Integrated Position and Attitude Control for Spacecraft Safe Approaching without Velocity Measurement

Aiming at the rendezvous and docking scenario for non-cooperative spacecraft with position and attitude coupling, in order to solve the problems of safety constraints, model uncertainty, actuator failure and input saturation simultaneously without velocity measurement, an autonomous safe approach method based on cubature Kalman filter ( CKF) is proposed. Firstly, the position and attitude information and relative velocity information of the target spacecraft are estimated based on the cubature Kalman filter and the expanded state observer ( ESO). Then an adaptive sliding mode controller is designed by combining a novel safety envelope with artificial potential function ( APF) , and a nonsingular auxiliary system is introduced to compensate the adverse influence from input saturation and actuator faults. The proposed control strategy can achieve position approach and attitude synchronization within a fixed timeframe without violating the security constraints. The fixed-time stability of the closed-loop system can be proven by Lyapunov method. Simulation results show that the proposed control method has high accuracy and good interference suppression ability. © 2022 China Spaceflight Society. All rights reserved.