Arduino UNO Obstacle Avoidance & Bluetooth Controlled Robot Car

The Arduino UNO-Based Obstacle Avoidance and Bluetooth Controlled Robot Car is an advanced multi-mode robotics project that combines autonomous navigation, wireless control, and intelligent sensor integration. Powered by the reliable Arduino Uno, this smart 4WD robot supports both automatic obstacle avoidance and manual Bluetooth control via smartphone.

This project is ideal for robotics competitions, engineering mini/major projects, and STEM learning programs.

Project Overview

This intelligent robotic system integrates:

Autonomous obstacle detection using HC-SR04 Ultrasonic Sensor
Line and obstacle sensing using dual IR sensor modules
Wireless smartphone control via HC-05 Bluetooth Module
Servo-based scanning using SG90 Servo Motor
Motor driving with L298N Motor Driver Module
Rechargeable 18650 Li-ion battery power system

The robot can switch between manual mode, line-following mode, and obstacle avoidance mode, making it a versatile robotics platform.

How the System Works

1️⃣ Autonomous Obstacle Avoidance Mode

The HC-SR04 ultrasonic sensor measures distance in front of the robot.
The SG90 servo motor rotates the ultrasonic sensor to scan left and right.
If an obstacle is detected within a set threshold:
- The robot stops
- Scans both sides
- Chooses the direction with more space
- Navigates safely around obstacles

This creates a 180° scanning smart navigation system.

2️⃣ Line Following Mode

Dual IR sensors detect black/white surface contrast.
Based on sensor readings:
- Moves forward
- Turns left or right
- Stops when necessary

This makes it suitable for track-based robotics competitions.

3️⃣ Bluetooth Manual Control Mode

The HC-05 Bluetooth module receives commands from a smartphone app.
The Arduino processes the command.
The L298N motor driver controls the four DC motors accordingly.

Supported movements:

Forward
Backward
Left
Right
Stop
Speed control (PWM-based)

Power System

The robot is powered by a rechargeable 18650 lithium-ion battery pack, providing:

Stable voltage supply
Portable operation
Energy-efficient performance

Key Features

✅ Dual mode operation (Autonomous + Bluetooth)
✅ 180° ultrasonic servo scanning
✅ Line following capability
✅ 4WD robotic platform
✅ Real-time wireless control
✅ PWM speed control
✅ Rechargeable battery-powered system
✅ Expandable architecture

SEO Keywords Naturally Included

Arduino obstacle avoidance robot
Bluetooth controlled robot car Arduino
Arduino smart robot car project
L298N motor driver robot
Ultrasonic sensor robot Arduino
4WD Arduino robot car
Line follower and obstacle avoiding robot
Engineering robotics project

Technical Concepts Demonstrated

Embedded systems programming
Multi-sensor integration
Ultrasonic distance measurement
Servo motor control (PWM timing)
H-bridge motor driver operation
Bluetooth serial communication
Mode switching logic
Autonomous navigation algorithm

Applications

Robotics competitions
Engineering mini & major projects
Autonomous navigation research
IoT-based robotics development
STEM & diploma robotics labs
Smart vehicle prototype systems

Future Upgrades & Enhancements

This smart robot can be upgraded with:

ESP32-CAM live video streaming
IoT cloud monitoring dashboard
GPS navigation module
Mobile app with joystick UI
Voice control integration
AI-based object recognition
Solar charging module

Ideal For

Robotics beginners and advanced learners
Engineering final year projects
School & college exhibitions
Automation and AI enthusiasts
Embedded systems training

Conclusion

The Arduino UNO Obstacle Avoidance and Bluetooth Controlled Robot Car is a powerful, scalable, and intelligent robotics platform that combines:

Autonomous obstacle detection
Line-following capability
Wireless Bluetooth control
4WD stability
Servo-based environmental scanning

This project demonstrates real-world applications of robotics, embedded systems, motor control, and wireless communication — all in one advanced yet beginner-friendly design.

Code:

#include <SoftwareSerial.h>
SoftwareSerial BT_Serial(2, 3); // RX, TX

#include <IRremote.h>
const int RECV_PIN = A5;
IRrecv irrecv(RECV_PIN);
decode_results results;

#define enA 10//Enable1 L298 Pin enA 
#define in1 9 //Motor1  L298 Pin in1 
#define in2 8 //Motor1  L298 Pin in1 
#define in3 7 //Motor2  L298 Pin in1 
#define in4 6 //Motor2  L298 Pin in1 
#define enB 5 //Enable2 L298 Pin enB 

#define servo A4

#define R_S A0 //ir sensor Right
#define L_S A1 //ir sensor Left

#define echo A2    //Echo pin
#define trigger A3 //Trigger pin

int distance_L, distance_F = 30, distance_R;
long distance;
int set = 20;

int bt_ir_data; // variable to receive data from the serial port and IRremote
int Speed = 130;  
int mode=0;
int IR_data;

void setup(){ // put your setup code here, to run once

pinMode(R_S, INPUT); // declare if sensor as input  
pinMode(L_S, INPUT); // declare ir sensor as input

pinMode(echo, INPUT );// declare ultrasonic sensor Echo pin as input
pinMode(trigger, OUTPUT); // declare ultrasonic sensor Trigger pin as Output  

pinMode(enA, OUTPUT); // declare as output for L298 Pin enA 
pinMode(in1, OUTPUT); // declare as output for L298 Pin in1 
pinMode(in2, OUTPUT); // declare as output for L298 Pin in2 
pinMode(in3, OUTPUT); // declare as output for L298 Pin in3   
pinMode(in4, OUTPUT); // declare as output for L298 Pin in4 
pinMode(enB, OUTPUT); // declare as output for L298 Pin enB 

irrecv.enableIRIn(); // Start the receiver
irrecv.blink13(true);

Serial.begin(9600); // start serial communication at 9600bps
BT_Serial.begin(9600); 

pinMode(servo, OUTPUT);

 for (int angle = 70; angle <= 140; angle += 5)  {
   servoPulse(servo, angle);  }
 for (int angle = 140; angle >= 0; angle -= 5)  {
   servoPulse(servo, angle);  }

 for (int angle = 0; angle <= 70; angle += 5)  {
   servoPulse(servo, angle);  }
delay(500);
}


void loop(){  

if(BT_Serial.available() > 0){  //if some date is sent, reads it and saves in state     
bt_ir_data = BT_Serial.read(); 
Serial.println(bt_ir_data);     
if(bt_ir_data > 20){Speed = bt_ir_data;}      
}

if (irrecv.decode(&results)) {
Serial.println(results.value,HEX);
bt_ir_data = IRremote_data();
Serial.println(bt_ir_data); 
irrecv.resume(); // Receive the next value
delay(100);
}

     if(bt_ir_data == 8){mode=0; Stop();}    //Manual Android Application and IR Remote Control Command   
else if(bt_ir_data == 9){mode=1; Speed=130;} //Auto Line Follower Command
else if(bt_ir_data ==10){mode=2; Speed=255;} //Auto Obstacle Avoiding Command

analogWrite(enA, Speed); // Write The Duty Cycle 0 to 255 Enable Pin A for Motor1 Speed 
analogWrite(enB, Speed); // Write The Duty Cycle 0 to 255 Enable Pin B for Motor2 Speed 

if(mode==0){     
//===============================================================================
//                          Key Control Command
//=============================================================================== 
     if(bt_ir_data == 1){forword(); }  // if the bt_data is '1' the DC motor will go forward
else if(bt_ir_data == 2){backword();}  // if the bt_data is '2' the motor will Reverse
else if(bt_ir_data == 3){turnLeft();}  // if the bt_data is '3' the motor will turn left
else if(bt_ir_data == 4){turnRight();} // if the bt_data is '4' the motor will turn right
else if(bt_ir_data == 5){Stop(); }     // if the bt_data '5' the motor will Stop

//===============================================================================
//                          Voice Control Command
//===============================================================================    
else if(bt_ir_data == 6){turnLeft();  delay(400);  bt_ir_data = 5;}
else if(bt_ir_data == 7){turnRight(); delay(400);  bt_ir_data = 5;}
}

if(mode==1){    
//===============================================================================
//                          Line Follower Control
//===============================================================================     
if((digitalRead(R_S) == 0)&&(digitalRead(L_S) == 0)){forword();}  //if Right Sensor and Left Sensor are at White color then it will call forword function
if((digitalRead(R_S) == 1)&&(digitalRead(L_S) == 0)){turnRight();}//if Right Sensor is Black and Left Sensor is White then it will call turn Right function  
if((digitalRead(R_S) == 0)&&(digitalRead(L_S) == 1)){turnLeft();} //if Right Sensor is White and Left Sensor is Black then it will call turn Left function
if((digitalRead(R_S) == 1)&&(digitalRead(L_S) == 1)){Stop();}     //if Right Sensor and Left Sensor are at Black color then it will call Stop function
} 

if(mode==2){    
//===============================================================================
//                          Obstacle Avoiding Control
//===============================================================================     
 distance_F = Ultrasonic_read();
 Serial.print("S=");Serial.println(distance_F);
  if (distance_F > set){forword();}
    else{Check_side();}
}

delay(10);
}

long IRremote_data(){
     if(results.value==0xFF02FD){IR_data=1;}  
else if(results.value==0xFF9867){IR_data=2;} 
else if(results.value==0xFFE01F){IR_data=3;} 
else if(results.value==0xFF906F){IR_data=4;} 
else if(results.value==0xFF629D || results.value==0xFFA857){IR_data=5;} 
else if(results.value==0xFF30CF){IR_data=8;} 
else if(results.value==0xFF18E7){IR_data=9;} 
else if(results.value==0xFF7A85){IR_data=10;} 
return IR_data;
}

void servoPulse (int pin, int angle){
int pwm = (angle*11) + 500;      // Convert angle to microseconds
 digitalWrite(pin, HIGH);
 delayMicroseconds(pwm);
 digitalWrite(pin, LOW);
 delay(50);                   // Refresh cycle of servo
}


//**********************Ultrasonic_read****************************
long Ultrasonic_read(){
  digitalWrite(trigger, LOW);
  delayMicroseconds(2);
  digitalWrite(trigger, HIGH);
  delayMicroseconds(10);
  distance = pulseIn (echo, HIGH);
  return distance / 29 / 2;
}

void compareDistance(){
       if (distance_L > distance_R){
  turnLeft();
  delay(350);
  }
  else if (distance_R > distance_L){
  turnRight();
  delay(350);
  }
  else{
  backword();
  delay(300);
  turnRight();
  delay(600);
  }
}

void Check_side(){
    Stop();
    delay(100);
 for (int angle = 70; angle <= 140; angle += 5)  {
   servoPulse(servo, angle);  }
    delay(300);
    distance_L = Ultrasonic_read();
    delay(100);
  for (int angle = 140; angle >= 0; angle -= 5)  {
   servoPulse(servo, angle);  }
    delay(500);
    distance_R = Ultrasonic_read();
    delay(100);
 for (int angle = 0; angle <= 70; angle += 5)  {
   servoPulse(servo, angle);  }
    delay(300);
    compareDistance();
}

void forword(){  //forword
digitalWrite(in1, HIGH); //Right Motor forword Pin 
digitalWrite(in2, LOW);  //Right Motor backword Pin 
digitalWrite(in3, LOW);  //Left Motor backword Pin 
digitalWrite(in4, HIGH); //Left Motor forword Pin 
}

void backword(){ //backword
digitalWrite(in1, LOW);  //Right Motor forword Pin 
digitalWrite(in2, HIGH); //Right Motor backword Pin 
digitalWrite(in3, HIGH); //Left Motor backword Pin 
digitalWrite(in4, LOW);  //Left Motor forword Pin 
}

void turnRight(){ //turnRight
digitalWrite(in1, LOW);  //Right Motor forword Pin 
digitalWrite(in2, HIGH); //Right Motor backword Pin  
digitalWrite(in3, LOW);  //Left Motor backword Pin 
digitalWrite(in4, HIGH); //Left Motor forword Pin 
}

void turnLeft(){ //turnLeft
digitalWrite(in1, HIGH); //Right Motor forword Pin 
digitalWrite(in2, LOW);  //Right Motor backword Pin 
digitalWrite(in3, HIGH); //Left Motor backword Pin 
digitalWrite(in4, LOW);  //Left Motor forword Pin 
}

void Stop(){ //stop
digitalWrite(in1, LOW); //Right Motor forword Pin 
digitalWrite(in2, LOW); //Right Motor backword Pin 
digitalWrite(in3, LOW); //Left Motor backword Pin 
digitalWrite(in4, LOW); //Left Motor forword Pin 
}

Key Features

Dual Mode Operation: Autonomous + Bluetooth Control
360° obstacle detection with servo scanning
Four-wheel drive robotic platform
Real-time wireless control via smartphone
Energy-efficient rechargeable power system
Suitable for beginners and advanced robotics learners

Applications

Obstacle avoidance robot projects
Bluetooth controlled robot car
Arduino robotics competitions
Smart navigation prototype systems
Engineering and diploma robotics projects
STEM and IoT educational demonstrations

This Arduino UNO smart robot car project demonstrates embedded system design, motor control, sensor integration, and wireless communication in a single powerful robotics platform. It is a scalable and customizable project suitable for school exhibitions, college projects, and robotics innovation labs.

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Arduino UNO Multi-Sensor Obstacle Avoidance & Bluetooth Controlled Robot Car Using L298N

Arduino UNO Obstacle Avoidance & Bluetooth Controlled Robot Car

Project Overview

How the System Works

1️⃣ Autonomous Obstacle Avoidance Mode

2️⃣ Line Following Mode

3️⃣ Bluetooth Manual Control Mode

Power System

Key Features

SEO Keywords Naturally Included

Technical Concepts Demonstrated

Applications

Future Upgrades & Enhancements

Ideal For

Conclusion

Key Features

Applications

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