Microcontroller Implementation of Digital Pid Controller

Abstract

A proportional-integral-derivative (PID) controller is widely used in industrial control systems to get the desired response by feedback. In this project, we attempt to implement a digital controller in a microcontroller. The primary difference between a digital controller and an
analogue controller is that with a digital controller the actual value is not measured continuously, rather it is periodically sampled at some fixed time interval. To study the issues in implementing a digital PID controller in Arduino microcontroller is the main objective of the project. Once the implementation issues are solved then one can tune the Kp, Kd and Ki gains of the PID controller. Based upon the error occurred and by changing the values suitably, the required output from the system can be obtained. In this project, PID controllers with input and output features are implemented in Arduino and its frequency response is studied in order to adjudge whether the implementation is correct or not. Two methods are used for generating the PID controller output. One by using a properly tuned RC filter that filters out the PWM signal generated by the Arduino and the other by using a digital to analog converter from the digital output of the Arduino.