System Error Modeling And Calibration For Industrial Robot In High Precision Applications

Industrial robots are widely used in the field of machinery, automobile, electronic and electrical.The replacement to the manual operation of robot is the development trend of intelligent manufacturing industry. However, the high precision requirement of negineering application poses a serious challenges to industrial robot technology. A large number of academic and industry researchers have been trying to improve the accuracy of the robot system through a variety of techniques and methods. This paper focuses on improving the accuracy of the kinematic and work cell(tool center point and work object coordinates system), including robot system error modeling, kinematic calibration and recalibration based on touch panel, work cell calibration and so on.Firstly, the concepts of the robot coordinate system have been introduced, the kinematics and work cell error sources and effect on different programing ways are analyzed. Traditional D-H model is built for kinematic calibration, which is then improved as distance error function. Robot work cell model is built for mapping the points from work object coordinates to robot base coordinates.Secondly, calibration system of robot based on touch panel has been proposed, which uses ABB IRB120 as the robot waited to be calibrated, touch panel as measuring device. For kinematic calibration, the parameters of D-H are optimized by using the LM algorithm, and propose improved algorithm based on recalibrating the touch panel. For work cell calibration, algorithm is designed followed by calibrating work object rotation angle, tool center point, and work object origin translation. mechanical adapters are needed for mounting the calibration devices in a robot cell for transferring the calibrated work cell to the real tool work cell with the known mechanical relationship.Then, evaluate the absolute error of touch panel, and build its error model. The model is used in calibration simulation for analysizing feasibility of calibration algorithms. For kinematic calibration, focus on the analysze of the algorithms robustness and anti-interference ability. For work cell calibration, focus on the analyze the effect of measurement error on cell calibration for understanding the limitation of this method and figure out the proper touch panel for industrial use.Finally, design the calibration experiments for the evaluation of practical performance and design the verificaiton experiments for verification of the accuracy of the calibration solution.