Workspace Analysis of a 6-DOF Cable Robot for Hardware-in-the-Loop Dynamic Simulation

This paper describes the study of the force-closure workspace of a 6-DOF, cable-driven, parallel robot for the application in a hardware-in-the-loop dynamic simulator, which is used for simulating microgravity contact dynamics of spacecraft or robotic systems. The workspace under study is defined as the set of all end-effector poses satisfying force-closure condition. Force-closure also means that the inverse dynamics problem of the manipulator has a feasible solution. Since there is no limitation on the external wrench and the dynamic motion of the end-effector, such a workspace is the most desirable (or nonrestricted) workspace for the intended application simulating low-speed impact-contact dynamics. A systematic method of determining whether or not a given end-effector's pose is inside the workspace is proposed with mathematical proof. Based on this method, the shape, boundary, dimensions, and volume of the workspace of a 6-DOF cable robot are displayed and discussed