4

Proportional–Integral–Derivative Control

PID controllers have been most widely used in industry due to their simplicity, good control performance and excellent robustness to uncertainties. In this chapter, the structure of the PID controller and the roles of the three parts (proportional, integral and derivative) of the PID controller are discussed, followed by the practical issues related to the PID controller, such as the integral windup, implementation and industrial versions of the controller.

4.1 Structure of Proportional–Integral–Derivative Controllers and Implementation in Computers/Microprocessors

In this section, the structure of the PID controller is explained and their implementation in computers or microprocessors is discussed.

4.1.1 Structure of Proportional–Integral–Derivative Controllers

PID controllers are composed of the following three parts:

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The output of the PID controller is the sum of the above-mentioned three parts:

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where ys(t), y(t) and u(t) denote the setpoint (the desired process output), the process output and the control output of the PID controller respectively. ...

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