Robust Nonlinear Full State Feedback Control for Autonomous Close Range Rendezvous and Docking of Spacecraft

This paper describes a robust nonlinear full state feedback control method that performs the precise translation and rotational maneuvers for autonomous close range rendezvous operations of spacecraft. The primary focus of this study is to design nonlinear state feedback control via the estimated states using extended Kalman filters. The presented nonlinear full state feedback control can achieve robust tracking performances in the presence of external disturbances and parameter uncertainties. This study assumes a Lidar sensor for the relative position and velocity estimations, and a quaternion producing star tracker and a rate-integrating gyro for the chief attitude estimation. The unified state-dependent Riccati equation (SDRE) method is used to design both the position and attitude controllers. The control design is based on a full, 6-degrees of freedom, nonlinear dynamic models, which are manipulated into a linear-like form in which system matrices are given explicitly as a function of the current state. The chaser spacecraft is required to be able to perform large position and attitude maneuvers with sufficient accuracy. Numerical simulation results show that the described control method can obtain good tracking performances to meet the requirements for autonomous proximity operations and docking.