Target rendezvous with a space robot using relative position and attitude measurements

This paper examines the problem of on-orbit rendezvous of a space robot with a target object. Due to uncertainty in Earth-based position measurements of both the target and the space robot, and the potential for no absolute attitude measurements of the target object, relative position and attitude measurements of the target are made on-board the space robot. It is shown that model-based control laws for space robots can be designed to carryout rendezvous maneuvers with these relative measurements due the invariance of the space robot´s dynamics to a particular location of the inertial frame. It is also shown that by approximating a coordinate frame on the target as an inertial frame, the gravitational forces and torques on the space robot become negligible. The principles described in this paper are implemented on a simulated space robot to perform an on-orbit rendezvous with a target satellite.