3-mode Bluetooth Robot Car

About the project

Robot car developed using Arduino that can operate in 3 modes - Manual, Automatic and Voice with additional features. The car is controlled wirelessly via Bluetooth from a dedicated Android app.

Project info

Difficulty: Moderate

Platforms: AndroidArduinoMIT App Inventor

Estimated time: 1 week

License: MIT license (MIT)

Items used in this project

Hardware components

Arduino Uno Rev 3 Arduino Uno Rev 3 x 1
Bluetooth Module Bluetooth Module HC-05 x 1
SG90 Servo SG90 Servo x 1
Ultrasonic Sensor Hc-sr04 Ultrasonic Sensor Hc-sr04 x 1
L298 Dual H-Bridge Motor Driver L298 Dual H-Bridge Motor Driver x 1
Robot car Kit- RC Smart Car Chassis Robot car Kit- RC Smart Car Chassis x 1
Lithium Ion Battery - 18650 Cell (2600mAh) Lithium Ion Battery - 18650 Cell (2600mAh) x 2

Software apps and online services

Arduino IDE Arduino IDE
MIT App Inventor MIT App Inventor

Hand tools and fabrication machines

Soldering Kit Soldering Kit x 1


About '3-Mode Bluetooth Robot'

A simple robot car can generally be controlled in one way as it is programmed to operate in certain way.

What if the same robot can switch between 3 modes of control instantaneously with minimal to no delay?

  • The 3-mode Bluetooth Robot is capable enough to be controlled in any of the 3 modes (Manual, Auto and Voice) instantaneously from one Android app.
  • Some more features are included for each mode in the app to enhance the functionality of the robot car.


  • Wireless control with Bluetooth
  • Dedicated Android app
  • Manual control using buttons on app
  • PWM based 3 levels of motor speed control.
  • Ultrasonic sensor based autonomous mode with direction display on the app.
  • Voice control using Google Speech Recognizer along with obstacle detection feature to avoid collision.


Robot Overview

The robot car is developed by modifying an existing RC car.

The body and motors of the car are kept intact while the included electronics are replaced with new components/modules.

Robot can be assembled on chassis as shown in the snapshot.


  • To program the microcontroller Arduino IDE is used which is commonly used with Arduino development boards.
  • In addition certain libraries are required for proper functioning of the microcontroller and interfaced components.


  • Servo
  • Soft PWM

Android App

The Android app is developed on MIT App Inventor platform.


Connecting to App

  • Connect/Disconnect button is provided in the app to connect with the robot car via Bluetooth.
  • HC-05 module is used for Bluetooth communication.

Manual Mode

  • The robot is controlled manually using buttons in the app.
  • PWM based 3 levels of motor speed control is implemented in the app which enables speed change on the go without delay.

Automatic Mode

  • This mode is autonomous where the robot finds its own path detecting obstacles with the help of ultrasonic sensor and servo motor.
  • The app displays the direction in which the robot is moving.

Voice Mode

  • The robot is controlled using voice commands provided by the user in the app using Google Speech Recognizer.
  • The robot car first scans for obstacle before executing the voice command and then proceeds.
  • It stops when an obstacle is detected by ultrasonic sensor and does not obey the command further displaying 'Obstacle Detected' on the opp.

Schematics, diagrams and documents

Circuit Connections



Code for the project


Photo of parikshitpagare


Electronics Engineer | Embedded Software


Leave your feedback...