The seam position detection and tracking for the mobile welding robot

To solve the problems that the current seam tracking process cannot find the weld line and the control method based on the kinematic model of welding mobile robot leads to low accuracy, a method for searching the welding seam is designed firstly. By this method, the initiation point of the weld line can be found and the attitude of the robot parallel to the weld line can be adjusted automatically. Secondly, for improving the tracking precision and anti-interference performance, a new controller based on the kinematic and dynamic model of the mobile welding robot is designed. To deal with the partial uncertainty and the disturbances of welding process, this controller combines the sliding mode variable structure control and low-pass filter, so that it is able to complete the controlling of cross-slider and wheels coordinately. The stability and convergence of the designed controller are proved through the use of Lyapunov theory. The effectiveness of the proposed method is verified by simulation and experiments. In the seam tracking process, the welding torch is able to track the welding seam well and the robot moves steadily without any obvious chattering.