Anti-Unwinding Attitude Maneuver Control Based on Fully Actuated System Approach for Spacecraft

In this paper, the attitude maneuver control without unwinding is addressed based on the fully actuated system approach, specifically for rigid spacecraft subject to strong coupled nonlinear characteristics and external disturbances. First of all, a second-order fully actuated system model is constructed by deriving the second-order derivative of the vector part of the attitude error quaternion. Then, by utilizing the fully actuated characteristics to eliminate the coupled nonlinear terms, a decoupled closed-loop system is obtained, which simplifies the controller design process. On this basis, an anti-unwinding sliding mode control law is designed to guarantee that the system state evolves strictly along the shortest path. Consequently, the unwinding phenomenon is avoided. Additionally, a boundary layer is introduced for the constructed controller to suppress the chattering problem. It is also proven by the Lyapunov method that the designed attitude control law ensures the stability of the closed-loop spacecraft attitude system, and prevents the spacecraft from experiencing the unwinding phenomenon during attitude maneuvers. Numerical simulations are performed to demonstrate the effectiveness of the proposed control algorithm.