Ultrasound Based Industrial Robot Kinematic Calibration Method

Abstract

The purpose of this paper is to present a kinematic calibration method for industrial robot based on ultrasound. It can be used to improve kinematic accuracy for robot used in ultrasonic nondestructive testing system. Articulated robot with six degree of freedom (DOF) is introduced in ultrasonic nondestructive testing system to test workpieces with complicated shape. Off-line teaching method is an effective way to realize complicated motion in robot application. However, absolute positioning plays an important role in such teaching method. Considering that ultrasound has ability to measure distance, we used ultrasonic transducer to calibrate kinematic parameters. Firstly, relative distance errors between actual and command distance are measured along three orthogonal orientations. Then, least square method is used to calculate errors between actual and nominal kinematic parameters. Experimental results show that this method can improve kinematic accuracy effectively. The proposed method makes it more convenient to calibrate kinematic parameters for robot used in ultrasonic nondestructive testing system.