PID LINE FOLLOWER ROBOT USING ARDUINO NANO

 

Most mechatronics and robotics enthusiasts will begin their robotics journey by developing a line follower robot. Because line follower robots are simple to construct and fun to watch. Since high school, I've been constructing line follower robots. To increase speed and stability, I experimented with various designs. Later on, I understood and learned that speed and stability are dependent not only on the design, but also on the algorithm. I'll show you how I used the PID algorithm to design and build my first line follower robot. So let's get this party started.

Arduino Nano

QTR 8 RC

DRV8835

N20 motors and clamp *2

AMS 1117 5.0 regulator*1

button switch*2

0805 SMD led*2

0805 1k resistor *2

0805 10k resistor *2

7.4volt battery

castor wheel

Most mechatronics and robotics enthusiasts will begin their robotics journey by developing a line follower robot. Because line follower robots are simple to construct and fun to watch. Since high school, I've been constructing line follower robots. To increase speed and stability, I experimented with various designs. Later on, I understood and learned that speed and stability are dependent not only on the design, but also on the algorithm. I'll show you how I used the PID algorithm to design and build my first line follower robot. So let's get th
is party started.

As i said earlier I am using the QTR sensor and PID algorithm. so in the program first I included the qtr8rc library of Pololu.

#include <QTRSensors.h>

Then with the help of the QTR library functions, i defined the sensors and other parameters

QTRSensors qtr;

const uint8_t SensorCount = 8;

uint16_t sensorValues[SensorCount];

Then I defined the ki, kp, kd constants. We should find the values of the constants by the trial and error method.

float Kp = 0;

float Ki = 0;

float Kd = 0;

int P;

int I;

int D;

int lastError = 0;

boolean onoff = false;

Next, I defined constant for defining the maximum and minimum speed of the robot. Also, I defined the pins for the motor driver and button

int mode = 8;

int aphase = 9;

int aenbl = 6;

int bphase = 5;

int benbl = 3;

int buttoncalibrate = 17

int buttonstart = 2;

In the setup section, I defined the pin modes and added the calibration programme

Serial.begin(9600);

 qtr.setTypeRC();

 qtr.setSensorPins((const uint8_t[]){10, 11, 12, 14, 15, 16, 18, 19}, SensorCount);

 qtr.setEmitterPin(7);

 pinMode(mode, OUTPUT);

 pinMode(aphase, OUTPUT);

 pinMode(aenbl, OUTPUT);

 pinMode(bphase, OUTPUT);

 pinMode(benbl, OUTPUT);

 digitalWrite(mode, HIGH);

delay(500);

 pinMode(LED_BUILTIN, OUTPUT);

boolean Ok = false;

 while (Ok == false) {

  if(digitalRead(buttoncalibrate) == HIGH)

{

   calibration();

   Ok = true;

  }

 }

 forward_brake(0, 0);

}

void calibration() {

 digitalWrite(LED_BUILTIN, HIGH);

 for (uint16_t i = 0; i < 400; i++)

 {

  qtr.calibrate();

 }

 digitalWrite(LED_BUILTIN, LOW);

}

Finally in the loop section

I read the values of the qtr 8rc sensor and driver motors according to the readings of the qtr sensors.

 if(digitalRead(buttonstart) == HIGH) {

  onoff =! onoff;

  if(onoff = true) {

   delay(1000);

  }

  else {

   delay(50);

  }

 }

 if (onoff == true) {

  PID_control();

 }

 else {

  forward_brake(0,0);

 }

}

void forward_brake(int posa, int posb) {

 digitalWrite(aphase, LOW);

 digitalWrite(bphase, HIGH);

 analogWrite(aenbl, posa);

 analogWrite(benbl, posb);

}

void PID_control() {

 uint16_t position = qtr.readLineBlack(sensorValues);

 int error = 3500 - position;

 P = error;

 I = I + error;

 D = error - lastError;

 lastError = error;

 int motorspeed = P*Kp + I*Ki + D*Kd;

 int motorspeeda = basespeeda + motorspeed;

 int motorspeedb = basespeedb - motorspeed;

 if (motorspeeda > maxspeeda) {

  motorspeeda = maxspeeda;

 }

 if (motorspeeda < 0) {

  motorspeeda = 0;

 }

 if (motorspeedb < 0) {

  motorspeedb = 0;

 } 

  forward_brake(motorspeeda, motorspeedb);

}