Motion Planning for a Cable-Driven Lower Limb Rehabilitation Robot with Movable Distal Anchor Points

Abstract

This article introduces a cable-driven lower limb rehabilitation robot with movable distal anchor points (M-CDLR). The traditional cable-driven parallel robots (CDPRs) control the moving platform by changing the length of cables, M-CDLR can also adjust the position of the distal anchor point when the moving platform moves. The M-CDLR this article proposed has gait and single-leg training modes, which correspond to the plane and space motion of the moving platform, respectively. After introducing the system structure configuration, the generalized kinematics and dynamics of M-CDLR are established. The fully constrained CDPRs can provide more stable rehabilitation training than the under-constrained one but requires more cables. Therefore, a motion planning method for the movable distal anchor point of M-CDLR is proposed to realize the theoretically fully constrained with fewer cables. Then the expected trajectory of the moving platform is obtained from the motion capture experiment, and the motion planning of M-CDLR under two training modes is simulated. The simulation results verify the effectiveness of the proposed motion planning method. This study serves as a basic theoretical study of the structure optimization and control strategy of M-CDLR.