Development of Orientation Measuring System of a Robot Using a Gyroscope. 2nd Report. Proposal of Position and Orientation Calibration Method of a Robot Using Both Laser Tracking System and Gyroscope.

Abstract

For the purpose of realizing not only positioning but also orientating accuracy of a robot, a position and orientation calibration method is newly proposed and applied to a 6-DOF articulated robot (PUMA 560). The existence of gear transmission errors and gear backlashes of the 4-6th axes of this robot is detected by using a high precision gyroscope and it is proved that these non-geometric errors cause the orientation error of robot arm's tip. A position and orientation measuring system using both a laser tracking system and this gyroscope is proposed. A calibration method, which uses both position and orientation data and considers non-geometric errors of 4-6th axes as parameters to be calibrated in the forward kinematics model, is proposed. The positioning accuracy of 0.2mm and roll, pitch, yaw orientating accuracy of (0.17°, 0.10°, 0.10°), which is near the limit value of calibration predicted by the orientating repeatability, are successfully achieved and it is experimentally proved that the proposed measuring system and the calibration method are very effective for improving the orientating accuracy while keeping the high positioning accuracy. The optimal weights of position and orientation data in the least squares estimation process of parameters are also discussed.