中文说明：
采用一种离散微分跟踪器的PID控制。被控对象是三阶传递函数，参考输入rin=20，干扰信号是0.5rands（1）。
English Description：
PID control using a discrete differential tracker. The controlled object is a third-order transfer function, the reference input Rin = 20, and the interference signal is 0.5 Rands (1)