Ali Reza Aghalari; Ahmad Kalhor; Farhad Shamim
Volume 8, Issue 1 , April 2015, , Pages 73-77
Abstract
In this paper, a designing procedure of a Variable Speed Control Moment Gyro (VSCMG) for performing an agile maneuver in an attitude control simulator is described, then a prototype is fabricated and finally the test results are presented. The design of actuator mechanism is based on simulator limitations ...
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In this paper, a designing procedure of a Variable Speed Control Moment Gyro (VSCMG) for performing an agile maneuver in an attitude control simulator is described, then a prototype is fabricated and finally the test results are presented. The design of actuator mechanism is based on simulator limitations (power consumption, dimensions and weight, simplicity) and direction of produced torque.Two DC electrical motors are used for controlling the angular velocity of flywheel and the gimbal slew rate. The motors controller and driver units are designed and implemented, so that the maximum accuracy, minimum errors and best response time could be accessible. Structural Design is based on strength, stiffness, volume and weightalso Necessary analysis are performed using ANSYS. Finally the functional tests of actuator such as measuring the produced torque (using simulator and load transducer), accuracy of gimbal position and gimbal slew rate, accuracy of flywheel rotational speed and power consumption are performed and then the results are presented.
A.R. Aghalari; A. Kalhor; S. M. M. Dehghan; S. H. Cheheltani
Volume 7, Issue 3 , October 2014, , Pages 51-67
Abstract
The Agile Satellite Attitude Control System Simulator (ASACSS) is a laboratory system designed for the purpose of developing and testing attitude control algorithms in a low-risk, low-cost environment. In this paper, the design and development of the ASACSS is described, including hardware and software. ...
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The Agile Satellite Attitude Control System Simulator (ASACSS) is a laboratory system designed for the purpose of developing and testing attitude control algorithms in a low-risk, low-cost environment. In this paper, the design and development of the ASACSS is described, including hardware and software. There are many papers that present a new mathematical technique or prove a new theory, but this study presents the design and development of a new experimental system. This simulator consists of four main components: 1) power supply system 2) on-board control system 3) supporting equipments and 4) monitoring computer. On-board control system includes a industrial computer, four single gimbal control moment gyros and a sensor for attitude determination. Supporting equipments include a platform for installing simulator subsystems, a semi-spherical air bearing and a pedestal. A high-speed wireless LAN connection enables remote command initiation, monitoring and data collection for post-experimental analysis. In this paper, The design and construction process of the simulator are described. More over some experimental results presented from the application of a simple PID attitude controller on the spacecraft simulator. Finally, experimental results are compared with those obtained from simulation.
Alireza Aghalari; Javad Tayebi; Ahmad Kalhor
Volume 5, Issue 4 , January 2013, , Pages 61-68
Abstract
Recently, many space missions have been using small satellites, because small satellites are easier and faster to develop and thereby, provide increased launch opportunities. Some of these missions include tasks that required agile maneuvers. In this paper, attitude stability testing of an agile three-degree-freedom ...
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Recently, many space missions have been using small satellites, because small satellites are easier and faster to develop and thereby, provide increased launch opportunities. Some of these missions include tasks that required agile maneuvers. In this paper, attitude stability testing of an agile three-degree-freedom micro-satellite simulator – which is equipped with a pyramid arrangement of single-gimbal control-moment gyros (SGCMGs) – is presented. In the attitude stability testing, the local quadratic regulator (LQR) control strategy is used, which has superiority to other approaches due to its independence of using steering law. This simulator allow to test different control laws by using SGCMGs. In this work, after introducing the actuator and satellite simulator and using the control strategy in the simulator, the attitude stability testing is performed and then, the experimental results are presented and discussed. The results show the attitude stability of the simulator which is exposed to the disturbing toques.
A. H. Tavakkoli; A. Kalhor; S. M. M. Dehghan
Volume 5, Issue 2 , July 2012, , Pages 59-68
Abstract
In this paper the performance of a three Degrees Of Freedom simulator is evaluated. This platform is considered as an important instrument generally used in performance tests of spacecraft attitude determination and control subsystem on the ground. A hemispherical air bearing is used to provide micro ...
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In this paper the performance of a three Degrees Of Freedom simulator is evaluated. This platform is considered as an important instrument generally used in performance tests of spacecraft attitude determination and control subsystem on the ground. A hemispherical air bearing is used to provide micro gravity condition. Reaction wheels produce required control torques and an integrated sensor is used for attitude determination. Commanding and visualization of the platform in monitoring station are provided by a wireless LAN. PD, QEF and LQR controllers are designed and implemented for slew maneuver to show the ability of the simulator. The desired attitude accuracy is obtained using these controllers. The test results verify the designed controllers and show the ability and functionality of the system, as a simulator for evaluating attitude controllers.
A. R. Aghalari; A. Kalhor; S. M. Dehghan; A. Abedian
Volume 2, Issue 1 , April 2009, , Pages 13-23
Abstract
In this paper, a designing procedure of Single Gimbal Control Moment Gyro (SGCMG) for performing an agile slew maneuver in a microsatellite is described, then a prototype is fabricated and finally the test results are presented. The design of actuator mechanism is based on simplicity, direction of produced ...
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In this paper, a designing procedure of Single Gimbal Control Moment Gyro (SGCMG) for performing an agile slew maneuver in a microsatellite is described, then a prototype is fabricated and finally the test results are presented. The design of actuator mechanism is based on simplicity, direction of produced torque, minimum volume and weight. A DC electrical and a stepper motor with accuracy of 0.024 degree are used for controlling the angular velocity of flywheel and the gimbal slew rate, respectively. The motors controller and driver units are designed and implemented, so that the maximum accuracy, minimum errors and best response time could be accessible. The flywheel design is based on the required angular momentum which should be stored. The gimbal consists of two in-line beams which are attached to bearing in one side and momentum wheel system in the other side. A specific approach was considered to avoid any deformation in beams in consequence of mounting the momentum wheel system.
