Finite-time relative pose tracking control for uncertain spacecraft rendezvous and docking

This study investigates the robust finite-time pose tracking control for spacecraft autonomous rendezvous and docking with parametric uncertainties and bounded external disturbances. Based on the uncertainly coupled relative pose dynamics, a fast terminal sliding mode controller is developed to achieve the finite-time convergence of the pose tracking errors. To reduce the control chattering results from the signum function in the controller, an exponential reaching law is employed to achieve the decreasing of the reaching time towards the sliding surface. The explicit tuning rules for designing parameters are derived based on the stability analysis of the closed-loop system. It is proved in Lyapunov framework that all closed-loop signals are always kept bounded and the pose tracking error converges to small neighborhood of zero in finite time. Simulation results validate the performance of the proposed robust finite-time control strategy.