Contact Dynamics and Force Control of Space Robotic Systems

Abstract

In this paper, a detailed modelling of contact dynamics involving a flexible space robotic system and a payload is considered. The components undergoing direct contact (the end-effector of a manipulator and a payload) are modelled using a finite element method, while the rest of the system is handled through the usual flexible multi-body formulation. Then, the system dynamics is composed of a set of differential equations subjected to sets of algebraic equations expressing kinematic or contact constraints. This dynamic model is then used to design a composite controller which must simultaneously achieve three goals: (i) trajectory tracking, (ii) force control, and (iii) stabilization of the flexible degrees of freedom of the multi body system. The singular perturbation method is used to obtain two reduced order models; subsequently, the slow subsystem is used to design a hybrid position/force controller based on impedance control, and the fast subsystem is used to design a Linear Quadratic Regulator (LQR).