基于观测器与前馈的送丝机模糊PI速度控制

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

送丝系统是焊接机器人的重要组成部分,稳定可靠的送丝是保证焊接质量的前提;焊丝从丝盘上抽取和经过绝缘管与导电嘴的过程中受到的阻力呈严重的非线性,所受的阻力严重影响送丝速度和焊接质量.采用状态观测对阻力进行观测,并根据观测值对系统进行前馈,以提高系统的速度响应,消除送丝阻力对系统的影响.因为电机存在阻尼,采用常规PI控制可以改善系统的稳态特性,抑制稳态误差;把模糊控制和PI控制有机地结合起来,利用模糊控制的动态响应和PI控制的稳态性能,实现送丝机安全可靠的送丝;仿真表明采用状态观测和前馈控制速度响应快、超调小、鲁棒性强,模糊PI控制较传统PI控制有更好的动、静特性;接管焊接试验结果表明焊接质量完全达到规定要求.

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.