模糊自整定PID液体混合系统

Liquid Mixing System Based on Fuzzy Self-tuning PID

为解决实际液体混合装置控制方法单一、不能连续进行液体混合和精确度较低等问题,采用PID控制。传统PID控制参数固定,难以适应系统状态改变后的要求,且控制系统超调量大、调节时间长。模糊自整定PID控制方式,以流量比为设定值,能在线实时调整PID参数,消除扰动,控制稳定。应用PLC实现模糊自整定PID控制,结合简单输入输出控制,具有连续性与间断性相结合、操作简单、鲁棒性好等优点。仿真结果表明,超调量比传统PID减少36%,过渡时间减少约3 s,从而提高了生产效率,降低了人工成本。

PID control theory is utilized to deal with the problems of simple input / output control,discontinuous liquid mixing and poor accuracy. There are some problems in traditional PID control,such as troubles in adjustment after the state change of the system,large overshoot and long setting time. In combination with the fuzzy theory,flow valves are adjusted and all disturbances in the system will be eliminated to achieve the accurate mixture. PLC realizes the fuzzy self tuning PID and manages with input / output control. It has advantages of continuous and discontinuous operation,less overshoot and good robustness. Its overshot is 36% less than that of the traditional PID. Moreover,the setting time is reduced by 3 seconds with higher production efficiency and lower labour cost.