基于小波变换、模糊控制的电解加工间隙检测与控制

Measurement and Control of Interelectrode Gap during Electrochemical Machining(ECM) Based on Wavelet Transform and Fuzzy Control

在线采集真实电解加工过程中的电流信号,用对实测信号进行小波包分解和重构后的小波系数计算各频段的能量,构造一个由不同频段能量组成的特征向量,发现特征向量的低频分量占总能量的大部分,随着平衡间隙的减小,低频分量能量增大。设计了一个二维模糊控制器,以进给速度的增量为模糊控制器输出,将间隙的误差转化为电流的误差及误差的变化,以此作为模糊控制器的二维输入向量,使加工维持在稳定的小间隙状态。创建了仿真模型,在MATLAB的SIMULINK模块中,通过对模糊控制器和电解加工系统组成的联合模型进行仿真试验来整定模糊控制器的3个增益参数,试验表明,采用此方法进行间隙控制具有较好的快速性、鲁棒性及总体效果。

The current signals were gathered in the tests, and processed by wavelet package transform. A characteristic vector was constructed by the energy of different frequency segment,which was calculated by using the coefficient of wavelet package transform of the current signals. The vector shows that the energy of low frequency segment is of the majority of the total energy, and becomes larger as the interelectrode gap decreasing. A two dimensional fuzzy controller was designed to keep the interelectrode gap at a stable and low value, the inputs of controller were the current error and the change of current error which was transferd from the error of interelectrode gap. The output of controller was the increment of feed velocity. A simulation model based on the simulink module of MATLAB was established. The fuzzy controller gives satisfactory performance.