A Novel Method on Parallel Robot's Pose Measuring and Calibration

Compared with serial robots, because of some advantages, e.g. higher stiffness, errors will not accumulate etc., parallel robot has much potential use on micro electromechanical systems. Although the robot is manufactured and assembled carefully, there are still some tiny errors between the nominal and actual values of parameters, which influence the system's final performance obviously. To satisfy precision requirements of micro electromechanical systems, it's necessary to do the calibration. Comparing strength and weakness of often-used equipments, coordinate measure machine (CMM) is adopted and a novel measurement method - 'three planes method' is proposed. The plane equation will be measured instead of the position of points to realize the CMM's strength and avoid errors made by human. This method is verified with a 6 DOFs parallel robot with parallel tracks. The results show that after calibration the error between the nominal and measured poses achieve the same level with the robot's repeatability, which is much improved than without calibration.