Composite anti-disturbance position and attitude control for spacecrafts with parametric uncertainty and flexible vibration

Abstract

The rendezvous and proximity operations with respect to a tumbling non-cooperative target pose high requirement for the position and attitude control accuracy of servicing spacecraft. However, multiple disturbances including parametric uncertainties, flexible vibration, and unknown nonlinear dynamics degrade the control performance significantly. In order to enhance the system anti-disturbance ability, this paper proposes a composite anti-disturbance control law for the spacecraft position and attitude tracking. Firstly, the relative position and attitude dynamic models with multiple disturbances are established, where the refined descriptions of multiple disturbances are accomplished based on their characteristics. Then, by combining a dual Disturbance Observer-Based Control (DOBC) and a sliding mode control, a composite controller with hierarchical architecture is proposed, where the dual DOBC in the feedforward channel is used to reject the flexible vibration, environment disturbance, and complicated nonlinear dynamics, while the parametric uncertainties are attenuated by the sliding mode control in the feedback channel. Stability analysis is carried out for the closed-loop system by unifying the sliding mode dynamics and observer dynamics. Finally, the effectiveness of the proposed controller is verified via numerical simulation and hardware-in-the-loop test.