Adaptive Fault-Tolerant Constrained Control of Cooperative Spacecraft Rendezvous and Docking

The relative pose control problem for spacecraft rendezvous and docking missions in the presence of control input constraints, actuators partial failures, and unknown external disturbances is studied in this paper. A smoothly adaptive fault-tolerant constrained controller is developed based on the adaptive nonlinear state feedback method. Different from the traditional fault-tolerant saturated controllers, the proposed control approach explicitly accounts for the control input constraints with straightforward tuning parameters in controller. Meanwhile, the exact knowledge of the actuator failures is not required and uncertain failure information can be rejected. A smooth control signal containing simple saturation functions is designed, and the unknown bounded external disturbances can be rejected by the proposed method. The proposed controller can ensure ultimately, uniformly bounded stability of the closed-loop system, where relative pose and velocities converge to the small neighborhoods of zero. Numerical simulation results demonstrate the effectiveness of the proposed control approach.