Analysis of a six-axis industrial robot's dynamic path accuracy based on an optical tracker

Although robot calibration has maturational fundamental theories, its practical application is still in the primary phase. In fact, most users are hard to manipulate an industrial robot with high absolute positioning accuracy. Thus, this study intends to measure the dynamic path accuracy of a six axis industrial robot based on an optical tracker, instead of an expensive laser tracker. The motion tracking approach was based on three robot motions, i.e. linear motion, circular motion, and cornering motion, with a series of varied motion speeds from 100 to 800mm/s. Results show the dynamic path errors (the difference between the presupposed position and the measured position) for linear, circular, and corner motions were 0.662 +/- 0.169mm, 1.901 +/- 0.109mm, and 17.334 +/- 7.572mm, respectively. Obviously, the corner path error was far more than the other two motions. Furthermore, we found that the relationship between path error and the robot motion speed, was not completely linear. The performance assessment aims to provide feedback information for the accurate robot motion control in a specific target workspace. It is therefore of paramount importance for industrial robot users who are interested in precise applications to fully understand the test methods used for assessing robot path precision.