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Sample records for attitude control method

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

    Science.gov (United States)

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

    2008-01-01

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

  2. 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.

  3. 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)

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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...

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

    Science.gov (United States)

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

    2015-06-01

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

  15. 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.

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

    Institute of Scientific and Technical Information of China (English)

    郭延宁; 李传江; 马广富

    2011-01-01

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

  17. 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 ...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  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. 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...

  4. 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.

  5. 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.

  6. 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...

  7. 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.

  8. 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...

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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...

  18. 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.

  19. 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.

  20. 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

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Motivation,Attitude and Teaching Methods

    Institute of Scientific and Technical Information of China (English)

    曹琪雯

    2014-01-01

    Motivation and attitude are two important factors that influence the students' foreign language learning. This paper focuses on the diverse influences from the different types of motivation and attitude that the students have. At the same time, it provides some suggestions for the language teachers and hopes that it may be helpful for their language teaching.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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...

  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. 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....

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. The Relationship between Values and Attitudes toward Three Therapy Methods.

    Science.gov (United States)

    Madell, Thomas O.

    1982-01-01

    Examined relationships between value dimensions and attitudes toward therapy with a sample of 65 college students who chose which counseling method they thought would be most helpful. Results showed attitudes toward the behavioral and rational-emotive approaches were related to values to a small degree. (JAC)

  19. 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.

  20. 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...

  1. 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.

  2. 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...

  3. 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...

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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…

  20. 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.

  1. 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.

  2. 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.

  3. 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…

  4. 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.

  5. 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.

  6. 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 ...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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...

  12. Student Attitudes to Traditional and Online Methods of Delivery

    Science.gov (United States)

    Wong, Lily; Fong, Michelle

    2014-01-01

    Rapid developments in education technology have provided educators and students new options in a constantly changing, competitive teaching and learning environment. As the number of online teaching resources continue to increase, research into student attitudes toward traditional and online methods of delivery is important in order to determine…

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. ASSESSMENT OF THE INFLUENCE OF 5E LEARNING METHOD AND COOPERATIVE LEARNING METHOD ON BIOLOGY ATTITUDE IN TERMS OF GENDER

    Directory of Open Access Journals (Sweden)

    Murat AKTAŞ

    2013-06-01

    Full Text Available The aim of this study is toassessment of the influence of cooperative learning method and cooperative learning method on biology attitude in terms of gender. In 2010-2011 school year 93 students who were in 3nd grade science field at Ankara Çankaya Milli Piyango Anadolu High School constituted the work group of the study. “Heredity, Genetic Engineering and Biotechnology” unit were worked by 5E learning model at 1th experimenta group, by cooperative learning at 2th experimental group and by traditional teaching method at control group.Data were collected by applying biology attitude scale at the beginning and the end of the investigation.The following results were obtained from this study: No differences in the students’ attitudes towards the biology lessons has been observed according to student’s gender.

  18. STUDENTS’ ATTITUDE TOWARDS DIFFERENT EVALUATION METHODS IN PHARMACOLOGY

    OpenAIRE

    Majagi Suneel Ishwar; Hiremath S.V.; Torgal S.S.

    2012-01-01

    Literature review suggests the importance and the need of students’ feedback which may be used to effectively reform evaluation methods in medical sciences. The present study has been conducted to obtain student’s attitude (perception of) towards different evaluation methods of pharmacology. The sample consisted of second phase M.B.B.S (n=108) students. Students answered 115 items/questions designed according to Likert’s five point (in agreement with items) scale. These items/questions assess...

  19. 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 ...

  20. 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.

  1. 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...

  2. 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..

  3. 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.

  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. 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...

  6. 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.

  7. 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.

  8. 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.

  9. 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...

  10. 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...

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  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. UKF-based attitude determination method for gyroless satellite

    Institute of Scientific and Technical Information of China (English)

    张红梅; 邓正隆

    2004-01-01

    UKF (unscented Kalman filtering) is a new filtering method suitable to nonlinear systems. The method need not linearize nonlinear systems at the prediction stage of filtering, which is indispensable in EKF (extended Kalman filtering). As a result, the linearization error is avoided, and the filtering accuracy is greatly improved. UKF is applied to the attitude determination for gyroless satellite. Simulations are made to compare the new filter with the traditional EKF.The results indicate that under same conditions, compared with EKF, UKF has faster convergence speed, higher filtering accuracy and more stable estimation performance.

  18. 柚子包装前端姿态调整方式的研究%Research on the Method of Controlling Front-end Attitudes of Grapefruit Packaging

    Institute of Scientific and Technical Information of China (English)

    李延苓; 黄志平; 张国全; 李爱华

    2013-01-01

    通过对柚子包装原理分析,提出了柚子包装材料的适宜性,研究了柚子前端姿态存在的机理,并得出了不同姿态柚子的处理方法,最后设计了一种用于柚子前端姿态调整的排序设备,且在现场验证了设备原理的可行性。%Through the theory of grapefruit packaging was analyzed , the suitability of packaging materials of the grapefruits was proposed .The mechanism of grapefruit in stance was too studied , and the grapefruit pro-cessing method in different attitude was obtained .At last, a kind of equipment for the grapefruit adjustment in attitude was designed , and the feasibility of the theory was verified on the spot .

  19. 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

  20. Effects of Using Case-Study Method in Social Studies on Students' Attitudes Towards Environment

    OpenAIRE

    Hamza Akengin; Gökhan Aydemir

    2012-01-01

    his study has aimed to inquired whether there was a significant difference between academic achievement and attitudes of 6th grade students who learned “The Resources of Our Country” unit of social studies through case studies and students who learned this unit with teaching based on existing unit. Besides it was aimed to present thoughts and feelings of the students about the case study method aided learning- teaching process. Pretest-posttest control group design was used in this study and...

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. STUDENTS’ ATTITUDE TOWARDS DIFFERENT EVALUATION METHODS IN PHARMACOLOGY

    Directory of Open Access Journals (Sweden)

    Majagi Suneel Ishwar

    2012-08-01

    Full Text Available Literature review suggests the importance and the need of students’ feedback which may be used to effectively reform evaluation methods in medical sciences. The present study has been conducted to obtain student’s attitude (perception of towards different evaluation methods of pharmacology. The sample consisted of second phase M.B.B.S (n=108 students. Students answered 115 items/questions designed according to Likert’s five point (in agreement with items scale. These items/questions assessed student’s attitude (perception of towards different constituents of evaluation methods of pharmacology like sessional exams, traditional practical exams, objective structured practical exam (OSPE, MCQs, long essays, viva voce, pharmacy practical exercise, experimental pharmacology exercise etc in relation with various aspects of pharmacology subject like understanding, retention, learning clinical applications, mechanism of action of drugs, pharmacological actions, therapeutic uses, prescribing drugs etc. Results of the present study indicated the degree to which each evaluation method like sessional/preliminary theory exams, traditional practical exams and OSPE helps to elicit different constituents of pharmacology subject (ex: mechanism of action of drugs, therapeutic uses etc and the reason for the same is discussed. Similarly usefulness of different constituents of theory exams (MCQs, long essay etc and practical exams (spotters, pharmacy exercises etc towards eliciting the understanding pharmacology is revealed. Present study indicated the merits and demerits of different evaluation methods used in pharmacology. If any reformations/changes have to be incorporated in the evaluation methods, outcomes of this study will definitely help towards improving/modifying the evaluation methods of teaching and learning of pharmacology subject.

  8. 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.

  9. 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

  10. 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...

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. Nurses`knowledge of and attitude towards exercise as a treatment method for hypertensive patients

    Directory of Open Access Journals (Sweden)

    L. Grobler

    2005-02-01

    Full Text Available Aerobic exercise is used in treating hypertension. Eventhough physiotherapists are the first choice in presenting exercise treatment, few are available to do so in primary health clinics. Nurses arepatients’ first contact and may be able to fulfil this role. Nurses’knowledge and attitude towards exercise as a treatment method for hypertensive patients was determined. This descriptive study included all nurses (n=67 working in 23 Bloemfontein clinics. Forty-three nursescompleted structured questionnaires that determined their knowledge of exercise as a treatment method. All nurses prescribed medication forhypertensive patients. Most nurses prescribed weight control (72.1%, diet control (76.7%, patient education (74.4%, and life-style modification (72.1%. Most (83.7% nurses were aware of exercise as a treatment method for hypertension. Only seven nurses, prescribing a brisk walk, recommended the correct type of exercise. The nurses’attitude towards exercise as a treatment method was determined using focus group interviews (n=16. Nurses reflected a positive attitude towards exercise with 198 positive responses. Nurses could express more than one opinion, all of which were recorded. Twenty responses reflected little or no knowledge, and four responses reflected an unsure/neutral attitude towards exercise. Ten responses reflected disinterest in prescribing exercise. Nurses do not have adequate knowledge to enable them to confidently prescribe exercise to patients. The need for more information was mentioned and some nurses were willing to present exercise classes. A training program, containing pertinent information, so that nurses can prescribe exercise for hypertension, needs to be developed.

  18. Sine Rotation Vector Method for Attitude Estimation of an Underwater Robot.

    Science.gov (United States)

    Ko, Nak Yong; Jeong, Seokki; Bae, Youngchul

    2016-01-01

    This paper describes a method for estimating the attitude of an underwater robot. The method employs a new concept of sine rotation vector and uses both an attitude heading and reference system (AHRS) and a Doppler velocity log (DVL) for the purpose of measurement. First, the acceleration and magnetic-field measurements are transformed into sine rotation vectors and combined. The combined sine rotation vector is then transformed into the differences between the Euler angles of the measured attitude and the predicted attitude; the differences are used to correct the predicted attitude. The method was evaluated according to field-test data and simulation data and compared to existing methods that calculate angular differences directly without a preceding sine rotation vector transformation. The comparison verifies that the proposed method improves the attitude estimation performance.

  19. Sine Rotation Vector Method for Attitude Estimation of an Underwater Robot

    Science.gov (United States)

    Ko, Nak Yong; Jeong, Seokki; Bae, Youngchul

    2016-01-01

    This paper describes a method for estimating the attitude of an underwater robot. The method employs a new concept of sine rotation vector and uses both an attitude heading and reference system (AHRS) and a Doppler velocity log (DVL) for the purpose of measurement. First, the acceleration and magnetic-field measurements are transformed into sine rotation vectors and combined. The combined sine rotation vector is then transformed into the differences between the Euler angles of the measured attitude and the predicted attitude; the differences are used to correct the predicted attitude. The method was evaluated according to field-test data and simulation data and compared to existing methods that calculate angular differences directly without a preceding sine rotation vector transformation. The comparison verifies that the proposed method improves the attitude estimation performance. PMID:27490549

  20. Sine Rotation Vector Method for Attitude Estimation of an Underwater Robot.

    Science.gov (United States)

    Ko, Nak Yong; Jeong, Seokki; Bae, Youngchul

    2016-01-01

    This paper describes a method for estimating the attitude of an underwater robot. The method employs a new concept of sine rotation vector and uses both an attitude heading and reference system (AHRS) and a Doppler velocity log (DVL) for the purpose of measurement. First, the acceleration and magnetic-field measurements are transformed into sine rotation vectors and combined. The combined sine rotation vector is then transformed into the differences between the Euler angles of the measured attitude and the predicted attitude; the differences are used to correct the predicted attitude. The method was evaluated according to field-test data and simulation data and compared to existing methods that calculate angular differences directly without a preceding sine rotation vector transformation. The comparison verifies that the proposed method improves the attitude estimation performance. PMID:27490549

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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...

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

    OpenAIRE

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

    2013-01-01

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

  12. 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.

  13. 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.

  14. 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)

  15. 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).

  16. 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

  17. 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…

  18. 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.

  19. Students' Attitudes toward Statistics across the Disciplines: A Mixed-Methods Approach

    Science.gov (United States)

    Griffith, James D.; Adams, Lea T.; Gu, Lucy L.; Hart, Christian L.; Nichols-Whitehead, Penney

    2012-01-01

    Students' attitudes toward statistics were investigated using a mixed-methods approach including a discovery-oriented qualitative methodology among 684 undergraduate students across business, criminal justice, and psychology majors where at least one course in statistics was required. Students were asked about their attitudes toward statistics and…

  20. 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.

  1. 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.

  2. 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....

  3. 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....

  4. 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.

  5. Comparing Efficacy of Four Preventive Methods on Attitude of Drug Substance Abuse and Self–Esteem in Students Supported by Emdad Committee

    OpenAIRE

    aziz allah agha babaei; daruosh jalali; hamid reza saeedzadeh; sohayla bagheri

    2012-01-01

    Introduction: This study was aimed to compare the efficacy of four drug substance abuse preventive methods: cognitive–behavioral social traioning, life skills training, poster presentation and short message system on attitude change and enhancement self-esteem in students supported by Emdad Committee. Method:This was a quasi experimental study. 150 students were selected and randomly assigned to the four experimental and control groups. The groups were completed attitude of drug substance ab...

  6. 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...

  7. 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...

  8. 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...

  9. 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.

  10. 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.

  11. 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.

  12. The influence of contextual teaching with the problem solving method on students' knowledge and attitudes toward horticulture, science, and school

    Science.gov (United States)

    Whitcher, Carrie Lynn

    2005-08-01

    Adolescence is marked with many changes in the development of higher order thinking skills. As students enter high school they are expected to utilize these skills to solve problems, become abstract thinkers, and contribute to society. The goal of this study was to assess horticultural science knowledge achievement and attitude toward horticulture, science, and school in high school agriculture students. There were approximately 240 high school students in the sample including both experimental and control groups from California and Washington. Students in the experimental group participated in an educational program called "Hands-On Hortscience" which emphasized problem solving in investigation and experimentation activities with greenhouse plants, soilless media, and fertilizers. Students in the control group were taught by the subject matter method. The activities included in the Hands-On Hortscience curriculum were created to reinforce teaching the scientific method through the context of horticulture. The objectives included evaluating whether the students participating in the Hands-On Hortscience experimental group benefited in the areas of science literacy, data acquisition and analysis, and attitude toward horticulture, science, and school. Pre-tests were administered in both the experimental and control groups prior to the research activities and post-tests were administered after completion. The survey questionnaire included a biographical section and attitude survey. Significant increases in hortscience achievement were found from pre-test to post-test in both control and experimental study groups. The experimental treatment group had statistically higher achievement scores than the control group in the two areas tested: scientific method (p=0.0016) and horticulture plant nutrition (p=0.0004). In addition, the students participating in the Hands-On Hortscience activities had more positive attitudes toward horticulture, science, and school (p=0

  13. 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

  14. 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...

  15. 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 ...

  16. Methods for structural control

    OpenAIRE

    Baratta, A.; Bourquin, F.; CORBI, O; HOCHRAINER, M; Luo, N; MAGONETTE, G; Marazzi, F; Rodellar, J.

    2004-01-01

    In the last decades significant advances have been produced in the field of structural control. This paper focuses on some issues related with the problem of controlling (reducing) undesired vibrations, summarizing the experiences of the authors in some specific issues on specific classes of structural control systems.

  17. 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…

  18. 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.

  19. 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.

  20. 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.

  1. A method for attitude measurement of a test vehicle based on the tracking of vectors

    International Nuclear Information System (INIS)

    In the vehicle simulation test, in order to improve the measuring precision for the attitude of a test vehicle, a measuring method based on the vectors of light beams is presented, in which light beams are mounted on the test vehicle as the cooperation target, and the attitude of the test vehicle is calculated with the light beams’ vectors in the test vehicle’s coordinate system and the world coordinate system. Meanwhile, in order to expand the measuring range of the attitude parameters, cooperation targets and light beams in each cooperation target are increased. On this basis, the concept of an attitude calculation container is defined, and the selection method for the attitude calculation container that participates in the calculation is given. Simultaneously, the vectors of light beams are tracked so as to ensure the normal calculation of the attitude parameters. The experiments results show that this measuring method based on the tracking of vectors can achieve the high precision and wide range of measurement for the attitude of the test vehicle. (paper)

  2. Attitudes of eighth-grade honors students toward the conceptual change methods of teaching science

    Science.gov (United States)

    Heide, Clifford Lee

    1998-12-01

    The study researched the attitude of eighth grade honors science students toward the steps of the conceptual change teaching method. The attitudes of 25 students in an honors 8th grade science class in the Greater Phoenix metropolitan area were assessed using a multi-method approach. A quantitative method (student survey) and a qualitative method (focus group) were triangulated for convergence. Since conceptual change is a relatively new reform teaching modality, the study assessed students' attitudes utilizing this method. Conceptual change teaching is characterized by connections between concepts and facts which are organized around key ideas. Knowledge connected through concepts is constantly revised and edited by students as they continue to learn and add new concepts. The results of this study produced evidence that the conceptual change method of teaching science and its six process steps have qualities that foster positive student attitude. The study demonstrated that students' attitudes toward science is positively influenced through the conceptual change teaching method by enabling students to: (1) choose problems and find solutions to those problems (student directed); (2) work together in large and small groups; (3) learn through student oral presentations; (4) perform hands-on laboratory experiences; (5) learn through conceptual understanding not memorization; (6) implement higher order learning skills to make connections from the lab to the real world. Teachers can use the information in the study to become aware of the positive and negative attitudes of students taught with the conceptual change method. Even if the conceptual change teaching strategy is not the modality utilized by an educator, the factors identified by this study that affect student attitude could be used to help a teacher design lesson plans that help foster positive student attitudes.

  3. Attitudes of Teachers of Arabic as a Foreign Language toward Methods of Foreign Language Teaching

    Science.gov (United States)

    Seraj, Sami A.

    2010-01-01

    This study examined the attitude of teachers of Arabic as a foreign language toward some of the most well known teaching methods. For this reason the following eight methods were selected: (1) the Grammar-Translation Method (GTM), (2) the Direct Method (DM), (3) the Audio-Lingual Method (ALM), (4) Total Physical Response (TPR), (5) Community…

  4. 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.

  5. 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)

  6. 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.

  7. 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

  8. Birth control - slow release methods

    Science.gov (United States)

    Contraception - hormonal methods; Progestin implants; Progestin injections; Skin patch; Vaginal ring ... might want to consider a different birth control method. SKIN PATCH The skin patch is placed on ...

  9. 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.

  10. Methods in Logic Based Control

    DEFF Research Database (Denmark)

    Christensen, Georg Kronborg

    1999-01-01

    Desing and theory of Logic Based Control systems.Boolean Algebra, Karnaugh Map, Quine McClusky's algorithm. Sequential control design. Logic Based Control Method, Cascade Control Method. Implementation techniques: relay, pneumatic, TTL/CMOS,PAL and PLC- and Soft_PLC implementation. PLC...

  11. 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...

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

    Science.gov (United States)

    Simon, Miguel

    testing any one or combination of the following attitude axes controlled flight: (1) pitch, (2) roll and (3) yaw. The subsequent development of a novel method to decouple, stabilize and teach the helicopter hover flight is a primary contribution of this thesis. The novel method included the development of a non-linear modeling technique for linearizing the RPM state equation dynamics so that a simple but accurate transfer function is derivable between the "available torque of the engine" and RPM. Specifically, the main rotor and tail rotor torques are modeled accurately with a bias term plus a nonlinear term involving the product of RPM squared times the main rotor blade pitch angle raised to the three-halves power. Application of this non-linear modeling technique resulted in a simple, representative and accurate transfer function model of the open-loop plant for the entire helicopter system so that all the feedback control laws for autonomous flight purposes could be derived easily using classical control theory. This is one of the contributions of this dissertation work. After discussing the integration of hardware and software elements of our helicopter research test bed system, we perform a number of experiments and tests using the two specially built test stands. Feedback gains are derived for controlling the following: (1) engine throttle to maintain prescribed main rotor angular speed, (2) main rotor collective pitch to maintain constant elevation, (3) longitudinal cyclic pitch to maintain prescribed pitch angle, (4) lateral cyclic pitch to maintain prescribed roll angle, and (5) yaw axis to maintain prescribed compass direction. (Abstract shortened by UMI.)

  13. 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...

  14. 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

  15. The Effects of Speech Training, Guidebook and Simultaneous Method, on the Knowledge and Attitude of Students about HIV/AIDS

    Directory of Open Access Journals (Sweden)

    Rahim Vakili

    2015-05-01

    Full Text Available Introduction: A great percentage of AIDS infections occure in adolescence and youth. since that,studing and finding the most efficient teaching methods in order to improve their information ( knowledge and attitude also to create o positive one and to creat preventive measures in the young and adolescent,is of great significance and priority. Materials and Methods: 7 school were picked randomy among different Mashhad educational districts.From these schools,650 students were  randomy  selected and divided into 4 groups:1-education with lecture, 2-education with guidebook, 3-education with lecture and guidebook,  4-without any education. Firstly ,  basic knowledge and attitude of students on AIDS were evaluated. Then their educational needs and curriculum were designed. Then 2 weeeks after cinducting the  education,student's knowledge ( study groups and attitude were evaluated. Results: Average Points for knowledge and attitude before education were 25.86 and 23.70 that were elevated to 27.68  and 25.27 after  aducation. There was no  statistical difference between average points of all 4 groups' knowledge and attitude before education. After education, average point of knowledge was 28.33+5.6 in  lecture group,28.19+6.26 in guidebook group, 29.77+4.49 in lecture and guidebook group and 26.90+4.95 in control group. After  education, average  points of attitude  was 25.77+3.7 in lecture group, 25.62+3.47 in guidebook group, 25.27+3.87 in lecture and guidebook  group  and 23.98+3.56 in  control group. Statistical analyses  showed that there is significant difference between points before and after education in the 3 study groups ( PConclusion:  To improve  student's  knowledge,  education by both lecture and guidebook, and to improve their attitude or to create a positive one, lecture method are preferred.

  16. 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.

  17. 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.

  18. 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.

  19. An Aerial Image Mosaic Method Based on UAV Position and Attitude Information

    Directory of Open Access Journals (Sweden)

    CHENG Zhenggang

    2016-06-01

    Full Text Available As the existing methods for aerial image mosaic take high computational, a fast and effective algorithm based on the position and attitude information of unmanned aerial vehicles (UAV is proposed. Firstly, the coordinates and attitude angles of UAV can be obtained by airborne GPS and inertial measurement unit (IMU, and each aerial image has a corresponding position and attitude information. The homography matrix between two aerial images with the positions and attitude information can be calculated. Then the registration of the mosaic images is obtained by the operation of homography matrix. Finally, the multiple images can be stitched and the whole panorama got. A large number of experiments demonstrate this algorithm is efficient.

  20. The Effect of Teaching Methods on Examination Performance and Attitudes in an Introductory Financial Accounting Course.

    Science.gov (United States)

    Marcheggiani, Joseph; Davis, Karel A.; Sander, James F.

    1999-01-01

    Comparison of accounting students taught with a group Socratic method (n=22) and interactive lecture method (n=15) found no evidence that either method significantly improved examination scores. Student attitudes toward the course or the accounting profession did not differ. (SK)

  1. Symbolic Drawings Reveal Changes in Preservice Teacher Mathematics Attitudes after a Mathematics Methods Course

    Science.gov (United States)

    Rule, Audrey C.; Harrell, Mary H.

    2006-01-01

    A new method of analyzing mathematics attitudes through symbolic drawings, situated within the field of Jungian-oriented analytical psychology, was applied to 52 preservice elementary teachers before and after a mathematics methods course. In this triangulation mixed methods design study, pretest images related to past mathematics experiences…

  2. Comparing two image research instruments: The Q-sort method versus the Likert attitude questionnaire

    NARCIS (Netherlands)

    Klooster, ten Peter M.; Visser, Martijn; Jong, de Menno D.T.

    2008-01-01

    Despite the attention for corporate, brand and product images, only few studies focus on methodological comparisons of image research methods. This article presents a comparison of two current instruments: the Q-sort method and a Likert attitude questionnaire. The study applies both methods to measu

  3. 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...

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. Understanding Factors that Shape Gender Attitudes in Early Adolescence Globally: A Mixed-Methods Systematic Review

    Science.gov (United States)

    Gibbs, Susannah; Blum, Robert Wm; Moreau, Caroline; Chandra-Mouli, Venkatraman; Herbert, Ann; Amin, Avni

    2016-01-01

    Background Early adolescence (ages 10–14) is a period of increased expectations for boys and girls to adhere to socially constructed and often stereotypical norms that perpetuate gender inequalities. The endorsement of such gender norms is closely linked to poor adolescent sexual and reproductive and other health-related outcomes yet little is known about the factors that influence young adolescents’ personal gender attitudes. Objectives To explore factors that shape gender attitudes in early adolescence across different cultural settings globally. Methods A mixed-methods systematic review was conducted of the peer-reviewed literature in 12 databases from 1984–2014. Four reviewers screened the titles and abstracts of articles and reviewed full text articles in duplicate. Data extraction and quality assessments were conducted using standardized templates by study design. Thematic analysis was used to synthesize quantitative and qualitative data organized by the social-ecological framework (individual, interpersonal and community/societal-level factors influencing gender attitudes). Results Eighty-two studies (46 quantitative, 31 qualitative, 5 mixed-methods) spanning 29 countries were included. Ninety percent of studies were from North America or Western Europe. The review findings indicate that young adolescents, across cultural settings, commonly express stereotypical or inequitable gender attitudes, and such attitudes appear to vary by individual sociodemographic characteristics (sex, race/ethnicity and immigration, social class, and age). Findings highlight that interpersonal influences (family and peers) are central influences on young adolescents’ construction of gender attitudes, and these gender socialization processes differ for boys and girls. The role of community factors (e.g. media) is less clear though there is some evidence that schools may reinforce stereotypical gender attitudes among young adolescents. Conclusions The findings from this

  10. Optimal attitude determination method in presence of noise and bias on different star sensors

    Directory of Open Access Journals (Sweden)

    Amir Moghtadaei Rad

    2014-03-01

    Full Text Available There are different attitude determination methods which have been used in satellite and spacecraft by star tracker. Each of these methods have its own advantages and disadvantages depending on their application, stochastic characteristic of noise on sensors (bias or noise, and weight of noise falling on different sensors. The present study has thus explored the major methods from two perspectives: the effect of input noise or bias on each star sensor and the corresponding weight of each noise or bias falling on each sensor. These aspects are compared in each method and the optimal method according to each condition is introduced. N Vector, Triad, Quest, Q method and least square method are the methods studied and simulated in this article. Finally, a comparison is made between the methods and the optimal method is introduced theoretically and practically.   Keywords: Attitude Determination, Celestial Navigation, Triad, Quest, Least Square, Satellite.

  11. 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.

  12. 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.

  13. 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.

  14. Efficacy of the Cooperative Learning Method on Mathematics Achievement and Attitude: A Meta-Analysis Research

    Science.gov (United States)

    Capar, Gulfer; Tarim, Kamuran

    2015-01-01

    This research compiles experimental studies from 1988 to 2010 that examined the influence of the cooperative learning method, as compared with that of traditional methods, on mathematics achievement and on attitudes towards mathematics. The related field was searched using the following key words in Turkish "matematik ve isbirlikli ögrenme,…

  15. 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.

  16. Understanding Factors that Shape Gender Attitudes in Early Adolescence Globally: A Mixed-Methods Systematic Review.

    Directory of Open Access Journals (Sweden)

    Anna Kågesten

    Full Text Available Early adolescence (ages 10-14 is a period of increased expectations for boys and girls to adhere to socially constructed and often stereotypical norms that perpetuate gender inequalities. The endorsement of such gender norms is closely linked to poor adolescent sexual and reproductive and other health-related outcomes yet little is known about the factors that influence young adolescents' personal gender attitudes.To explore factors that shape gender attitudes in early adolescence across different cultural settings globally.A mixed-methods systematic review was conducted of the peer-reviewed literature in 12 databases from 1984-2014. Four reviewers screened the titles and abstracts of articles and reviewed full text articles in duplicate. Data extraction and quality assessments were conducted using standardized templates by study design. Thematic analysis was used to synthesize quantitative and qualitative data organized by the social-ecological framework (individual, interpersonal and community/societal-level factors influencing gender attitudes.Eighty-two studies (46 quantitative, 31 qualitative, 5 mixed-methods spanning 29 countries were included. Ninety percent of studies were from North America or Western Europe. The review findings indicate that young adolescents, across cultural settings, commonly express stereotypical or inequitable gender attitudes, and such attitudes appear to vary by individual sociodemographic characteristics (sex, race/ethnicity and immigration, social class, and age. Findings highlight that interpersonal influences (family and peers are central influences on young adolescents' construction of gender attitudes, and these gender socialization processes differ for boys and girls. The role of community factors (e.g. media is less clear though there is some evidence that schools may reinforce stereotypical gender attitudes among young adolescents.The findings from this review suggest that young adolescents in different

  17. 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.

  18. 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 ...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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…

  5. 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,…

  6. 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.

  7. 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...

  8. 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...

  9. 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.

  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. 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 ...

  12. 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.

  13. 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.

  14. 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.

  15. Effect of Book Reading Method upon Attitudes of Students towards Learning and Reading Habit

    Science.gov (United States)

    Ahmet, Kara; Ali, Ünisen; Eyup, Izci

    2015-01-01

    The purpose of this study was to determine the effect of lessons trained through large group discussion method in a classroom environment during 10-15 min at the end of silent book reading activity for the first thirty minutes during a term upon attitudes of students towards learning and reading habit. The research was carried out with totally 89…

  16. Educating Linguistically Diverse Students: A Mixed Methods Study of Elementary Teachers' Coursework, Attitudes, and Practice

    Science.gov (United States)

    Greenfield, Renée A.

    2016-01-01

    This study followed a mixed-methods sequential explanatory design. Phase I involved the collection of quantitative data to examine inservice teachers' (N = 69) attitudes about language and linguistic diversity as well as their teacher education coursework. All participants were graduates from the same teacher education program. Phase II included…

  17. The Effect of a Modified Moore Method on Attitudes and Beliefs in Precalculus

    Science.gov (United States)

    Bailey, Brad; Cooper, Thomas E.; Briggs, Karen S.

    2012-01-01

    As part of a study on the effects of teaching with a Modified Moore Method (MMM), a survey containing 20 items from Schoenfeld's (1989) investigation of attitudes and beliefs about mathematics was administered to students in undergraduate precalculus classes. The study included one section of precalculus taught with an MMM, a student-centered and…

  18. 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.

  19. A brief measure of attitudes toward mixed methods research in psychology

    OpenAIRE

    Roberts, Lynne D.; Povee, Kate

    2014-01-01

    The adoption of mixed methods research in psychology has trailed behind other social science disciplines. Teaching psychology students, academics, and practitioners about mixed methodologies may increase the use of mixed methods within the discipline. However, tailoring and evaluating education and training in mixed methodologies requires an understanding of, and way of measuring, attitudes toward mixed methods research in psychology. To date, no such measure exists. In this article we presen...

  20. Awareness and Attitude toward Refractive Error Correction Methods: A Population Based Study in Mashhad

    OpenAIRE

    Saber Moghaddam Ranjbar AK; Pourmazar R; Gohary I

    2013-01-01

    Objectives: This study was designed to determine the level of awareness and attitude toward refractive correction methods in a randomly selected population in Mashhad, Iran. Materials and Methods: A random cluster sampling method was applied to choose 193 subjects aged 12 years and above from Mashhad population. A structured questionnaire with open-ended and closed-ended questions was designed to gather the participants' demographic data such as: gender, age, educational status and occupation...

  1. 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

  2. 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.

  3. Measurement of student attitudes in first year engineering - A mixed methods approach

    Science.gov (United States)

    Malik, Qaiser Hameed

    This research study focused on freshman attitudes towards engineering in a newly implemented cornerstone sequence that emphasized holistic design experiences. The students' initial attitudes and changes in these attitudes were examined with the explanatory mixed methods approach that allows a sequential examination of the target population with two methods, using two sets of data, to investigate the treatment effects. In the quantitative phase, the study compared changes in freshman attitude towards engineering, between the new 'design sequence' group (composed of freshmen in the cornerstone sequence) and the prior 'traditional sequence' group (composed of all other freshmen), over the course of one semester. The data were collected in fall 2008 at two time intervals and changes in the two groups' attitudes were examined with repeated measures analysis of covariance models. The analyses reported here include data from 389 students out of the total population of 722 freshmen. The analyses revealed that engineering freshmen joined the program with positive or strongly positive attitudes towards engineering. Those strong attitudes were durable and resistant to change. Students in the design sequence group had higher ACT scores, enjoyed math and science the most, and did not believe engineering to be an exact science. However, no appreciable time-group interaction was observed. To validate the quantitative results, an interview protocol was developed to investigate initial freshman attitudes and changes, if any, that took place as a result of the new cornerstone sequence. One-on-one interviews with a sample of ten students out of the population of 272 freshmen revealed that freshmen in the cornerstone sequence entered the program full of enthusiasm and idealism, and with strongly positive attitudes towards engineering. The strong motivational factors included parental/teacher influences, childhood motivations, and high school extra-curricular experiences. The

  4. University and Student Segmentation: Multilevel Latent-Class Analysis of Students' Attitudes towards Research Methods and Statistics

    Science.gov (United States)

    Mutz, Rudiger; Daniel, Hans-Dieter

    2013-01-01

    Background: It is often claimed that psychology students' attitudes towards research methods and statistics affect course enrolment, persistence, achievement, and course climate. However, the inter-institutional variability has been widely neglected in the research on students' attitudes towards research methods and statistics, but it is important…

  5. Do women's attitudes towards abortion and contraceptive methods influence their option for sterilization?

    Directory of Open Access Journals (Sweden)

    Elisabeth Meloni Vieira

    1999-10-01

    Full Text Available This paper analyzes the attitudes of low-income women towards abortion and contraception. A survey was conducted in 1992 with a total of 3,149 childbearing-age women living on the outskirts of the Greater Metropolitan São Paulo Area. The study focuses on a sub-sample of 583 women. Attitudes of sterilized and non-sterilized women are compared. Women, especially those sterilized, found the most important attribute of a contraceptive method to be its effectiveness. Women currently taking the pill were less likely than those sterilized to agree that sterilization was the best method because of its effectiveness. Sterilized women were less likely than non-sterilized women to trust the pill. Sterilized women were more likely than non-sterilized to have reported adverse effects from the pill. Most women found abortion unacceptable except in the case of risk to the woman's life. Women using more effective methods showed stronger negative attitudes towards abortion. The tendency to be sterilized while still young was associated with more negative attitudes towards abortion. Family planning activities in basic health care services should include individual counseling for contraceptive use.

  6. 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.

  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. 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)

  10. 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.

  11. The Effect of Matrix Method on Anxiety and Attitude Toward Methamphetamine and Crack Abuse in Males Referring to Addiction Treatment Centers in Tonkabon, Iran

    Directory of Open Access Journals (Sweden)

    Hemmati Sabet

    2015-11-01

    Full Text Available Background Drug abuse is a major problem in the communities and has many harmful effects on human body. Objectives The current study aimed to compare the efficacy of matrix method on anxiety and attitude of male crack abusers referred to addiction treatment centers in Tonkabon, Iran, in 2014. Patients and Methods The current semi -experimental study included 1,000 males referred to addiction treatment centers in Tonkabon with crack abuse history in 2014. Based on Morgan sample volume formula, 278 males with anxiety and higher attitude to drug abuse were randomly selected from 1,000 males referred to addiction treatment centers in Tonkabon. Then, 30 subjects were reselected out of them and equally assigned into two groups of experimental and control, 15 subjects in each group. The experimental group received 24 sessions of 30 - 60 minutes matrix treatment method in group, but the control group received no training. At the end of training period the post-test was carried out. The research findings confirmed the efficacy of matrix method on anxiety and attitude to crack abuse among those referring to the addition treatment center. Results The single covariance analysis of ANCOVA indicated that the value of Eta about 72% of variance of anxiety variable and about 76% of variance of drug abuse variable are taken in to account for variable of group. The intervention was effective in reducing anxiety and attitude to crack in males. Evaluating the adjusted mean showed the effectiveness of matrix method on anxiety and attitude to crack abuse in males. Conclusions The research result showed that matrix method affected the reduction of methamphetamine and attitude to crack abuse in males referred to the addition treatment center.

  12. [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

  13. The History of English Education in Japan - Motivations, Attitudes and Methods

    OpenAIRE

    Løfsgaard, Kjersti Aasness

    2015-01-01

    In today's globalised society English is vital to international communication and cooperation and English education therefore holds a central spot in education systems worldwide. In this thesis I look at the history of English education in Japan by analysing motivations for learning (or not learning) English, attitudes to English education and methods that have been utilised in teaching English throughout in Japan. I also introduce one teaching method that has recently caught on among Japanes...

  14. Relative Attitude Determination of Earth Orbiting Formations Using GPS Receivers

    Science.gov (United States)

    Lightsey, E. Glenn

    2004-01-01

    Satellite formation missions require the precise determination of both the position and attitude of multiple vehicles to achieve the desired objectives. In order to support the mission requirements for these applications, it is necessary to develop techniques for representing and controlling the attitude of formations of vehicles. A generalized method for representing the attitude of a formation of vehicles has been developed. The representation may be applied to both absolute and relative formation attitude control problems. The technique is able to accommodate formations of arbitrarily large number of vehicles. To demonstrate the formation attitude problem, the method is applied to the attitude determination of a simple leader-follower along-track orbit formation. A multiplicative extended Kalman filter is employed to estimate vehicle attitude. In a simulation study using GPS receivers as the attitude sensors, the relative attitude between vehicles in the formation is determined 3 times more accurately than the absolute attitude.

  15. 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.

  16. 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.

  17. Modification of attitudes of elementary preservice teachers toward science and science teaching within the elementary science methods class

    Science.gov (United States)

    Paulson, Patricia C.

    Modifications of student attitudes toward science and science teaching during an elementary science methods course were investigated within an action research format. Attitudes were measured at the onset and completion of the course using Thompson and Shrigley's Revised Science Attitude Scale (1986). Pre- and post-course interviews were conducted by a teaching assistant with a randomly selected sample of ten students to obtain more detailed descriptions of student attitudes. Five ongoing journals documented student reflections on course activities to determine subsequent interventions within the timeframe. Analysis of data involved the triangulation of the three sources of evidence of student attitudes using initial and emergent themes. Results indicated strong support for more positive attitudes and feelings of competence and confidence toward science and science teaching.

  18. 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)

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

    Science.gov (United States)

    Ibrahim, Awab Ali; Elshafie, Sittana Shamseldin

    2016-01-01

    Background Medical students can be exposed to serious health care-associated infections, if they are not following infection prevention and control (IPC) measures. There is limited information regarding the knowledge, awareness, and practices of medical students regarding IPC and the educational approaches used to teach them these practices. Aim To evaluate the knowledge, awareness, and attitude of medical students toward IPC guidelines, and the learning approaches to help improve their knowledge. Methods A cross-sectional, interview-based survey included 73 medical students from Weill Cornell Medical College, Qatar. Students completed a questionnaire concerning awareness, knowledge, and attitude regarding IPC practices. Students’ knowledge was assessed by their correct answers to the survey questions. Findings A total of 48.44% of the respondents were aware of standard isolation precautions, 61.90% were satisfied with their training in IPC, 66.13% were exposed to hand hygiene training, while 85.48% had sufficient knowledge about hand hygiene and practiced it on a routine basis, but only 33.87% knew the duration of the hand hygiene procedure. Conclusion Knowledge, attitude, and awareness of IPC measures among Weill Cornell Medical Students in Qatar were found to be inadequate. Multifaceted training programs may have to target newly graduated medical practitioners or the training has to be included in the graduate medical curriculum to enable them to adopt and adhere to IPC guidelines. PMID:27579002

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

    Science.gov (United States)

    Ibrahim, Awab Ali; Elshafie, Sittana Shamseldin

    2016-01-01

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

  1. Propagation of Uncertainty in Rigid Body Attitude Flows

    OpenAIRE

    Lee, Taeyoung; Chaturvedi, Nalin A.; Sanyal, Amit K.; Leok, Melvin; McClamroch, N. Harris

    2007-01-01

    Motivated by attitude control and attitude estimation problems for a rigid body, computational methods are proposed to propagate uncertainties in the angular velocity and the attitude. The nonlinear attitude flow is determined by Euler-Poincar\\'e equations that describe the rotational dynamics of the rigid body acting under the influence of an attitude dependent potential and by a reconstruction equation that describes the kinematics expressed in terms of an orthogonal matrix representing the...

  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. 一种有效的中性浮力下实验体姿态机动模拟控制律设计%An Effective Method for Designing Attitude Maneuver Analog Control Law with Neutral Buoyancy for Experimental Model

    Institute of Scientific and Technical Information of China (English)

    陈诗瑜; 袁建平; 方群

    2012-01-01

    In the ground simulation technology of space microgravity environment,by using water buoyancy to keep floating,neutral buoyancy can make a 6-DOF free motion with longtime and space similarity. The analog control with neutral buoyancy should be designed for complex underwater environment. In our opinion,theoretical validation and simulation for space missions with neutral buoyancy appear to be quite inadequate. Section 2 of the full paper explains the design method mentioned in the title,which we believe is effective and whose core consists of;" First, derive the equation of attitude dynamics based on hydrodynamics and moment of momentum theorem and derive the e-quation of attitude kinematics based on the relationship of quaternion and angular velocity. And then, on the basis of the dynamical equation under the perfect state,the attitude maneuver control law is designed by the Lyapunov approach, following a proof of asymptotic stability of the closed loop system. " Finally, simulation results, presented in Figs. 4 through 8 and Table 1, and their analysis show preliminarily that our design method is indeed effective.%在空间微重力环境的地面模拟技术中,中性浮力法利用水的浮力使实验体处于漂浮状态,可以提供六自由度运动模拟,并且可进行长时间的与空间十分相似的自由运动.因此可以采用该方法实现空间飞行器空间任务的地面模拟演示和功能验证.姿态控制作为空间任务的基本操作之一,其在中性浮力实验环境下的控制模拟非常重要,需要针对复杂的水下环境进行设计.目前针对水下航行器的研究非常广泛,但是专门针对中性浮力环境下空间任务模拟的研究并不多,缺少理论验证与仿真.本文针对中性浮力环境下实验体姿态机动模拟控制律设计问题进行研究.首先根据流体力学和动量矩定理推导出实验体的姿态动力学方程,根据四元数与角速度的关系得到实验体的姿态

  4. 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

  5. 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.

  6. 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.

  7. Rotation Matrix Method Based on Ambiguity Function for GNSS Attitude Determination.

    Science.gov (United States)

    Yang, Yingdong; Mao, Xuchu; Tian, Weifeng

    2016-06-08

    Global navigation satellite systems (GNSS) are well suited for attitude determination. In this study, we use the rotation matrix method to resolve the attitude angle. This method achieves better performance in reducing computational complexity and selecting satellites. The condition of the baseline length is combined with the ambiguity function method (AFM) to search for integer ambiguity, and it is validated in reducing the span of candidates. The noise error is always the key factor to the success rate. It is closely related to the satellite geometry model. In contrast to the AFM, the LAMBDA (Least-squares AMBiguity Decorrelation Adjustment) method gets better results in solving the relationship of the geometric model and the noise error. Although the AFM is more flexible, it is lack of analysis on this aspect. In this study, the influence of the satellite geometry model on the success rate is analyzed in detail. The computation error and the noise error are effectively treated. Not only is the flexibility of the AFM inherited, but the success rate is also increased. An experiment is conducted in a selected campus, and the performance is proved to be effective. Our results are based on simulated and real-time GNSS data and are applied on single-frequency processing, which is known as one of the challenging case of GNSS attitude determination.

  8. A novel method for low-cost MIMU aiding GNSS attitude determination

    Science.gov (United States)

    Yang, Yingdong; Mao, Xuchu; Tian, Weifeng

    2016-07-01

    Global navigation satellite systems (GNSS) are well suited for attitude determination. In most cases, the success rate of the initialization is always a difficult problem, especially the single-frequency measurement model of the double-difference carrier phase. The main reason for this is excessively large noise error that arises in the measurement of the double-difference carrier phase. When the geometric relations of the equations are not good, the difference between the residual error of the optimal solution and that of the suboptimal solution is not very obvious. In this study, we design a smoothing model based on MEMS. The noise error of the measurement of the double-difference carrier phase is suppressed and smoothed via this model. It is designed to reduce the initialization time and improve the success rate of the solution. In addition, we propose a new method based on the rotation matrix to resolve the attitude angle. This method produces a better performance in reducing computation time and selecting satellites. The condition of the baseline length is combined with the ambiguity function method (AFM) to search for integer ambiguity, and this method is validated in reducing the span of candidates. The experiment is conducted in a selected campus, and the performance is proved to be effective. Our results are based on simulated and real-time GNSS data and are applied on single-frequency processing, which is known as one of the challenging cases of GNSS attitude determination.

  9. 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...

  10. 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...

  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. 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.

  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. 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

  16. Realization of LOS (Line of Sight) stabilization based on reflector using carrier attitude compensation method

    Science.gov (United States)

    Mao, Yao; Tian, Jing; Ma, Jia-guang

    2015-02-01

    The techonology of LOS stabilization is widely applicated in moving carrier photoelectric systems such as shipborne, airborne and so on. In application situations with compact structure, such as LOS stabilization system of unmanned aerial vehicle, LOS stabilization based on reflector is adopted, and the detector is installed on the carrier to reduce the volume of stabilized platform and loading weight. However, the LOS deflection angle through reflector and the rotation angle of the reflector has a ratio relation of 2:1, simple reflector of stable inertial space can not make the optical axis stable. To eliminate the limitation of mirror stabilizing method, this article puts forward the carrier attitude compensation method, which uses the inertial sensor installed on the carrier to measure the attitude change of the carrier, and the stabilized platform rotating half of the carrier turbulence angle to realize the LOS stabilization.

  17. 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.

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

    Directory of Open Access Journals (Sweden)

    Rise Marit By

    2011-11-01

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

  19. 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.

  20. 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.

  1. Pharmacists’ knowledge and attitudes about natural health products: a mixed-methods study

    OpenAIRE

    Kheir, Nadir

    2014-01-01

    Nadir Kheir, Hoda Y Gad, Safae E Abu-Yousef College of Pharmacy, Qatar University, Al Tarfa, Doha, Qatar Objectives: To explore knowledge and attitude of pharmacists in Qatar towards natural health products (NHPs). Methods: The quantitative component of this study consisted of an anonymous, online, self-administered questionnaire to assess knowledge about NHPs among pharmacists in Qatar. Descriptive statistics and inferential analysis were conducted using Statistical Package of Social Scienc...

  2. 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

  3. 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

  4. 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.

  5. 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. 

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

    Science.gov (United States)

    Viswanathan, Sasi Prabhakaran

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

  7. Optimal control linear quadratic methods

    CERN Document Server

    Anderson, Brian D O

    2007-01-01

    This augmented edition of a respected text teaches the reader how to use linear quadratic Gaussian methods effectively for the design of control systems. It explores linear optimal control theory from an engineering viewpoint, with step-by-step explanations that show clearly how to make practical use of the material.The three-part treatment begins with the basic theory of the linear regulator/tracker for time-invariant and time-varying systems. The Hamilton-Jacobi equation is introduced using the Principle of Optimality, and the infinite-time problem is considered. The second part outlines the

  8. Comparing Efficacy of Four Preventive Methods on Attitude of Drug Substance Abuse and Self–Esteem in Students Supported by Emdad Committee

    Directory of Open Access Journals (Sweden)

    aziz allah agha babaei

    2012-05-01

    Full Text Available Introduction: This study was aimed to compare the efficacy of four drug substance abuse preventive methods: cognitive–behavioral social traioning, life skills training, poster presentation and short message system on attitude change and enhancement self-esteem in students supported by Emdad Committee. Method:This was a quasi experimental study. 150 students were selected and randomly assigned to the four experimental and control groups. The groups were completed attitude of drug substance abuse and self-esteem inventories. Experimental groups received: group 1 received 10 sessions of group cognitive-behavioral social training 120 minutes each, group 2, 10 sessions of life skills training, 120 minutes each, group 3 for 10 weeks into presented of 40 posters and group 4 short message service for 10 weeks. Findings: The results revealed that preventive techniques were effected on attitude and self–esteem. Also results of post-hoc (LSD test revealed that preventive techniques with difference effectiveness were effected on change attitude of substance abuse. Also cognitive–behavioral social training and life skills training techniques were effected on self esteem. Conclusion: The results of the study revealed that all the four techniques were effective in the generation negative attitude into drug abuse, otherwise only cognitive–behavioral social training and life skills training enhancement on self esteem.

  9. Method for controlling powertrain pumps

    Science.gov (United States)

    Sime, Karl Andrew; Spohn, Brian L; Demirovic, Besim; Martini, Ryan D; Miller, Jean Marie

    2013-10-22

    A method of controlling a pump supplying a fluid to a transmission includes sensing a requested power and an excess power for a powertrain. The requested power substantially meets the needs of the powertrain, while the excess power is not part of the requested power. The method includes sensing a triggering condition in response to the ability to convert the excess power into heat in the transmission, and determining that an operating temperature of the transmission is below a maximum. The method also includes determining a calibrated baseline and a dissipation command for the pump. The calibrated baseline command is configured to supply the fluid based upon the requested power, and the dissipation command is configured to supply additional fluid and consume the excess power with the pump. The method operates the pump at a combined command, which is equal to the calibrated baseline command plus the dissipation command.

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    Kathryn Rosecrans

    2014-03-01

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

  12. A Mixed-Method Approach on Digital Educational Games for K12: Gender, Attitudes and Performance

    Science.gov (United States)

    Law, Effie Lai-Chong; Gamble, Tim; Schwarz, Daniel; Kickmeier-Rust, Michael D.; Holzinger, Andreas

    Research on the influence of gender on attitudes towards and performance in digital educational games (DEGs) has quite a long history. Generally, males tend to play such games more engagingly than females, consequently attitude and performance of males using DEGs should be presumably higher than that of females. This paper reports an investigation of a DEG, which was developed to enhance the acquisition of geographical knowledge, carried out on British, German and Austrian K12 students aged between 11 and 14. Methods include a survey on initial design concepts, user tests on the system and two single-gender focus groups. Gender and cultural differences in gameplay habit, game type preferences and game character perceptions were observed. The results showed that both genders similarly improved their geographical knowledge, although boys tended to have a higher level of positive user experience than the girls. The qualitative data from the focus groups illustrated some interesting gender differences in perceiving various aspects of the game.

  13. 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.

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

    Directory of Open Access Journals (Sweden)

    Norio Sugawara

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

  15. Analog neural network control method proposed for use in a backup satellite control mode

    Energy Technology Data Exchange (ETDEWEB)

    Frigo, J.R.; Tilden, M.W.

    1998-03-01

    The authors propose to use an analog neural network controller implemented in hardware, independent of the active control system, for use in a satellite backup control mode. The controller uses coarse sun sensor inputs. The field of view of the sensors activate the neural controller, creating an analog dead band with respect to the direction of the sun on each axis. This network controls the orientation of the vehicle toward the sunlight to ensure adequate power for the system. The attitude of the spacecraft is stabilized with respect to the ambient magnetic field on orbit. This paper develops a model of the controller using real-time coarse sun sensor data and a dynamic model of a prototype system based on a satellite system. The simulation results and the feasibility of this control method for use in a satellite backup control mode are discussed.

  16. 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...

  17. 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.

  18. The Effect of Blended Learning Method on Preservice Elementary Science Teachers’ Attitudes Toward Technology, Self-Regulation And Science Process Skills

    Directory of Open Access Journals (Sweden)

    Bekir Güler

    2015-06-01

    Full Text Available The purpose of this study was to investigate the effects of blended learning method on pre-service science and technology teachers’ attitudes towards technology, self-regulation and science process skills. The study was conducted with 61 pre-service teachers at Dokuz Eylul University Science Education Department in the academic year 2012-2013. The applications were conducted within the scope of a science method course. The experimental group (n=30 was taught with blended learning method while the control group was taught with face to face method. In the study, “Scale for Attitudes Towards Technology”, “Self-Regulation Skills Scale” and “Science Process Skills Test” were used as data collection tools. The scales were applied as pre and post-test to pre-service teachers at the beginning and end of the semester. According to findings of the study, no difference was found between the experimental and control group preservice teachers’ attitudes towards technology.. There was no difference between experimental group students’ pre-post scores in self-regulation skills. However, , control group’s self-regulation skills score decreased from pre to post application. Similarly, while control group’s science process skills pre-test scores were significantly higher than that of experimental group, no difference was seen between post-test scores of the groups. Suggestions are provided in the light of the results.

  19. 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.

  20. The Quadrotor Dynamic Modeling and Indoor Target Tracking Control Method

    Directory of Open Access Journals (Sweden)

    Dewei Zhang

    2014-01-01

    Full Text Available A reliable nonlinear dynamic model of the quadrotor is presented. The nonlinear dynamic model includes actuator dynamic and aerodynamic effect. Since the rotors run near a constant hovering speed, the dynamic model is simplified at hovering operating point. Based on the simplified nonlinear dynamic model, the PID controllers with feedback linearization and feedforward control are proposed using the backstepping method. These controllers are used to control both the attitude and position of the quadrotor. A fully custom quadrotor is developed to verify the correctness of the dynamic model and control algorithms. The attitude of the quadrotor is measured by inertia measurement unit (IMU. The position of the quadrotor in a GPS-denied environment, especially indoor environment, is estimated from the downward camera and ultrasonic sensor measurements. The validity and effectiveness of the proposed dynamic model and control algorithms are demonstrated by experimental results. It is shown that the vehicle achieves robust vision-based hovering and moving target tracking control.

  1. 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.

  2. 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...

  3. A STUDY OF KNOWLEDGE, ATTITUDE & PRACTICE OF FAMILY PLANNING METHODS AMONG ANTENATAL WOMEN OF ANDHRA PRADESH

    Directory of Open Access Journals (Sweden)

    Shailaja

    2015-01-01

    Full Text Available OBJECTIVE: To assess the knowledge and attitude regarding family planning and the practice of contraceptives among Antenatal women attending OPD and to determine the prevalence of unintended pregnancy among them. METHOD: A cross sectional descriptive study was done in the Obstetrics and Gynecology Department of Andhra Medical College Visakhapatnam which is a tertiary center for three districts Visakhapatnam , Vijayanagaram , and Srika kulam. 499 antenatal women attending the OPD were included in the study. Their knowledge , attitude and practice on contraceptives were evaluated with the help of a predesigned questionnaire. RESULTS: Overall awareness of permanent methods of family plannin g 96.3% and that of temporary methods is only 62.9% (314. 69.9% of women became aware of contraceptive method , by obtaining information from relatives and friends and 23.2% from media (television. 42.1% are of the opinion that these contraceptive methods are available in the medical shops and only 13% know that they are available in the government hospitals. 99.8% are aware of female sterilization , and 92.8% are aware of vasectomy. But awareness of temporary methods is very poor. CONCLUSION: The study hig hlights that knowledge and awareness doesn’t always lead to the use of contraceptives. There is still a need to educate and motivate the couples and improve family planning services to achieve more effective and appropriate use of contraceptives and to arr est the trend towards increase in population

  4. Sexual and contraceptives attitudes, the locus of health control and self-esteem among higher education students

    Directory of Open Access Journals (Sweden)

    José Manuel da Silva Vilelas Janeiro

    2014-09-01

    Full Text Available Objective: To analyze the relationship between sexual and contraceptive attitudes, the locus of health control and self-esteem among students of a private institution of higher education. Methods: Descriptive and correlational study with a quantitative approach, performed in a higher education school in Lisbon, with 152 students, from the 1st to the 4th year of undergraduate courses in Nursing, Physiotherapy, Cardiopneumology and Radiology. As research instrument, it was used a questionnaire with rating scales on ‘sexual attitudes’, ‘contraception attitudes’, ‘locus of health control’ and ‘self-esteem’. The data obtained was analyzed using descriptive and inferential statistics. Results: The majority of students (90.7% have already had sexual intercourse. Sexual attitudes were influenced by gender (p=0.0035, but not by the start of sexual activity or by the course’s year (p>0.05. Contraceptive attitudes were related to the year that students attended (p=0.031 and to gender (p=0.029. The external locus of control, on average, was higher among girls (29.2 than boys (30.1. The self-esteem increased with the student’s age (p=0.003. Conclusion: Investment in the area of sexual education is needed in the undergraduate programs, since the young people live their days in the school setting, spending little time with their families. The university should assume a special position in the development of the concept of sexuality based on the holistic perspective of the human being, promoting sexual education as essential in the construction of human identity and fundamental for health promotion doi: http://dx.doi.org/10.5020/18061230.2013.p505

  5. EFFECTS OF LECTURE AND ACTIVITY BASED METHODS ON THE ATTITUDES OF JUNIOR SECONDARY SCHOOL STUDENTS TO ESSAY WRITING IN FRENCH

    OpenAIRE

    R., BORODE BOLAJI.

    2014-01-01

    This study sets out to examine the effect of Lecture and Activity based methods on the attitude of Junior Secondary School Students in Essay writing in French with the purpose of finding out which of the methods could promote higher positive attitude in students towards essay writing in French. The population for the study was 2319 Junior Secondary School students in Ekiti State and the sample consisted of 120 students from six mixed secondary schools. The study adopted the quasi experimental...

  6. Ambiguity Function Method Scheme for Aircraft Attitude Sensor Utilising GPS/GLONASS Carrier Phase Measurement

    Directory of Open Access Journals (Sweden)

    Wenrui Jin

    2009-09-01

    Full Text Available When the receivers of GPS, GLONASS, COMPASS and other such systems are equipped with multiple antennas, they can give attitude information. Based on the difference carrier phase equations established in local level frame (LLF, a new algorithm is presented to resolve aircraft attitude determination problems in real-time. Presuming that the cycle integer ambiguity is known, the measurement equations have attitude analytical resolutions using single difference (SD equations of two navigation satellites in-view. Similar with SD process, the doubledifference (DD measurements are established and analysed. In addition, the SD and DD algorithms are capable of reducing the integer search space into some discrete point space and then the ambiguity function method (AFM resolves the ambiguity function within the point solutions space. Therefore the procedures have very low computation, thus saving time. The hardware architecture has been realised using multiple  GPS/GLONASS OEMs. The experimental results have demonstrated that the proposed approach is effective and can satisfy the requirement of real-time application in cases of GPS, and combined GPS, and GLONASS.Defence Science Journal, 2009, 59(5, pp.466-470, DOI:http://dx.doi.org/10.14429/dsj.59.1548

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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...

  13. 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...

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. Helicopter flight-control design using an H(2) method

    Science.gov (United States)

    Takahashi, Marc D.

    1991-01-01

    Rate-command and attitude-command flight-control designs for a UH-60 helicopter in hover are presented and were synthesized using an H(2) method. Using weight functions, this method allows the direct shaping of the singular values of the sensitivity, complementary sensitivity, and control input transfer-function matrices to give acceptable feedback properties. The designs were implemented on the Vertical Motion Simulator, and four low-speed hover tasks were used to evaluate the control system characteristics. The pilot comments from the accel-decel, bob-up, hovering turn, and side-step tasks indicated good decoupling and quick response characteristics. However, an underlying roll PIO tendency was found to exist away from the hover condition, which was caused by a flap regressing mode with insufficient damping.

  19. 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.

  20. 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

  1. Awareness and Attitude toward Refractive Error Correction Methods: A Population Based Study in Mashhad

    Directory of Open Access Journals (Sweden)

    Saber Moghaddam Ranjbar AK

    2013-10-01

    Full Text Available Objectives: This study was designed to determine the level of awareness and attitude toward refractive correction methods in a randomly selected population in Mashhad, Iran. Materials and Methods: A random cluster sampling method was applied to choose 193 subjects aged 12 years and above from Mashhad population. A structured questionnaire with open-ended and closed-ended questions was designed to gather the participants' demographic data such as: gender, age, educational status and occupation, as well as their awareness and attitude toward refractive correction methods (Spectacles, Contact lenses and Refractive surgery. Results:  In overall, 39% of the participants had a clear perception of 'ophthalmologist' and 'optometrist' terms. 80.3%, 87% and 71% of respondents had no information of contact lens application instead of spectacles, cosmetic contact lenses and contact lenses with both refractive correction and cosmetic properties, respectively. 82.5% of participants were not aware of the possibility of refractive surgery for improving their eyesight and decreasing their dependency on spectacles. Awareness about contact lenses and refractive surgery’s adverse effects were only 16% and 8%, respectively. Conclusion: Awareness and perception of refractive correction methods was low among the participants of this study. Although, ophthalmologists were the first source of consultation on sight impairments among respondents, a predominant percentage of subjects were not even aware of obvious differences between an ophthalmologist and an optometrist. These findings emphasize the necessity for proper public education on ophthalmic care and the available services, specially the new correction methods for improvement of quality of life.

  2. 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.

  3. 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.

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

    Science.gov (United States)

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

    2016-01-01

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

  5. 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.

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

    Directory of Open Access Journals (Sweden)

    McKenzie Suzanne H

    2009-08-01

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

  7. Effects of cooperative learning plus inquiry method on student learning and attitudes: a comparative study for engineering economic classrooms

    Science.gov (United States)

    Salehizadeh, M. Reza; Behin-Aein, Noureddin

    2014-03-01

    In the Iranian higher education system, including engineering education, effective implementation of cooperative learning is difficult because classrooms are usually crowded and the students never had a formal group working background in their previous education. In order to achieve the benefits of cooperative learning in this condition, this paper proposes a combination of cooperative learning and inquiry method. The method is implemented by grouping students in a way that the learning procedure is done in non-official class sessions by each group, while the inquiry method is done in the regular programmed class sessions. The study is performed in Islamic Azad University and the methods are implemented in two engineering economic classes with different numbers of students in each working group. The results are compared with a control class in which traditional teaching style is implemented. The results of analysis show simultaneous improvement of learning and behavioural attitudes of the students with cooperative learning plus inquiry method in the classroom with a fewer number of students in each working group.

  8. An enhanced Cramér-Rao bound weighted method for attitude accuracy improvement of a star tracker

    Science.gov (United States)

    Zhang, Jun; Wang, Jian

    2016-06-01

    This study presents a non-average weighted method for the QUEST (QUaternion ESTimator) algorithm, using the inverse value of root sum square of Cramér-Rao bound and focal length drift errors of the tracking star as weight, to enhance the pointing accuracy of a star tracker. In this technique, the stars that are brighter, or at low angular rate, or located towards the center of star field will be given a higher weight in the attitude determination process, and thus, the accuracy is readily improved. Simulations and ground test results demonstrate that, compared to the average weighted method, it can reduce the attitude uncertainty by 10%-20%, which is confirmed particularly for the sky zones with non-uniform distribution of stars. Moreover, by using the iteratively weighted center of gravity algorithm as the newly centroiding method for the QUEST algorithm, the current attitude uncertainty can be further reduced to 44% with a negligible additional computing load.

  9. An enhanced Cramér-Rao bound weighted method for attitude accuracy improvement of a star tracker.

    Science.gov (United States)

    Zhang, Jun; Wang, Jian

    2016-06-01

    This study presents a non-average weighted method for the QUEST (QUaternion ESTimator) algorithm, using the inverse value of root sum square of Cramér-Rao bound and focal length drift errors of the tracking star as weight, to enhance the pointing accuracy of a star tracker. In this technique, the stars that are brighter, or at low angular rate, or located towards the center of star field will be given a higher weight in the attitude determination process, and thus, the accuracy is readily improved. Simulations and ground test results demonstrate that, compared to the average weighted method, it can reduce the attitude uncertainty by 10%-20%, which is confirmed particularly for the sky zones with non-uniform distribution of stars. Moreover, by using the iteratively weighted center of gravity algorithm as the newly centroiding method for the QUEST algorithm, the current attitude uncertainty can be further reduced to 44% with a negligible additional computing load.

  10. 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.

  11. The Effect of Creative Drama Method on Pre-Service Classroom Teachers' Writing Skills and Attitudes towards Writing

    Science.gov (United States)

    Erdogan, Tolga

    2013-01-01

    The aim of the study is to explore the effect of the creative drama method on pre-service classroom teachers' writing skills and attitudes towards writing. Additionally, the views of the pre-service teachers concerning the creative drama method were also investigated in the study. The participants of the study were 24 pre-service teachers studying…

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

    Directory of Open Access Journals (Sweden)

    Fahimeh Jafari

    2016-10-01

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

  13. 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.

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    Cinthia A Acka

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

  16. 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

  17. Controlling the Attitude Maneuvers of Flexible Spacecraft by Using Time-Optimal Shaped Inputs

    Science.gov (United States)

    Parman, S.; Koguchi, H.

    1999-04-01

    A three-dimensional rest-to-rest attitude maneuver of flexible spacecraft equipped with on-off reaction jets is studied. Equations of motion of the spacecraft are developed by using Lagrangian formulation. The finite element method is used to discretize elastic deformations of a particular model of satellite with flexible solar panels by modelling the panels as flat plate structures in bending. Under unshaped inputs, the maneuvers induce an undesirable motion of the satellite as well as vibration of the solar panels. Time-optimal and fuel-efficient input shapers are then applied to reduce the residual oscillation of its motion at several natural frequencies in order to get an expected pointing precision of the satellite. Once the shaped inputs are given to the satellite, the performance improves significantly. Results indicate that, the fuel-efficient shaped inputs give smaller maximum deflections of flexible members compared with the time-optimal ones.

  18. 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.

  19. GNSS Single Frequency, Single Epoch Reliable Attitude Determination Method with Baseline Vector Constraint

    Directory of Open Access Journals (Sweden)

    Ang Gong

    2015-12-01

    Full Text Available For Global Navigation Satellite System (GNSS single frequency, single epoch attitude determination, this paper proposes a new reliable method with baseline vector constraint. First, prior knowledge of baseline length, heading, and pitch obtained from other navigation equipment or sensors are used to reconstruct objective function rigorously. Then, searching strategy is improved. It substitutes gradually Enlarged ellipsoidal search space for non-ellipsoidal search space to ensure correct ambiguity candidates are within it and make the searching process directly be carried out by least squares ambiguity decorrelation algorithm (LAMBDA method. For all vector candidates, some ones are further eliminated by derived approximate inequality, which accelerates the searching process. Experimental results show that compared to traditional method with only baseline length constraint, this new method can utilize a priori baseline three-dimensional knowledge to fix ambiguity reliably and achieve a high success rate. Experimental tests also verify it is not very sensitive to baseline vector error and can perform robustly when angular error is not great.

  20. GNSS Single Frequency, Single Epoch Reliable Attitude Determination Method with Baseline Vector Constraint.

    Science.gov (United States)

    Gong, Ang; Zhao, Xiubin; Pang, Chunlei; Duan, Rong; Wang, Yong

    2015-12-02

    For Global Navigation Satellite System (GNSS) single frequency, single epoch attitude determination, this paper proposes a new reliable method with baseline vector constraint. First, prior knowledge of baseline length, heading, and pitch obtained from other navigation equipment or sensors are used to reconstruct objective function rigorously. Then, searching strategy is improved. It substitutes gradually Enlarged ellipsoidal search space for non-ellipsoidal search space to ensure correct ambiguity candidates are within it and make the searching process directly be carried out by least squares ambiguity decorrelation algorithm (LAMBDA) method. For all vector candidates, some ones are further eliminated by derived approximate inequality, which accelerates the searching process. Experimental results show that compared to traditional method with only baseline length constraint, this new method can utilize a priori baseline three-dimensional knowledge to fix ambiguity reliably and achieve a high success rate. Experimental tests also verify it is not very sensitive to baseline vector error and can perform robustly when angular error is not great.

  1. A new robust fuzzy method for unmanned flying vehicle control

    Institute of Scientific and Technical Information of China (English)

    Mojtaba Mirzaei; Mohammad Eghtesad; Mohammad Mahdi Alishahi

    2015-01-01

    A new general robust fuzzy approach was presented to control the position and the attitude of unmanned flying vehicles (UFVs). Control of these vehicles was challenging due to their nonlinear underactuated behaviors. The proposed control system combined great advantages of generalized indirect adaptive sliding mode control (IASMC) and fuzzy control for the UFVs. An on-line adaptive tuning algorithm based on Lyapunov function and Barbalat lemma was designed, thus the stability of the system can be guaranteed. The chattering phenomenon in the sliding mode control was reduced and the steady error was also alleviated. The numerical results, for an underactuated quadcopter and a high speed underwater vehicle as case studies, indicate that the presented adaptive design of fuzzy sliding mode controller performs robustly in the presence of sensor noise and external disturbances. In addition, online unknown parameter estimation of the UFVs, such as ground effect and planing force especially in the cases with the Gaussian sensor noise with zero mean and standard deviation of 0.5 m and 0.1 rad and external disturbances with amplitude of 0.1 m/s2 and frequency of 0.2 Hz, is one of the advantages of this method. These estimated parameters are then used in the controller to improve the trajectory tracking performance.

  2. 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…

  3. 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…

  4. Linguistically Diverse Students and Special Education: A Mixed Methods Study of Teachers' Attitudes, Coursework, and Practice

    Science.gov (United States)

    Greenfield, Renee A.

    2011-01-01

    While the number of linguistically diverse students (LDS) grows steadily in the U.S., schools, research and practice to support their education lag behind (Lucas & Grinberg, 2008). Research that describes the attitudes and practices of teachers who serve LDS and how those attitudes and practice intersect with language and special education is…

  5. Attitude of Students Towards Cooperative Learning Methods at Knox Community College: A Descriptive Study

    Science.gov (United States)

    McLeish, Keritha

    2009-01-01

    The study was conducted to determine the attitude of students towards cooperative learning at a community college. Questionnaires were administered to ninety (90) students and twelve (12) lecturers, in-depth interviews were conducted with three lecturers and two classes were observed to investigate the students attitude towards cooperative…

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

    Directory of Open Access Journals (Sweden)

    Aguiar Pedro

    2011-09-01

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

  7. Further development of the attitude difference method for estimating deflections of the vertical in real time

    Science.gov (United States)

    Zhu, Jing; Zhou, Zebo; Li, Yong; Rizos, Chris; Wang, Xingshu

    2016-07-01

    An improvement of the attitude difference method (ADM) to estimate deflections of the vertical (DOV) in real time is described in this paper. The ADM without offline processing estimates the DOV with a limited accuracy due to the response delay. The proposed model selection-based self-adaptive delay feedback (SDF) method takes the results of the ADM as the a priori information, then uses fitting and extrapolation to estimate the DOV at the current epoch. The active region selection factor F th is used to take full advantage of the Earth model EGM2008 and the SDF with different DOV exhibitions. The factors which affect the DOV estimation accuracy are analyzed and modeled. An external observation which is specified by the velocity difference between the global navigation satellite system (GNSS) and the inertial navigation system (INS) with DOV compensated is used to select the optimal model. The response delay induced by the weak observability of an integrated INS/GNSS to the violent DOV disturbances in the ADM is compensated. The DOV estimation accuracy of the SDF method is improved by approximately 40% and 50% respectively compared to that of the EGM2008 and the ADM. With an increase in GNSS accuracy, the DOV estimation accuracy could improve further.

  8. Prospective Science Teachers' Attitudes and Views of Using Journal Writing in the "Methods of Teaching Science" Course

    Science.gov (United States)

    Ambusaidi, Abdullah

    2014-01-01

    The aim of this study was to investigate the attitudes of prospective science teachers at Sultan Qaboos University towards and their views about using journal writing in the Methods of Teaching Science course. Twenty-six prospective science teachers were asked to write about each topic in the course in their journal to show their understanding of…

  9. Attitudes toward Using Social Networking Sites in Educational Settings with Underperforming Latino Youth: A Mixed Methods Study

    Science.gov (United States)

    Howard, Keith E.; Curwen, Margie Sauceda; Howard, Nicol R.; Colón-Muñiz, Anaida

    2015-01-01

    The researchers examined the online social networking attitudes of underperforming Latino high school students in an alternative education program that uses technology as the prime venue for learning. A sequential explanatory mixed methods study was used to cross-check multiple sources of data explaining students' levels of comfort with utilizing…

  10. 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....

  11. Power control system and method

    Science.gov (United States)

    Steigerwald, Robert Louis; Anderson, Todd Alan

    2006-11-07

    A power system includes an energy harvesting device, a battery coupled to the energy harvesting device, and a circuit coupled to the energy harvesting device and the battery. The circuit is adapted to deliver power to a load by providing power generated by the energy harvesting device to the load without delivering excess power to the battery and to supplement the power generated by the energy harvesting device with power from the battery if the power generated by the energy harvesting device is insufficient to fully power the load. A method of operating the power system is also provided.

  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. 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.

  15. 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...

  16. 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...

  17. 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.

  18. Knowledge attitude and practices of family planning methods among postnatal mothers-A hospital based study

    Directory of Open Access Journals (Sweden)

    Rekha Udgiri

    2016-04-01

    Full Text Available Background: All the couple have the basic rights to decide freely and responsibly on the number and spacing of their children and to have the information, education and means to do so. In developing countries, especially in India where deep rooted belief, customs and superstition regarding pregnancy, child birth, are still widely prevalent and women with poor socioeconomic background are more vulnerable to the health risks associated with child bearing in quick succession. Hence the present study provides excellent opportunities to educate the mother in postnatal ward regarding family planning method and help them to adopt birth spacing in the face of changing circumstances. Objectives: a To assess the knowledge, attitude & practices regarding family planning methods among postnatal mothers. b To educate them to use one of the family planning method. Material and Methods: Cross-sectional study was carried out for a period of one month. A total of 162 postnatal mother who were admitted in postnatal general ward of OBG Dept., Shri.BM.Patil medical college constitutes the sample size. After obtaining ethical clearance from the institute, the mothers were interviewed after taking verbal consent. The data was collected using semi-structured questionnaires. Statistical test like percentage, chi-square test was applied to know the association. Result: In the present study 65.4% of mothers knew about family planning methods. Significant association was found in relation to education (p= 0.000, religion (p= 0.055 and parity (p= 0.01. Conclusion: The literacy level will definitely help to gain the information regarding family planning.

  19. 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.

  20. The Effectiveness of Pole Placement Method in Control System Design for an Autonomous Helicopter Model in Hovering Flight

    Directory of Open Access Journals (Sweden)

    Abas Ab. Wahab

    2009-12-01

    Full Text Available This paper presents the results of attitude, velocity, heave and yaw controller design for an autonomous model scaled helicopter using identified model of vehicle dynamic from parameterized state-space model with quasi-steady attitude dynamic approximation (6 Degree of Freedom model. Multivariable state-space control methodology such as pole placement was used to design the linear state-space feedback for the stabilization of helicopter because of its simple controller architecture. The design specification for controller design was selected according to Military Handling Qualities Specification ADS-33C. Results indicate that acceptable controller can be designed using pole placement method with quasi-steady attitude approximation and it has been shown that the controller design was compliance with design criteria of hover requirement in ADS-33C.

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

    Directory of Open Access Journals (Sweden)

    Zhijun Li

    2015-07-01

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

  2. Knowledge and attitude of women regarding the human papillomavirus (HPV) infection, its relationship to cervical cancer and prevention methods.

    Science.gov (United States)

    Farzaneh, Farah; Shirvani, Hamidreza Esmaeilnia; Barouti, Esmat; Salehpour, Saghar; Khodakarami, Nahid; Alizadeh, Kamyab

    2011-12-01

    This study aimed to determine knowledge and attitude of women to HPV and its association with cervical cancer and prevention methods. In a cross-sectional study, 500 women, aged between 20 and 50 presenting to local health centers in Tehran, were asked about demographic factors and questioned about cervical cancer, HPV, and prevention methods. Responses were tabulated and summarized. Although knowledge of HPV, its relation to cervical cancer and prevention methods among Iranian women is not enough, their attitude towards education in this regards is extremely high. The results reflect the need of advertising and educational programs for public about HPV prevention methods, to reduce the prevalence of this infection and its severe consequences. PMID:22390103

  3. 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.

  4. Survey of attitudes, materials and methods employed in endodontic treatment by general dental practitioners in North Jordan

    OpenAIRE

    Al-Omari Wael M

    2004-01-01

    Abstract Background General dental practitioners provide the majority of endodontic treatment in Jordan. The aim of this study was to gather information on the methods, materials and attitudes employed in root canal treatment by dentists in North Jordan, in order to evaluate and improve the quality of current practice. Methods A questionnaire was posted to all registered general dental practitioners working in private practice in Irbid Governate in North Jordan (n = 181). The questionnaire in...

  5. Adaptive Method Using Controlled Grid Deformation

    Directory of Open Access Journals (Sweden)

    Florin FRUNZULICA

    2011-09-01

    Full Text Available The paper presents an adaptive method using the controlled grid deformation over an elastic, isotropic and continuous domain. The adaptive process is controlled with the principal strains and principal strain directions and uses the finite elements method. Numerical results are presented for several test cases.

  6. 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.

  7. 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).

  8. 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

  9. Locus of control and contraceptive knowledge, attitude and practice among university students Locus de control y conocimiento, actitud y práctica contraceptivas entre adolescentes universitarios Lócus de controle e conhecimento, atitude e prática contraceptivas entre adolescentes universitários

    OpenAIRE

    Aline Salheb Alves; Maria Helena Baena de Moraes Lopes

    2010-01-01

    OBJECTIVE: To assess the relationship between locus of control and knowledge, attitude and practice regarding pill and condom use among university students. METHODS: The inquiry was developed in Campinas, a city in Southeastern Brazil, in 2006. A total of 295 adolescent newcomers to a public university answered a structured questionnaire and Levenson's multidimensional locus of control scale. The scores of the dimensions of locus of control were calculated and Spearman's correlation coefficie...

  10. A motion-based integer ambiguity resolution method for attitude determination using the global positioning system (GPS)

    International Nuclear Information System (INIS)

    Loss of the satellite signal and noise disturbance will cause cycle slips to occur in the carrier phase observation of the attitude determination system using the global positioning system (GPS), especially in the dynamic situation. Therefore, in order to reject the error by cycle slips, the integer ambiguity should be re-computed. A motion model-based Kalman predictor is used for the ambiguity re-computation in dynamic applications. This method utilizes the correct observation of the last step to predict the current ambiguities. With the baseline length as a constraint to reject invalid values, we can solve the current integer ambiguity and the attitude angles, by substituting the obtained ambiguities into the constrained LAMBDA method. Experimental results demonstrate that the proposed method is more efficient in the dynamic situation, which takes less time to obtain new fixed ambiguities with a higher mean success rate

  11. Nonlinear system compound inverse control method

    Institute of Scientific and Technical Information of China (English)

    Yan ZHANG; Zengqiang CHEN; Peng YANG; Zhuzhi YUAN

    2005-01-01

    A compound neural network is utilized to identify the dynamic nonlinear system.This network is composed of two parts: one is a linear neural network,and the other is a recurrent neural network.Based on the inverse theory a compound inverse control method is proposed.The controller has also two parts:a linear controller and a nonlinear neural network controller.The stability condition of the closed-loop neural network-based compound inverse control system is demonstrated based on the Lyapunov theory.Simulation studies have shown that this scheme is simple and has good control accuracy and robustness.

  12. 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.

  13. Robust Control Methods for a Recycle Bioreactor

    Directory of Open Access Journals (Sweden)

    Cosmin IONETE

    2001-12-01

    Full Text Available The paper presents a robust control design strategy for bioprocesses, which are characterized by strongly nonlinear dynamics. More precisely, we present the H2 methodology in order to compute the controller for a recycle Continuous Stirred Tank Bioreactor (CSTB. We consider a general method of formulating control problem, which makes use of linear fractional transformation as introduced by Doyle (1978. The formulation makes use of the general two-port configuration of the generalized plant with a generalized controller. The H2 norm is the quadratic criterion used in optimal control as LQG. The overall control objective is to minimize the H2 norm of the transfer matrix function from the weighted exogenous inputs to the weighted controlled outputs. The advantage of H2 control technique, which uses the linearized model of the CSTB, is that it is completely automated and very flexible. Finally, we prove that the closed loop control structure has very good inner robustness.

  14. Lost and Found, Letters and Methods: Assessing Attitudes toward Chiropractic and Medical Care

    Directory of Open Access Journals (Sweden)

    Hannah Kern

    2010-10-01

    Full Text Available Attitudes toward traditional and chiropractic medicine were compared using Milgram's lost letter technique. A total of 192 letters were placed on the windshields of vehicles in parking lots at six restaurants and department stores in each of four quadrants of a medium-sized, Southeastern city. These letters were addressed to "Admissions" at either a fictitious Institute of Medicine or Institute of Chiropractic Care. Return addresses included either a male or a female name. Thus, those who found a lost letter were faced with the option of returning or not returning a letter from either a male or a female, addressed to an Institute of traditional or non-traditional medicine. After examining previous studies which had used the lost letter technique, numerous methodological improvements were implemented. For example, letters were randomly assigned to potential drop spots for each of 24 study locations (six study locations in each of four city quadrants, and a Latin square design was used to control for possible order effects in the four study conditions that were implemented. Nearly 65% of the letters (124 of 192 were returned. We found: 1 letters addressed to a fictitious Institute of Chiropractic Care were just as likely to be returned as those addressed to a fictitious Institute of Medicine; 2 letters with female return addresses were as likely to be returned as those with male return addresses; 3 there was no interaction between study conditions; 4 based on what was essentially a replication study, a comparison of the pattern of returns using the first and second cycle of lost letters (n = 96 for each cycle revealed an equivalent pattern of no-difference findings. DOI: 10.2458/azu_jmmss.v1i1.78

  15. 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...

  16. Strike Point Control on EAST Using an Isoflux Control Method

    Science.gov (United States)

    Xing, Zhe; Xiao, Bingjia; Luo, Zhengping; L. Walker, M.; A. Humphreys, D.

    2015-09-01

    For the advanced tokamak, the particle deposition and thermal load on the divertor is a big challenge. By moving the strike points on divertor target plates, the position of particle deposition and thermal load can be shifted. We could adjust the Poloidal Field (PF) coil current to achieve the strike point position feedback control. Using isoflux control method, the strike point position can be controlled by controlling the X point position. On the basis of experimental data, we establish relational expressions between X point position and strike point position. Benchmark experiments are carried out to validate the correctness and robustness of the control methods. The strike point position is successfully controlled following our command in the EAST operation. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2012GB105000 and 2014GB103000)

  17. Pharmacists’ knowledge and attitudes about natural health products: a mixed-methods study

    Directory of Open Access Journals (Sweden)

    Kheir N

    2014-01-01

    Full Text Available Nadir Kheir, Hoda Y Gad, Safae E Abu-Yousef College of Pharmacy, Qatar University, Al Tarfa, Doha, Qatar Objectives: To explore knowledge and attitude of pharmacists in Qatar towards natural health products (NHPs. Methods: The quantitative component of this study consisted of an anonymous, online, self-administered questionnaire to assess knowledge about NHPs among pharmacists in Qatar. Descriptive statistics and inferential analysis were conducted using Statistical Package of Social Sciences (SPSS®. Means and standard deviation were used to analyze descriptive data, and statistical significance was expressed as P-value, where P≤0.05 was considered statistically significant. Associations between variables were measured using Pearson correlation. The qualitative component utilized focus group (FG meetings with a purposive sample of community pharmacists. Meetings were conducted until a point of saturation was reached. FG discussions were audio-taped and transcribed verbatim. Data were analyzed using a framework approach to sort the data according to emerging themes. Results: The majority of participants had average to poor knowledge about NHPs while only around 7% had good knowledge. In the FG meetings, participants considered the media, medical representatives, and old systems of natural health as major source of their knowledge. They criticized undergraduate pharmacy courses (for inadequately preparing pharmacists to deal with NHPs and the pharmacy regulations (for being irrelevant. A perception of NHPs as being “safe” still exists among pharmacists. Conclusions: Pharmacists’ ability to provide effective services associated with NHPs is limited by poor access to evidence-based information and poor knowledge. A perception of NHPs and CAM as 'safe' still exists among pharmacists, and regulations related to NHPs require addressing to follow best practice and ensure patient safety. Keywords: Qatar, focus group, complimentary alternative

  18. The 'Antiretrovirals, Sexual Transmission Risk and Attitudes' (ASTRA study. Design, methods and participant characteristics.

    Directory of Open Access Journals (Sweden)

    Andrew Speakman

    Full Text Available Life expectancy for people diagnosed with HIV has improved dramatically however the number of new infections in the UK remains high. Understanding patterns of sexual behaviour among people living with diagnosed HIV, and the factors associated with having condom-less sex, is important for informing HIV prevention strategies and clinical care. In addition, in view of the current interest in a policy of early antiretroviral treatment (ART for all people diagnosed with HIV in the UK, it is of particular importance to assess whether ART use is associated with increased levels of condom-less sex. In this context the ASTRA study was designed to investigate current sexual activity, and attitudes to HIV transmission risk, in a large unselected sample of HIV-infected patients under care in the UK. The study also gathered background information on demographic, socio-economic, lifestyle and disease-related characteristics, and physical and psychological symptoms, in order to identify other key factors impacting on HIV patients and the behaviours which underpin transmission. In this paper we describe the study rationale, design, methods, response rate and the demographic characteristics of the participants. People diagnosed with HIV infection attending 8 UK HIV out-patient clinics in 2011-2012 were invited to participate in the study. Those who agreed to participate completed a confidential, self-administered pen-and-paper questionnaire, and their latest CD4 count and viral load test results were recorded. During the study period, 5112 eligible patients were invited to take part in the study and 3258 completed questionnaires were obtained, representing a response rate of 64% of eligible patients. The study includes 2248 men who have sex with men (MSM, 373 heterosexual men and 637 women. Future results from ASTRA will be a key resource for understanding HIV transmission within the UK, targeting prevention efforts, and informing clinical care of individuals

  19. Physical activity attitudes, intentions and behaviour among 18–25 year olds: A mixed method study

    OpenAIRE

    Poobalan Amudha S; Aucott Lorna S; Clarke Amanda; Smith W Cairns S

    2012-01-01

    Abstract Background Young people (18–25 years) during the adolescence/adulthood transition are vulnerable to weight gain and notoriously hard to reach. Despite increased levels of overweight/obesity in this age group, physical activity behaviour, a major contributor to obesity, is poorly understood. The purpose of this study was to explore physical activity (PA) behaviour among 18–25 year olds with influential factors including attitudes, motivators and barriers. Methods An explanatory mixed ...

  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. 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.

  2. Linear systems control deterministic and stochastic methods

    CERN Document Server

    Hendricks, Elbert; Sørensen, Paul Haase

    2008-01-01

    Linear Systems Control provides a very readable graduate text giving a good foundation for reading more rigorous texts. There are multiple examples, problems and solutions. This unique book successfully combines stochastic and deterministic methods.

  3. 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.

  4. 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.

  5. 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.

  6. An enhanced Cramér-Rao bound weighted method for attitude accuracy improvement of a star tracker.

    Science.gov (United States)

    Zhang, Jun; Wang, Jian

    2016-06-01

    This study presents a non-average weighted method for the QUEST (QUaternion ESTimator) algorithm, using the inverse value of root sum square of Cramér-Rao bound and focal length drift errors of the tracking star as weight, to enhance the pointing accuracy of a star tracker. In this technique, the stars that are brighter, or at low angular rate, or located towards the center of star field will be given a higher weight in the attitude determination process, and thus, the accuracy is readily improved. Simulations and ground test results demonstrate that, compared to the average weighted method, it can reduce the attitude uncertainty by 10%-20%, which is confirmed particularly for the sky zones with non-uniform distribution of stars. Moreover, by using the iteratively weighted center of gravity algorithm as the newly centroiding method for the QUEST algorithm, the current attitude uncertainty can be further reduced to 44% with a negligible additional computing load. PMID:27370431

  7. 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.

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

    OpenAIRE

    Kerry O'Brien; Walter Forrest; Dermot Lynott; Michael Daly

    2013-01-01

    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 wh...

  9. LED lamp color control system and method

    Science.gov (United States)

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A.M.

    2013-02-05

    An LED lamp color control system and method including an LED lamp having an LED controller 58; and a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 determines whether the LED source 80 is in a feedback controllable range, stores measured optical flux for the LED source 80 when the LED source 80 is in the feedback controllable range, and bypasses storing the measured optical flux when the LED source 80 is not in the feedback controllable range.

  10. Power Control Method for Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Baang, Dane; Suh, Yongsuk; Park, Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Considering safety-oriented design concept and other control environment, we developed a simple controller that provides limiting function of power change- rate as well as fine tracking performance. The design result has been well-proven via simulation and actual application to a TRIGA-II type research reactor. The proposed controller is designed to track the PDM(Power Demand) from operator input as long as maintaining the power change rate lower than a certain value for stable reactor operation. A power control method for a TRIGA-II type research reactor has been designed, simulated, and applied to actual reactor. The control performance during commissioning test shows that the proposed controller provides fine control performance for various changes in reference values (PDM), even though there is large measurement noise from neutron detectors. The overshoot at low power level is acceptable in a sense of reactor operation.

  11. Evaluation of Controller Tuning Methods Applied to Distillation Column Control

    DEFF Research Database (Denmark)

    Nielsen, Kim; W. Andersen, Henrik; Kümmel, Professor Mogens;

    1998-01-01

    A frequency domain approach is used to compare the nominal performance and robustness of dual composition distillation column control tuned according to Ziegler-Nichols (ZN) and Biggest Log Modulus Tuning (BLT) for three binary distillation columns, WOBE, LUVI and TOFA. The scope...... of this is to examine whether ZN and BLT design yield satisfactory control of distillation columns. Further, PI controllers are tuned according to a proposed multivariable frequency domain method. A major conclusion is that the ZN tuned controllers yield undesired overshoot and oscillation and poor stability robustness...

  12. 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.

  13. Farmers' Attitude towards a Participatory Research Method Used to Evaluate Weed Management Strategies in Bananas

    Science.gov (United States)

    Ganpat, Wayne G.; Isaac, Wendy-Ann P.; Brathwaite, Richard A. I.; Bekele, Isaac

    2009-01-01

    In this study, farmers were engaged in a participatory research project and their attitudes evaluated. The purpose was to identify the characteristics of farmers who are favourably predisposed towards meaningful participation in the process. Several cover crops were tested for possible use in the management of watergrass ("Commelina diffusa"), a…

  14. Improving the GNSS attitude ambiguity success rate with the multivariate constrained LAMBDA method

    NARCIS (Netherlands)

    Giorgi, G.; Teunissen, P.J.G.; Verhagen, S.; Buist, P.J.

    2009-01-01

    GNSS Attitude Determination is a valuable technique for the estimation of platform orientation. To achieve high accuracies on the angular estimations, the GNSS carrier phase data has to be used. These data are known to be affected by integer ambiguities, which must be correctly resolved in order to

  15. Findings, theories and methods in the study of children's national identifications and national attitudes

    NARCIS (Netherlands)

    M. Barrett; L. Oppenheimer

    2011-01-01

    This paper reviews some of the relevant background findings against which the empirical studies reported in this special issue were designed. Particular attention is given to previous findings on the development of children’s national knowledge, national attitudes and national identifications. The p

  16. Learning Might Not Equal Liking: Research Methods Course Changes Knowledge But Not Attitudes

    Science.gov (United States)

    Sizemore, O. J.; Lewandowski, Gary W., Jr.

    2009-01-01

    Students completed surveys at the beginning and end of a sophomore-level course on research and statistics. We hypothesized that the course would produce advances in knowledge of research and statistics and that those changes would be accompanied by more favorable attitudes toward the subject matter. Results showed that knowledge did increase…

  17. Knowledge, attitude and utilization of sub-dermal birth control implants among married rural women of Pakistan

    Directory of Open Access Journals (Sweden)

    Mehwish Mubarik

    2016-06-01

    Methods: This descriptive cross sectional study was conducted at reproductive health services center at Panoaqil, Sindh, Pakistan. A sample of 120 married women of age 18-45 years, who attended RHS center were included in the study. Data was collected through a standardized questionnaire and analyzed using IBM SPSS version 22 and Microsoft excel. Results: The mean age of sample was 29.48+/-5.05 years, almost half (44.2% were illiterate, and 39% were educated up to primary. Three forth (73% were housewives and 91.7% were poor. Majority (80% had heard about one method but only one forth (26% have used one while Implant was used by only 21.9% women. About two third (68% didn't know about Implant while 14.2% had good knowledge about Implant. Overall attitude was positive as 85% continued the method but 14.29% quitted due to side effects. Among never users; half (46% would go for Implant if they would be provided with the insertion services. Conclusions: The current study concludes that knowledge about sub-dermal Implant among women of reproductive age reaching the optimum level. The attitude of women was found positive. The factors which affect the knowledge and the attitude of women are age, parity, family type, level of education, employments status, SE status, previous use of family planning nad source of information. [Int J Res Med Sci 2016; 4(6.000: 2229-2239

  18. 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.

  19. 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.

  20. Invasive brain-machine interfaces: a survey of paralyzed patients’ attitudes, knowledge and methods of information retrieval

    Science.gov (United States)

    Lahr, Jacob; Schwartz, Christina; Heimbach, Bernhard; Aertsen, Ad; Rickert, Jörn; Ball, Tonio

    2015-08-01

    Objective. Brain-machine interfaces (BMI) are an emerging therapeutic option that can allow paralyzed patients to gain control over assistive technology devices (ATDs). BMI approaches can be broadly classified into invasive (based on intracranially implanted electrodes) and noninvasive (based on skin electrodes or extracorporeal sensors). Invasive BMIs have a favorable signal-to-noise ratio, and thus allow for the extraction of more information than noninvasive BMIs, but they are also associated with the risks related to neurosurgical device implantation. Current noninvasive BMI approaches are typically concerned, among other issues, with long setup times and/or intensive training. Recent studies have investigated the attitudes of paralyzed patients eligible for BMIs, particularly patients affected by amyotrophic lateral sclerosis (ALS). These studies indicate that paralyzed patients are indeed interested in BMIs. Little is known, however, about the degree of knowledge among paralyzed patients concerning BMI approaches or about how patients retrieve information on ATDs. Furthermore, it is not yet clear if paralyzed patients would accept intracranial implantation of BMI electrodes with the premise of decoding improvements, and what the attitudes of a broader range of patients with diseases such as stroke or spinal cord injury are towards this new kind of treatment. Approach. Using a questionnaire, we surveyed 131 paralyzed patients for their opinions on invasive BMIs and their attitude toward invasive BMI treatment options. Main results. The majority of the patients knew about and had a positive attitude toward invasive BMI approaches. The group of ALS patients was especially open to the concept of BMIs. The acceptance of invasive BMI technology depended on the improvements expected from the technology. Furthermore, the survey revealed that for paralyzed patients, the Internet is an important source of information on ATDs. Significance. Websites tailored to

  1. 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...

  2. 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)

  3. 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.

  4. Evaluating the effect of Focus Farms on Ontario dairy producers' knowledge, attitudes, and behavior toward control of Johne's disease.

    Science.gov (United States)

    Roche, S M; Jones-Bitton, A; Meehan, M; Von Massow, M; Kelton, D F

    2015-08-01

    This study evaluated a participatory-based, experiential learning program, Ontario Focus Farms (FF), which aimed to change dairy producer behavior to control Johne's disease (JD) in Ontario, Canada. The goals were to (1) assess the effect of FF on participating dairy producers' knowledge, attitudes, and behavior with regard to JD control; (2) compare changes in these factors among FF participants to changes among a group of nonparticipating dairy producers; and (3) describe the characteristics of producers who made at least one on-farm management change. Pre- and post-FF intervention questionnaires collected data on respondents' knowledge, attitudes, behavior, herd production, and demographic information; before and after JD-risk assessments were used to assess respondents' on-farm risk of JD transmission. Overall, 176 dairy producers participated in the FF process; 39.8% (70/176) of FF and 14.6% (52/357) of control participants responded to both the pre- and postintervention questionnaires. Upon comparison, FF respondents were more likely to be younger, have larger herds, and have higher management scores. The proportion of FF participants who reported making at least one on-farm change (81%) was significantly higher than that of control respondents (38%). Overall, FF respondents significantly changed their risk score in 4 out of 5 risk areas and had an average reduction of 13 points in their overall risk score between before and after risk assessments. Control respondents' risk assessment scores did not significantly change during the study period. In a JD knowledge assessment, FF and control respondents exhibited a moderate knowledge score before the intervention period, with median scores of 75.9% (22/29) in each group. The FF respondents significantly increased their score at the postintervention assessment, with a median of 82.8% (24/29); control-respondent scores did not significantly change. Both FF and control respondents held strong positive attitudes

  5. A Survey of Quantum Lyapunov Control Methods

    Directory of Open Access Journals (Sweden)

    Shuang Cong

    2013-01-01

    Full Text Available The condition of a quantum Lyapunov-based control which can be well used in a closed quantum system is that the method can make the system convergent but not just stable. In the convergence study of the quantum Lyapunov control, two situations are classified: nondegenerate cases and degenerate cases. For these two situations, respectively, in this paper the target state is divided into four categories: the eigenstate, the mixed state which commutes with the internal Hamiltonian, the superposition state, and the mixed state which does not commute with the internal Hamiltonian. For these four categories, the quantum Lyapunov control methods for the closed quantum systems are summarized and analyzed. Particularly, the convergence of the control system to the different target states is reviewed, and how to make the convergence conditions be satisfied is summarized and analyzed.

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

    Science.gov (United States)

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

    2013-01-01

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

  7. Designing a New Nonlinear PID Attitude Controller for Small Quad-rotor Aircraft%小型四旋翼飞行器新型非线性PID姿态控制器设计

    Institute of Scientific and Technical Information of China (English)

    李杰; 齐晓慧; 韩帅涛

    2013-01-01

    针对小型四旋翼飞行器姿态控制问题,设计了一种新型非线性PID姿态控制器.针对传统PID的不足,通过引入两个跟踪微分器以及误差反馈的非线性组合构成非线性PID,并结合简化的小型四旋翼飞行器数学模型,提出了一种基于新型非线性PID姿态控制方法.仿真结果表明,所设计的控制器具有较强的鲁棒性、抗干扰性以及良好的滤波性能,系统具有良好的动态和稳态性能.由于保留了传统PID优点,设计简单,对实际工程具有较大的指导价值.%A new nonlinear PID attitude controller was designed to control the attitude of a small quad-rotor aircraft.Combined with the simplified mathematical model of small quad-rotor aircraft,an attitude control method was proposed by using the new nonlinear PID attitude controller.Two tracking differentiators and a nonlinear state error feedback are used to overcome the deficiency of the traditional PID controller.The simulation results indicate that our attitude controller achieves strong robustness,anti-disturbance and high filtering performances,having high-dynamic and steady-state performances.

  8. Method for controlling xenone control rod in nuclear reactors

    International Nuclear Information System (INIS)

    Purpose: To adequately conduct entire withdrawal or entire insertion of xenone control rods by comparing the control rod worths of the xenone control rods and the xenone amount. Method: A turbine output signal is inputted to a load variation detection circuit and, if the variation coefficient is with a predetermined setting value, it is judged that the load variation has been completed and the load is settled constant, the result of which is inputted to the control rod selection device. The reactor power signal is inputted to a control rod selection device and the number density of iodine and the number density of xenone are determined based on the neutron flux and the maximum or minimum value of the xenone at a constant load is calculated based on both of the data. Then, a function representing the variation amount of the xenone reactivity having the maximum or minimum value as the variant is determined. By comparing the function and the constant load signal, the operation for the xenone control rods is judged or selected. According to this invention, the conventional method of compensating the xenone amount variation with the adjustment of the boron concentration can be substituted with the xenone control rods. (Kawakami, Y.)

  9. Clustering of attitudes towards obesity: a mixed methods study of Australian parents and children

    OpenAIRE

    Olds, Tim; Thomas, Samantha; Lewis, Sophie; Petkov, John

    2013-01-01

    Background Current population-based anti-obesity campaigns often target individuals based on either weight or socio-demographic characteristics, and give a ‘mass’ message about personal responsibility. There is a recognition that attempts to influence attitudes and opinions may be more effective if they resonate with the beliefs that different groups have about the causes of, and solutions for, obesity. Limited research has explored how attitudinal factors may inform the development of both u...

  10. 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.

  11. Precise control of a magnetically suspended double-gimbal control moment gyroscope using differential geometry decoupling method

    Institute of Scientific and Technical Information of China (English)

    Chen Xiaocen; Chen Maoyin

    2013-01-01

    Precise control of a magnetically suspended double-gimbal control moment gyroscope (MSDGCMG) is of vital importance and challenge to the attitude positioning of spacecraft owing to its multivariable,nonlinear and strong coupled properties.This paper proposes a novel linearization and decoupling method based on differential geometry theory and combines it with the internal model controller (IMC) to guarantee the system robustness to the external disturbance and parameter uncertainty.Furthermore,by introducing the dynamic compensation for the inner-gimbal rate-servo system and the magnetically suspended rotor (MSR) system only,we can eliminate the influence of the unmodeled dynamics to the decoupling control accuracy as well as save costs and inhibit noises effectively.The simulation results verify the nice decoupling and robustness performance of the system using the proposed method.

  12. Don't give me attitude: Can perceptions of social norms, behavioral control and moral intensity help bridge the attitude-behavior gap in ethical consumer behavior?

    OpenAIRE

    Gloukhovtsev, Alexei

    2014-01-01

    The last couple of decades have seen a significant increase in positive attitudes towards ethical products and services. However, this increase is has yet to lead to a marked growth in the sales of such products. This thesis looks at the consumer decision-making process in situations where a moral issue or dilemma is present, and examines possible reasons for the disconnect between consumers' attitudes and behavioral intentions. Drawing on Icek Ajzen's (1985) theory of planned behavior, t...

  13. Gender Differences in the Attitude and Strategy towards Weight Control among Government Employees in Penang, Malaysia

    OpenAIRE

    Aina Mardiah, B; Hazizi, AS; Nasir, MT Mohd; Zaitun, Y; Jan, JM Hamid

    2012-01-01

    Background: This was a cross-sectional study on the gender differences in weight-control behavior. The strategies used, weight status, weight satisfaction, and proportion of individuals attempting to lose weight among 233 government employees (104 men and 129 women) working in the Federal Government Building in Penang, Malaysia, were assessed. Methods: Anthropometric indicators such as body mass index, waist-to-hip ratio, and body fat percentage were measured to determine the subjects’ body w...

  14. Gender Differences in the Attitude and Strategy towards Weight Control among Government Employees in Penang, Malaysia

    OpenAIRE

    Zaitun, Y; MT, Mohd Nasir; AS Hazizi; Aina Mardiah, B; JM, Hamid Jan

    2012-01-01

    "nBackground: This was a cross-sectional study on the gender differences in weight-control behavior. The strategies used, weight status, weight satisfaction, and proportion of individuals attempting to lose weight among 233 government employees (104 men and 129 women) working in the Federal Government Building in Penang, Malaysia, were assessed."nMethods: Anthropometric indicators such as body mass index, waist-to-hip ratio, and body fat percentage were measured to determine the sub...

  15. 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.

  16. 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.

  17. Materials, methods and quality control, ch. 3

    International Nuclear Information System (INIS)

    A description of the chemical reagents, the 125I-labelled angiotensin I, the antiserum and the standards is given. A modified measuring method with the New England Nuclear kit for angiotensin I radioimmunoassay is presented as well as the quality control data

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

    Science.gov (United States)

    Metzger, J. R.

    1974-01-01

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

  19. Actively controlled vibration welding system and method

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Wayne W.; Kang, Bongsu; Tan, Chin-An

    2013-04-02

    A vibration welding system includes a controller, welding horn, an active material element, and anvil assembly. The assembly may include an anvil body connected to a back plate and support member. The element, e.g., a piezoelectric stack or shape memory alloy, is positioned with respect to the assembly. The horn vibrates in a desirable first direction to form a weld on a work piece. The element controls any vibrations in a second direction by applying calibrated response to the anvil body in the second direction. A method for controlling undesirable vibrations in the system includes positioning the element with respect to the anvil assembly, connecting the anvil body to the support member through the back plate, vibrating the horn in a desirable first direction, and transmitting an input signal to the element to control vibration in an undesirable second direction.

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

    Science.gov (United States)

    Kuijer, Roeline G; Boyce, Jessica A

    2014-03-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

    Lam, Quang M.; Barkana, Itzhak

    2014-12-01

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

  4. Control and estimation methods over communication networks

    CERN Document Server

    Mahmoud, Magdi S

    2014-01-01

    This book provides a rigorous framework in which to study problems in the analysis, stability and design of networked control systems. Four dominant sources of difficulty are considered: packet dropouts, communication bandwidth constraints, parametric uncertainty, and time delays. Past methods and results are reviewed from a contemporary perspective, present trends are examined, and future possibilities proposed. Emphasis is placed on robust and reliable design methods. New control strategies for improving the efficiency of sensor data processing and reducing associated time delay are presented. The coverage provided features: ·        an overall assessment of recent and current fault-tolerant control algorithms; ·        treatment of several issues arising at the junction of control and communications; ·        key concepts followed by their proofs and efficient computational methods for their implementation; and ·        simulation examples (including TrueTime simulations) to...

  5. Methods of algebraic geometry in control theory

    CERN Document Server

    Falb, Peter

    1999-01-01

    "Control theory represents an attempt to codify, in mathematical terms, the principles and techniques used in the analysis and design of control systems. Algebraic geometry may, in an elementary way, be viewed as the study of the structure and properties of the solutions of systems of algebraic equations. The aim of this book is to provide access to the methods of algebraic geometry for engineers and applied scientists through the motivated context of control theory" .* The development which culminated with this volume began over twenty-five years ago with a series of lectures at the control group of the Lund Institute of Technology in Sweden. I have sought throughout to strive for clarity, often using constructive methods and giving several proofs of a particular result as well as many examples. The first volume dealt with the simplest control systems (i.e., single input, single output linear time-invariant systems) and with the simplest algebraic geometry (i.e., affine algebraic geometry). While this is qui...

  6. 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.

  7. Control rod housing alignment and repair method

    International Nuclear Information System (INIS)

    This patent describes a method for underwater welding of a control rod drive housing inserted through a stub tube to maintain requisite alignment and elevation of the top of the control rod drive housing to an overlying and corresponding aperture in a core plate as measured by an alignment device which determines the relative elevation and angularity with respect to the aperture. It comprises providing a welding cylinder dependent from the alignment device such that the elevation of the top of the welding cylinder is in a fixed relationship to the alignment device and is gas-proof; pressurizing the welding cylinder with inert welding gas sufficient to maintain the interior of the welding cylinder dry; lowering the welding cylinder through the aperture in the core plate by depending the cylinder with respect to the alignment device, the lowering including lowering through and adjusting the elevation relationship of the welding cylinder to the alignment device such that when the alignment device is in position to measure the elevation and angularity of the new control rod drive housing, the lower distal end of the welding cylinder extends below the upper periphery of the stub where welding is to occur; inserting a new control rod drive housing through the stub tube and positioning the control rod drive housing to a predetermined relationship to the anticipated final position of the control rod drive housing; providing welding implements transversely rotatably mounted interior of the welding cylinder relative to the alignment device such that the welding implements may be accurately positioned for dispensing weldment around the periphery of the top of the stub tube and at the side of the control rod drive housing; measuring the elevation and angularity of the control rod drive housing; and dispensing weldment along the top of the stub tube and at the side of the control rod drive housing

  8. 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.

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

    Science.gov (United States)

    Jikuya, Ichiro; Fujii, Kenta; Yamada, Katsuhiko

    2016-10-01

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

  10. A method for controlling catalytic reforming

    Energy Technology Data Exchange (ETDEWEB)

    Karamyshev, M.S.; Denilov, N.A.; Kamyshnikov, A.I.; Kirilin, Yu.A.; Lozinskiy, V.N.; Melman, A.Z.; Ovchinnikova, T.F.; Shpunt, M.I.; Shuvalov, V.V.; Zayashnikov, Ye.N.

    1983-01-01

    In the method for controlling the process of catalytic reforming, which includes mixing the raw material components with the production of a raw material, reforming and isolation of the final products, through changing the relationship of the expenditures of the raw material components relative to the content of the target components in the raw material, in order to support and stabilize an assigned production of the final products, the relationship of the expenditures of the raw material components are changed with correction based on the flow rates of the final products. A block diagram of the installation which realizes the proposed method is cited.

  11. A stable toolkit method in quantum control

    International Nuclear Information System (INIS)

    Recently the 'toolkit' discretization introduced to accelerate the numerical resolution of the time-dependent Schroedinger equation arising in quantum optimal control problems demonstrated good results on a large range of models. However, when coupling this class of methods with the so-called monotonically convergent algorithms, numerical instabilities affect the convergence of the discretized scheme. We present an adaptation of the 'toolkit' method which preserves the monotonicity of the procedure. The theoretical properties of the new algorithm are illustrated by numerical simulations. (fast track communication)

  12. A stable toolkit method in quantum control

    Energy Technology Data Exchange (ETDEWEB)

    Belhadj, M [Institut Superieur des Mathematiques Appliquees et d' Informatique de Kairouan, Av. Assad Ibn El Fourat, 3100 Kairouan (Tunisia); Salomon, J; Turinici, G [CEREMADE, Universite Paris Dauphine, Place du Marechal De Lattre De Tassigny, 75775 Paris Cedex 16 (France)], E-mail: mohamed.belhadj@ismai.rnu.tn, E-mail: salomon@ceremade.dauphine.fr, E-mail: gabriel.turinici@dauphine.fr

    2008-09-12

    Recently the 'toolkit' discretization introduced to accelerate the numerical resolution of the time-dependent Schroedinger equation arising in quantum optimal control problems demonstrated good results on a large range of models. However, when coupling this class of methods with the so-called monotonically convergent algorithms, numerical instabilities affect the convergence of the discretized scheme. We present an adaptation of the 'toolkit' method which preserves the monotonicity of the procedure. The theoretical properties of the new algorithm are illustrated by numerical simulations. (fast track communication)

  13. Cascade plant control by timer method

    International Nuclear Information System (INIS)

    The present invention relates to a method of controlling uranium flow rate through a cascaded centrifuge plant for the purpose of enriching uranium 235. Such a cascade includes multiple gas separation stage each of which consists of a plurality of centrifuges. The product gas usually includes a large amount of He gas, and a cold trap is used to eliminate the He from UF6. The cold trap is operated periodically in such a way that the mixed gas of He and UF6 is cooled to solidify only UF6 and then warmed to obtain UF6 by gasification. In order to operate the plant continuously, parallel multiple cold traps are operated alternatively. The operating conditions in such a complex cascade system are difficult to alter by conventional control methods. The present invention provides a rapid method of controlling the system when a certain percentage of the centrifuges in one stage malfunction. The control system consists of timers which are provided one for each cold trap to control the operational period of the trap. For example, if 20% of the centrifuges in a particular stage malfunction, the timer period of the cold traps attached to the normally operating centrifuge within the stage is maintained, and the period of all the other centrifuges are changed to 10/8 times that of the initial value. In this way the flow volume through all centrifuges except that in the particular stage is reduced to 80% of the initial value and the operation of the system can be continued with reduced efficiency. (Masui, R.)

  14. Stability Control of Propeller Autonomous Underwater Vehicle Based on Combined Sections Method

    Directory of Open Access Journals (Sweden)

    Qi Duo

    2015-09-01

    Full Text Available Learning from the motion principle of quadrotor, a symmetric propeller AUV, which has small size and low velocity is designed. Compared with the AUV equipped with rudders, it has better maneuverability and manipulation at low velocity. According to the Newton-Euler method, the 6 DOF kinematic model and dynamic model of the propeller AUV are established. A stability controller that consists of 3 different PID controllers is designed. It makes the depth and attitude angle as trigger conditions, and the relevant controller is chosen in different moving process. The simulation experiments simulate ideal motion state and disturbed motion state, and experiments results show that the stability controller based on combined sections method can make the best of mature technology of PID, and meet the control requirements in different stages. It has a higher respond speed and accuracy, improving the stability of the propeller AUV under the disturbance of complex ocean currents.

  15. An integer ambiguity resolution method for the global positioning system (GPS)-based land vehicle attitude determination

    International Nuclear Information System (INIS)

    During attitude determination using a global positioning system (GPS), cycle slips occur due to the loss of lock and noise disturbance. Therefore, the integer ambiguity needs re-computation to isolate the error in carrier phase. This paper presents a fast method for integer ambiguity resolution for land vehicle application. After the cycle slips are detected, the velocity vector is utilized to obtain the rough baseline vector. The obtained baseline vector is substituted into carrier phase observation equations to solve the float ambiguity solution which can be used as a constraint to accelerate the integer ambiguity search procedure at next epochs. The probability of correct integer estimation in the expanded search space is analyzed. Experimental results demonstrate that the proposed method gives a fast approach to obtain new fixed ambiguities while the regular method takes longer time and sometimes results in incorrect solutions

  16. Creation and Application of a Replicable Analytic Method to Determine Attitudes and Beliefs of Undergraduate Science Professors Toward the Discipline of Education

    Directory of Open Access Journals (Sweden)

    Katherine Fogelberg

    2016-07-01

    Full Text Available Detailed here is the creation and application of a replicable method bricolage that brings together Discourse Analysis, discourse analysis, and the theory of reasoned action to examine attitudes and beliefs of university science professors toward the discipline of education. This method used a two-phase method for analysis. The first phase looked for phrases that could be defined as either an attitude or a belief based on definitions taken from the social psychology and communication studies literature. The second phase interpreted the overall data to explore the influences on the formation of the attitudes and beliefs as well as to support or refute the findings from Phase 1. The need for a replicable Discourse Analysis method is apparent in the education literature, as is a solid definition of what constitutes an attitude or a belief. The method outlined here provides good definitions for attitudes and beliefs, a method for extracting both constructs from the data, and incorporates an internal crystallization process for looking at and comparing emergent themes from both phases of analysis.

  17. TWO-STEP CONTROL GRADING METHOD

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The incorrectness of function grading in value engineering has been an essential problem for de- cades. This paper proposes a new method, where the functions under consideration are ranked in queue ac- cording to their importance and then graded quantitatively. By using this method, the reviewers are more aware of the degrees of importance, and therefore will have an easier time grasping the standard and reducing the erroneous grading. In the first step, the sign test is used to discard incorrect data, to count the grading re- sult and to arrange in queue according to the degrees of functional importance. In the second step the queued up functions undergo quantitative grading, where the “average value of fluctuation coefficient” is proposed to determine the control levels and to delete unreasonable data outside the controlled region so as to get more sati- sfactory grading value. The proposed method solves the problem of the incorrectness of function grading in val- ue engineering. It has been proved that the correctness has been raised from the original 70% to over 95% . This new method is not only contributive to the discipline of value engineering but also suitable in the evalu- ation of technical economy.

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

    Science.gov (United States)

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

    2015-12-01

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

  19. Gender Differences in the Attitude and Strategy towards Weight Control among Government Employees in Penang, Malaysia

    Directory of Open Access Journals (Sweden)

    Y Zaitun

    2012-01-01

    Full Text Available "nBackground: This was a cross-sectional study on the gender differences in weight-control behavior. The strategies used, weight status, weight satisfaction, and proportion of individuals attempting to lose weight among 233 government employees (104 men and 129 women working in the Federal Government Building in Penang, Malaysia, were assessed."nMethods: Anthropometric indicators such as body mass index, waist-to-hip ratio, and body fat percentage were measured to determine the subjects' body weight status. A questionnaire covering the following items was used to assess weight-control behavior: social support, self-monitoring, self-efficacy, outcome expectations, planning, preparation/buying, portion control, social interactions, and cognitive behavioral strategies."nResults: About 50% of the subjects were classified as overweight. Based on percent body fat percentage, 70% of them were classified as having unhealthy levels of body fat. Women were found to be more dissatisfied with their current weight, and were more likely to attempt weight reduction compared to men. Women reported higher levels of social support for dieting and had better expectations for diet and exercise (P < 0.05. They also reported higher use of weight control strategies. For self-monitoring, although no gender-dependent differences (P > 0.05 were observed, women reported more frequent self-monitoring of diet, whereas men reported more frequent self-monitoring of exercise."nConclusion: Health care professionals and researchers should be aware of the different strategies used by men and women in order to plan and/or implement community-wide weight management programmes.

  20. Automating the Transition Between Sensorless Motor Control Methods for the NASA Glenn Research Center Flywheel Energy Storage System

    Science.gov (United States)

    Fehrmann, Elizabeth A.; Kenny, Barbara H.

    2004-01-01

    The NASA Glenn Research Center (GRC) has been working to advance the technology necessary for a flywheel energy storage system for the past several years. Flywheels offer high efficiency, durability, and near-complete discharge capabilities not produced by typical chemical batteries. These characteristics show flywheels to be an attractive alternative to the more typical energy storage solutions. Flywheels also offer the possibility of combining what are now two separate systems in space applications into one: energy storage, which is currently provided by batteries, and attitude control, which is currently provided by control moment gyroscopes (CMGs) or reaction wheels. To date, NASA Glenn research effort has produced the control algorithms necessary to demonstrate flywheel operation up to a rated speed of 60,000 RPM and the combined operation of two flywheel machines to simultaneously provide energy storage and single axis attitude control. Two position-sensorless algorithms are used to control the motor/generator, one for low (0 to 1200 RPM) speeds and one for high speeds. The algorithm allows the transition from the low speed method to the high speed method, but the transition from the high to low speed method was not originally included. This leads to a limitation in the existing motor/generator control code that does not allow the flywheels to be commanded to zero speed (and back in the negative speed direction) after the initial startup. In a multi-flywheel system providing both energy storage and attitude control to a spacecraft, speed reversal may be necessary.

  1. Sexual Risk Attitudes and Intentions of Youth Aged 12-14 Years: Survey Comparisons of Parent-Teen Prevention and Control Groups

    Science.gov (United States)

    Lederman, Regina P.; Chan, Wenyaw; Roberts-Gray, Cynthia

    2004-01-01

    In this study, the authors compared differences in sexual risk attitudes and intentions for three groups of youth (experimental program, n = 90; attention control, n = 80; and nonparticipant control, n = 634) aged 12-14 years. Two student groups participated with their parents in programs focused on strengthening family interaction and prevention…

  2. ADAPTIVE FLIGHT CONTROL SYSTEM OF ARMED HELICOPTER USING WAVELET NEURAL NETWORK METHOD

    Institute of Scientific and Technical Information of China (English)

    ZHURong-gang; JIANGChangsheng; FENGBin

    2004-01-01

    A discussion is devoted to the design of an adaptive flight control system of the armed helicopter using wavelet neural network method. Firstly, the control loop of the attitude angle is designed with a dynamic inversion scheme in a quick loop and a slow loop. respectively. Then, in order to compensate the error caused by dynamic inversion, the adaptive flight control system of the armed helicopter using wavelet neural network method is put forward, so the BP wavelet neural network and the Lyapunov stable wavelet neural network are used to design the helicopter flight control system. Finally, the typical maneuver flight is simulated to demonstrate its validity and effectiveness. Result proves that the wavelet neural network has an engineering practical value and the effect of WNN is good.

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

    Directory of Open Access Journals (Sweden)

    Tabither M Gitau

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

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

    Science.gov (United States)

    Gitau, Tabither M; 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; and, to describe perceptions around body shape at age 17 years. A total of 1435 urban South African black and mixed ancestry boys and girls, who had data at both age 13 and 17 years from the Birth to Twenty cohort were included. Data were collected through self-administered questionnaires on eating attitudes (EAT-26), body esteem and weight control behaviours for either weight loss or muscle gain attempts. Height and weight were measured at both time points and BMI was calculated. Black females had a higher BMI (pesteem compared to black adolescents. The prevalence of possible eating disorders was 11% and 13.1% in early and late adolescents respectively. Males and females shared similar opinions on normal silhouettes being the 'best', 'getting respect' and being the 'happiest', while the obese silhouette was associated with the 'worst' and the 'unhappiest', and the underweight silhouette with the "weakest". Black females had a higher BMI and an increased risk of developing eating disorders. Adolescent females engaged more in weight loss practices whereas, males in muscle gain practices indicating that Western norms of thinness as the ideal are becoming more common in South Africa. PMID:25310343

  5. Relative position and attitude test method for optical elements utilizing LVDT%基于LVDT的光学器件相对位姿检测方法

    Institute of Scientific and Technical Information of China (English)

    马立; 欧阳航空; 荣伟彬; 何正峰; 孙立宁

    2011-01-01

    针对光学精密装配工艺特点,提出一种基于LVDT的三维相对位姿检测方法.采用4个对称分布的LVDT检测光学装配过程中球面镜与谐振腔体的位姿关系,根据LVDT的读数推导得出球面镜与谐振腔体的相对位姿.设计采用集成信号调理芯片AD598的LVDT处理电路作为位姿检测的控制系统,通过实验得出LVDT微位移检测的分辨率为0.1 μm,重复检测精度为±0.3μm,并能较好地跟踪方波及正弦波信号.采用PID算法实现球面镜的快速位姿定位.实验结果表明:当球面镜的加工及安装误差在允许范围内时,位姿检测系统可以在25 s内完成球面镜相对于谐振腔体的位姿调整,最大距离误差为0.5 μn,最大角度误差为8″,充分验证了基于LVDT相对位姿检测方法的可行性.%A linear variable differential transformer (LVDT) is presented, which can measure 3 degree-of-freedom (DOF) position and attitude relations between a spherical mirror and a resonator in an optical assembly process. Four symmetrically distributed LVDT sensors are utilized to realize the position and attitude measurement. Position and attitude relations of the two optical elements are deduced according to the readings of the four LVDT sensors. A position and attitude test circuit is designed, which uses an integrated signal conditioning chip AD598. The design achieves a resolution of 0.1 (xm and repeatability of ±0.3 jtm. And the LVDT sensors can track sine wave signal and square wave signal well. A PID algorithm improves the efficiency of the optical assembly. Experimental results show that the test method can accomplish position and attitude adjustment in 25 seconds when the processing and installation error of the spherical mirror is controlled in an allowable range. The maximum distance error is 0.5ujn and maximum angle error is 8" , which verify the feasibility of the proposed method.

  6. Consumers' attitudes about milk quality and fertilization methods in dairy cows in Germany.

    Science.gov (United States)

    Pieper, Laura; Doherr, M G; Heuwieser, W

    2016-04-01

    Major advances in assisted reproductive technologies have improved reproductive efficiency in dairy cattle. However, these developments occurred regardless of the perception of consumers, who often distrust biotechnology in food production. Therefore, the objective of this study was to investigate consumers' attitudes toward reproductive management practices in dairy cattle. In November 2012, 1,646 participants were interviewed by a commercial market research institute. Participants were selected from all regions and demographic categories to represent the general public in Germany. Seven questions regarding milk-drinking preferences and reproductive technologies were asked in face-to-face interviews. Descriptive statistics and multivariable logistic regression models were used. The majority of people drank milk at least weekly (63%) and found the taste of milk important (60%). Most people perceived advanced reproductive technologies negatively [e.g., the use of sexed semen (53%), embryo transfer (58%), cloning (81%), and hormone treatments to increase fertility (65%)]. Many people lacked basic knowledge about milk production (22% did not know that cows only give milk after calving; 51% did not know that milk naturally contains hormones); however, participants with a high school education, older participants, and those who had concerned themselves with dairy farming were more knowledgeable. Education and providing information might help to inform the public about reproductive management practices in dairy cows.

  7. Consumers' attitudes about milk quality and fertilization methods in dairy cows in Germany.

    Science.gov (United States)

    Pieper, Laura; Doherr, M G; Heuwieser, W

    2016-04-01

    Major advances in assisted reproductive technologies have improved reproductive efficiency in dairy cattle. However, these developments occurred regardless of the perception of consumers, who often distrust biotechnology in food production. Therefore, the objective of this study was to investigate consumers' attitudes toward reproductive management practices in dairy cattle. In November 2012, 1,646 participants were interviewed by a commercial market research institute. Participants were selected from all regions and demographic categories to represent the general public in Germany. Seven questions regarding milk-drinking preferences and reproductive technologies were asked in face-to-face interviews. Descriptive statistics and multivariable logistic regression models were used. The majority of people drank milk at least weekly (63%) and found the taste of milk important (60%). Most people perceived advanced reproductive technologies negatively [e.g., the use of sexed semen (53%), embryo transfer (58%), cloning (81%), and hormone treatments to increase fertility (65%)]. Many people lacked basic knowledge about milk production (22% did not know that cows only give milk after calving; 51% did not know that milk naturally contains hormones); however, participants with a high school education, older participants, and those who had concerned themselves with dairy farming were more knowledgeable. Education and providing information might help to inform the public about reproductive management practices in dairy cows. PMID:26874425

  8. American Consumer’s Attitudes towards Different Airline Companies Channels: A Comparison of transaction Methods

    Directory of Open Access Journals (Sweden)

    Talha Harcar

    2012-03-01

    Full Text Available Consumers are increasingly challenging better performance from companies, and these demands are being met through improvements in technology and flexibility of services. As a result of recent progresses and developments in electronic marketing, the physical locations of brick and mortar businesses have become less significant since transactions can now be accomplished in cyberspace. In this paper, consumer attitudes towards online transactions for the airline industry are examined. Despite the growing acceptance of alternative delivery channels, the travel agencies remain an essential part of the customer-airline company. It can be argued that the travel agencies not only represent an opportunity for implementing costumer relationship, but they also remain an important point of contact for sales, service, and consultative interactions. Data has been analyzed using factor analysis technique. The study presents a broad picture of the level of preference of airline customers among the available distribution channels and sheds light on how airline companies should allocate resources among the different channels. The empirical study findings indicate that online transactions for the airline industry will gain in importance and its use will accelerate at a faster rate in the coming years.

  9. Method of airborne attitude estimation based on its discrete state%一种离散运动状态的载机姿态估计方法

    Institute of Scientific and Technical Information of China (English)

    范雄华; 江晶; 谢振华

    2014-01-01

    机载预警雷达观测目标时受到载机姿态的影响,在仿真条件下估计载机姿态是一个难点。基于载机离散状态矢量,通过分析载机的运动与受力关系,建立用运动状态描述的载机姿态模型,提出一种实时性强,易于实现的载机姿态估计的方法。仿真和实测数据处理结果表明该方法既能有效用于仿真研究,在已知载机精确运动状态条件下也可以用来估计载机姿态。%Airborne early warning radar is affected by attitude when detecting. It is hard to estimate attitude in simulation. By analyzing the relationship between airborne dynamics and force, an attitude model described with airborne state is built and a method of airborne attitude estimation is presented. The method can be real time and easy to implement. Simu-lations and experiments of real measurements show that the method is effective not only for simulation but also for air-borne attitude estimation if its state is known.

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

    Science.gov (United States)

    Dubanchet, Vincent

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

  11. Physical activity attitudes, intentions and behaviour among 18–25 year olds: A mixed method study

    Directory of Open Access Journals (Sweden)

    Poobalan Amudha S

    2012-08-01

    Full Text Available Abstract Background Young people (18–25 years during the adolescence/adulthood transition are vulnerable to weight gain and notoriously hard to reach. Despite increased levels of overweight/obesity in this age group, physical activity behaviour, a major contributor to obesity, is poorly understood. The purpose of this study was to explore physical activity (PA behaviour among 18–25 year olds with influential factors including attitudes, motivators and barriers. Methods An explanatory mixed method study design, based on health Behaviour Change Theories was used. Those at university/college and in the community, including those Not in Education, Employment or Training (NEET were included. An initial self reported quantitative questionnaire survey underpinned by the Theory of Planned Behaviour and Social Cognitive Theory was conducted. 1313 questionnaires were analysed. Results from this were incorporated into a qualitative phase also grounded in these theories. Seven focus groups were conducted among similar young people, varying in education and socioeconomic status. Exploratory univariate analysis was followed by multi staged modelling to analyse the quantitative data. ‘Framework Analysis’ was used to analyse the focus groups. Results Only 28% of 18–25 year olds achieved recommended levels of PA which decreased with age. Self-reported overweight/obesity prevalence was 22%, increasing with age, particularly in males. Based on the statistical modelling, positive attitudes toward PA were strong predictors of physical activity associated with being physically active and less sedentary. However, strong intentions to do exercise, was not associated with actual behaviour. Interactive discussions through focus groups unravelled attitudes and barriers influencing PA behaviour. Doing PA to feel good and to enjoy themselves was more important for young people than the common assumptions of ‘winning’ and ‘pleasing others’. Further

  12. Attitude Assessment Using Pleiades-Hr Capabilities

    Science.gov (United States)

    Delevit, J. M.; Greslou, D.; Amberg, V.; Dechoz, C.; de Lussy, F.; Lebegue, L.; Latry, C.; Artigues, S.; Bernard, L.

    2012-07-01

    Since SPOT1, the French national space centre (CNES) has worked on improving the geometry of Earth observation spacecrafts. The accuracy of sensor calibration is one of the main key points for any Earth observation application such as orthorectification, DEM generation or surface change detection. For the last twenty years CNES has developed two families of methods: absolute methods and relative methods. These methods are used to characterize a pushbroom acquisition along the detector line and the time line. By this way, the viewing directions are measured and the residual of the spacecraft's attitude angles (not restituted by the Attitude and Orbit Control System) is estimated. This information can complete the geometric model of all the scenes acquired by the instrument and is used in all geometric applications. This paper presents new attitude assessment methods taking advantage of the capabilities of Pléiades-HR in terms of agility and focal plane arrangement - panchromatic band and multispectral (MS) bands.

  13. Yaw controller design of stratospheric airship based on phase plane method

    Institute of Scientific and Technical Information of China (English)

    Miao Jinggang; Zhou Jianghua; Nie Ying; Yang Xin

    2016-01-01

    Recently, stratospheric airships prefer to employ a vectored tail rotor or differential main propellers for the yaw control, rather than the control surfaces like common low-altitude airship. The load capacity of vectored mechanism and propellers are always limited by the weight and strength, which bring challenges for the attitude controller. In this paper, the yaw channel of airship dynamics is firstly rewritten as a simplified two-order dynamics equation and the dynamic charac-teristics is analyzed with a phase plane method. Analysis shows that when ignoring damping, the yaw control channel is available to the minimum principle of Pontryagin for optimal control, which can obtain a Bang–Bang controller. But under this controller, the control output could be bouncing around the theoretical switch curve due to the presence of disturbance and damping, which makes adverse effects for the servo structure. Considering the structure requirements of actuators, a phase plane method controller is employed, with a dead zone surrounded by several phase switch curve. Thus, the controller outputs are limited to finite values. Finally, through the numerical simulation and actual flight experiment, the method is proved to be effective.

  14. Yaw controller design of stratospheric airship based on phase plane method

    Directory of Open Access Journals (Sweden)

    Miao Jinggang

    2016-06-01

    Full Text Available Recently, stratospheric airships prefer to employ a vectored tail rotor or differential main propellers for the yaw control, rather than the control surfaces like common low-altitude airship. The load capacity of vectored mechanism and propellers are always limited by the weight and strength, which bring challenges for the attitude controller. In this paper, the yaw channel of airship dynamics is firstly rewritten as a simplified two-order dynamics equation and the dynamic characteristics is analyzed with a phase plane method. Analysis shows that when ignoring damping, the yaw control channel is available to the minimum principle of Pontryagin for optimal control, which can obtain a Bang–Bang controller. But under this controller, the control output could be bouncing around the theoretical switch curve due to the presence of disturbance and damping, which makes adverse effects for the servo structure. Considering the structure requirements of actuators, a phase plane method controller is employed, with a dead zone surrounded by several phase switch curve. Thus, the controller outputs are limited to finite values. Finally, through the numerical simulation and actual flight experiment, the method is proved to be effective.

  15. Vehicle speed control transition module and method

    Energy Technology Data Exchange (ETDEWEB)

    Mangan, E.L.; Conklin, B.

    1986-12-16

    An apparatus is described for automatically controlling the speed of a driverless vehicle comprising a stationary frame supporting first, second and third aligned drive tubes between tracks on the frame and which are adapted to support a driverless vehicle. A means is included for independently driving the first, second and third drive tubes such that each tube, when driven, rotates about its longitudinal axis, sensor means disposed along the frame for actuation by a driverless vehicle. The means for independently driving the drive tubes includes variable speed drive means responsive to the sensor means fro driving the second tube between first and second speeds. A method is described of automatically controlling the speed of a driverless vehicle which travels along first, second and third aligned drive tubes by frictional contact therewith. It maintains the first, second, and third drive tubes out of mechanical engagement with each other at all times, sensing the location of the driverless vehicle, driving the first drive tube at a first speed, driving the third drive tube at a second at a second speed. It also varies the speed of the second drive tube from the first speed to the second speed based on the sensed location of the driverless vehicle while the vehicle is driven by contact with the second drive tube.

  16. 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

  17. 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.

  18. Students’ and Teachers’ Attitudes toward E-study and Teaching Methods in Higher Education

    OpenAIRE

    Viktorija Sulcic

    2011-01-01

    The paper presents the results of research on teachers’ and students’ preferences for various teaching and learning methods used in higher education. In our study we found that despite our expectations teachers are not too keen on conventional teaching methods. Interestingly, these methods are even more suitable for students than for teachers. However, research has confirmed our hypothesis that students and teachers in favor of e-study are not fond of conventional teaching methods. According ...

  19. Attitude scale and general health questionnaire subscales predict depression?

    OpenAIRE

    Amrollah Ebrahimi; Hamid Afshar; Hamid Taher Neshat Doost; Seyed Ghafur Mousavi; Hoseyn Moolavi

    2012-01-01

    Background: According to Beck theory, dysfunctional attitude has a central role in emergence of depression. The aim of this study was to determine contributions of dysfunctional attitude and general health index to depression. Methods: In this case-control study, two groups of subjects participated. The first group consisted of 65 patients with major depression and dysthymic disorder, who were recruited from Noor and Navab Safavi Psychiatry Clinics in Isfa-han. The control group was consi...

  20. Older adults and the emerging digital service delivery. A mixed methods study on Informations and Communications Technology use, skills and attitudes

    DEFF Research Database (Denmark)

    Siren, Anu; Knudsen, Sine Grønborg

    2016-01-01

    Based on data from a survey (n = 3291) and 14 qualitative interviews among Danish older adults, this study investigated the use of, and attitudes towards, Information Communications Technology (ICT) and the digital delivery of public services. While age, gender, and socio-economic status were...... associated with use of ICT, these determinants lost their explanatory power when we controlled for attitudes and experiences. We identified three segments that differed in their use of ICT and attitudes towards digital service delivery. As non-use of ICT often results from the lack of willingness to use...... it rather than from material or cognitive deficiencies, policy measures for bridging the digital divide should focus on skills and confidence rather than on access or ability....

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

    Science.gov (United States)

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

    2013-01-01

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

  2. Knowledge-based methods for control systems

    International Nuclear Information System (INIS)

    This thesis consists of three projects which combine artificial intelligence and control. The first part describes an expert system interface for system identification, using the interactive identification program Idpac. The interface works as an intelligent help system, using the command spy strategy. It contains a multitude of help system ideas. The concept of scripts is introduced as a data structure used to describe the procedural part of the knowledge in the interface. Production rules are used to represent diagnostic knowledge. A small knowledge database of scripts and rules has been developed and an example run is shown. The second part describes an expert system for frequency response analysis. This is one of the oldest and most widely used methods to determine the dynamics of a stable linear system. Though quite simple, it requires knowledge and experience of the user, in order to produce reliable results. The expert system is designed to help the user in performing the analysis. It checks whether the system is linear, finds the frequency and amplitude ranges, verifies the results, and, if errors should occur, tries to give explanation and remedies for them. The third part describes three diagnostic methods for use with industrial processes. They are measurement validation, i.e., consistency checking of sensor and measurement values using any redundancy of instrumentation; alarm analysis, i.e. analysis of multiple alarm situations to find which alarms are directly connected to primary faults and which alarms are consequential effects of the primary ones; and fault diagnosis, i.e., a search for the causes of and remedies for faults. The three methods use multilevel flow models, (MFM), to describe the target process. They have been implemented in the programming tool G2, and successfully tested on two small processes. (164 refs.) (au)

  3. 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.

  4. The effect of teaching methods on cognitive achievement, retention, and attitude among in biology studying

    Directory of Open Access Journals (Sweden)

    Snezana Stavrova Veselinovskaa

    2011-12-01

    Full Text Available The purpose of this paper is to determine the effects of usage of sequential teaching method on the academic achievement and retention level of students. Three student groups of biology students in University “Goce Delcev”, Faculty of Natural and Technical Sciences, Institute of Biology, - Stip, R. Macedonia were offered a topic on general characteristics of Proteins: Their Biological Functions and Primary Structure with different sequences of 3 teaching methods. The teaching methods were Laboratory method (student experiment, slide demonstration and lecture method. The first group started to course with experiments in the laboratory, then the relevant theory of proteins was given lecture method, and then the slides was shown (Group I. The sequence of these three teaching methods used in the first group was changed in both second and third group as follow: The lecture methods, slide show and experiment in Group II, and slide show, experiment and lecture method in Group III, respectively. Laboratory method used in the study was focused on the topic of this diversity and abundance reflect the central role of proteins in virtually all aspects of cell structure and function. Achievement test contained 20 questions, testing the knowledge of facts as well as the ability to transfer the knowledge and problem solving ability. This test was used as pre-test before methods’ application, post-test after the methods’ application and retention test after 30 days from methods’ applied.

  5. Nature and operation of attitudes.

    Science.gov (United States)

    Ajzen, I

    2001-01-01

    This survey of attitude theory and research published between 1996 and 1999 covers the conceptualization of attitude, attitude formation and activation, attitude structure and function, and the attitude-behavior relation. Research regarding the expectancy-value model of attitude is considered, as are the roles of accessible beliefs and affective versus cognitive processes in the formation of attitudes. The survey reviews research on attitude strength and its antecedents and consequences, and covers progress made on the assessment of attitudinal ambivalence and its effects. Also considered is research on automatic attitude activation, attitude functions, and the relation of attitudes to broader values. A large number of studies dealt with the relation between attitudes and behavior. Research revealing additional moderators of this relation is reviewed, as are theory and research on the link between intentions and actions. Most work in this context was devoted to issues raised by the theories of reasoned action and planned behavior. The present review highlights the nature of perceived behavioral control, the relative importance of attitudes and subjective norms, the utility of adding more predictors, and the roles of prior behavior and habit. PMID:11148298

  6. The effect of teaching methods on cognitive achievement, retention, and attitude among in biology studying

    OpenAIRE

    Snezana Stavrova Veselinovskaa

    2011-01-01

    The purpose of this paper is to determine the effects of usage of sequential teaching method on the academic achievement and retention level of students. Three student groups of biology students in University “Goce Delcev”, Faculty of Natural and Technical Sciences, Institute of Biology, - Stip, R. Macedonia were offered a topic on general characteristics of Proteins: Their Biological Functions and Primary Structure with different sequences of 3 teaching methods. The teaching methods were Lab...

  7. The Impact of a Multifaceted Approach to Teaching Research Methods on Students' Attitudes

    Science.gov (United States)

    Ciarocco, Natalie J.; Lewandowski, Gary W., Jr.; Van Volkom, Michele

    2013-01-01

    A multifaceted approach to teaching five experimental designs in a research methodology course was tested. Participants included 70 students enrolled in an experimental research methods course in the semester both before and after the implementation of instructional change. When using a multifaceted approach to teaching research methods that…

  8. Synchronous Control Method and Realization of Automated Pharmacy Elevator

    Science.gov (United States)

    Liu, Xiang-Quan

    Firstly, the control method of elevator's synchronous motion is provided, the synchronous control structure of double servo motor based on PMAC is accomplished. Secondly, synchronous control program of elevator is implemented by using PMAC linear interpolation motion model and position error compensation method. Finally, the PID parameters of servo motor were adjusted. The experiment proves the control method has high stability and reliability.

  9. The Robust Control Mixer Module Method for Control Reconfiguration

    DEFF Research Database (Denmark)

    Yang, Z.; Blanke, M.

    1999-01-01

    into a LTI dynamical system, and furthermore multiple dynamical control mixer modules can be employed in our consideration. The H_{\\infty} control theory is used for the analysis and design of the robust control mixer modules. Finally, one practical robot arm system as benchmark is used to test the proposed...

  10. The Earth Education Program Sunship™ Earth: A Mixed Methods Study of the Long-Term Influence on Environmental Attitudes and Actions

    Science.gov (United States)

    Bires, Nancy K.

    2013-01-01

    There have been a limited number of studies on the short-term influence of environmental and earth education programs, however, not much information is available about the long-term influence of these programs on participants' environmental attitudes and actions. This mixed methods study explores the long-term influence of the earth education…

  11. The Effectiveness of a Facebook-Assisted Teaching Method on Knowledge and Attitudes about Cervical Cancer Prevention and HPV Vaccination Intention among Female Adolescent Students in Taiwan

    Science.gov (United States)

    Lai, Ching-Yi; Wu, Wei-Wen; Tsai, Shao-Yu; Cheng, Su-Fen; Lin, Kuan-Chia; Liang, Shu-Yuan

    2015-01-01

    Background: Lack of education is a known barrier to vaccination, but data on the design and effectiveness of interventions remain limited. Objective: This study aims to identify the effectiveness of a Facebook-assisted teaching method on female adolescents' knowledge and attitudes about cervical cancer prevention and on their human papillomavirus…

  12. The Effects of Teaching Science Methods Through an Open Learning Environment on Selected Attitudes and Perceptions of Prospective Elementary School Teachers.

    Science.gov (United States)

    Mitchell, Charles W.

    The study was designed to assess the effects of three different instructional strategies of teaching science methods on selected attitudes and perceptions held by 30 prospective elementary school teachers, as well as the effects of these instructional strategies on children's perceptions of teacher behavior variables of warmth, demand and…

  13. Optimization of Inventories for Multiple Companies by Fuzzy Control Method

    OpenAIRE

    Kawase, Koichi; Konishi, Masami; Imai, Jun

    2008-01-01

    In this research, Fuzzy control theory is applied to the inventory control of the supply chain between multiple companies. The proposed control method deals with the amountof inventories expressing supply chain between multiple companies. Referring past demand and tardiness, inventory amounts of raw materials are determined by Fuzzy inference. The method that an appropriate inventory control becomes possible optimizing fuzzy control gain by using SA method for Fuzzy control. The variation of ...

  14. 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.

  15. Attitude, perception and feedback of second year medical students on teaching-learning methodology and evaluation methods in pharmacology: A questionnaire-based study

    OpenAIRE

    Bhosale, Uma A.; Radha Yegnanarayan; Yadav, Gauri E

    2013-01-01

    Background: To assess the student's attitude, perception and feedback on teaching–learning methodology and evaluation methods in pharmacology. Materials and Methods: One hundred and forty second year medical students studying at Smt. Kashibai Navale Medical College, Pune, were selected. They were administered a pre-validated questionnaire containing 22 questions. Suggestions were also asked regarding the qualities of good pharmacology teachers and modification in pharmacology teaching methods...

  16. 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.

  17. Agile attitude:Review of agile methods for use in design education

    OpenAIRE

    Ovesen, Nis; Eriksen, Kaare; Tollestrup, Christian

    2011-01-01

    Motivated by the growing number of hybrid products with extensive software and service components, this paper reviews four representative agile methods from the domain of software for their applicability to both the industrial design education and practice. The review is based on a comparative analysis of the methods through four scopes, including their application spectrum, level of guidance, process coverage and project management capabilities. Based on the analysis, it is argued that agile...

  18. 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.

  19. 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...

  20. 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。

  1. Distributed control of large space structures

    Science.gov (United States)

    Schaechter, D. B.

    1981-01-01

    Theoretical developments and the results of laboratory experiments are treated as they apply to active attitude and vibration control, as well as static shape control. Modern control theory was employed throughout as the method for obtaining estimation and control laws.

  2. 轮缘驱动式姿控飞轮电机设计%Design of rim-driven attitude control flywheel motor

    Institute of Scientific and Technical Information of China (English)

    王辉; 武俊峰; 吴一辉

    2012-01-01

    为了提高小卫星用姿控飞轮的转动惯量/质量比,实现飞轮调姿系统的轻量化,设计了一种飞轮用永磁无刷直流电机.根据电机磁路,推导了磁钢尺寸与最大磁能积的关系;采用有限元法分析了磁路参数对飞轮性能的影响;针对飞轮电机大气隙、大径长比的结构特点,给出了气隙磁通密度的计算方法;建立了绕组参数与电机额定数据间的关系;仿真分析了电机性能.通过对一台最高转速为6 000 r/min、角动量为5 Nms的飞轮电机样机进行实验验证,得出最大设计误差为6.5%,证明了设计方法的正确性.%To improve the inertia / mass ratio of attitude control flywheel used in small satellite and lighten the weight of flywheel attitude adjustment system,a brushless DC motor used in flywheel was designed. According to the motor magnetic circuit,the corresponding relationship between the size and maximum energy of magnet was derived. The influence of magnetic circuit parameters on the flywheel performance was analyzed by using the Finite Element Method (FEM). For the flywheel structure feature of large equivalent air-gap and large ratio of diameter to length, a method for calculating air-gap magnetic flux density was proposed. The relationship between winding parameters and the motor rated data was established. Simulation method was used to analyze the motor performances. Compared with a flywheel motor with the angular moment of 5 Nms at the highest speed of 6 000 r/min,the maximum error is 6. 5% .which proves the correctness of the design method.

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

    Directory of Open Access Journals (Sweden)

    Joshua Fogel

    2009-01-01

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

  4. 四旋翼两栖机器人姿态求解与控制%Attitude Solving and Control of an Amphibious Robot Based on Four rotor

    Institute of Scientific and Technical Information of China (English)

    李涛; 魏强; 付龙; 骆敏舟; 陈赛旋; 王美玲; 刘效; 庄晓明

    2015-01-01

    This paper mainly introduces the atti-tude solving and control of an amphibious robot based on four rotor mechanism.Firstly,it introduces the mechanism,control and sensor system,then it intro-duces the working principle that four rotor works as actuator,and by configuring rotating velocity and direc-tion of the four rotors,the robot can both fly in the air and rolling on the ground.Then,the attitude solving is carried out by using quaternion method,and then con-trol algorithm is developed as based on PID algorithm, after then corresponding simulation is implemented. Finally,experiments are presented to verify that the ro-bot can generate two motion modes,namely flying in the air and rolling on the ground,as expected.This amphibious robot enhances the environment adaptabili-ty of conventional mobile robots which just have a sin-gle motion mode.%介绍了一种基于四旋翼驱动的两栖移动机器人。首先简要介绍了该机器人的机械结构与控制及传感系统,并介绍了机器人由四旋翼机构提供动力,并通过对4个旋翼的转动速度和方向进行配置,从而实现在空中飞行或在地面滚动的原理。然后,采用四元数方法对该两栖机器人进行了姿态求解,在此基础上,基于 PID 算法开发了机器人的飞行控制算法,并进行了相应的仿真。最后通过实验验证了该两栖机器人能够实现预期的两种运动模式,即空中飞行和地面滚动。该机器人提高了传统只具有单一运动模式的移动机器人的环境适应能力。

  5. Method for vessel attitude estimation by spatial correlation function for bottom reverberation

    Institute of Scientific and Technical Information of China (English)

    FENG Lei; DENG Kai; WANG Changhong

    2006-01-01

    Under the assumption that the sea bottom is an almost-flat and randomly rough thin layer, a spatial correlation model for bottom reverberation is constructed. At high signal noise ratio, the phase of the spatial correlation function is the product of sound wave number and the vertical vector between two hydrophones. In a nominally horizontal plane, roll and pitch bring on the vertical vector between the hydrophones. Then an equation including roll, pitch and the phase of the spatial correlation function is found. If a parallelogram can be constructed by 3 hydrophones and the ratios of its acreage to diagonals are not smaller than half of the wavelength, roll and pitch can be obtained analytically or by optimal method. However, the ranges of roll and pitch are restricted because of the phase ambiguity. Using Fisher information matrix, the Cramer-Rao lower bound is obtained. Results from computer simulation and sea test data prove the feasibility of the method.

  6. Computational methods to obtain time optimal jet engine control

    Science.gov (United States)

    Basso, R. J.; Leake, R. J.

    1976-01-01

    Dynamic Programming and the Fletcher-Reeves Conjugate Gradient Method are two existing methods which can be applied to solve a general class of unconstrained fixed time, free right end optimal control problems. New techniques are developed to adapt these methods to solve a time optimal control problem with state variable and control constraints. Specifically, they are applied to compute a time optimal control for a jet engine control problem.

  7. Cassini Orbit Trim Maneuvers at Saturn - Overview of Attitude Control Flight Operations

    Science.gov (United States)

    Burk, Thomas A.

    2011-01-01

    The Cassini spacecraft has been in orbit around Saturn since July 1, 2004. To remain on the planned trajectory which maximizes science data return, Cassini must perform orbit trim maneuvers using either its main engine or its reaction control system thrusters. Over 200 maneuvers have been executed on the spacecraft since arrival at Saturn. To improve performance and maintain spacecraft health, changes have been made in maneuver design command placement, in accelerometer scale factor, and in the pre-aim vector used to align the engine gimbal actuator prior to main engine burn ignition. These and other changes have improved maneuver performance execution errors significantly since 2004. A strategy has been developed to decide whether a main engine maneuver should be performed, or whether the maneuver can be executed using the reaction control system.

  8. Healthcare workers' attitudes towards working during pandemic influenza: A multi method study

    Directory of Open Access Journals (Sweden)

    Petts Judith

    2008-06-01

    Full Text Available Abstract Background Healthcare workers (HCWs will be key players in any response to pandemic influenza, and will be in the front line of exposure to infection. Responding effectively to a pandemic relies on the majority of medical, nursing, laboratory and hotel services staff continuing to work normally. Planning assumes that during a pandemic normal healthcare service levels will be provided, although it anticipates that as caseloads increase only essential care will be provided. The ability of the NHS to provide expected service levels is entirely dependent upon HCWs continuing to work as normal. Methods/design This study is designed as a two-phase multi-method study, incorporating focus groups and a questionnaire survey. In phase one, qualitative methods will be used to collect the views of a purposive sample of HCWs, to determine the range of factors associated with their responses to the prospect of working through pandemic influenza. In phase two, the findings from the focus groups, combined with the available literature, will be used to inform the design of a survey to determine the generalisability of these factors, enabling the estimation of the likely proportion of HCWs affected by each factor, and how likely it is that they would be willing and/or able to continue to work during an influenza pandemic. Discussion There are potentially greater than normal health risks for some healthcare workers working during a pandemic, and these workers may be concerned about infecting family members/friends. HCWs will be as liable as other workers to care for sick family members and friends. It is vital to have information about how motivated HCWs will be to continue to work during such a crisis, and what factors might influence their decision to work/not to work. Through the identification and subsequent management of these factors it may be possible to implement strategies that will alleviate the concerns and fears of HCWs and remove potential

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

    Science.gov (United States)

    Hagger, Martin S; Chatzisarantis, Nikos L D

    2005-12-01

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

  10. Tobacco use among black South African university students: attitudes, risk awareness and health locus of control

    Directory of Open Access Journals (Sweden)

    K Peltzer

    2001-09-01

    Full Text Available Objectives: To provide data on African/black South African university students’ tobacco use status, belief in the benefits to health of not smoking, risk awareness in terms of knowledge of the links between smoking and disease, health locus of control, value for health, subjective health status and well-being. Design: Cross sectional. Setting: University of the North Subjects: 793 Black University students from non-health courses chosen by random sampling, of these 370 (46.7% were males and 423 (53.3% were females in the age range of 18 to 25 years (M age 21.0 years, SD=3.48. Main Outcome Measures: A measure of smoking, the Multidimensional Health Locus of Control Scale, the Health as a Value Scale, and a measure for subjective health and subjective well-being. Results: The average prevalence of current tobacco use was 15% in men and 1% in women. The proportion of tobacco users who were classified as light users (1-10 per day averaged 10% in men and 1% in women. Age and being male were significantly positively associated with status and frequency of tobacco use. Awareness of the link between smoking and lung cancer was high (93%, but awareness of the role of smoking in heart disease was very low (16%. The importance to health of not smoking was associated with smoking status (non-smoking versus smoking. Overall, 75% of the current smokers stated that they would like to reduce the amount they smoked. Poor subjective health status and low subjective well-being was associated with smoking status. No significant differences were found among non-tobacco users and tobacco users in relation to the three subscales of the Health Locus of Control (Internal, Chance, and Powerful others and Value for health. Conclusion: For about 9% of the male students investigated, a high risk exists to become regular tobacco users for the next 30 years.

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

    OpenAIRE

    Joshua Fogel; Solomon Israel

    2009-01-01

    Los estudiantes universitarios utilizan internet para comunicarse y obtener información sobre salud. Se realizó un estudio descriptivo mediante una encuesta a 227 estudiantes para determinar si había diferencias entre aquellos que utilizan internet y el correo electrónico para informarse sobre salud y aquellos que no. Las variables dependientes fueron la Escala de Estrés Percibido y las subescalas de la Escala Multidimensional de Locus de Control de la Salud. Las variables independientes incl...

  12. Set-theoretic methods in control

    CERN Document Server

    Blanchini, Franco

    2015-01-01

    The second edition of this monograph describes the set-theoretic approach for the control and analysis of dynamic systems, both from a theoretical and practical standpoint.  This approach is linked to fundamental control problems, such as Lyapunov stability analysis and stabilization, optimal control, control under constraints, persistent disturbance rejection, and uncertain systems analysis and synthesis.  Completely self-contained, this book provides a solid foundation of mathematical techniques and applications, extensive references to the relevant literature, and numerous avenues for further theoretical study. All the material from the first edition has been updated to reflect the most recent developments in the field, and a new chapter on switching systems has been added.  Each chapter contains examples, case studies, and exercises to allow for a better understanding of theoretical concepts by practical application. The mathematical language is kept to the minimum level necessary for the adequate for...

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

    Science.gov (United States)

    Kurt, Hakan

    2014-01-01

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

  14. Re-entry Attitude Double-loop SMC of the Spacecraft and Its Logic Selection

    Institute of Scientific and Technical Information of China (English)

    CHEN Yu-wen; BI Kai-bo

    2007-01-01

    A spacecraft re-entry attitude control method using sliding mode control (SMC) theory is developed. The controller utilizes double-loop SMC scheme and provides the robust, de-coupled tracking of both the angular velocity and the shuttle orientation angles. In accordance with the hybrid-controlling characteristics of the aerodynamic surfaces and reaction control system of the spacecraft, the control torque commands are allocated into the actuators such as the aerodynamic surfaces and reaction control system by using the optimal control selection allocation algorithm. The simulation of the spacecraft re-entry attitude controlling demonstrates the robust, de-coupled tracking performance of the proposed method and its validity.

  15. IDENTIFICATION OF GYRO DRIFTS UNDER THREE AXIS ATTITUDE COUPLING

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Optical gyros and star sensors are primary measurement hardware in an attitude control system with high accuracy.The drifts of the optical gyros, however, make an unfavorable impact on the accuracy of the attitude control system.In order for compensations to be provided, this paper presents a least-square method to identify the optical gyro drifts by using flight attitude data from the star sensors and the optical gyros.Equations for identification are formulated by quaternion.Integration of the identification equations and the data from the star sensors are utilized to form a least-square index, in which lower sampling frequency of the star sensors than that of the optical gyros is dealt with effectively.An iterative identification algorithm is presented to minimize the index.Identification procedure under three-axis attitude coupling is illustrated .Simulation results show the effectiveness of the method presented.Proper sample size and sampling frequency are also recommended.

  16. The Learners’ Attitudes towards Using Different Learning Methods in E-Learning Portal Environment

    Directory of Open Access Journals (Sweden)

    Issham Ismail

    2011-09-01

    Full Text Available This study investigates the learners’ preference of academic, collaborative and social interaction towards interaction methods in e-learning portal. Academic interaction consists of interaction between learners and online learning resources such as online reading, online explanation, online examination and also online question answering. Collaborative interaction occurs when learners interact among themselves using online group discussion. Social interaction happens when learners and instructors participate in the session either via online text chatting or voice chatting. The study employed qualitative methodology where data were collected through questionnaire that was administered to 933 distance education students from Bachelor of Management, Bachelor of Science, Bachelor of Social Science and Bachelor of Art. The survey responses were tabulated in a 5-point Likert scale and analyzed using the Statistical Package for Social Science (SPSS Version 12.0 based on frequency and percentage distribution. The result of the study suggest that among three types of interaction, most of the student prefer academic interaction for their learning supports in e-learning portal compared to collaborative and social interaction. They wish to interact with learning content rather than interact with people. They prefer to read and learn from the resources rather than sharing knowledge among themselves and instructors via collaborative and social interaction.

  17. 对残疾人态度测量方法的述评①%Measurement Methods of Attitudes towards People with Disabilities (review)

    Institute of Scientific and Technical Information of China (English)

    陈光华; 张治星

    2013-01-01

      对于残疾人态度的研究是特殊教育学、康复心理学和康复咨询领域的关注焦点之一。本文分别从直接测量和间接测量两大方面详细地介绍对于残疾人态度的测量方法及其局限性,并为其在未来研究中的应用趋向提出建议。%The study on attitudes towards people with disabilities is one focus of special education, rehabilitation psychology and reha-bilitation counseling. This article reviewed the measurement methods of the attitude towards people with disabilities from directed methods and indirect methods, and their limitation and future research tendency in this field were prospected.

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

    Directory of Open Access Journals (Sweden)

    Lorenza S Colzato

    2010-09-01

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

  19. A case-control study of maternal knowledge of malnutrition and health-care-seeking attitudes in rural South India.

    OpenAIRE

    K. Saito(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan); Korzenik, J R; Jekel, J. F.; Bhattacharji, S.

    1997-01-01

    INTRODUCTION: In India, approximately 20 percent of children under the age of four suffer from severe malnutrition, while half of all the children suffer from undernutrition. The contributions of knowledge and attitudes of nutrition-conscious behaviors of the mothers to childhood malnutrition has been unclear. The purpose of this study was to explore maternal knowledge of the causes of malnutrition, health-care-seeking attitudes and socioeconomic risk factors in relation to children's nutriti...

  20. Case-based e-learning to improve the attitude of medical students towards occupational health, a randomised controlled trial

    OpenAIRE

    Smits, P.B.A.; de Graaf, L; Radon, Katja; de Boer, A G; Bos, N. R.; van Dijk, F. J. H.; Verbeek, J.H.A.M.

    2012-01-01

    Undergraduate medical teaching in occupational health (OH) is a challenge in universities around the world. Case-based e-learning with an attractive clinical context could improve the attitude of medical students towards OH. The study question is whether case-based e-learning for medical students is more effective in improving knowledge, satisfaction and a positive attitude towards OH than non-case-based textbook learning.