Circuit Documentation

Summary

This document provides a detailed overview of a line-following robot circuit. The circuit consists of an Arduino UNO microcontroller, an L298N DC motor driver, multiple IR sensors, two hobby motors, a rocker switch, and a 7.4V battery. The Arduino UNO reads the IR sensor values to determine the position of the line and adjusts the motor speeds accordingly using a PID control algorithm.

Component List

1. Arduino UNO

   • Description: Microcontroller board based on the ATmega328P.
   • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

2. L298N DC Motor Driver

   • Description: Dual H-Bridge motor driver module.
   • Pins: OUT1, OUT2, 12V, GND, 5V, OUT3, OUT4, 5V-ENA-JMP-I, 5V-ENA-JMP-O, +5V-J1, +5V-J2, ENA, IN1, IN2, IN3, IN4, ENB

3. 7.4V Battery

   • Description: Power source for the circuit.
   • Pins: +, -

4. IR Sensor

   • Description: Infrared sensor for line detection.
   • Pins: out, gnd, vcc

5. Motor (Hobby)

   • Description: DC motor with gearbox.
   • Pins: vcc, GND

6. Rocker Switch

   • Description: On/Off switch.
   • Pins: 1, 2

Wiring Details

Arduino UNO

• 5V: Connected to vcc of all IR sensors.
• GND: Connected to gnd of all IR sensors and the GND of the L298N DC motor driver.
• IOREF: Connected to 5V of the L298N DC motor driver.
• A0: Connected to out of the first IR sensor.
• A1: Connected to out of the second IR sensor.
• A2: Connected to out of the third IR sensor.
• A3: Connected to out of the fourth IR sensor.
• D11: Connected to ENA of the L298N DC motor driver.
• D10: Connected to IN3 of the L298N DC motor driver.
• D9: Connected to IN4 of the L298N DC motor driver.
• D6: Connected to IN1 of the L298N DC motor driver.
• D5: Connected to IN2 of the L298N DC motor driver.
• D3: Connected to ENB of the L298N DC motor driver.

L298N DC Motor Driver

• 5V: Connected to IOREF of the Arduino UNO.
• GND: Connected to - of the 7.4V battery and GND of the Arduino UNO.
• 12V: Connected to pin 1 of the rocker switch.
• ENA: Connected to D11 of the Arduino UNO.
• IN3: Connected to D10 of the Arduino UNO.
• IN4: Connected to D9 of the Arduino UNO.
• IN1: Connected to D6 of the Arduino UNO.
• IN2: Connected to D5 of the Arduino UNO.
• ENB: Connected to D3 of the Arduino UNO.
• OUT1: Connected to vcc of the first hobby motor.
• OUT2: Connected to GND of the first hobby motor.
• OUT3: Connected to GND of the second hobby motor.
• OUT4: Connected to vcc of the second hobby motor.

7.4V Battery

• +: Connected to pin 2 of the rocker switch.
• -: Connected to GND of the L298N DC motor driver and Arduino UNO.

IR Sensors

• vcc: Connected to 5V of the Arduino UNO.
• gnd: Connected to GND of the Arduino UNO.
• out: Connected to A0, A1, A2, and A3 of the Arduino UNO respectively.

Hobby Motors

• vcc: Connected to OUT1 and OUT4 of the L298N DC motor driver.
• GND: Connected to OUT2 and OUT3 of the L298N DC motor driver.

Rocker Switch

• 1: Connected to 12V of the L298N DC motor driver.
• 2: Connected to + of the 7.4V battery.

Code Documentation

// Define sensor pins
#define LEFT_SENSOR A0
#define LEFT_CENTER_SENSOR A1
#define RIGHT_CENTER_SENSOR A2
#define RIGHT_SENSOR A3

// Define motor pins
#define LEFT_MOTOR_FWD 5
#define LEFT_MOTOR_BWD 6
#define RIGHT_MOTOR_FWD 9
#define RIGHT_MOTOR_BWD 10

// PID control variables
float Kp = 1.0;     // Proportional gain
float Ki = 0.0;     // Integral gain
float Kd = 0.5;     // Derivative gain
float error, lastError = 0, integral = 0, derivative = 0;
int baseSpeed = 150; // Base motor speed (adjust based on testing)
int maxSpeed = 255;  // Maximum motor speed

// Infrared sensor values
int left, leftCenter, rightCenter, right;

void setup() {
  // Set motor pins as outputs
  pinMode(LEFT_MOTOR_FWD, OUTPUT);
  pinMode(LEFT_MOTOR_BWD, OUTPUT);
  pinMode(RIGHT_MOTOR_FWD, OUTPUT);
  pinMode(RIGHT_MOTOR_BWD, OUTPUT);

  // Set sensor pins as inputs
  pinMode(LEFT_SENSOR, INPUT);
  pinMode(LEFT_CENTER_SENSOR, INPUT);
  pinMode(RIGHT_CENTER_SENSOR, INPUT);
  pinMode(RIGHT_SENSOR, INPUT);

  // Start serial monitor for debugging (optional)
  Serial.begin(9600);
}

void loop() {
  readSensors();
  followLine();
}

// Function to read IR sensors
void readSensors() {
  left = analogRead(LEFT_SENSOR);
  leftCenter = analogRead(LEFT_CENTER_SENSOR);
  rightCenter = analogRead(RIGHT_CENTER_SENSOR);
  right = analogRead(RIGHT_SENSOR);
}

// Function to follow the line using PID control
void followLine() {
  error = calculateError();
  integral += error;
  derivative = error - lastError;

  // PID calculation
  int adjust = Kp * error + Ki * integral + Kd * derivative;
  int leftMotorSpeed = constrain(baseSpeed + adjust, 0, maxSpeed);
  int rightMotorSpeed = constrain(baseSpeed - adjust, 0, maxSpeed);

  // Set motor speeds based on PID adjustment
  setMotorSpeeds(leftMotorSpeed, rightMotorSpeed);

  lastError = error;  // Update lastError for the next loop
}

// Function to calculate error based on sensor values
float calculateError() {
  if (left && !leftCenter && !rightCenter && right) return 0;       // Centered
  if (left && leftCenter && !rightCenter && !right) return -2;      // Slightly left
  if (!left && !leftCenter && rightCenter && right) return 2;       // Slightly right
  if (left && leftCenter && rightCenter && !right) return -3;       // Far left
  if (!left && leftCenter && rightCenter && right) return 3;        // Far right
  return 0;                                                         // Default to center
}

// Function to control motor speeds based on PID adjustments
void setMotorSpeeds(int leftSpeed, int rightSpeed) {
  if (leftSpeed >= 0) {
    analogWrite(LEFT_MOTOR_FWD, leftSpeed);
    digitalWrite(LEFT_MOTOR_BWD, LOW);
  } else {
    analogWrite(LEFT_MOTOR_BWD, -leftSpeed);
    digitalWrite(LEFT_MOTOR_FWD, LOW);
  }

  if (rightSpeed >= 0) {
    analogWrite(RIGHT_MOTOR_FWD, rightSpeed);
    digitalWrite(RIGHT_MOTOR_BWD, LOW);
  } else {
    analogWrite(RIGHT_MOTOR_BWD, -rightSpeed);
    digitalWrite(RIGHT_MOTOR_FWD, LOW);
  }
}

This code defines the pins for the IR sensors and motors, sets up the pins in the setup() function, and continuously reads the sensor values and adjusts the motor speeds in the loop() function using a PID