By Toys.Engineering Team — Jul 1, 2024

How to Build an RC Car with Arduino Using One DC Motor and a Servo Motor for Steering

Building an RC (remote-controlled) car with Arduino is a fun and educational project that combines electronics, programming, and basic robotics. In this guide, we’ll cover how to build a simple Arduino-powered RC car that uses one DC motor for propulsion and a servo motor for steering. This configuration simplifies the design, reducing the number of components, and makes it an ideal project for beginners or anyone looking to understand the basics of RC car mechanics and Arduino programming.

Introduction
Materials Needed
Understanding the Circuit and Components
Assembling the Chassis and Components
Programming Your Arduino
Testing and Troubleshooting
Conclusion and Next Steps

1. Introduction

Arduino makes it easy for beginners and hobbyists to create custom RC cars by handling input and output controls for various components. In this project, we’ll use a single DC motor for forward and backward movement, while a servo motor will be used to control the car's steering. A Bluetooth module will allow us to wirelessly control the car from a smartphone, making it a fully functional RC vehicle.

This setup is simple yet effective and is a great introduction to robotics and remote control systems.

2. Materials Needed

To build this RC car, gather the following components:

Electronics

Arduino Uno: The main controller for the car.
Motor Driver (L298N): Used to control the DC motor’s direction and speed.
DC Motor (x1): Drives the wheels for forward and reverse motion.
Servo Motor (x1): Controls the steering.
Bluetooth Module (HC-05 or HC-06): For wireless control.
Battery Pack (6-9V): Powers the motor and Arduino.
Jumper Wires: Connect components to the Arduino.
Breadboard (optional): Useful for organizing wiring.

Mechanical Parts

Chassis: A frame to mount all components.
Wheels: Two wheels for the drive motor and one caster wheel for stability.
Caster Wheel: Used to stabilize the car, allowing it to pivot smoothly during steering.
Screws, Nuts, and Adhesive: For securing components.

3. Understanding the Circuit and Components

Before assembling, it’s essential to understand each component’s role and how they connect.

Arduino Uno: This microcontroller will be programmed to read Bluetooth commands and control the motor and servo accordingly.
Motor Driver (L298N): The L298N motor driver module allows the Arduino to control the DC motor’s speed and direction.
DC Motor: This motor will move the car forward and backward.
Servo Motor: This motor will adjust the car’s steering angle, controlling the front wheels’ direction.
Bluetooth Module (HC-05): The HC-05 Bluetooth module enables the car to receive control commands from a smartphone or any Bluetooth-enabled device.

4. Assembling the Chassis and Components

Step 1: Assemble the Chassis and Mount the Wheels

Secure the two main wheels to the DC motor shaft or axle, depending on your chassis design. Attach the caster wheel to the back end of the chassis to support the car’s weight and enable it to pivot smoothly when the servo steers the front wheels.

Step 2: Mount the Arduino and Motor Driver

Secure the Arduino and the L298N motor driver module onto the chassis using screws or double-sided tape. Ensure they are placed in a way that allows easy access to power connections and wiring.

Step 3: Attach the DC Motor to the Motor Driver

Connect the DC motor to the motor driver’s output terminals (OUT1 and OUT2). The motor driver will control the motor’s speed and direction based on commands from the Arduino.

Step 4: Connect the Servo Motor to the Front Wheels

Mount the servo motor onto the front of the chassis, and connect it to the front wheels using a simple linkage system. This setup will allow the servo to steer the wheels left and right by adjusting its position angle. Connect the servo’s signal pin to one of the PWM-capable pins on the Arduino (e.g., Pin 9).

Step 5: Connect the Bluetooth Module to Arduino

Wire the Bluetooth module to the Arduino as follows:

VCC to 5V on the Arduino
GND to GND
TX of HC-05 to RX on Arduino (Pin 0)
RX of HC-05 to TX on Arduino (Pin 1)

Step 6: Power Connections

Connect the battery pack to the motor driver module’s power input. You can power the Arduino either through a USB connection or by connecting it directly to the battery pack if it supports the voltage range. Ensure the power supply is sufficient to run both the Arduino and the motor driver without overheating.

5. Programming Your Arduino

Step 1: Set Up Arduino IDE

Download and install the Arduino IDE if you haven’t already. Connect your Arduino to your computer using a USB cable, and ensure the correct board and port are selected in the IDE.

Step 2: Write the Code

Here’s a sample Arduino code to get started. This program reads data from the Bluetooth module and controls the DC motor and servo motor based on the commands received.

#include <Servo.h>

int motorPin1 = 5; // Motor driver pin
int motorPin2 = 6; // Motor driver pin
int speedPin = 3;  // PWM pin for speed control
int servoPin = 9;  // Servo signal pin

Servo steeringServo;

void setup() {
  pinMode(motorPin1, OUTPUT);
  pinMode(motorPin2, OUTPUT);
  steeringServo.attach(servoPin);
  
  Serial.begin(9600); // Bluetooth communication rate
}

void loop() {
  if (Serial.available()) {
    char command = Serial.read();
    if (command == 'F') {
      forward();
    } else if (command == 'B') {
      backward();
    } else if (command == 'L') {
      left();
    } else if (command == 'R') {
      right();
    } else if (command == 'S') {
      stopMotors();
    }
  }
}

void forward() {
  digitalWrite(motorPin1, HIGH);
  digitalWrite(motorPin2, LOW);
  analogWrite(speedPin, 200); // Adjust speed as desired
}

void backward() {
  digitalWrite(motorPin1, LOW);
  digitalWrite(motorPin2, HIGH);
  analogWrite(speedPin, 200); // Adjust speed as desired
}

void left() {
  steeringServo.write(45); // Turn left
}

void right() {
  steeringServo.write(135); // Turn right
}

void stopMotors() {
  digitalWrite(motorPin1, LOW);
  digitalWrite(motorPin2, LOW);
  analogWrite(speedPin, 0); // Stop motor
  steeringServo.write(90); // Center steering
}

Step 3: Upload the Code

Upload the code to your Arduino board, and verify that it compiles without errors.

Step 4: Test with Bluetooth

Pair the Bluetooth module with your smartphone. Use a Bluetooth terminal app to send commands such as 'F' (forward), 'B' (backward), 'L' (left), 'R' (right), and 'S' (stop) to control the car.

6. Testing and Troubleshooting

Common Issues and Fixes:

Motor Not Responding: Double-check motor connections to the motor driver, and verify the motor driver is receiving power.
Bluetooth Not Pairing: Make sure your Bluetooth module is in pairing mode and verify your smartphone’s Bluetooth settings.
Steering Not Turning Correctly: Adjust the servo’s turning angle in the code, or check that the linkage is connected securely.
Power Issues: Ensure the battery pack can handle the load of the motor and servo motor.

Testing the RC car in small increments can help troubleshoot these issues effectively.

7. Conclusion and Next Steps

Congratulations on building your first Arduino RC car with one DC motor and a servo for steering! This project introduced you to the basics of controlling motors, using Bluetooth with Arduino, and creating a simple steering mechanism.

Ideas for Next Steps:

Add Ultrasonic Sensors for obstacle detection.
Incorporate Speed Control by adjusting PWM values based on Bluetooth input.
Upgrade the Power Supply with a rechargeable battery for longer run times.

Experiment with these ideas to make your RC car even more functional and enjoyable. With a solid foundation in Arduino robotics, the possibilities are endless!

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