Build a Rubik's Cube Solving Robot | Fun Kids Robotics Project

Kids Robotics Project

Build a Rubik's Cube
Solving Robot!

Learn robotics, coding & electronics — and watch your robot solve the cube in seconds!

⏱ ~6 Hours 🧠 Intermediate 💰 ~₹2,000 👶 Age 12+ ⚡ Arduino

What Will You Build?

A quick look at this awesome project

Colour Scanner

A camera scans all 6 faces of your scrambled Rubik's Cube and maps each coloured sticker into a digital model.

Smart Solver Brain

An Arduino Mega runs the famous Kociemba algorithm to calculate the shortest path to a solved cube — often in under 20 moves!

Robot Arms

Six servo motors act as arms that grip and spin the cube layers precisely until every colour is in the right place!

🌟 Cool fact! The fastest Rubik's Cube robot in the world solved it in just 0.38 seconds! Yours might take a few more — but it's still super impressive!

🛒

Parts You'll Need

Gather these before you start building

🎛️

Arduino Mega 2560

The "brain" that runs all your code

Must Have

⚙️

Servo Motors (×6)

SG90 or MG996R — spins the cube

Must Have

📷

Webcam or Pi Camera

Reads the cube colours

Must Have

🔩

3D Printed Frame

Holds everything together

Must Have

🔌

5V Power Supply (3A+)

Powers all 6 servo motors

Must Have

🟩

Breadboard + Jumper Wires

For connecting all components

Must Have

💡

RGB LED Ring

Status light — looks cool!

Nice to Have

📺

Small OLED Screen

Shows solve progress

Nice to Have

🔘

Push Button

Press to start solving!

Must Have

⚡

Circuit Diagram

How to wire everything together

Servo Signal Wires

Camera (USB/Data)

Button Signal

LED Ring Data

I2C (OLED)

Power (5V/GND)

⚠️ Important! Connect all servo GND wires to the power supply GND and also to Arduino GND. If you skip this step, your servos may act glitchy or not work at all!

🔨

Step-by-Step Build Guide

Follow these steps carefully and you'll have a robot in no time!

🖨️ Print or Build Your Robot Frame

Download free 3D print files for a Rubik's Cube robot frame from Thingiverse (search "Rubik's Cube Robot"). If you don't have a 3D printer, you can build a frame using:

Acrylic sheets (2–3mm thickness)
Wooden craft sticks and hot glue
PVC pipes and connectors

The frame needs to hold the cube in the center with 6 servo arms approaching from each face.

💡 Tip: If 3D printing, use PLA plastic at 20% infill. It's strong enough and prints fast!

⚙️ Mount the Servo Motors

Attach one servo motor to each of the 6 sides of your frame. Each servo needs to:

Align perfectly with the center of each cube face
Have a custom gripper arm attached to its shaft
Be securely screwed in (use M3 screws if 3D printed)

The servo gripper should grip the cube layer firmly enough to turn it, but not crush it!

💡 Tip: Use MG996R servo motors for the 4 side arms (they have more torque) and SG90s for top and bottom.

🔌 Wire Up the Circuit

Follow the circuit diagram above. Here's a quick wiring checklist:

Servo 1 (Top) signal → Arduino pin D2
Servo 2 (Bottom) signal → Arduino pin D3
Servo 3 (Left) signal → Arduino pin D4
Servo 4 (Right) signal → Arduino pin D5
Servo 5 (Front) signal → Arduino pin D6
Servo 6 (Back) signal → Arduino pin D7
Push button → D8 and GND
LED Ring data → D9
OLED SDA → A4, SCL → A5
All servo VCC → 5V power supply (+)
All servo GND → power supply (−) AND Arduino GND

⚠️ Never power servos directly from Arduino's 5V pin! They draw too much current and will fry your Arduino board.

💻 Upload the Arduino Code

Install the Arduino IDE on your computer, then copy the code below and upload it to your Arduino Mega via USB. Make sure you also install these libraries:

Servo.h — built-in with Arduino IDE
Adafruit_SSD1306 — for the OLED display
Adafruit_NeoPixel — for the LED ring

💡 In Arduino IDE: go to Tools → Manage Libraries and search for each library name to install!

📷 Set Up the Colour Scanner

Connect your webcam to your computer (not Arduino). Run a Python script that:

Captures images of all 6 faces of the scrambled cube
Detects the colour of each sticker using OpenCV
Sends the cube state (as a string like "UUUUUUUUU...") to Arduino via Serial port

You'll need Python 3 with pip install opencv-python pyserial kociemba

💡 Tip: Use a solid white or grey background behind the cube when scanning for the most accurate colour detection!

🧪 Test & Calibrate

Before solving a real cube, test everything:

Test each servo one at a time (upload the servo test sketch)
Make sure each arm grips and releases properly
Run the colour detection on a solved cube — all colours should map correctly
Do a dry run with a solved cube (robot should do nothing — it's already solved!)

🎉 When everything works, scramble the cube and press the START button. Watch your robot solve it!

💻

The Arduino Code

Copy this into Arduino IDE and upload!

RubiksCubeRobot.ino

// ===================================
// 🤖 RUBIK'S CUBE SOLVING ROBOT
//    Arduino Mega 2560 Code
// ===================================

#include <Servo.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_NeoPixel.h>
#include <Wire.h>

// ── PIN DEFINITIONS ──────────────────
#define SERVO_TOP    2
#define SERVO_BOT    3
#define SERVO_LEFT   4
#define SERVO_RIGHT  5
#define SERVO_FRONT  6
#define SERVO_BACK   7
#define BTN_PIN      8
#define LED_PIN      9
#define LED_COUNT    12
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 32

// ── SERVO POSITIONS ──────────────────
#define GRIP_ANGLE   60    // degrees to grip
#define OPEN_ANGLE   10    // degrees to release
#define TURN_90     150    // 90° clockwise turn
#define TURN_NEG90   30    // 90° counter-clockwise

Servo servoTop, servoBot, servoLeft;
Servo servoRight, servoFront, servoBack;
Adafruit_NeoPixel ring(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

String solveMoves = "";
bool readyToSolve = false;

// ── SETUP ────────────────────────────
void setup() {
  Serial.begin(9600);

  // Attach all servos
  servoTop.attach(SERVO_TOP);
  servoBot.attach(SERVO_BOT);
  servoLeft.attach(SERVO_LEFT);
  servoRight.attach(SERVO_RIGHT);
  servoFront.attach(SERVO_FRONT);
  servoBack.attach(SERVO_BACK);

  // Move all arms to open/home position
  openAllArms();

  // Start button pin
  pinMode(BTN_PIN, INPUT_PULLUP);

  // Start LED ring
  ring.begin();
  ring.setBrightness(80);
  setLEDs(0, 0, 255);  // Blue = ready

  // Start OLED display
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("CUBE ROBOT READY!");
  display.println("Waiting for scan...");
  display.display();
}

// ── MAIN LOOP ────────────────────────
void loop() {
  // Check if Python sent us move instructions
  if (Serial.available() > 0) {
    solveMoves = Serial.readStringUntil('\n');
    solveMoves.trim();
    readyToSolve = true;

    showMessage("Got moves!", "Press button!");
    setLEDs(255, 165, 0);  // Orange = moves received
  }

  // Check if button pressed
  if (readyToSolve && digitalRead(BTN_PIN) == LOW) {
    delay(200);  // debounce
    setLEDs(255, 0, 0);  // Red = solving!
    showMessage("SOLVING...", solveMoves.substring(0, 20));
    executeMoves(solveMoves);
    setLEDs(0, 255, 0);  // Green = solved!
    showMessage("SOLVED! :)", "Press RESET");
    readyToSolve = false;
  }
}

// ── EXECUTE MOVE SEQUENCE ────────────
void executeMoves(String moves) {
  int i = 0;
  while (i < moves.length()) {
    char face = moves[i];
    bool prime = (i + 1 < moves.length() && moves[i+1] == '\');
    bool twice = (i + 1 < moves.length() && moves[i+1] == '2');

    turnFace(face, prime, twice);
    delay(300);  // brief pause between moves

    if (prime || twice) i += 2; else i += 2;
  }
}

// ── TURN A FACE ──────────────────────
void turnFace(char face, bool prime, bool twice) {
  Servo* srv = nullptr;
  switch(face) {
    case 'U': srv = &servoTop;   break;
    case 'D': srv = &servoBot;   break;
    case 'L': srv = &servoLeft;  break;
    case 'R': srv = &servoRight; break;
    case 'F': srv = &servoFront; break;
    case 'B': srv = &servoBack;  break;
  }
  if (!srv) return;

  // Grip, turn, open
  srv->write(GRIP_ANGLE);   delay(150);
  int angle = prime ? TURN_NEG90 : TURN_90;
  srv->write(angle);         delay(300);
  if (twice) { delay(50); srv->write(angle); delay(300); }
  srv->write(OPEN_ANGLE);   delay(150);
}

// ── HELPERS ──────────────────────────
void openAllArms() {
  servoTop.write(OPEN_ANGLE);   servoBot.write(OPEN_ANGLE);
  servoLeft.write(OPEN_ANGLE);  servoRight.write(OPEN_ANGLE);
  servoFront.write(OPEN_ANGLE); servoBack.write(OPEN_ANGLE);
  delay(500);
}

void setLEDs(int r, int g, int b) {
  for(int i=0; i<LED_COUNT; i++) ring.setPixelColor(i, ring.Color(r,g,b));
  ring.show();
}

void showMessage(String line1, String line2) {
  display.clearDisplay();
  display.setCursor(0,0);
  display.setTextSize(1);
  display.println(line1);
  display.println(line2);
  display.display();
}

🧠

How the Robot Thinks!

The clever steps your robot follows to solve the cube

Step 1 📷

Scan the Cube

Camera takes a photo of each of the 6 faces. Computer detects the colour of all 54 stickers.

Step 2 🗺️

Build a Map

Each sticker is turned into a letter (U=Up, D=Down, L=Left, R=Right, F=Front, B=Back).

Step 3 🔢

Find the Shortest Path

The Kociemba algorithm searches millions of possibilities and finds the shortest solution — usually in under 20 moves!

Step 4 🤖

Execute the Moves

Each move (like "R2" or "U'") is sent to Arduino, which fires the right servo to turn that face.

Step 5 🎉

Ta-da! Solved!

After all moves are done, the cube is fully solved — every face is a single solid colour!

🤔 Why Kociemba Algorithm?

Herbert Kociemba invented a clever two-phase algorithm that solves any Rubik's Cube in 20 moves or fewer! That's why robots use it — fewer moves means faster solving. The Python library kociemba does all the hard maths for you. 🎓

🛡️

Stay Safe! Important Tips

Always follow these rules when building electronics

⚡

No Loose Wires

Loose wires can cause short circuits. Tape or tie all wires neatly.

🔌

Unplug First

Always unplug the power before changing any wires or connections.

🧑‍🦱

Ask for Help

If you're under 14, do the electrical wiring with a parent or teacher.

🔥

No Overheating

If a servo or wire feels very hot, switch off immediately!

💧

Keep Dry

Never use electronics near water or in a wet environment.

👓

Wear Safety Specs

Wear safety glasses when cutting plastic or drilling your frame.

❓

Frequently Asked Questions

Things kids ask us all the time!

🤔 How fast will my robot solve the cube?

For a beginner build, expect around 3–5 minutes. As you fine-tune the servo speeds and reduce delays in the code, you can get it down to under a minute. The world record robot does it in under 1 second — that's super advanced!

💸 How much does this project cost?

Budget around ₹1,500–₹2,500 (or $20–$35 USD). The biggest costs are the Arduino Mega (~₹800), servo motors (~₹600 for 6), and 3D printing (~₹300 at a local shop). The Rubik's Cube itself is around ₹150!

🖨️ What if I don't have a 3D printer?

Many cities have local 3D printing shops or libraries (called FabLabs or Maker Spaces) where you can print for a small fee. You can also build a frame from cardboard, ice cream sticks, or PVC pipes!

🧩 Does it work with any Rubik's Cube?

Yes! The algorithm works for any standard 3×3 Rubik's Cube. Just make sure the cube you use isn't too loose or too tight — a smooth-turning cube works best for the robot arms.

🐍 Do I need to know Python to do this project?

A little bit! The colour scanning script uses Python, but you can copy-paste the code we provide. Even if you've never coded Python before, this is a great way to learn! The Arduino code uses C++, which is also beginner-friendly.

🏆 Can I enter this in a Science Fair?

Absolutely! This project combines robotics, computer vision, algorithms, and electronics — perfect for any STEM or science fair. Add a poster explaining each part and you'll really impress the judges! 🎖️

🎓

What You've Learned!

This project covers so many cool STEM skills

🤖

Robotics

How mechanical arms and servo motors can work together to perform physical tasks

🔢

Algorithms

How computers can solve complex puzzles by finding the shortest path through possibilities

👁️

Computer Vision

How cameras and software can "see" and understand colours in the real world

💻

Coding

Arduino C++ for hardware control and Python for image processing — two real-world languages!

⚡

Electronics

Circuit design, servo control, I2C displays, NeoPixel LEDs, and proper power management

🔧

Engineering

Mechanical design, 3D printing, structural assembly — real engineering skills!