Yeti v4 – Line Follower Robot (Arduino)

Yeti v4 is a high-performance line follower robot based on Arduino.
It uses a 5-sensor infrared array, PID correction and dual-motor control to follow a line smoothly and at high speed.

This repository includes two versions of the project:

• Modular version → clean, professional C++ structure (multiple .cpp/.h files)
• Single-file version (Yeti_v4/) → easy to upload and run

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🚗 Features

• 5-sensor analog IR array
• Automatic sensor calibration
• PID controller (P + D active)
• Smooth motor steering
• LED feedback (line detected / lost)
• Two buttons:
  • BTN1 → Calibration
  • BTN2 → Start race
• Failsafe direction recovery when the line is lost

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📁 Repository Structure

📦 root

├── 🧠 main.cpp

├── 🏎️ race.cpp

├── 🏎️ race.h

├── 👁️ sensors.cpp

├── 👁️ sensors.h

├── ⚙️ motors.cpp

├── ⚙️ motors.h

├── 📐 pid.cpp

├── 📐 pid.h

├── 🗂️ utils.h

│

└── 📁 Yeti_v4

└── 📄 Yeti_v4.ino (single-file version)

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✔️ Use the modular version if:

• you want a clean professional codebase
• you use VSCode + PlatformIO
• you want to extend the robot (new sensors, extra features, etc.)

✔️ Use the single-file version if:

• you want a quick upload through Arduino IDE
• you prefer everything in one file
• you are showing the project to beginners or students

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🧠 How the Robot Works

1. Calibration

Press BTN1
The robot rotates left and right and records per-sensor:

• minimum reflectance
• maximum reflectance

This makes readings stable in different lighting conditions.

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2. Line Position Detection

Every loop:

• Read sensors
• Normalize values (0–1000)
• Apply weighted average
• Center result around 0 (left = negative, right = positive)

If no sensor detects the line → fallback based on last known direction.

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3. PID Correction

The correction is computed as:

-correction = KPP + KDD + KI*I

Only P and D are used (KI = 0), which is ideal for fast line followers.

Correction is then applied by reducing one motor’s speed.

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4. Race Mode

Press BTN2 to start.
LED blinks while waiting → release BTN2 → race begins.

Press any button to stop.

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🔧 Hardware Requirements

• Arduino Uno / Nano
• 2× DC motors + H-bridge driver (L298N or similar)
• 5× analog IR sensors
• 2× momentary buttons
• 1× LED indicator

Default Pin Mapping

Component	Pin
BTN1	7
BTN2	6
LED	13
Motor1 DIR	2
Motor1 PWM	3
Motor2 DIR	4
Motor2 PWM	5
Sensors	A0 – A4

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▶️ Upload Instructions

Single-file version

1. Open Yeti_v4/Yeti_v4.ino in Arduino IDE
2. Select board (e.g. Arduino Uno)
3. Upload

Modular version (recommended)

Arduino IDE

1. Create a sketch
2. Replace all generated files with the .cpp + .h files
3. Compile & upload

VSCode + PlatformIO

1. Create new project
2. Copy .cpp and .h files into src/ and include/
3. Build & upload

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⚙️ Tuning Parameters

Inside the code you can adjust:

Parameter	Meaning
SPEED	base motor speed
KP	proportional gain
KD	derivative gain
KI	integral gain (usually 0)
P_LINE_MIN	line detection threshold

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🏎️ Performance Tips

• Increase SPEED for higher speed
• Raise KD if the robot oscillates
• Raise KP for tighter turns
• Ensure calibration is done on the race track
• Keep sensors as close to the line as possible

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📜 License

Open-source, freely usable for education, competition and personal learning.

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✨ Author

Developed and maintained by Alessandro Han.