Self-Balancing Robot

A self-balancing robot using an Arduino microcontroller, MPU6050/MPU6500 IMU sensor, and PID control algorithm to maintain equilibrium on two wheels.

Overview

This robot uses a gyroscope (and accelerometer from the MPU6050/MPU6500) to measure its tilt angle in real-time. A PID controller processes this data to adjust motor speeds, keeping the robot balanced even when pushed or tilted. The system operates without using the MPU's Digital Motion Processor (DMP).

Hardware Requirements

Microcontroller

• Arduino UNO, Arduino Nano, or compatible board

Sensors

• MPU6050/MPU6500 - 6-DOF IMU sensor (accelerometer + gyroscope)

Motor Driver

• L298N - Dual H-Bridge motor driver module

Motors

• 2x DC Motors - With wheels attached (5V-12V)

Other Components

• Power Supply - Battery pack (5V-12V depending on motors)
• Wires - Jumper and connecting wires
• Structural Frame - Robot chassis/body

Connection Diagram

MPU6050/MPU6500 to Arduino

MPU Pin	Arduino Pin	Notes
VCC	5V (or 3.3V)	Power for sensor
GND	GND	Common ground
SCL	A5 (UNO/Nano) / 21 (MEGA)	I²C clock
SDA	A4 (UNO/Nano) / 20 (MEGA)	I²C data
INT	D2 (optional)	Not used in this sketch

L298N Motor Driver to Arduino

Function	Arduino Pin	L298N Pin	Description
ENA	D5 (PWM)	ENA	Left motor speed control
IN1	D6	IN1	Left motor direction 1
IN2	D7	IN2	Left motor direction 2
IN3	D9	IN3	Right motor direction 1
IN4	D8	IN4	Right motor direction 2
ENB	D10 (PWM)	ENB	Right motor speed control
+5V	—	+5V	Logic power for L298N
GND	GND	GND	Common ground

L298N Motor Connections

• Left Motor: Connect to OUT1 and OUT2
• Right Motor: Connect to OUT3 and OUT4
• +12V IN / GND: Connect to battery (for motor power)

Software Requirements

Arduino IDE Libraries

Install these libraries in the Arduino IDE (Sketch → Include Library → Manage Libraries):

1. MPU6050_tockn - IMU sensor library

   • Search: "MPU6050_tockn"
   • Author: tockn

2. PID_v1 - PID controller library

   • Search: "PID"
   • Author: Brett Beauregard

3. Wire - Built-in (I²C communication)

Installation

1. Clone/Download the project files
2. Open self_balancing.ino in Arduino IDE
3. Install the required libraries (see Software Requirements)
4. Connect your Arduino board via USB
5. Select the correct board and COM port
6. Upload the sketch to your Arduino

Configuration

PID Tuning (Lines 71-74)

Adjust these values to fine-tune balancing behavior:

double Kp = 60;     // Proportional gain
double Ki = 270;    // Integral gain
double Kd = 2.2;    // Derivative gain

• Kp: Increases responsiveness. Higher values = faster response but may cause oscillation.
• Ki: Corrects steady-state errors. Use carefully to avoid instability.
• Kd: Dampens oscillations. Helps smooth out movements.

Motor Speed Calibration (Lines 92-93)

Adjust to balance left and right motor speeds:

double motorSpeedFactorLeft = 0.6;   // Multiply left motor speed
double motorSpeedFactorRight = 0.5;  // Multiply right motor speed

If the robot drifts left, increase motorSpeedFactorRight or decrease motorSpeedFactorLeft.

GPIO Pins (Lines 86-91)

If using different Arduino pins, update these:

int ENA = 5;    // Left motor PWM
int IN1 = 6;    // Left motor direction
int IN2 = 7;    // Left motor direction
int IN3 = 9;    // Right motor direction
int IN4 = 8;    // Right motor direction
int ENB = 10;   // Right motor PWM

How It Works

1. Sensor Reading: The MPU6050 measures the robot's pitch angle (tilt)
2. Error Calculation: The PID controller compares actual angle vs. setpoint (0°)
3. Motor Adjustment: Based on PID output, motor speeds are adjusted to correct the tilt
4. Feedback Loop: This repeats ~100 times per second (10ms interval)

The balancing principle: If the robot tilts forward, the motor speeds increase to move forward and restore balance. If it tilts backward, motors move backward.

Calibration Steps

1. Power on the robot and observe serial output (9600 baud)
2. Keep the robot still during gyroscope calibration (takes ~5 seconds)
3. Place the robot on a flat surface at a slight angle (15-30°)
4. Gradually adjust PID values starting with small increments
5. Test responsiveness to gentle pushes
6. Fine-tune motor speed factors if drifting occurs

Troubleshooting

Issue	Solution
Robot doesn't balance	Check MPU6050 connection; recalibrate gyro offsets
Robot unresponsive	Verify L298N connections; check PWM pins
Drifts left/right	Adjust motor speed factors
Vibrates/oscillates	Decrease Kp or increase Kd
Slow response	Increase Kp
Power issues	Verify battery voltage matches motor specs

Notes

• Gyro Calibration: Performed automatically on startup with robot held still
• Serial Monitor: Set baud rate to 9600 to view sensor data
• Optimal Balance: Robot balances around pitch angle ≈ 0° (vertical)
• No DMP: Uses direct gyro/accel integration instead of MPU's Digital Motion Processor

Future Enhancements

• Add wireless remote control (Bluetooth/RF)
• Implement smartphone app control
• Add obstacle avoidance (distance sensors)
• Improve balance algorithm (use Kalman filter)
• Add speed/direction control via joystick

License

This project is open-source. Feel free to modify and improve it!

Author

Created for Arduino-based robotics learning and experimentation.