An IOT project on Microcontroller based, Bluetooth enabled robotic car model making and controlled by smart phone

 

  Smart Bluetooth Car System

 Code

1.     Abstract

This project presents a Bluetooth-Controlled Smart Car equipped with an automated obstacle scanning system. The system is built using an Arduino Uno microcontroller, an L293D motor driver shield, four DC gear motors, an HC-05 Bluetooth module, a servo motor, and an ultrasonic distance sensor. The Arduino receives directional commands from a mobile device through Bluetooth, allowing the car to move forward, backward, left, or right. The servo-driven ultrasonic sensor continuously scans its surroundings from 0° to 180° to measure distance. Based on predefined threshold values, the Arduino determines whether an obstacle is near. If an object is detected within the restricted range, the system automatically stops the car to prevent collision. This project demonstrates a combination of wireless control and autonomous safety features for improved navigation.

 

 

 

2. Introduction

 

I. Modern robotics and automation focus on creating machines that can move intelligently while ensuring safety. Traditional remote-controlled cars lack automatic sensing features, making collision avoidance difficult.

 

II. Smart robotic vehicles with wireless control and obstacle-detection systems address this problem by combining manual operation with autonomous decision-making.

 

III. This project focuses on developing a Bluetooth-Controlled Smart Car using Arduino Uno that can be manually driven through a mobile app while also scanning its surroundings using an ultrasonic sensor.

 

IV. The system uses an HC-05 Bluetooth module to receive directional commands from a smartphone, enabling movement in forward, backward, left, and right directions.

 

V. A servo-mounted ultrasonic sensor rotates from 0° to 180°, continuously measuring distance. Based on the detected range, the Arduino automatically stops the car if an obstacle is too close.

 

VI. The car uses an L293D motor driver shield and four DC gear motors for stable and smooth movement, while the servo adds a dynamic scanning capability.

 

VII. This project aims to combine wireless control with autonomous safety features to create a smarter and safer robotic vehicle suitable for robotics learning, obstacle-avoidance applications, and intelligent navigation demonstrations.

 

 

3. OBJECTIVE

 

1.    To design a robotic car controlled wirelessly through a smartphone using Bluetooth communication.

2.    To implement smooth directional control (forward, backward, left, right, stop).

3.    To integrate microcontroller-based automation for efficient motor control.

4.    To analysis response time, stability, and wireless range.

5.    To demonstrate practical application of embedded systems and wireless technology in various sectors like automatic drug injector for medical purpose.

 

 

4. Required Components:

 

·      Arduino Uno

·      L293D Motor Driver Shield

·      4 × DC Gear Motors

·      HC-05 Bluetooth Module

·      HC-SR04 Ultrasonic Sensor

·      SG90 Servo Motor

·      Li-ion Battery Pack

·      Jumper Wires

·      Car Chassis

·      Switch and Battery Holder

 

 

 

 

 

4.1 Arduino Uno

 

·      Role: Acts as the brain of the system. It reads the analog signal from the soil sensor, processes the value using pre-set thresholds, and sends control signals to other components.

·      Internal Mechanism: Converts analog voltage from the sensor to a digital value using a 10-bit ADC (Analog to Digital Converter).

 

 

4.2     L293D Motor Driver Shiel

·      Drives the four DC gear motors by providing the required current. 

·      Allows bidirectional motor control (FORWARD/BACKWARD).

·      Works using H-bridge motor control technology.

 

4.3 DC Gear Motors (4x)

·      Provide movement to the robotic car in all directions.

·      Each motor is mounted on the chassis to allow stable motion.

·      Operates using DC electromagnetic rotation.

 

    4.5 HC-05 Bluetooth Module

·      Enables wireless communication between smartphone and Arduino.

 

       

·      Supports simple serial commands (F/B/L/R/S).

 

·      Operates using Bluetooth SPP (Serial Port Protocol).

 

   

4.6 HC-SR04 Ultrasonic Sensor

·      Detects distance by measuring time between sound pulse and echo.

 

·      Provides obstacle information to prevent collisions.

·      Works on ultrasonic sound wave reflection principle.

 

 

 

 

        4.7 SG90 Servo Motor

·      Rotates the ultrasonic sensor from 0°–180° for wide-area scanning.

·      Provides precise angular control using PWM signals.

 

·      Works using geared DC motor + position feedback system.

 

         4.8 Li-ion Battery Pack

·      Powers the motors and electronic modules.

·      Rechargeable and lightweight for long runtime.

·      Uses lithium-ion chemical energy storage.

 

4.9     Jumper Wires

·      Provide electrical connections between all sensors and modules.

 

           

 

·      Male-to-male, male-to-female, and female-to-female types.

·      Based on copper conductor wiring.

4.10 Robot Car Chassis

•   Supports all hardware components like motors, sensors, and battery

·      Ensures stability while moving on different surfaces.

·      Usually made from acrylic or metal sheets.

4.11                   Switch and Battery Holder

 

·      Allows easy ON/OFF control of the entire system

·      Securely holds rechargeable batteries.

·      Uses simple mechanical switching mechanism

 

5. System Architecture Block Diagram

 

6. System and Hardware setup and Bluetooth Interface:

1.     Microcontroller Integration -The Arduino/ESP32 acts as the central controller, receiving Bluetooth commands and generating control signals for motors and sensors.

2.     Motor Driver Connection-The L298N motor driver is connected to the microcontroller to regulate the speed and direction of the DC motors safely.

3.     Bluetooth Module Interface-An HC-05/HC-06 module is interfaced with the microcontroller via serial communication (TX/RX pins) for wireless control.

4.     Sensor and Peripheral Setup-Ultrasonic sensor and servo motor are connected to dedicated I/O pins for obstacle detection and dynamic steering.

5.     Power Supply and Wiring Layout-A stable power system (battery + voltage regulation) ensures continuous operation of motors, sensors, Bluetooth, and the microcontroller.

6.     Code the Arduino – We write a program in Arduino IDE and save the code on .ino file, then after compiling we upload the code on Arduino

7.     Bluetooth Application – We designing an application or install readymade app, then connect this with HC-05 Module. Then the car is ready to run wirelessly.

 

 

8. Overall System Process:

1.    The HC-05 Bluetooth module receives directional commands (F/B/L/R/S) from the mobile device and sends them to the Arduino.

 

2.    The Arduino reads the incoming command and activates the motors through the L293D motor driver shield to move the car accordingly.

 

3.    Simultaneously, the servo motor rotates the ultrasonic sensor from 0° to 180° to continuously scan the environment.

 

4.    The ultrasonic sensor measures the distance of nearby obstacles and sends the echo-time data to the Arduino.

 

5.    The Arduino compares the detected distance to a preset safety threshold to determine if an object is too close.

 

6.    If an obstacle is detected within the restricted distance, the Arduino automatically stops the car to prevent collision.

 

7.    The system repeats this scanning and movement process continuously while the car is being controlled over Bluetooth.

 

 

 

 

8.  Summary of Physics & Electronics Concepts Used

·      Ultrasonic wave propagation & echo reflection (distance measurement using sound waves)

·      Pulse Width Modulation (PWM) (servo motor angle control and motor speed control

·      Electromagnetism (DC motor rotation in all four wheels)

·      Serial communication (Bluetooth data transfer between smartphone and Arduino)

·      H-Bridge motor control (bidirectional control using L293D driver)

·      Time-of-flight measurement (ultrasonic distance detection based on echo timing)

·      Energy conversion (Li-ion battery powering motors and electronics) Digital signal processing (Arduino interpreting direction commands and sensor inputs)