A fast calibration method of the tool frame for industrial robots

Industrial robots perform tasks through tools installed on the end flange. The position and orientation of the tools are essential factors that affect the motion accuracy of industrial robots. However, existing calibration methods for the tool frame mainly depend on manual observation. To solve this problem, this paper proposes an automatic calibration method of the tool frame based on the fact that the accurate position and orientation of the tools relative to the flange can be obtained through the calibration of the tool frame. First, the tool carried by the robot moves in a uniform circle at different heights. The origin and orientation calibration models of the tool frame are established respectively based on the similarity of the motion track of each point on a rigid body. Through two pairs of vertically mounted laser beam sensors, the time when the tool passes through the laser beam and the position of the corresponding robot flange are obtained. Second, the simulation platform with the robot and sensors is built in a 3-dimensional software to simulate the motion and measurement of the tool. The data required for calibration are acquired, by which the parameters of the origin and orientation of the tool frame are identified and compensated in the motion controller of the robot. Finally, the accuracy of the tool frame before and after calibration is tested in the simulation platform, and the simulation results verify the effectiveness of the proposed model and method.