Using PID (Proportional-Integral-Derivative) control in Arduino

PID (Proportional-Integral-Derivative) control is a common feedback control method used in automation and control systems to regulate a process variable, such as temperature, pressure, or speed. Arduino can be used to implement PID control algorithms to regulate a process variable by adjusting the output of a control system based on the difference between the desired setpoint and the measured process variable.

Here’s an overview of how to use PID control in Arduino:

1. Choose your hardware: For implementing PID control in Arduino, you will need an Arduino board, a sensor to measure the process variable, and an actuator to control the output. The choice of hardware will depend on the specific requirements of your application, such as the range of the process variable, the accuracy of the measurement, and the response time of the actuator.

2. Define the PID parameters: To implement PID control, you will need to define the three parameters of the PID algorithm: the proportional gain (Kp), the integral gain (Ki), and the derivative gain (Kd). The values of these parameters will depend on the characteristics of the process being controlled, such as the response time and the steady-state error. You can start with some initial values and adjust them based on the performance of the control system.

3. Code the PID algorithm: Write the code for the PID algorithm, which calculates the output of the control system based on the measured process variable, the desired setpoint, and the PID parameters. Arduino provides several libraries that can be used for implementing PID control, such as the PID library and the PID_v1 library.

Here’s an example code that uses the PID_v1 library to implement PID control for regulating the temperature of a heating element:

#include 
#include 
#include 

#define ONE_WIRE_BUS 2
#define HEATER_PIN 3
#define SETPOINT 25.0
#define KP 4.0
#define KI 0.2
#define KD 1.0

OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature tempSensor(&oneWire);
double processVariable = 0;
double output = 0;
double setpoint = SETPOINT;
double kp = KP;
double ki = KI;
double kd = KD;

PID pid(&processVariable, &output, &setpoint, kp, ki, kd, DIRECT);

void setup() {
  Serial.begin(9600);
  tempSensor.begin();
  pinMode(HEATER_PIN, OUTPUT);
  pid.SetMode(AUTOMATIC);
  pid.SetSampleTime(1000);
}

void loop() {
  tempSensor.requestTemperatures();
  processVariable = tempSensor.getTempCByIndex(0);
  pid.Compute();
  analogWrite(HEATER_PIN, output * 255 / 5);
  Serial.print("Setpoint: ");
  Serial.print(setpoint);
  Serial.print(" | Process variable: ");
  Serial.print(processVariable);
  Serial.print(" | Output: ");
  Serial.println(output);
  delay(1000);
}

4. Test and tune the control system: Test the control system by adjusting the setpoint and observing the response of the process variable. Use the Serial Monitor to monitor the values of the process variable, the setpoint, and the output. Tune the PID parameters by adjusting their values and observing the response of the process variable. The goal is to achieve a fast and stable response with minimal overshoot and steady-state error.

Overall, using PID control in Arduino can be an effective way to regulate a process variable and automate control systems. By understanding how to choose the right hardware, define the PID parameters, code the PID algorithm, and test and tune the control system, you can create customized and efficient control solutions that meet the specific needs of your application.