说明：  此程序是变型PID控制算法的仿真程序，采用了变速积分方法，系统偏差大时，积分作用应减小，反之应加强。变速积分可以根据系统误差大小改变积分速度，提高了系统品质。
(this procedure is a change in the PID control algorithm simulation program using the variable integration method, the system deviation, the integral role should be reduced, on the contrary should be strengthened. Integral variable speed system error can change the size of integration of speed, quality of the system.)