Gesture Controlled Robot

Two-wheeled robot controlled entirely by hand gestures using Bluetooth. An MPU6050 on the controller detects hand tilt and sends directional commands wirelessly via HC-05 Bluetooth modules to the robot. The biggest challenge was calibrating the gyroscope thresholds and getting the two Bluetooth modules to pair correctly.

Engineer	School	Area of Interest	Grade
Adhrit M	Fallon Middle School	Bioengineering	Incoming 9th Grader

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Final Milestone

For my final milestone I completed all 3 modifications I planned — a direct 9V battery connection to the motor driver for more speed, an LCD screen that displays the current direction in real time, and a DFPlayer Mini that plays different sound effects for each movement using MP3 files on a micro SD card.

Biggest Challenges and Triumphs: The hardest part of the whole project was debugging hardware — things like a missing GND wire or a loose breadboard connection would break everything and take forever to find. My biggest triumph was getting the full robot working with all 3 modifications together — motors, Bluetooth, screen, and sound all running at the same time.

Key Topics I Learned:

• Bluetooth communication with HC-05 modules
• Gesture sensor data with MPU6050
• Motor control with L298N motor driver
• I2C communication for the LCD screen
• Serial communication for DFPlayer Mini
• Arduino SoftwareSerial library

What I Hope to Learn Next: I want to learn more about PCB design so I can make my own custom circuit boards instead of using jumper wires everywhere. I also want to explore more advanced sensors and eventually build something that can do way more things at the same time.

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First Milestone

For my first milestone I finished the base project — all the wiring and code for the gesture controlled robot.

How It Works:

• You tilt your hand
• The MPU6050 detects that and sends the tilt coordinates to the hand Arduino
• The hand Arduino reads the tilt values and sends commands over Bluetooth via HC-05 to the robot’s Arduino
• The robot Arduino receives the commands and controls the L298N motor driver
• The L298N drives the two DC motors according to the gesture you chose

Hardest Parts:

• Getting the two HC-05 modules to pair
• MPU6050 not being detected due to a breadboard connection issue
• Calibrating the tilt thresholds for each direction
• Motor directions being reversed

Plans After First Milestone:

• Connecting a battery directly to the motor driver for more speed
• Adding a screen that displays the current direction
• Adding sound effects with DFPlayer Mini

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Schematics

📐 Wiring Schematic

🔄 Pin Substitution Chart

HC-05 Bluetooth Module → HC-SR04 (substitute)

Used twice — once on the transmitter Arduino, once on the receiver Arduino.

Real HC-05 Pin	Function	HC-SR04 Substitute Pin	Wire Color
VCC	Power 3.3V–5V	VCC	🔴 Red
GND	Ground	GND	⚫ Black
TXD	Transmit data → Arduino RX	TRIG	🔵 Blue
RXD	Receive data ← Arduino TX	ECHO	🟢 Green

MPU6050 Gyroscope → LM393 Comparator IC (substitute)

Real MPU6050 Pin	Function	LM393 Substitute Pin	Wire Color
VCC	Power 3.3V	Pin 8 (V+)	🔴 Red
GND	Ground	Pin 4 (GND)	⚫ Black
SDA	I2C data → Arduino A4	Pin 2 (IN-)	🟡 Yellow
SCL	I2C clock → Arduino A5	Pin 3 (IN+)	🟠 Orange
INT	Interrupt → Arduino D2 (optional)	Pin 1 (OUT)	🟣 Purple

DFPlayer Mini → Passive Buzzer (substitute)

The buzzer only beeps in Fritzing — the real DFPlayer plays audio files via Serial.

Real DFPlayer Pin	Function	Buzzer Substitute Pin	Wire Color
VCC	Power 5V	+ (positive)	🔴 Red
GND	Ground	- (negative)	⚫ Black
RX	Serial from Arduino TX	+ (signal)	🔵 Blue

✅ No Substitution Needed

Component	Fritzing Part	Status
Arduino Uno × 2	Arduino Uno	✅ Exact match
L298N Motor Driver	L298N	✅ Exact match
LCD 16×2 (I2C)	LCD 16×2	✅ Exact match
DC Motors × 2	DC Motor (yellow gearbox)	✅ Exact match
9V Battery × 2	9V Battery	✅ Exact match
Breadboard	Breadboard	✅ Exact match

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Code

Glove Code:

#include <SoftwareSerial.h>
#include <Wire.h>
#include <MPU6050.h>

SoftwareSerial BTSerial(2, 3);
MPU6050 mpu;

void setup() {
  Serial.begin(9600);
  BTSerial.begin(9600);
  Wire.begin();
  mpu.initialize();
}

void loop() {
  int16_t ax, ay, az, gx, gy, gz;
  mpu.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);

  char cmd;
  if (ay > 5000) cmd = 'F';
  else if (ay < -8000) cmd = 'B';
  else if (ax < 9000) cmd = 'L';
  else if (ax > 14000) cmd = 'R';
  else cmd = 'S';

  Serial.println(cmd);
  BTSerial.print(cmd);
  delay(100);
}

Robot Code:

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <SoftwareSerial.h>
#include <DFRobotDFPlayerMini.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);
SoftwareSerial mySoftwareSerial(7, 8);
DFRobotDFPlayerMini myDFPlayer;

#define IN1 5
#define IN2 6
#define IN3 10
#define IN4 11

char lastCmd = ' ';

void setup() {
  Serial.begin(9600);
  mySoftwareSerial.begin(9600);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Robot Ready!");
  myDFPlayer.begin(mySoftwareSerial);
  myDFPlayer.volume(30);
  myDFPlayer.EQ(DFPLAYER_EQ_NORMAL);
  myDFPlayer.play(1);
  stopMotors();
}

void loop() {
  if (Serial.available()) {
    char cmd = Serial.read();
    if (cmd != lastCmd) {
      lastCmd = cmd;
      if (cmd == 'R') { stopMotors(); showDirection("STOPPED"); myDFPlayer.stop(); myDFPlayer.play(5); }
      else if (cmd == 'B') { forward(); showDirection("GOING BACKWARD"); myDFPlayer.stop(); myDFPlayer.play(3); }
      else if (cmd == 'F') { backward(); showDirection("GOING FORWARD"); myDFPlayer.stop(); myDFPlayer.play(2); }
      else if (cmd == 'L') { turnLeft(); showDirection("GOING RIGHT"); myDFPlayer.stop(); myDFPlayer.play(4); }
      else if (cmd == 'S') { turnRight(); showDirection("GOING LEFT"); myDFPlayer.stop(); myDFPlayer.play(4); }
    } else {
      if (cmd == 'R') stopMotors();
      else if (cmd == 'B') forward();
      else if (cmd == 'F') backward();
      else if (cmd == 'L') turnLeft();
      else if (cmd == 'S') turnRight();
    }
  }
}

void showDirection(String dir) {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Direction:");
  lcd.setCursor(0, 1);
  lcd.print(dir);
}

void forward() {
  digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW);
}

void backward() {
  digitalWrite(IN1, LOW); digitalWrite(IN2, HIGH);
  digitalWrite(IN3, LOW); digitalWrite(IN4, HIGH);
}

void turnLeft() {
  digitalWrite(IN1, LOW); digitalWrite(IN2, HIGH);
  digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW);
}

void turnRight() {
  digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW); digitalWrite(IN4, HIGH);
}

void stopMotors() {
  digitalWrite(IN1, LOW); digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW); digitalWrite(IN4, LOW);
}

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Bill of Materials

Part	Note	Price	Link
Car Chassis Kit	Robot base with motors and wheels	$39.99	Link
Screwdriver Kit	For assembly	$5.94	Link
Arduino Uno Clone x2	Main controllers for robot and glove	$14.98	Link
Electronics Kit	Jumper wires, resistors, components	$14.00	Link
Breadboard Kit	For prototyping connections	$8.79	Link
Micro USB Cable	For programming Arduinos	$5.00	Link
MPU6050 Accelerometer	Detects hand tilt gestures	$9.00	Link
HC-05 Bluetooth x2	Wireless communication between glove and robot	$9.00	Link
Breadboard Power Supply	Powers breadboard components	$8.00	Link
9V Batteries	Powers robot and glove	$8.69	Link
Velcro Tape	Mounts components to glove and robot	$8.00	Link
DMM	Multimeter for debugging	$9.99	Link
LCD Screen 16x2 with I2C	Displays current direction on robot	$9.00	Link
DFPlayer Mini	Plays sound effects for each movement	$9.00	Link
Jumper Wires	Connects all components together	$6.00	Link
8GB Micro SD Card	Stores MP3 sound files for DFPlayer	$20.00	Link
L298N Mini Motor Driver	Controls the two DC motors	$7.00	Link
Speaker 8 Ohm	Outputs sound from DFPlayer Mini	$10.00	Link

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Other Resources/Examples

• Hand Gesture Control Robot via Bluetooth - Hackster.io
• Hand Gesture Controlled Robot - YouTube