Fuzzy PI speed control for welding wire feed system based on state observer and feedforward

Welding wire feeding device is an important component of welding robot,stabilization and reliability of welding wire feed is the essential for welding quality.The resistance was highly nonlinear and both wire feed rate and welding quality are severely affected by the resistance.A state observer was adopted to evaluate the resistance,and then the observed resistance was forward fed in order to increase speed response and eliminate the impact of resistance on the welding wire feed system.Because of DC motor damping,the steady-state characteristics can be improved and the steady-state error can be inhibited when conventional PI control is adopted.The fuzzy control and PI control arc organically introduced by means of dynamic response of fuzzy control and steady-state performance of PI control,it is reliable to achieve stable weld wire feeding.The simulations indicate that there are fast speed response,small overshoot and strong robustness with state observer and forward feed,the dynamic and static characteristics of fuzzy PI control are better than PI control.