Muhammad Sheraz
Published © LGPL

Artificial Intelligence (AI) Based Line Following Robot

Artificial Intelligence (AI) based line Following robot is a robot that a sense of detecting the correct path for its route.

IntermediateFull instructions provided10 hours2,989
Artificial Intelligence (AI) Based Line Following Robot

Things used in this project

Hardware components

Arduino Nano
×1
Seeed Wireless Bluetooth RF Transceiver Master Slave
×1
Amazon Web Services IR Infrared Sensor Module Reflective Photoelectric Light
×1
Sony Continuous Rotation Servo
×1
Android 4.8 Volt Battery
×1

Software apps and online services

Arduino IDE
Arduino IDE

Story

Read more

Schematics

Circuit Diagram

Code

RoBot_Maze_Solve_2

C/C++
/*------------------------------------------------------------------
7 sensors Smart Robot - Maze Solver and Line Follower with programable PID controller via BT
==> Basic movement based on Nano Mouse Robot, developed by Michael Backus (http://www.akrobotnerd.com/ )
==> Line follow based on http://samvrit.tk/tutorials/pid-control-arduino-line-follower-robot/?ckattempt=1
==> CREDIT to Patrick McCabe for the path Solving Code, visit patrickmccabemakes.com!!
Marcelo Jose Rovai - 23 April, 2016 - Visit: http://mjrobot.org
-------------------------------------------------------------------*/

#include <Servo.h>
#include "robotDefines.h"

String command;
String device;

// BT Module
#include <SoftwareSerial.h>
SoftwareSerial BT1(10, 11); // El pin 10 es Rx y el pin 11 es Tx

//---------------------------------------------
void setup() 
{
  
  Serial.begin(9600);
  BT1.begin(9600);
  
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  
  // line follow sensors
  pinMode(lineFollowSensor0, INPUT);
  pinMode(lineFollowSensor1, INPUT);
  pinMode(lineFollowSensor2, INPUT);
  pinMode(lineFollowSensor3, INPUT);
  pinMode(lineFollowSensor4, INPUT);
  
  // servos
  leftServo.attach(5);
  rightServo.attach(3);
  
  BT1.print("check the PID constants to be sent to Robot");
  Serial.print("check the PID constants to be sent to Robot");
  BT1.println('\n');
  
  while (digitalRead(buttonPin) && !mode)
  {  
    checkBTcmd();  // verify if a comand is received from BT remote control
    manualCmd ();    
    command = "";  
  }
  
  checkPIDvalues();
  mode = STOPPED;
  status = 0; // 1st pass
}

void loop() 
{
  ledBlink(1);
  BT1.println("Start First Pass");
  Serial.println("Start First Pass");
  readLFSsensors();  
  mazeSolve(); // First pass to solve the maze
  ledBlink(2);
  BT1.println("End First Pass"); 
  Serial.println("End First Pass"); 
  
   while (digitalRead(buttonPin) && !mode)
  {  
    checkBTcmd();  // verify if a comand is received from BT remote control
    manualCmd ();    
    command = "";  
  }
  
  BT1.println("Starting 2nd Pass"); 
  Serial.println("Starting 2nd Pass"); 
  pathIndex = 0;
  status = 0;
  mazeOptimization(); //run the maze as fast as possible
  ledBlink(3);
  BT1.println("End 2nd Pass"); 
  Serial.println("End 2nd Pass"); 
  
  while (digitalRead(buttonPin) && !mode)
  {  
    checkBTcmd();  // verify if a comand is received from BT remote control
    manualCmd ();    
    command = "";  
  }
  
  mode = STOPPED;
  status = 0; // 1st pass
  pathIndex = 0;
  pathLength = 0;
}

Functions

C/C++
void mazeSolve(void)
{
    while (!status)
    {
        readLFSsensors();  
        switch (mode)
        {   
          case NO_LINE:  
            motorStop();
            goAndTurn (LEFT, 180);
            recIntersection('B');
            break;
          
          case CONT_LINE: 
            runExtraInch();
            readLFSsensors();
            if (mode != CONT_LINE) {goAndTurn (LEFT, 90); recIntersection('L');} // or it is a "T" or "Cross"). In both cases, goes to LEFT
            else mazeEnd(); 
            break;
            
         case RIGHT_TURN: 
            runExtraInch();
            readLFSsensors();
            if (mode == NO_LINE) {goAndTurn (RIGHT, 90); recIntersection('R');}
            else recIntersection('S');
            break;   
            
         case LEFT_TURN: 
            goAndTurn (LEFT, 90); 
            recIntersection('L');
            break;   
         
         case FOLLOWING_LINE: 
            followingLine();
            break;      
        
         }
    }
}

//---------------------------------------------
void recIntersection(char direction)
{
  path[pathLength] = direction; // Store the intersection in the path variable.
  pathLength ++;
  simplifyPath(); // Simplify the learned path.
}

//----------------------------------------------
void mazeEnd(void)
{
  motorStop();
  BT1.print("The End  ==> Path: ");
  for(int i=0;i<pathLength;i++)
    BT1.print(path[i]);
    //Serial.print(path[i]);
  BT1.println("");
  Serial.print("  pathLenght ==> ");
  Serial.println(pathLength);
  status = 1;
  mode = STOPPED;
}

//----------------------------------------------
void followingLine(void)
{
   //readLFSsensors(); 
   calculatePID();
   motorPIDcontrol();   
}

//------------------------------------------------------------------------------------------
// Path simplification.  The strategy is that whenever we encounter a
// sequence xBx, we can simplify it by cutting out the dead end.  For
// example, LBL -> S, because a single S bypasses the dead end
// represented by LBL.
void simplifyPath()
{
  // only simplify the path if the second-to-last turn was a 'B'
  if(pathLength < 3 || path[pathLength-2] != 'B')
    return;

  int totalAngle = 0;
  int i;
  for(i=1;i<=3;i++)
  {
    switch(path[pathLength-i])
    {
      case 'R':
        totalAngle += 90;
	break;
      case 'L':
	totalAngle += 270;
	break;
      case 'B':
	totalAngle += 180;
	break;
    }
  }

  // Get the angle as a number between 0 and 360 degrees.
  totalAngle = totalAngle % 360;

  // Replace all of those turns with a single one.
  switch(totalAngle)
  {
    case 0:
	path[pathLength - 3] = 'S';
	break;
    case 90:
	path[pathLength - 3] = 'R';
	break;
    case 180:
	path[pathLength - 3] = 'B';
	break;
    case 270:
	path[pathLength - 3] = 'L';
	break;
  }

  // The path is now two steps shorter.
  pathLength -= 2;
  
} 

//----------------------------------------------------------------------------------------------
void mazeOptimization (void)
{
  while (!status)
  {
    readLFSsensors();  
    switch (mode)
    {
      case FOLLOWING_LINE:
        followingLine();
        break;    
      case CONT_LINE:
        if (pathIndex >= pathLength) mazeEnd (); 
        else {mazeTurn (path[pathIndex]); pathIndex++;}
        break;  
      case LEFT_TURN:
        if (pathIndex >= pathLength) mazeEnd (); 
        else {mazeTurn (path[pathIndex]); pathIndex++;}
        break;  
      case RIGHT_TURN:
        if (pathIndex >= pathLength) mazeEnd (); 
        else {mazeTurn (path[pathIndex]); pathIndex++;}
        break;   
    }    
   }  
}

//-----------------------------------------------------
void mazeTurn (char dir) 
{
  switch(dir)
  {
    case 'L': // Turn Left
       goAndTurn (LEFT, 90);      
       break;   
    
    case 'R': // Turn Right
       goAndTurn (RIGHT, 90);     
       break;   
       
    case 'B': // Turn Back
       goAndTurn (RIGHT, 800);     
       break;   
       
    case 'S': // Go Straight
       runExtraInch(); 
       break;
  }
}

GeneralFunctions.

C/C++
void ledBlink(int times)
{
   for (int i = 0; i<times; i++)
   { 
      digitalWrite (ledPin, HIGH);
      delay (500);
      digitalWrite (ledPin, LOW);
      delay (500);
   } 
}

//-----------------------------------------------------------------------------

 void checkBTcmd()  
 { 
   while (BT1.available())   //Check if there is an available byte to read
   {
     delay(10); //Delay added to make thing stable 
     char c = BT1.read(); //Conduct a serial read
     device += c; //build the string.
   }  
   if (device.length() > 0) 
   {
     Serial.print("Command received from BT ==> ");
     Serial.println(device); 
     command = device;
     device ="";  //Reset the variable
     BT1.flush();
    } 
}

//------------------------------------------------------------------------
void manualCmd()
{
  switch (command[0])
  {
    case 'g':
      mode = FOLLOWING_LINE;
      break;
    
    case 's': 
      motorStop(); //turn off both motors
      break;

    case 'f':  
      motorForward();  
      break;

    case 'r':     
      motorTurn(RIGHT, 30);
      motorStop();
      
      break;

   case 'l': 
      motorTurn(LEFT, 30);
      motorStop();
      break;
    
    case 'b':  
      motorBackward();
      break;
      
    case 'p':
      Kp = command[2];
      break;
    
    case 'i':
      Ki = command[2];
      break; 
    
    case 'd':
      Kd = command[2];
      break;
  }
}

//------------------------------------------------------------------------
void sendBTdata (int data) // send data to BT

{
    digitalWrite (ledPin, HIGH);
    BT1.print("Data from Arduino");
    BT1.print(data);
    BT1.print(" xx");
    BT1.println('\n');
    digitalWrite (ledPin, LOW);
}

//--------------------------------------------------------
void calculatePID()
{
  P = error;
  I = I + error;
  D = error-previousError;
  PIDvalue = (Kp*P) + (Ki*I) + (Kd*D);
  previousError = error;
}

//--------------------------------------------------------
void checkPIDvalues()
{
  
  BT1.print("PID: ");
  BT1.print(Kp);
  BT1.print(" - ");
  BT1.print(Ki);
  BT1.print(" - ");
  BT1.println(Kd);  
  
  Serial.print("PID: ");
  Serial.print(Kp);
  Serial.print(" - ");
  Serial.print(Ki);
  Serial.print(" - ");
  Serial.println(Kd);  
  
}

//-----------------------------------------------
void testLineFollowSensors()
{
     int LFS0 = digitalRead(lineFollowSensor0);
     int LFS1 = digitalRead(lineFollowSensor1);
     int LFS2 = digitalRead(lineFollowSensor2);
     int LFS3 = digitalRead(lineFollowSensor3);
     int LFS4 = digitalRead(lineFollowSensor4);
     
     Serial.print ("LFS: L  0 1 2 3 4  R ==> "); 
     Serial.print (LFS0); 
     Serial.print (" ");
     Serial.print (LFS1); 
     Serial.print (" ");
     Serial.print (LFS2); 
     Serial.print (" ");
     Serial.print (LFS3); 
     Serial.print (" ");
     Serial.print (LFS4); 
     Serial.print ("  ==> ");
    
     Serial.print (" P: ");
     Serial.print (P);
     Serial.print (" I: ");
     Serial.print (I);
     Serial.print (" D: ");
     Serial.print (D);
     Serial.print (" PID: ");
     Serial.println (PIDvalue);
}

sensorFuntions

C/C++
//-------------------------------------------------------------
/* read line sensors values 

Sensor Array 	Error Value
0 0 0 0 1	 4              
0 0 0 1 1	 3              
0 0 0 1 0	 2              
0 0 1 1 0	 1              
0 0 1 0 0	 0              
0 1 1 0 0	-1              
0 1 0 0 0	-2              
1 1 0 0 0	-3              
1 0 0 0 0	-4              

1 1 1 1 1        0 Robot found continuous line - test if an intersection or end of maze
0 0 0 0 0        0 Robot found no line: turn 180o

*/
void readLFSsensors()
{
  LFSensor[0] = digitalRead(lineFollowSensor0);
  LFSensor[1] = digitalRead(lineFollowSensor1);
  LFSensor[2] = digitalRead(lineFollowSensor2);
  LFSensor[3] = digitalRead(lineFollowSensor3);
  LFSensor[4] = digitalRead(lineFollowSensor4);
  
  farRightSensor = analogRead(farRightSensorPin);
  farLeftSensor = analogRead(farLeftSensorPin);
  
  if     ((LFSensor[0]== 1 )&&(LFSensor[1]== 1 )&&(LFSensor[2]== 1 )&&(LFSensor[3]== 1 )&&(LFSensor[4]== 1 ))  {mode = CONT_LINE; error = 0;}
  else if((LFSensor[0]== 0 )&&                                                   (farRightSensor < THRESHOLD)) {mode = RIGHT_TURN; error = 0;}
  else if ((farLeftSensor <  THRESHOLD)                                                  &&(LFSensor[4]== 0 )) {mode = LEFT_TURN; error = 0;}
  else if((LFSensor[0]== 0 )&&(LFSensor[1]== 0 )&&(LFSensor[2]== 0 )&&(LFSensor[3]== 0 )&&(LFSensor[4]== 0 ))  {mode = NO_LINE; error = 0;}
  else if((LFSensor[0]== 0 )&&(LFSensor[1]== 0 )&&(LFSensor[2]== 0 )&&(LFSensor[3]== 0 )&&(LFSensor[4]== 1 ))  {mode = FOLLOWING_LINE; error = 4;}
  else if((LFSensor[0]== 0 )&&(LFSensor[1]== 0 )&&(LFSensor[2]== 0 )&&(LFSensor[3]== 1 )&&(LFSensor[4]== 1 ))  {mode = FOLLOWING_LINE; error = 3;}
  else if((LFSensor[0]== 0 )&&(LFSensor[1]== 0 )&&(LFSensor[2]== 0 )&&(LFSensor[3]== 1 )&&(LFSensor[4]== 0 ))  {mode = FOLLOWING_LINE; error = 2;}
  else if((LFSensor[0]== 0 )&&(LFSensor[1]== 0 )&&(LFSensor[2]== 1 )&&(LFSensor[3]== 1 )&&(LFSensor[4]== 0 ))  {mode = FOLLOWING_LINE; error = 1;}
  else if((LFSensor[0]== 0 )&&(LFSensor[1]== 0 )&&(LFSensor[2]== 1 )&&(LFSensor[3]== 0 )&&(LFSensor[4]== 0 ))  {mode = FOLLOWING_LINE; error = 0;}
  else if((LFSensor[0]== 0 )&&(LFSensor[1]== 1 )&&(LFSensor[2]== 1 )&&(LFSensor[3]== 0 )&&(LFSensor[4]== 0 ))  {mode = FOLLOWING_LINE; error =- 1;}
  else if((LFSensor[0]== 0 )&&(LFSensor[1]== 1 )&&(LFSensor[2]== 0 )&&(LFSensor[3]== 0 )&&(LFSensor[4]== 0 ))  {mode = FOLLOWING_LINE; error = -2;}
  else if((LFSensor[0]== 1 )&&(LFSensor[1]== 1 )&&(LFSensor[2]== 0 )&&(LFSensor[3]== 0 )&&(LFSensor[4]== 0 ))  {mode = FOLLOWING_LINE; error = -3;}
  else if((LFSensor[0]== 1 )&&(LFSensor[1]== 0 )&&(LFSensor[2]== 0 )&&(LFSensor[3]== 0 )&&(LFSensor[4]== 0 ))  {mode = FOLLOWING_LINE; error = -4;}
  
  Serial.print (farLeftSensor);
  Serial.print (" <== LEFT  RIGH==> ");
  Serial.print (farRightSensor);
  Serial.print ("  mode: ");
  Serial.print (mode);
  Serial.print ("  error:");
  Serial.println (error);
    
}

//-----------------------------------------------------------
void readLateralSensors(void)

{
  
}

RobotDefines.h

C/C++
int mode = 0;

# define STOPPED 0
# define FOLLOWING_LINE 1
# define NO_LINE 2
# define CONT_LINE 3
# define POS_LINE 4
# define RIGHT_TURN 5
# define LEFT_TURN 6

const int power = 250;
const int iniMotorPower = 250;
const int adj = 0;
float adjTurn = 8;
int extraInch = 200;
int adjGoAndTurn = 800;

const int ledPin = 13;
const int buttonPin = 9;

// LFSensor more to the Left is "0"
const int lineFollowSensor0 = 12; 
const int lineFollowSensor1 = 18; 
const int lineFollowSensor2 = 17; 
const int lineFollowSensor3 = 16;
const int lineFollowSensor4 = 19;

const int farRightSensorPin = 0; //Analog Pin A0
const int farLeftSensorPin = 1; //Analog Pin A0
const int THRESHOLD = 150;
int farRightSensor = 0;
int farLeftSensor = 0;


int LFSensor[5]={0, 0, 0, 0, 0};

// PID controller
float Kp=50;
float Ki=0;
float Kd=0;

float error=0, P=0, I=0, D=0, PIDvalue=0;
float previousError=0, previousI=0;

#define RIGHT 1
#define LEFT -1

Servo leftServo;
Servo rightServo;

//-------------------------------------------------
//Specific Maze Phase 2 (optimization) definitions and variables 

unsigned char dir; 

// The path variable will store the path that the robot has taken:
//  'L' for left
//  'R' for right
//  'S' for straight (going straight through an intersection)
//  'B' for back (U-turn)

char path[100] = "";
unsigned char pathLength = 0; // the length of the path
int pathIndex = 0;
unsigned int status = 0; // solving = 0; reach end = 1

MotorFuntions

C/C++
void motorStop()
{
  leftServo.writeMicroseconds(1500);
  rightServo.writeMicroseconds(1500);
  delay(200);
}

//--------------------------------------------- 
void motorForward()
{
  leftServo.writeMicroseconds(1500 - (power+adj));
  rightServo.writeMicroseconds(1500 + power);
}

//---------------------------------------------
void motorBackward()
{
  leftServo.writeMicroseconds(1500 + power);
  rightServo.writeMicroseconds(1500 - power);
}

//---------------------------------------------
void motorFwTime (unsigned int time)
{
  motorForward();
  delay (time);
  motorStop();
}

//---------------------------------------------
void motorBwTime (unsigned int time)
{
  motorBackward();
  delay (time);
  motorStop();
}

//------------------------------------------------
void motorTurn(int direction, int degrees)
{
  leftServo.writeMicroseconds(1500 - (iniMotorPower+adj)*direction);
  rightServo.writeMicroseconds(1500 - iniMotorPower*direction);
  delay (round(adjTurn*degrees+20));
  motorStop();
}

//---------------------------------------------------
void motorPIDcontrol()
{
  
  int leftMotorSpeed = 1500 - (iniMotorPower+adj) - PIDvalue;
  int rightMotorSpeed = 1500 + iniMotorPower - PIDvalue;
  
  // The motor speed should not exceed the max PWM value
   constrain(leftMotorSpeed, 1000, 2000);
   constrain(rightMotorSpeed, 1000, 2000);
  
  leftServo.writeMicroseconds(leftMotorSpeed);
  rightServo.writeMicroseconds(rightMotorSpeed);
  
  //Serial.print (PIDvalue);
  //Serial.print (" ==> Left, Right:  ");
  //Serial.print (leftMotorSpeed);
  //Serial.print ("   ");
  //Serial.println (rightMotorSpeed);
}

//---------------------------------------------------
void runExtraInch(void)
{
  motorPIDcontrol();
  delay(extraInch);
  motorStop();
}

//---------------------------------------------------
void goAndTurn(int direction, int degrees)
{
  motorPIDcontrol();
  delay(adjGoAndTurn);
  motorTurn(direction, degrees);
}

Credits

Muhammad Sheraz

Muhammad Sheraz

11 projects • 45 followers
Student of Bsc electrical engineering at 7th semester In NFCIET Multan Pakistan. CONTACT: sheraz9345@gmail.com
Thanks to Maze.

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