Self-calibration method for two DOF cable-driven joint module

Abstract

A modular cable-driven robot consists of a number of consecutively connected cable-driven joint modules. It has the advantages of lightweight structure and compliant behavior so that it can perform intrinsically safe human–robot interactions. However, a modular cable-driven robot normally has a low positioning accuracy due to the manufacturing and assembly errors in each of the cable-driven joint modules. In this work, a self-calibration method is proposed for the 2-DOF cable-driven universal joint module by utilizing its actuation redundancy. Different from the conventional self-calibration method where the absolute cable lengths need to be measured, the proposed error model is formulated based on the relative lengths changes of the diving cables. The effectiveness of the self-calibration method is verified through computer simulations.