chap2_3

代码说明：

  在过程控制中，按偏差的比例（P）、积分（I）和微分（D）进行控制的PID控制器（亦称PID调节器）是应用最为广泛的一种自动控制器。(In process control, according to the percentage of deviation (P), Integral (I) and differential (D) control of PID controller (also known as PID regulators) is the most widely used of an automatic controller.)