6-DOF Multi-Constrained Adaptive Tracking Control for Noncooperative Space Target

This paper addresses the problem of six-degree-of-freedom (6-DOF) relative position and attitude-tracking control for noncooperative space targets subject to multiple constraints, including input and full-state constraints. First, a novel 6-DOF integrated relative motion dynamics with control command coupling is established for the final approaching stage of a rendezvous task. Second, a Barrier Lyapunov function (BLF)-based controller is developed to guarantee the relative position, attitude, and velocity constraints of the spacecraft at all times. The requirement of less restrictive initial conditions compared with the quadratic Lyapunov function is presented via a detailed theoretical analysis. Third, a novel 6-DOF integrated multi-constrained adaptive tracking control scheme is proposed to simultaneously deal with input constraints, full-state constraints, unknown disturbances, and uncertainties. In particular, a solution to the chattering phenomenon, arising from the existence of sign function, is explored in an adaptive manner. Detailed controller design procedures and rigorous theoretical proof of all related closed-loop uniform ultimate bounded (UUB) stability are provided. In addition, the numerical simulation results are also exhibited to demonstrate the effectiveness and superior control performance of the proposed control scheme.