Vision based trajectory dynamic compensation system of industrial robot

Abstract

This study aims to enhance the flexibility of robots in the manufacturing process to meet the growing demand for flexible manufacturing systems by constructing a dynamic compensation system. The system enables the end effector of the robot to track the trajectory contour on the horizontal plane, even if there is a deviation between the teaching trajectory and the target trajectory contour. The proposed system employs an innovative mechanism design and algorithm that enables dynamic compensation of the robot’s absolute position in the XY-plane, even when the end effector is obstructed. The system uses an XY-stage and two industrial cameras, with each axis being separately controlled. To detect and compensate for errors in the end effector and target trajectory, the two cameras are aligned with the X- and Y-direction linear stage, respectively. The cameras are fixed with respect to the linear stage, and the end effector is placed on the stage work surface. Unlike traditional stereo cameras, the cameras in this system do not require calibration for their positional relationship. To verify the system’s effectiveness, this study set a group of teaching and target trajectory contours with a maximum deviation of over than 8 mm. Under the compensation of the system, the maximum error between the end effector and the target trajectory contour was 22.8 pixels (1.34 mm), with an average absolute error of 5.4 pixels (0.32 mm). Compared to the maximum error of 8.45 mm before compensation, the error has been reduced by 84 %.