Dynamics Modelling and Safe Motion Control of Space Robotic Manipulator

Abstract

Space exploration relies on various space structures that require many on-orbit services. To improve safety, Space Robotic Manipulator (SRMs) with a moving spacecraft base could play as a substitute for human astronauts to perform the risky Extra Vehicular Activities (EVA). The key difference of a control problem between SRMs and terrestrial robots is the inherent coupling effect of SRMs, i.e., the motions of manipulator will inevitably affect that of base and verse versa. On top of that, for the safety concern, the system states of SRMs should be always constrained within the given regions (e.g., the tracking errors of manipulator’s end-effector should not exceed a predefined safe region). Although both the controllers of SRMs and the approaches of handling constrained system states have been extensively studied over the recent years, the state of the art lacks the practical complete solution for constrained state control of SRMs subject to system uncertainty and external disturbance. In this thesis, the kinematics and dynamics of SRMs are modelled. Then, a robust Prescribed Performance Control (PPC) scheme of attitude against actuator saturation is designed to achieve a proper attitude of spacecraft base ready to perform SRMs. After that, a novel coordinate motion controller of SRMs achieving full state constraints without any BLF terms is proposed. Subsequently, an inverse optimal controller strictly guaranteeing non-overshooting response with output constraints are proposed for the coordinate motion control of SRMs.