A New Decoupling Method for Cable-Driven Joints Based on an Anti-Parallelogram Mechanism

Abstract

This paper proposes a novel anti-parallelogram mechanism (APM)-based cable-driven joint that achieves both the kinematic decoupling characteristic of rolling joints and the surface-contact robustness of link structures. Through the optimization of internal idlers, the cable path length remains nearly constant without complex gears or ligaments. Experimental validation using a 2-DOF prototype demonstrated negligible distal joint interference (0.0815 deg RMSE) during actuation. Furthermore, the system exhibited sub-millimeter positional repeatability (maximum RMSE of 0.2786 mm), establishing the proposed design as a robust, high-precision decoupling solution.