time swing angle measurement is significant to improve the efficiency and safety of industrial crane systems. This paper presents a wireless microelectromechanical system (MEMS-based swing angle measurement system. The system consists of two attitude heading reference system (AHRS sensing units with a wireless communication function, which are mounted on the hook (or payload and the jib (or base of the crane, respectively. With a combination of a three-axis accelerometer, a three-axis gyroscope and a three-axis magnetometer, the standard extended Kalman filter (EKF is used to estimate the desired orientation of the payload and the base. Wireless ZigBee communication is employed to transmit the orientation of the payload to the sensing unit mounted on the base, which measures the orientation of the base. Because several physical parameters from the payload to the base can be acquired from the original crane control system, the swing angles of the payload can be calculated based on the two measured orientation parameters together with the known physical parameters. Experiments were performed to show the feasibility and effectiveness of the proposed swing angle measurement system.

  20. Attitudes and attitude change

    DEFF Research Database (Denmark)

    Scholderer, Joachim

    2010-01-01

    attitude theory. Why is this important? Attitudinal concepts can be found in every area of marketing. Concepts like ad liking, brand attitude, quality perception, product preference, perceived benefit, perceived risk, perceived value, and customer satisfaction can all be understood as particular types...... of attitudes. This is the reason why a thorough understanding of attitudes is one of the most important skills a marketer can have. That same is true in related areas such as communications research: concepts like public opinion, corporate reputation, and corporate image are nothing more than particular types...

  1. Application of MAVEN Accelerometer and Attitude Control Data to Mars Atmospheric Characterization

    Science.gov (United States)

    Zurek, Richard W.; Tolson, Robert H.; Baird, Darren; Johnson, Mark Z.; Bougher, Stephen W.

    2015-12-01

    The structure of the upper atmosphere of Mars (above ˜100 km) has been probed in situ mainly using spacecraft accelerometers during the aerobraking phases of 3 Mars orbiters. In a similar manner, the Mars Atmosphere and Volatile Evolution (MAVEN) Accelerometer Experiment (ACC) will also use atmospheric drag accelerations sensed by inertial measurement units (IMU) onboard the spacecraft to recover atmospheric density along the orbiter path. These densities are used to estimate hydrostatic `vertical' density and temperature profiles, along track and altitudinal density waves, and latitudinal and longitudinal density variations. The IMU accelerometer signal-to-noise should permit profile reconstructions from spacecraft periapsis, nominally at 150 km altitude, to ˜170 km, an altitude range nominally spanning densities of 0.05-0.15 kg/km3. However, in situ measurements over a much greater altitude range, down to ˜125 km (reaching densities of ˜2-3.5 kg/km3), can be made during each of five week-long "Deep Dip" (DD) campaigns, and these are the prime focus of the Accelerometer Experiment. Judicious choice of the timing of these Deep-Dip campaigns during the MAVEN periapsis progression through local time, latitude and longitude in both hemispheres and in different seasons will add significantly to the existing data base of lower thermospheric densities. Other IMU and attitude control data may be used to estimate torques in order to improve the atmospheric density analysis, especially in the higher altitudes of the nominal science orbit, and, more challengingly, to estimate cross-track winds during the Deep-Dips.

  2. Attitudes of Germans towards distributive issues in the German health system.

    Science.gov (United States)

    Ahlert, Marlies; Pfarr, Christian

    2016-05-01

    Social health care systems are inevitably confronted with the scarcity of resources and the resulting distributional challenges. Since prioritization implies distributional effects, decisions regarding respective rules should take citizens' preferences into account. In this study we concentrate on two distributive issues in the German health system: firstly, we analyze the acceptance of prioritizing decisions concerning the treatment of certain patient groups, in this case patients who all need a heart operation. We focus on the patient criteria smoking behavior, age and whether the patient has or does not have young children. Secondly, we investigate Germans' opinions towards income-dependent health services. The results reveal the strong effects of individuals' attitudes regarding general aspects of the health system on priorities, e.g. that individuals with an unhealthy lifestyle should not be prioritized. In addition, experience of limited access to health services is found to have a strong influence on citizens' attitudes, too. Finally, decisions on different prioritization criteria are found to be not independent.

  3. Attitudes of Germans towards distributive issues in the German health system.

    Science.gov (United States)

    Ahlert, Marlies; Pfarr, Christian

    2016-05-01

    Social health care systems are inevitably confronted with the scarcity of resources and the resulting distributional challenges. Since prioritization implies distributional effects, decisions regarding respective rules should take citizens' preferences into account. In this study we concentrate on two distributive issues in the German health system: firstly, we analyze the acceptance of prioritizing decisions concerning the treatment of certain patient groups, in this case patients who all need a heart operation. We focus on the patient criteria smoking behavior, age and whether the patient has or does not have young children. Secondly, we investigate Germans' opinions towards income-dependent health services. The results reveal the strong effects of individuals' attitudes regarding general aspects of the health system on priorities, e.g. that individuals with an unhealthy lifestyle should not be prioritized. In addition, experience of limited access to health services is found to have a strong influence on citizens' attitudes, too. Finally, decisions on different prioritization criteria are found to be not independent. PMID:26013279

  4. Rationale for an experimental test for flexible space structure attitude control

    Science.gov (United States)

    Lange, T.; Heimbold, G.; Schaefer, B.; Holzach, H.

    1985-01-01

    The problems of large flexible spacecraft control are characterized by the infinite bandwidth of structural vibrations, which cannot be accounted for in the dynamic design model. This may lead to instability even, if ideal control hardware is assumed, which can be concluded from preceding numerical investigations. Additional performance limitations are expected to occur due to hardware constraints. A laboratory experiment is proposed to investigate the key problems in more detail. The test setup requirements being defined by the idealized control system are extremely high demanding a high speed processor and special hardware component developments. The test element is a wire suspended plate being controlled by an array processor via high performance sensors and actuators. First tests on component level indicate the feasibility of the system presently being developed.

  5. Learning fuzzy logic control system

    Science.gov (United States)

    Lung, Leung Kam

    1994-01-01

    The performance of the Learning Fuzzy Logic Control System (LFLCS), developed in this thesis, has been evaluated. The Learning Fuzzy Logic Controller (LFLC) learns to control the motor by learning the set of teaching values that are generated by a classical PI controller. It is assumed that the classical PI controller is tuned to minimize the error of a position control system of the D.C. motor. The Learning Fuzzy Logic Controller developed in this thesis is a multi-input single-output network. Training of the Learning Fuzzy Logic Controller is implemented off-line. Upon completion of the training process (using Supervised Learning, and Unsupervised Learning), the LFLC replaces the classical PI controller. In this thesis, a closed loop position control system of a D.C. motor using the LFLC is implemented. The primary focus is on the learning capabilities of the Learning Fuzzy Logic Controller. The learning includes symbolic representation of the Input Linguistic Nodes set and Output Linguistic Notes set. In addition, we investigate the knowledge-based representation for the network. As part of the design process, we implement a digital computer simulation of the LFLCS. The computer simulation program is written in 'C' computer language, and it is implemented in DOS platform. The LFLCS, designed in this thesis, has been developed on a IBM compatible 486-DX2 66 computer. First, the performance of the Learning Fuzzy Logic Controller is evaluated by comparing the angular shaft position of the D.C. motor controlled by a conventional PI controller and that controlled by the LFLC. Second, the symbolic representation of the LFLC and the knowledge-based representation for the network are investigated by observing the parameters of the Fuzzy Logic membership functions and the links at each layer of the LFLC. While there are some limitations of application with this approach, the result of the simulation shows that the LFLC is able to control the angular shaft position of the

  6. Component Control System for a Vehicle

    Science.gov (United States)

    Fraser-Chanpong, Nathan (Inventor); Spain, Ivan (Inventor); Dawson, Andrew D. (Inventor); Bluethmann, William J. (Inventor); Lee, Chunhao J. (Inventor); Vitale, Robert L. (Inventor); Guo, Raymond (Inventor); Waligora, Thomas M. (Inventor); Akinyode, Akinjide Akinniyi (Inventor); Reed, Ryan M. (Inventor)

    2016-01-01

    A vehicle includes a chassis, a modular component, and a central operating system. The modular component is supported by the chassis. The central operating system includes a component control system, a primary master controller, and a secondary master controller. The component control system is configured for controlling the modular component. The primary and secondary master controllers are in operative communication with the component control system. The primary and secondary master controllers are configured to simultaneously transmit commands to the component control system. The component control system is configured to accept commands from the secondary master controller only when a fault occurs in the primary master controller.

  7. Passivity based nonlinear attitude control of the Rømer satellite

    DEFF Research Database (Denmark)

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

    configuration of Wide Angle Telescopes for Cosmic Hard x-rays (WATCH), that server the dual purpose of X-ray detectors and momentum wheels. By employing passivity theory it is shown, that the satellite is a passive system. This paper shows, that global asymptotic can be obtained with a passive and an imput and...... output strictly passive system in a feedback interconnection. It is demonstrated in a simulation study that the resultant control has a potential for on-board implementation in the acquistion phase, where global stabillity of the control law is vital...

  8. Using the global positioning satellite system to determine attitude rates using doppler effects

    Science.gov (United States)

    Campbell, Charles E. (Inventor)

    2003-01-01

    In the absence of a gyroscope, the attitude and attitude rate of a receiver can be determined using signals received by antennae on the receiver. Based on the signals received by the antennae, the Doppler difference between the signals is calculated. The Doppler difference may then be used to determine the attitude rate. With signals received from two signal sources by three antennae pairs, the three-dimensional attitude rate is determined.

  9. The CERN SPS Control System

    CERN Multimedia

    CERN Neyrac Films

    2012-01-01

    Part of the series of films produced by CERN about the SPS. Names, facts and credits added on the 1975 version by Bengt Sagnell, Meyrin, Oct 2012. The project leader for the SPS accelerator (with 400 staff) was John Adams - later Sir John. The group responsible for the design and installation of the control system was led by Michael Crowley-Milling. 00:02:14 Bernard Sutton00:02:48 Michael Crowley-Milling, Head of the Controls Group00:03:01 Designed in the Controls Group, this was probably the first use of touch screens in an industrial control system00:04:37 Louis Burnod, Section leader, Beam Instrumentation00:05:36 Claes Frisk, Computer technician 00:06:03 The system contained 24 Norsk Data NORD-10 16-bit mini computers with 16-64 kB of magnetic core memory and external hard disks of from 5MB to 256 MB in size00:06:23 Frank Beck, Section leader, Central Controls00:06:26 Véronique Frammery, Programmer 00:06:31 Hans-Karl Kuhn, Power Supply Controls00:07:55 Raymond Rausch, Control electronics00:10:23 Paul Acti...

  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. Solar Dynamics Observatory Guidance, Navigation, and Control System Overview

    Science.gov (United States)

    Morgenstern, Wendy M.; Bourkland, Kristin L.; Hsu, Oscar C.; Liu, Kuo-Chia; Mason, Paul A. C.; O'Donnell, James R., Jr.; Russo, Angela M.; Starin, Scott R.; Vess, Melissa F.

    2011-01-01

    The Solar Dynamics Observatory (SDO) was designed and built at the Goddard Space Flight Center, launched from Cape Canaveral on February 11, 2010, and reached its final geosynchronous science orbit on March 16, 2010. The purpose of SDO is to observe the Sun and continuously relay data to a dedicated ground station. SDO remains Sun-pointing throughout most of its mission for the instruments to take measurements of the Sun. The SDO attitude control system (ACS) is a single-fault tolerant design. Its fully redundant attitude sensor complement includes sixteen coarse Sun sensors (CSSs), a digital Sun sensor (DSS), three two-axis inertial reference units (IRUs), and two star trackers (STs). The ACS also makes use of the four guide telescopes included as a part of one of the science instruments. Attitude actuation is performed using four reaction wheels assemblies (RWAs) and eight thrusters, with a single main engine used to provide velocity-change thrust for orbit raising. The attitude control software has five nominal control modes, three wheel-based modes and two thruster-based modes. A wheel-based Safehold running in the attitude control electronics box improves the robustness of the system as a whole. All six modes are designed on the same basic proportional-integral-derivative attitude error structure, with more robust modes setting their integral gains to zero. This paper details the final overall design of the SDO guidance, navigation, and control (GN&C) system and how it was used in practice during SDO launch, commissioning, and nominal operations. This overview will include the ACS control modes, attitude determination and sensor calibration, the high gain antenna (HGA) calibration, and jitter mitigation operation. The Solar Dynamics Observatory mission is part of the NASA Living With a Star program, which seeks to understand the changing Sun and its effects on the Solar System, life, and society. To this end, the SDO spacecraft carries three Sun

  12. Study of the control-equilibrium of control systems

    Institute of Scientific and Technical Information of China (English)

    Liu Qiaoge; Fu Mengyin; Sun Changsheng

    2008-01-01

    Not so much had been talked about equilibrium in control area.On the basis of the phenomenon of balance,the concept of control-equilibrium and control-equilibrium of a control system is proposed.According to this theory,a perfect control method should not only guarantee stability of the system,but also ensure the control-equilibrium of the system.To achieve the control-equilibrium,feed-forward control is required.

  13. System identification for multivariable control

    Science.gov (United States)

    Vanzee, G. A.

    1981-05-01

    System identification methods and modern control theory are applied to industrial processes. These processes must often be controlled in order to meet certain requirements with respect to the product quality, safety, energy consumption, and environmental load. Modern control system design methods which take the occurring interaction phenomena and stochastic disturbances into account are used. An accurate dynamic mathematical model of the process, by theoretical modelling and/or by system identification is obtained. The computational aspects of two important types of identifications methods, i.e., stochastic realization and prediction error based parameter estimation are studied. The studied computational aspects are the robustness, the accuracy, and the computational costs of the methods. Theoretical analyses and applications to a multivariable pilot scale process, operating under closed loop conditions are investigated.

  14. Power system dynamics and control

    CERN Document Server

    Kwatny, Harry G

    2016-01-01

    This monograph explores a consistent modeling and analytic framework that provides the tools for an improved understanding of the behavior and the building of efficient models of power systems. It covers the essential concepts for the study of static and dynamic network stability, reviews the structure and design of basic voltage and load-frequency regulators, and offers an introduction to power system optimal control with reliability constraints. A set of Mathematica tutorial notebooks providing detailed solutions of the examples worked-out in the text, as well as a package that will enable readers to work out their own examples and problems, supplements the text. A key premise of the book is that the design of successful control systems requires a deep understanding of the processes to be controlled; as such, the technical discussion begins with a concise review of the physical foundations of electricity and magnetism. This is followed by an overview of nonlinear circuits that include resistors, inductors, ...

  15. Radiation-hardened control system

    International Nuclear Information System (INIS)

    A radiation-hardened bit-slice control system with associated input/output circuits was developed to prove that programmable circuits could be constructed to successfully implement intelligent functions in a highly radioactive environment. The goal for this effort was to design and test a programmable control system that could withstand a minimum total dose of 107 rads (gamma). The Radiation Hardened Control System (RHCS) was tested in operation at a dose rate that ranged up to 135 krad/h, with an average total dose of 10.75 Mrads. Further testing beyond the required 107 rads was also conducted. RHCS performed properly through the target dose of 107 rads, and sporadic intermittent failures in some programmable logic devices were noted after ∼ 13 Mrads

  16. Proton beam therapy control system

    Science.gov (United States)

    Baumann, Michael A.; Beloussov, Alexandre V.; Bakir, Julide; Armon, Deganit; Olsen, Howard B.; Salem, Dana

    2008-07-08

    A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

  17. Antenna surface contour control system

    Science.gov (United States)

    Ahl, Elvin L.; Miller, James B.

    1989-03-01

    The invention is a system for automatically controlling the surface contour of a deployable and restowable antenna having a mesh reflector surface supported by a circular, folding hoop affixed to a central, telescoping column. The antenna, when deployed, forms a quad-aperture reflector with each quadrant of the mesh surface shaped to provide an offset parabolic radio frequency (RF) reflector. The hoop is supported and positioned by quartz support cords attached to the top of a column and by lower graphite hoop control cords that extend between the hoop and base of the column. The antenna, an RF reflective surface, is a gold plated molybdenum wire mesh supported on a graphite cord truss structure that includes the hoop control cords and a plurality of surface control cords attached at selected points on the surface and to the base of the column. The contour of the three-dimensional surface of the antenna is controlled by selectively adjusting the lengths of the surface control cords and the graphite hoop control cords by means of novel actuator assemblies that automatically sense and change the lengths of the lower hoop control cords and surface control cords.

  18. 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)

  19. Control System of the Bepcii

    CERN Document Server

    Zhao, J; Kong, X C; Lei, G; Xu, S F; Le, Q

    2001-01-01

    Recently the Chinese Academy of Sciences has chosen BEPCII as the future development of the BEPC, i.e. upgrade of both the machine and detector. The luminosity of the machine is expected to increase to 1.0x1033cm-2s-1. The project will be started at the beginning of 2002 and finished with in 3-4 years. The BEPC control system was built in 1987 and upgraded in 1994. According to the design of the BEPCII, a double ring schema will be adopted and a number of new devices will be added in the system. The existing control system has to be upgraded. The BEPCII will be distributed architecture and developed by EPICS. We are going to apply the standard hardware interfaces and mature technologies in the system. A number of VME IOCs will be added in the system and the feildbus, PLCs will be used as device control for some kind of equipment. We will keep the existing system in use, such as CAMAC modules and PC front-ends, and merge it into EPICS system. Recently the development of the prototype is in progress. This paper...

  20. 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, p<0.05) and a significant negative relationship between internal locus of control and positive attitude toward PAS (r=-0.263, p<0.01). Multivariate analyses revealed differing predictor models for attitudes towards euthanasia 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.