Error compensation method of industrial robots considering non-kinematic and weak rigid base errors

Abstract

Industrial robots are receiving increasing attention owing to their numerous advantages, such as flexibility, maneuverability, and low cost. In robotic machining systems, improving the absolute positioning accuracy of the robot is essential for improving workpiece quality. This study proposes a robot error compensation method that considers nonkinematic and weak rigid base errors. A mapping model between the theoretical position of the robot and the actual error was established based on an incremental support vector machine (ISVM), and the nonkinematic error compensation of the robot was realized. The robot error before and after axis 1 rotation is compensated for by modeling the rotational error of axis 1 and the deformation error of the robot base and is verified on the milling robot KUKA KR 160. The experimental results show that the maximum absolute position error of the robot end-effector is reduced by 85.27% (from 1.3277 to 0.1956 mm) after compensation. Milling experiments have shown that the position error of the empty running trajectory before compensation is reduced from −1.3231 to −0.1297 mm, and the z-direction error of the workpiece is reduced from −0.8771 to 0.3267 mm, which meets the machining accuracy requirements of the milling robot system in this paper.