Dynamics of a Robotics-based Hardware-in-the-Loop Simulator for Verifying Microgravity Contact Dynamics

This paper presents the concept of a cable-manipulator based 6-DOF hardware-in-the-loop (HIL) dynamics simulation system for testing and verification of microgravity contact-dynamics behavior of a space system. It then focuses on the inverse dynamics problem of the 6-DOF cable-driven manipulator which is designed for the simulation system. Accurate modeling and solution of the inverse dynamics is a key requirement for the control and high-fidelity performance of the complex simulation system. The inverse dynamics problem is solved completely under the basic operational conditions of a cable manipulator all the cables must be always in tension for any possible end-effector motion of the manipulator. It is the first time that a systematic method of determining whether or not the inverse dynamics problem has a solution is proposed with full mathematical proof. Based upon this proven method, two numerical examples are presented to demonstrate the inverse dynamics solution of a 6-DOF cable manipulator. The study results support the feasibility of using such a manipulator for hardware-in-the-loop simulation of microgravity contact-dynamics.