PID与遗传算法，为进行pid参数整定，首先设置采样周期t，后建立带零阶保持器的连续对象的离散化模型，最后转化为差分方程-PID and genetic algorithm for the conduct of pid parameter setting, first set the sampling period t, after the establishment of discrete model with a continuous target of zero-order hold, and finally converted to a differential equation