Design, Kinematics and Stiffness Analysis of a Reconfigurable Cable-Driven Parallel Robot

Abstract

Cable-driven parallel robots (CDPRs) have advantages of larger workspace and load capacity than conventional parallel robots while existing interference problems among cables, workpieces and the end-effector. In order to avoid collision and improve the flexibility of the robots, this study proposes a reconfigurable cable-driven parallel robot (RCDPR) having characteristics of large load-to-weight ratio, easy modularity and variable stiffness. Adjustable brackets are connected to the moving platform to adjust the position of the pull-out point with the movement of the end-effector. In addition, a variable stiffness actuator (VSA) accompanied by finite element analysis is designed to optimize the cable tension to adapt different task requirements. Firstly, a new idea of reconfiguration is given, and an inverse kinematic model is established using the vector closure principle to derive its inverse kinematic expressions focusing on one of the configurations. Second, the VSA is attached to each cable to achieve stiffness adjustment, and the system stiffness is derived in detail. Finally, the rationality and accuracy of the robot are verified through numerical analysis, providing a reference for subsequent trajectory planning with implications.