Dynamics and adaptive backstepping control of multibody spacecraft connected with active magnetic bearing

Abstract

In this paper, to realize the high-resolution observation mission, a new type of multibody optical spacecraft connected with active magnetic bearing (AMB) is introduced. Then, to address the attitude control problem facing high-precision observation for multibody spacecraft, the dynamic model of the multibody system is developed and an adaptive backstepping controller (ABC) is subsequently proposed. First, a high-precision electromagnetic force model of AMB is developed. Different from traditional models that only consider rotor position and current, the relative attitude between rotor and platform is considered. Then, based on the AMB model, the dynamic and kinematic model of multibody spacecraft is derived. Additionally, considering the electromagnetic bearing is unstable statically, an ABC method is proposed. The stability of the closed-loop system is guaranteed by the Lyapunov theorem. Finally, to indicate the effectiveness of the proposed method, some numerical simulations of comparison with the iterative learning control (ILC) method are performed. As indicated by the simulation results, the ABC is capable of eliminating periodic deviation, and it is more effective than the ILC in solving the control problem caused by periodic disturbance.