PID Controller

Page last updated 26 Jul 2010, by Aaron Berk. 0 replies

A proportional-integral-derivative controller (PID controller) is a generic loop feedback mechanism. It measures a process variable (e.g. temperature), and checks it against a desired set point (e.g. 100 degrees celsius); it then attempts to adjust the process variable by changing the controller output (e.g. PWM signal to an electric heater) which will bring it closer to the desired set point.

The wikipedia article is an excellent place to start in understanding the concepts of a PID controller. The controlguru website also contains a wealth of easy to digest information of how to implement and tune a PID controller.

As these resources can already explain the fundamentals and implementation of a PID controller, this page will detail the PID library and then present an example of putting it into practice.

Software

Example: Velocity Control

This example will explain how to use a PID controller to control the velocity of a motor using a quadrature encoder and an H-bridge.

Step Test

The first thing to do when designing our PID controller is to observe how our process variable changes with respect to the controller output. In this case, our process variable is the velocity of the motor (measured as counts per second from the quadrature encoder), and our controller output is the PWM signal to the H-bridge. In our step test,

Library

Reference

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