Adaptive Sliding Mode Control for Spacecraft Rendezvous with Unknown System Parameters and Input Saturation

Abstract

In this study, we investigated the sliding mode control (SMC) for the spacecraft rendezvous maneuver under unknown system parameters and input saturations. On the basis of the attitude and position tracking subsystem, two anti-saturation sliding mode surfaces (SMSs) are constructed to guarantee the exponential convergence of tracking errors between the target spacecraft and the pursuer spacecraft. In connection with hyperbolic tangent, a modified auxiliary system is established to compensate the nonlinear constraint caused by the actuator saturation. Meanwhile, in order to enhance the practicability and reliability of the controller, unknown inertial information is taken into consideration. The resulting system uncertainties are estimated accurately via adaptive laws. Additionally, it is concluded that the designed controller is capable of ensuring the boundedness of the closed-loop signals with reasonable selection of control parameters. Finally, the effectiveness and advantages of the proposed methods are verified through numerical simulations.