Maze Solver Robot (Arduino + Ultrasonic Sensors + L298N)

Arduino se bana hua maze solving robot jo Left Hand Rule aur PID wall following use karta hai. 3 Ultrasonic sensors se Left, Front aur Right distances measure karta hai aur maze solve karta hai.

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🔧 Required Components

Component	Quantity
Arduino Uno / Nano	1
HC-SR04 Ultrasonic Sensor	3
L298N Motor Driver	1
DC Gear Motors (with encoder or plain)	2
Wheels	2
Castor Wheel (back support)	1
Li-ion Battery (7.4V) or 9V Battery	1
Robot Chassis	1
Jumper Wires	—

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📌 Pin Connections

L298N Motor Driver

L298N Pin	Arduino Pin	Description
ENA	5 (PWM)	Right Motor Speed
IN1	4	Right Motor Direction
IN2	7	Right Motor Direction
ENB	6 (PWM)	Left Motor Speed
IN3	8	Left Motor Direction
IN4	12	Left Motor Direction

HC-SR04 — LEFT Sensor

Sensor Pin	Arduino Pin
TRIG	A0
ECHO	A1

HC-SR04 — FRONT Sensor

Sensor Pin	Arduino Pin
TRIG	A2
ECHO	A3

HC-SR04 — RIGHT Sensor

Sensor Pin	Arduino Pin
TRIG	A4
ECHO	A5

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⚙️ Key Settings (Tuning)

Parameter	Value	Description
TARGET_DIST	15 cm	Left wall se kitna door chalna hai
WALL_THRESHOLD	90 cm	Is se zyada door = rasta khula mana jayega
FRONT_STOP	15 cm	Samne is se qareeb = ruk jao
BASE_SPEED	90	Seedha chalne ki speed
TURN_SPEED	70	Turn lene ki speed
Kp	4.0	PID Proportional gain
Kd	14.0	PID Derivative gain

Tip: Agar robot zigzag kare toh Kp kam karein. Agar slow react kare toh Kd badhayein.

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🔄 How It Works

1. 3 Ultrasonic sensors se Left, Front, Right distances read hoti hain
2. PID Wall Following — Left wall se 15cm ka faasla maintain karta hai
3. Left Hand Rule (LSRB) se turns decide hote hain:
   • Left open → Left turn
   • Left band, Front open → Seedha jao
   • Left + Front band, Right open → Right turn
   • Sab band → U-Turn
4. State Machine — 2 states: PID_WALL_FOLLOW aur CHECK_INTERSECTION

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🚀 How to Use

1. Robot ko maze ke start pe rakhein
2. Code upload karein — 2 second ka delay hai hath hatane ke liye
3. Serial Monitor (9600 baud) se L/F/R distances monitor kar sakte hain
4. Zaroorat ho toh TARGET_DIST aur WALL_THRESHOLD adjust karein

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⚠️ Notes

• Sensors ko seedha aur level lagayein
• Battery fully charged ho — L298N voltage drop hoti hai
• Maze ki minimum corridor width 20cm honi chahiye