Analysis and Accuracy Improvement of Robot Manipulators with Joint Clearance

This study presents a method to improve manipulator accuracy by predicting uncertainty from the trajectory of manipulators. We construct the dynamic of manipulators with clearances equations and use them to obtain the operation error of a given trajectory. We are able to predict the joint clearance and arrange a trajectory with smaller error through optimization technics using the proposed method. This study reduces the average error at target points from 0.637 mm to 0.031 mm for robot manipulator with joint clearance 0.328 mm, 0.171 mm, and 0.483 mm, that is a 95.1% improvement in accuracy over the same manipulator before optimization. Our method can not only compare the true manufacturing quality of two robot manipulators, but also provide a more accurate operation.