Kinematic Calibration and Compensation for Industrial Robots using a Telescoping Ballbar

Abstract

Robot calibration, as one of the key technologies of off-line programming, is very important in robotic applications. To improve the accuracy, this paper presents a kinematic calibration and compensation method for six-axis serial industrial robots in the specific workspace. By measuring seven poses of the robot under static conditions, with a single telescoping ballbar and one fixture which consists of three equidistant magnetic cups, we can get the actual geometric parameters first. And then a compensation function is proposed to eliminate the position errors for every joints. The validation experiments of the proposed method is conducted in the specific workspace by using a COMAU NJ220 industrial robot. The results illustrate that the proposed calibration method can obtain the robot parameters with high accuracy, and the position error can be compensated effectively.