Arduino PID Implementation

README.md

Arduino PID

This is a basic implementation of a PID controller on an Arduino.

To replicate this, wire up the system as shown below:

For more info, check out the YouTube video here.

arduino_pid_system.png

circuit.png

pid.ino

const int INPUT_PIN = A0;
const int OUTPUT_PIN = DD3;

double dt, last_time;
double integral, previous, output = 0;
double kp, ki, kd;
double setpoint = 75.00;

void setup()
{
  kp = 0.8;
  ki = 0.20;
  kd = 0.001;
  last_time = 0;
  Serial.begin(9600);
  analogWrite(OUTPUT_PIN, 0);
  for(int i = 0; i < 50; i++)
  {
    Serial.print(setpoint);
    Serial.print(",");
    Serial.println(0);
    delay(100);
  }
  delay(100);
}

void loop()
{
  double now = millis();
  dt = (now - last_time)/1000.00;
  last_time = now;

  double actual = map(analogRead(INPUT_PIN), 0, 1024, 0, 255);
  double error = setpoint - actual;
  output = pid(error);

  analogWrite(OUTPUT_PIN, output);

  // Setpoint VS Actual
  Serial.print(setpoint);
  Serial.print(",");
  Serial.println(actual);

  // Error
  //Serial.println(error);

  delay(300);
}

double pid(double error)
{
  double proportional = error;
  integral += error * dt;
  double derivative = (error - previous) / dt;
  previous = error;
  double output = (kp * proportional) + (ki * integral) + (kd * derivative);
  return output;
}

I come back to this code from now and then to remember how to implement a PID, more useful than many of the Arduino sites out there. Thanks.

Thank's