Combined Attitude Control Of Small Satellite By Using Reaction Wheels And Magnetorquers

Aiming at the high performance attitude control system (ACS) of three-axis stabilized small satellite, this thesis studied the ACS of the small satellite based on reaction wheel and manetorquer. The combined control problem is mainly studied, and attitude control scheme and algorithm during wheel failure mode is discussed. The following are creative achievements:First, as to small satellites with three-axis orthonormal reaction wheels and three-axis magnetorquers, combined control scheme based on magnetorquers and wheels is applied in order to draw out the hardware resources and thus to raise the power density of small satellite. A combined scheme consisting of control algorithm and control allocation is designed to lower the complexity of control system design. Cascade-saturation algorithm for large angle attitude maneuvers is introduced, and maximum magnetic torque and energy optimized control allocation algorithms are proposed. The numerical simulation in the last part indicates that the reasonability of the control scheme and the effective of the control algorithms.Secondly, as to the reaction wheel failure mode which could only produce two-axis control torque, a failure handling scheme which applies the effective two-axis reaction wheels and three-axis magnetorquers to perform combined control is designed, the combined attitude control algorithm during failure mode is introduced. And maximum magnetic torque and performance optimized control allocation algorithms are proposed. The numerical simulation in the last part indicates the availability of the control scheme and the effective of the control algorithms.Finally, as to the reaction wheel failure mode which could only produce one-axis control torque, the control performance of the scheme which applies the effective one-axis reaction wheel and three-axis magnetorquers to perform combined control is testified, the result indicates that this scheme could not perform high precision control task of small satellite. Considering a specified condition which the pitch axis wheel is effective, a failure handling scheme which adopts this reaction wheel rotating as a momentum wheel and combined with three-axis magnetorquers is proposed to progress the system control precision. What is more, the wheel rotating control policy using magnetorquers and controller parameter design method based on genetic algorithm are designed. The numerical simulation in the last part indicates that the scheme can achieve relatively high control precision and can prolong the task life of small satellite.Some useful discussions are presented, as to the combined control technology which applies reaction wheels and magnetorquers, and attitude control schemes and algorithms during wheel failure modes, to provide effective technology means for the small satellite design and development of our country.