AN OPTIMAL AND ROBUST ATTITUDE-TRACKING CONTROL OF SPACECRAFT BASED ON INVERSE SYSTEM METHOD

This paper deals with the attitude tracking control of spacecraft. For many space missions, spacecrafts are required to point their payload, such as high-gain antenna and high-gain camera, at a fixed target on the Earth or a moving target on orbit. A new method is presented to calculate the reference attitude angle, angular velocity and acceleration. An analytical expression is given. The attitude dynamics is strong-coupled and non-linear during large angle maneuver, thus it is difficult to apply the traditional robust control design methods. On this account, error quaternion is introduced to describe the dynamics, which avoids the problem of singularity. Besides, in order to utilize the design of the robust controller, a desired approximate pseudo-linear system is obtained by inverse system method in the presence of model error and disturbances. Furthermore, based on the transition theorem between the robust control and the optimal control, the robust control problem is transformed into an optimal control problem. This approach can also be applied to more complex object such as multi-body spacecraft, and the simulation results are presented to demonstrate the effectiveness of the proposed design method.