Design and Control of Approach Trajectory by Impulsive Velocity Change

This paper presents a method of designing and keeping the approach trajectory for a space robot (chaser) flying around a troubled satellite (target) on a circular orbit around the earth. The approach trajectory is designed by considering orbital dynamics of the chaser represented by the Hill’s equation. The extended Kalman filter is employed to estimate state and control variables that are not available for measurement. An optimal feedback control scheme for the thrust is proposed to maintain trajectory in the presence of disturbances. Simulation results that verify the trajectory keeping capability of the proposed thrust control are also presented.