Research On The Seam Tracking Control System For Crawl Type Welding Robot

With the development of manufacturing industry, the traditional manual welding has not been able to meet the requirements of modern high-tech manufacturing in quality or quantity. Therefore, improving the degree of welding automation has become a key issue in modern welding technology. The invention of welding robot was a revolutionary progress in welding automation, which rapidly improved the automatic level of welding and brought essential advances in efficiency and quality of the welding production. A mobile welding robot system designed for large diameter pipelines'welding was proposed in this paper.At first, the system architecture of welding robot was introduced. There are four major parts in the system: motion mechanism, welding system, detection system and control system. The function and scheme of each part was analyzed.Secondly, the paper focuses on the control method of seam tracking system. The robot's kinematics model was established. Based on the model, two control methods which are suitable for the system were introduced: PID control and fuzzy control. Then the PID controller and the fuzzy controller were designed according to the control algorithms'characteristics and actual requirements.Subsequently, two robot's simulation models were established based on PID controller and fuzzy controller respectively, and simulating experiments were proceeded by tracking four typical trajectories. According to simulating results, the performances of two control methods were compared, the causes for the tracking errors were analyzed and some possible improvement plans were proposed.Finally, a control implementation method was proposed by using PLC as the main controller, and the hardware and software's architectures of the control system were designed concretely.