Study On Crucial Technologies Of The Welding Seam Tracking System

Nowadays, robot welding has become a sign of automated welding. Using robots during welding can increase the productivity, improve the working condition, guarantee the welding quality and realize welding automation for low-volume manufacture. As welding condition changes in real time in the course of arc-welding, in order to track the welding seam accurately, the welding robot needs to adjust its welding route in real time according to the changes of the welding seam position and posture.The thesis mainly focuses on two crucial technologies of the welding seam tracking system: the design of the driving circuit for the scanning motor in the laser scanning unit of the sensor and the calibration of the robot. In this thesis, two different direct current motors, a brush and a brushless motor, were selected as the scanning motor, and corresponding printed circuit boards as well as relevant software programming were completed. Moreover, experiments were conducted to test the performance of the circuits. The results of the experiment indicate that the stability of the motor rotation speed can meet the sensor's precision. Besides, in this thesis, the calibration method based on distance accuracy was used to correct the robot's link parameter and the least square solution was adopted to process the data. Although the positioning accuracy of the robot after calibration still can not meet the system's precision, it has been improved a lot. To further enhance the positioning accuracy, the positioning error caused by other factors needs correcting.