Pose error analysis in redundantly cable-driven parallel robots under hybrid joint-space control: Effects of force errors and cable modeling

Abstract

This paper analyzes pose errors in redundantly Cable-Driven Parallel Robots (CDPRs) under hybrid joint-space control, focusing on the coupled effects of force control inaccuracies and cable modeling simplifications. To enhance trajectory tracking performance, the non-negligible cable effects, namely elasticity and elastic catenary behavior, are incorporated into the control model. Within the specific strategy, redundant cables are force-controlled, while the rest are length-controlled. The inherent coupling among cable elasticity, catenary behavior, tension, and end-effector pose is revealed, with two performance indices employed to evaluate the position and orientation deviations arising from cable deformation. The core contribution of this paper lies in integrating the aforementioned indicators, thereby providing a systematic method to support modeling fidelity analysis and configuration selection. The study examines two robot configurations and analyzes two scenarios: (1) the impact of cable model simplification on pose accuracy, (2) combined effects of force control errors and cable compensation. The proposed framework enables systematic error source decoupling, compensation assessment, control accuracy prediction, and error management guidance for CDPR design, while offering an effective solution to ill-conditioned matrix issues avoiding matrix inversion with physical constraints.