Build a Rubik's Cube
Solving Robot!
A super cool step-by-step guide for young makers to build their very own cube-solving machine using Arduino!
What is a Rubik's Cube Solving Robot? 🤔
Have you ever stared at a Rubik's Cube wishing someone else could solve it? What if a robot could do it for you in just seconds?!
A Rubik's Cube solving robot is a machine that uses cameras, servo motors, and a tiny computer called an Arduino to look at a scrambled cube, figure out the best solution, and turn the faces until it's perfectly solved!
This project teaches you real engineering skills used by scientists and robotics engineers every day. Let's build it!
The fastest robot ever built solved a Rubik's Cube in just 0.38 seconds — that's faster than a blink of an eye! Your robot might take a minute, and that's still totally amazing! 🎊
Parts You Need 🛒
Ask a grown-up to help you get these parts from an electronics shop or order them online. Total cost is roughly ₹1,500 – ₹2,500 (or $20–$35 USD).
An Arduino Starter Kit from Amazon or a local electronics store usually has many of these items together! Great for kids learning robotics.
Circuit Connections ⚡
Now for the fun electronics part! This is how you connect everything together. Always ask a grown-up to help with wiring.
Always disconnect from power before connecting or disconnecting wires. Never touch bare wires when powered on. Ask an adult to double-check your connections!
Pin Connection Table
| Component | Pin / Wire | Arduino Pin | Color |
|---|---|---|---|
| Servo 1 (Top face) | Signal | Digital Pin 3 | Orange wire |
| Servo 2 (Bottom face) | Signal | Digital Pin 4 | Orange wire |
| Servo 3 (Front face) | Signal | Digital Pin 5 | Orange wire |
| Servo 4 (Back face) | Signal | Digital Pin 6 | Orange wire |
| Servo 5 (Left face) | Signal | Digital Pin 7 | Orange wire |
| Servo 6 (Right face) | Signal | Digital Pin 8 | Orange wire |
| All Servos (Power) | VCC | 5V Power Supply | Red wire |
| All Servos (Ground) | GND | GND Pin | Black/Brown wire |
| Camera Module | Data | USB / I2C | USB cable |
Step-by-Step Build Guide 🔧
Put on your builder hat — it's time to assemble your robot! Follow each step carefully.
Build the Robot Frame 🏗️
Cut 6 pieces of thick cardboard or acrylic (each about 12×12 cm). These will hold each servo motor facing one side of the cube. Arrange them in a cube-shaped cage with an opening in the middle for the Rubik's Cube. Use hot glue or bolts to hold them together.
Attach Servo Motors ⚙️
Glue or screw one SG90 servo motor onto each of the 6 frame pieces. The servo horn (the plastic arm that sticks out) should point toward the center — it'll grip and turn the cube face. Make sure each servo is lined up with the center of that cube face.
Make Cube Grippers 🤲
Cut small "+" shaped pieces of cardboard and glue them to the servo horns. These will grip the center piece of each Rubik's Cube face. You can use rubber bands or foam tape on the tips for a better grip. Test that each gripper can turn smoothly.
Plug in the Servo Shield 🔌
Press the Servo Shield gently onto the top of your Arduino Uno — the pins should line up perfectly! Now connect each servo's 3-wire cable (orange/white = signal, red = power, brown/black = ground) to the numbered slots on the shield. Servo 1 goes to slot 3, Servo 2 to slot 4, and so on up to slot 8.
Connect the Power Supply 🔋
Servo motors need more power than the Arduino can provide alone! Connect your 5V 3A power supply to the power terminals on the servo shield (usually marked VCC and GND). This keeps the servos strong and fast. Connect the Arduino separately to your computer via USB for programming.
Mount the Cameras 📷
Position two webcams so they can see all 6 faces of the cube (one from above, one from the front-right). Tape or clamp them to your frame. These cameras will photograph the cube and send the color information to your computer to figure out the solution.
Place the Cube and Test Movement 🎲
Put the Rubik's Cube in the center of your robot frame. Check that all grippers touch the center piece of each face firmly but not too tight. Manually turn the servo motors a tiny bit to see if they grip and rotate the face properly. Adjust if needed!
Take photos of your build at each step! If something goes wrong later, you can look back and spot any wiring mistakes. Plus, it makes an amazing science fair presentation!
The Arduino Code 💻
Now we teach the robot what to do! Copy this code into the Arduino IDE and upload it to your board. We've added lots of comments (lines starting with //) to explain every part!
// ============================================ // Rubik's Cube Solving Robot — Arduino Code // Made for young makers and STEM learners! // ============================================ #include <Servo.h> // Library to control servo motors // ---- Create 6 servo objects (one per face) ---- Servo servoTop; // Top face of the cube Servo servoBottom; // Bottom face Servo servoFront; // Front face Servo servoBack; // Back face Servo servoLeft; // Left face Servo servoRight; // Right face // ---- Servo angle settings ---- const int HOME = 90; // Resting position (degrees) const int TURN_CW = 180; // Turn clockwise 90 degrees const int TURN_CCW = 0; // Turn counter-clockwise 90 deg const int MOVE_DELAY = 300; // Milliseconds to wait per move // ---- Solution moves received from computer ---- String solutionMoves = ""; // Will be filled by computer // ========================================== // SETUP — runs once when Arduino powers on // ========================================== void setup() { // Attach each servo to its Arduino pin servoTop.attach(3); servoBottom.attach(4); servoFront.attach(5); servoBack.attach(6); servoLeft.attach(7); servoRight.attach(8); // Move all servos to home (resting) position allServosHome(); // Start serial communication with computer Serial.begin(9600); Serial.println("🤖 Rubik's Cube Robot Ready!"); } // ========================================== // LOOP — runs over and over after setup // ========================================== void loop() { // Wait for solution moves from computer if (Serial.available() > 0) { solutionMoves = Serial.readStringUntil('\n'); Serial.print("Solving with moves: "); Serial.println(solutionMoves); executeSolution(solutionMoves); // Do the moves! } } // ========================================== // FUNCTION: Move all servos to home // ========================================== void allServosHome() { servoTop.write(HOME); servoBottom.write(HOME); servoFront.write(HOME); servoBack.write(HOME); servoLeft.write(HOME); servoRight.write(HOME); delay(500); // Wait half a second } // ========================================== // FUNCTION: Do one cube move // face = which face (U/D/F/B/L/R) // clockwise = true for CW, false for CCW // ========================================== void doMove(char face, bool clockwise) { Servo* s; // Pointer to the right servo switch(face) { case 'U': s = &servoTop; break; // U = Up (Top) case 'D': s = &servoBottom; break; // D = Down (Bottom) case 'F': s = &servoFront; break; // F = Front case 'B': s = &servoBack; break; // B = Back case 'L': s = &servoLeft; break; // L = Left case 'R': s = &servoRight; break; // R = Right default: return; // Unknown move, skip it } // Turn the face the right direction! s->write(clockwise ? TURN_CW : TURN_CCW); delay(MOVE_DELAY); // Wait for it to reach position s->write(HOME); // Return gripper to home delay(100); // Short pause before next move } // ========================================== // FUNCTION: Execute the full solution // Reads moves like "U F R' D2 B L'" // ' means counter-clockwise, 2 means twice // ========================================== void executeSolution(String moves) { int i = 0; while (i < moves.length()) { char face = moves[i]; // Get face letter if (face == ' ') { i++; continue; } // Skip spaces bool cw = true; // Default: clockwise int times = 1; // Default: one turn // Check for modifier: ' or 2 if (i+1 < moves.length()) { if (moves[i+1] == '\'') { cw = false; i++; } // Apostrophe = counter-CW if (moves[i+1] == '2') { times = 2; i++; } // 2 = turn twice } // Perform the move (once or twice) for (int t = 0; t < times; t++) { doMove(face, cw); } i++; } Serial.println("✅ CUBE SOLVED! Great job robot!"); }
The Arduino waits for your computer to send a list of moves (like "U F R' D2"). When it receives them, it tells each servo to turn the right face in the right direction until the cube is solved!
Python Code — Color Scanner (Runs on Computer)
This short Python script takes a photo, reads the colors on each face, and sends the solution to the Arduino:
# ============================================ # Rubik's Cube Color Scanner + Solver # Runs on your computer, sends moves to Arduino # pip install opencv-python kociemba pyserial # ============================================ import cv2 # For camera / image reading import kociemba # Cube solving algorithm! import serial # To talk to Arduino import time # Connect to Arduino (change COM3 to your port) arduino = serial.Serial('COM3', 9600) time.sleep(2) # Wait for Arduino to start up def get_face_colors(face_name): """Capture a photo and read the 9 sticker colors""" cam = cv2.VideoCapture(0) # Open webcam ret, frame = cam.read() # Take photo cam.release() # Each face has 9 squares in a 3x3 grid # We sample the color at each square's center colors = [] grid_size = 50 # Each square = 50 pixels start_x, start_y = 150, 100 # Cube position in image for row in range(3): for col in range(3): # Find center of each sticker px = start_x + col * grid_size + grid_size//2 py = start_y + row * grid_size + grid_size//2 bgr = frame[py, px] # Get pixel color (BGR) colors.append(bgr_to_face(bgr)) return colors def bgr_to_face(bgr): """Convert a pixel color to a face letter""" b, g, r = bgr if r > 150 and g < 80: return 'R' # Red if b > 150 and r < 80: return 'B' # Blue if g > 150 and r < 80: return 'G' # Green if r > 200 and g > 150: return 'Y' # Yellow if r > 200 and g > 50: return 'O' # Orange return 'W' # White (default) # ---- Main Program ---- print("🎲 Scanning Rubik's Cube faces...") cube_state = "" # Scan each face (robot rotates cube between each) for face in ['U', 'R', 'F', 'D', 'L', 'B']: colors = get_face_colors(face) cube_state += "".join(colors) print(f"Face {face}: {colors}") # Use Kociemba algorithm to find the solution print("\n🧠 Calculating solution...") solution = kociemba.solve(cube_state) print(f"✅ Solution found: {solution}") # Send the solution moves to Arduino! arduino.write((solution + '\n').encode()) print("🤖 Robot is now solving the cube!")
How Does It Solve the Cube? 🧠
This is the really magical part! Your robot uses a famous algorithm (a set of rules) called Kociemba's Algorithm to find the shortest possible solution — usually in under 20 moves! Here's how it works step by step:
1. Scan
Camera takes pictures of all 6 faces of the scrambled cube
2. Detect Colors
Python reads the color of each of the 54 stickers (9 per face)
3. Map the Cube
Builds a digital map showing where every piece currently is
4. Calculate
Kociemba's algorithm finds the fewest moves to solve it
5. Send Moves
Solution is sent via USB to the Arduino as move commands
6. SOLVE!
Servo motors turn the faces one by one until it's perfectly solved!
A Rubik's Cube has 43 quintillion possible scrambled positions — that's 43,000,000,000,000,000,000! Kociemba's algorithm can solve any of them in 20 moves or fewer. That's math superpowers! 🔢✨
Testing Your Robot 🧪
Test Each Servo First
Upload a simple test sketch that moves each servo one by one. Make sure all 6 move smoothly without getting stuck. If one doesn't move, check its wiring on the shield!
Test the Camera Reading
Run the Python script with a solved cube and see if it correctly reads all 6 faces as one color each. Good lighting really helps — try near a window or under a bright lamp.
Do a Simple Scramble First
Only turn the top face 2 times to create a simple scramble. Then run the full program. If it works — amazing! Gradually try harder scrambles.
Fix and Improve! 🔨
If something doesn't work, don't give up — that's just engineering! Check your wiring, adjust the servo angles in the code (try 170 instead of 180), and make sure the grippers hold the cube firmly.
Every servo motor is a little bit different. You might need to change TURN_CW = 180 to 175 or 185 to get a perfect 90° rotation. Test and adjust!
FAQ — Questions Kids Ask ❓
Here are the most common questions young makers ask about this project!
How old do you need to be to build this?
Kids aged 10 and up can build this project with some help from a grown-up! Younger kids (7-9) can do it fully with adult help. The coding parts might need some learning, but that's the fun of it!
Do I need to know how to code first?
No! You can start by just copying the code from this guide. But if you want to understand it, ask your teacher or try free Arduino tutorials on YouTube. Even copying code teaches you a lot!
Can I use LEGO instead of cardboard for the frame?
Yes! LEGO Technic pieces are perfect for building the robot frame. Many kids have built amazing Rubik's Cube robots using only LEGO! It's actually a great idea because you can easily adjust the design.
What if I don't have a webcam?
You can manually type the cube's colors into the computer instead of scanning automatically! Look up "Rubik's Cube manual input solver" — websites like ruwix.com let you enter the colors and give you the moves to send to your robot.
How long does it take to solve the cube?
Your robot will likely take 1-3 minutes to solve a fully scrambled cube. Each servo move takes about 0.3 seconds, and the solution has around 20 moves. As you improve the design and code, it can get faster!
What other cool things can I build next?
Great question! After this, you could try: a line-following robot 🚗, a robotic arm 🦾, a maze-solving robot 🌀, or even a robot that writes your name! Robotics is a superpower you keep growing.
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