A calibration method of workpiece frames for ultrasonic testing using twin-robot

A calibration method of workpiece frames using twin-robot is presented in this paper. Path planning for workpiece is based on its frame. Thus, the workpiece frames of two robots should be calibrated to make sure the motion of the twin-robot is under the same coordinate system. However, when twin-robot are separated from the workpiece, the twin-robot cannot reach some calibration points on workpiece at the same time. So a new method is proposed to solve the problem. The translation and rotation matrices between the base frames of two robots can be obtained by measuring the coordinate values of any three non-collinear points in working space. When only one robot can actually reach the calibration point of the workpiece frame, the coordinate value of this point in another robot base frame can be obtained by the matrices calculation. Experiment results show that the calibration method is relatively precision and convenient.