Transition Process Control of Pneumatic Servo Welding Gun Based on Pressure Feedback and Position Backstepping Strategy

With the continuous development of automation technology, the pneumatic servo system has been more and more widely used in industrial field, especially in automobile manufacturing, because of its low cost, easy maintenance and environmental cleaning. Speeding up welding efficiency, improving the quality of resistance spot welding, avoiding the damage caused by excessive impact force are of significance. The transition from position control to force control of pneumatic servo gun system is the key process to solve these problems.The working process of proportional valve control cylinder system for pneumatic servo welding gun is presented in this paper through the analysis of spot welding process. This paper proposes a transition control method for the pneumatic servo welding gun. The designed controller is composed of a pressure controller and a position backstepping controller. The welding gun contact force is reduced by controlling the pressure of the rod chamber. The motion time is shorten through the position backstepping controller. The control effects of conventional switch control and proposed algorithm are compared by experiments. The results indicate the capabilities of the proposed method.