Attitude control simulation of small satellites with reaction wheels

• Main Author: Ismail, Zuliana
• Format: Thesis
• Language: English
• Published: 2009
• Online Access: http://psasir.upm.edu.my/id/eprint/51549/1/FK%202009%20119RR.pdf; http://psasir.upm.edu.my/id/eprint/51549/
• Institution: Universiti Putra Malaysia

Nowadays, most of the designed satellites are dedicated for high performance missions, which require high attitude pointing accuracies. The reaction wheel is the most suitable satellite actuator that can provide high attitude pointing accuracies (0.1°-0.001°). Commonly, three or four reaction wheel configurations are used for a 3-axis satellite attitude control. In fact, higher power is consumed when multiple reaction wheels are employed. Thus, it is rather challenging to adopt multiple reaction wheels for the small satellite missions because of the power constraint. On the other hand, reaction wheels lack of the ability to remove the excess angular momentum and that the wheels have a limited capacity to store momentum. Without a momentum management control, the satellite may be uncontrollable. Therefore, to make the implementation of multiple reaction wheels reliable for a small satellite, it is necessary to find a way to minimize the wheel’s power consumption. Also, it is compulsory for a satellite to be equipped with a momentum management scheme in order to maintain the angular momentum within their allowable limits. Momentum management control using magnetic torquers are chosen in this work. Indeed, the wheel’s power consumption can be lowered by particularly arranging the reaction wheels’ orientation onboard the satellite. In this research, several configurations, based on three or four reaction wheels, are investigated in order to identify the most suitable orientation with the total minimum power. All the related mathematical models are implemented in Matlab-SimulinkTM software. Numerical simulations are performed for all the possible reaction wheel configurations with respect to an identical reference mission. Two simulation analyses are presented for their performance evaluations. First simulation focuses on the satellite attitude control only and the second simulation focuses on the satellite attitude control with momentum management control. Based on the simulations, the reaction wheel configuration that produces a minimum total control torque is identified, which also corresponds to the configuration with a minimum power intake. The wheel angular momentums and satellite attitude accuracies are also well maintained during the control task.