NAVIX-4
Autonomous Maze-Solving Robot
A 10×10 cm autonomous robot that explores, learns, and optimizes maze paths in real time. Built for Robofest 4.0 (National Level, Gujarat), it fuses three time-of-flight distance sensors with a 9-axis IMU to navigate unknown mazes, record every decision, eliminate dead ends via string-based path optimization, and replay the shortest route at full speed.
Indian Patent Published — Application No. 202521042150
┌─────────────────────────────────────────────────────────┐
│ SENSOR LAYER │
│ ┌──────────┐ ┌──────────┐ ┌──────────┐ │
│ │ VL53L1X │ │ VL53L1X │ │ VL53L1X │ │
│ │ LEFT │ │ FRONT │ │ RIGHT │ │
│ └────┬─────┘ └────┬─────┘ └────┬─────┘ │
│ └───────────┬───┴───┬──────────┘ │
│ ┌─────┴─────┐ │
│ │ TCA9548A │ I²C Multiplexer │
│ │ (0x70) │ │
│ └─────┬─────┘ │
│ │ I²C │
│ ┌────────────────┼────────────────────┐ │
│ │ TEENSY 4.1 │ │
│ │ ┌─────────────────────────────┐ │ │
│ │ │ Decision Engine │ │ │
│ │ │ ┌────────┐ ┌──────────┐ │ │ ┌─────────┐ │
│ │ │ │ LSRB / │ │ Path │ │ │ │ BMX160 │ │
│ │ │ │ RSLB │ │ Optimize │ │ │◄──┤ 9-axis │ │
│ │ │ └────────┘ └──────────┘ │ │ │ IMU │ │
│ │ └─────────────────────────────┘ │ └─────────┘ │
│ └───────────┬─────────────┬───────────┘ │
│ │ │ │
│ ┌────┴────┐ ┌────┴────┐ │
│ │ HW-121 │ │ HW-121 │ Dual H-Bridge │
│ │ Motor │ │ Motor │ │
│ │ Driver │ │ Driver │ │
│ └────┬────┘ └────┬────┘ │
│ ┌────┴────┐ ┌────┴────┐ │
│ │ N20 L │ │ N20 R │ DC Gear Motors │
│ └─────────┘ └─────────┘ │
└─────────────────────────────────────────────────────────┘
The robot enters the maze blind. At every junction it reads left/front/right distances and follows the selected priority rule:
| Algorithm | Priority Order | Use Case |
|---|---|---|
| LSRB | Left → Straight → Right → Back | Left-wall-hugging traversal |
| RSLB | Right → Straight → Left → Back | Right-wall-hugging traversal |
Every turn is appended to a path string (L, S, R, U). During forward segments, the robot uses wall-following PID (when walls are visible) or magnetometer heading lock (in open corridors) to stay centered.
Dead-end U-turns are collapsed using iterative string replacement:
LUL → S RUR → S SUS → U
LUR → U RUL → U
SUR → L RUS → L
SUL → R LUS → R
This reduces a path like LLULSURRS into the shortest equivalent without dead-end detours.
The optimized path is executed turn-by-turn at full speed — no exploration, no hesitation.
| Component | Part | Role |
|---|---|---|
| MCU | Teensy 4.1 (ARM Cortex-M7, 600 MHz) | Core controller |
| Distance | 3× VL53L1X Time-of-Flight | Left / Front / Right ranging |
| IMU | BMX160 (mag + gyro + accel) | Absolute heading & compass calibration |
| Mux | TCA9548A I²C Multiplexer | Addresses 3 identical-address ToF sensors |
| Drive | 2× N20 DC gear motors + HW-121 H-bridge | Differential drive |
| PCB | Custom NAVIX-4 (stacked design) | Fits within 10×10 cm footprint |
| Pin | Function | Pin | Function |
|---|---|---|---|
| 2 | Left motor PWM | 5 | Right motor PWM |
| 3, 4 | Left motor DIR | 6, 7 | Right motor DIR |
| 35 | Reset | 36 | Optimize path |
| 37 | Start optimized run | 38 | RSLB select |
| 39 | LSRB select | 40 | Calibration |
 Perspective |
 Top |
 Front (ToF sensor array) |
 Back |
 Left |
 Right |
 Bottom — NAVIX-4 PCB |
 Competition arena |
| Top Layer | Bottom Layer |
|---|---|
 |
 |
| Application | 202521042150 |
| Title | Autonomous Robot for Real-Time Pathfinding and Obstacle Avoidance |
| Filed / Published | 01 May 2025 / 23 May 2025 |
| Institution | Birla Vishvakarma Mahavidyalaya Engineering College, Gujarat |
| Journal | Patent Office Journal No. 21/2025 |
Full publication available in Patent/.
# 1. Clone
git clone https://github.com/<your-username>/maze-solving-robot.git
# 2. Open in Arduino IDE
# File → Open → src/Project-final.ino
# 3. Install dependencies (Library Manager)
# - DFRobot BMX160
# - Adafruit VL53L1X
# 4. Select board: Teensy 4.1 → UploadCalibration: Power on → press calibration button facing North → rotate to West, South, East, pressing at each cardinal point.
maze-solving-robot/
├── src/
│ └── Project-final.ino # Complete firmware (sensor fusion, algorithms, motor control)
├── media/ # Robot photos
├── schematics/ # PCB layer images
├── Patent/ # Published patent document
├── docs/ # GitHub Pages site
│ └── index.html # Project landing page
│
└── README.md
| Library | Purpose |
|---|---|
DFRobot_BMX160 |
9-axis IMU (magnetometer for heading) |
Adafruit_VL53L1X |
Time-of-flight distance sensing |
Wire.h |
I²C bus communication |
| Arduino / Teensyduino | Framework + board support |
Anshul Majmudar Electronics & Communication Engineering, BVM Gujarat Competed at Robofest 4.0 — National Robotics Competition