Closed-loop control for a cable-driven parallel manipulator with joint angle feedback

This paper presents a closed-loop control scheme of the cable-driven parallel manipulator (CDPM) to improve control accuracy. The mentioned three degrees of freedom (3-DOF) CDPM has a spherical joint with self-measured property to overcome intrinsic default of CDPM because of cable flexibility. The spherical joint is constructed by three passive 1-DOF revolute joints, in which three rotary encoders are accommodated to measure joint angles. This self-feedback method can complete close-loop control of the proposed cable-driven spherical-joint platform without the supporting of external devices. The matched control algorithm has been derived from the inverse kinematic solution, which results in closed-loop control with joint angle feedback. Additionally through robustness analysis, the proposed control method has been demonstrated that it has tolerance for parameter errors. The experimental results demonstrate that the proposed closed-loop control method perform well on motion control of the 3-DOF CDPM.