Theory & Background

Flame sensors detect IR radiation in the 760–1100nm wavelength range emitted by fire. Three sensors (left, center, right) provide directional fire information. In darkness, analog value drops when flame detected. Digital output triggers below threshold. Algorithm: if center sensor detects flame → move forward. If left sensor → turn left. If right sensor → turn right. If all three detect flame (very close) → stop and activate extinguisher.

Components & Requirements

10 components required for this project.

#	Component	Purpose	Qty
1	Arduino Mega	Main controller	x1
2	Flame Sensor (YDJSB IR)	Fire detection in left, center, right zones	x3
3	DC Water Pump (5V, 3L/min)	Water spray for extinguishing	x1
4	Servo Motor for nozzle	Directing water spray	x1
5	L298N Motor Driver	Drive motors	x1
6	HC-SR04 Ultrasonic	Obstacle avoidance	x2
7	12V 4WD Robot Chassis	Stable off-road platform	x1
8	Water Tank (500ml)	Water reservoir	x1
9	Temperature Sensor (MLX90614 IR)	Measuring flame temperature	x1
10	Fan (5V blower)	Alternative extinguishing for small flames	x1

Step-by-Step Implementation

Follow these 4 steps carefully.

1

Flame Detection Algorithm

Flame sensors detect IR radiation in the 760–1100nm wavelength range emitted by fire. Three sensors (left, center, right) provide directional fire information. In darkness, analog value drops when flame detected. Digital output triggers below threshold. Algorithm: if center sensor detects flame → move forward. If left sensor → turn left. If right sensor → turn right. If all three detect flame (very close) → stop and activate extinguisher.

2

Navigation to Fire Source

Use a state machine: PATROL (wandering/searching with obstacle avoidance), DETECTED (flame sensor triggered, navigate toward), EXTINGUISH (within 20cm of flame, activate pump and servo). During navigation, use ultrasonic sensors to avoid walls. Implement proportional turning: flame sensor analog value guides turn sharpness — stronger signal → sharper turn toward fire.

3

Water Pump Control

Control pump via MOSFET transistor (relay alternative). Servo sweeps nozzle 45°–135° during extinguishing for coverage. Activate pump for 3 seconds, stop, re-check if flame still detected. Repeat up to 5 times (limited by water supply). If flame not extinguished after 5 attempts, retreat and alert (buzzer + LED). Monitor water tank level with a float sensor to prevent dry-pump damage.

4

Fire Localization Accuracy Improvement

Use MLX90614 IR thermometer for precise temperature reading. When flame detected, stop robot, sweep thermometer servo (if installed) left-right to find peak temperature direction. This is more accurate than broad-area flame sensors for precise positioning. Alternatively, use a camera with OpenCV fire detection algorithm for vision-based localization — identifies orange/yellow pixel clusters with flickering pattern analysis.

Code & Implementation

Core code for firefighter.ino:

firefighter.ino
  C/C++

#define FL A0 #define FC A1 #define FR A2
#define PUMP 12 #define SERVO_PIN 11

int flameL, flameC, flameR;
void loop() {
  flameL = analogRead(FL); flameC = analogRead(FC); flameR = analogRead(FR);
  bool l = flameL < 300, c = flameC < 300, r = flameR < 300;
  if(!l && !c && !r) { patrol(); return; }
  if(c) { // Center - go straight to flame
    if(flameC < 100) { extinguish(); } // Very close
    else { forward(150); }
  } else if(l && !r) { turnLeft(); }
  else if(r && !l) { turnRight(); }
}
void extinguish() {
  stopMotors();
  for(int a=60; a<=120; a+=10) { servo.write(a); delay(100); }
  digitalWrite(PUMP, HIGH); delay(3000);
  digitalWrite(PUMP, LOW);
}

Testing & Troubleshooting

Test Firefighting Robot by verifying each subsystem individually before full integration.

!

Troubleshooting Tips

Verify power voltages, check ground connections, use serial monitor for debug.

Real-World Applications

*Hazardous facility autonomous fire detection

*Industrial fire response assistance

*Remote fire monitoring stations

*Education and competition robotics

*Mine and tunnel fire detection

*Data center fire response

*Research in autonomous emergency response

*Agricultural fire prevention monitoring

Extensions & Next Steps

Add CO2/Halon extinguishing for electrical fire safety
Implement thermal imaging camera for fire mapping
Add GPS and 4G for remote operation and alerting
Build a multi-robot coordinated firefighting swarm
Add smoke and gas sensors for hazard assessment

Interactive Playground

Coming Soon

An interactive simulator will be available here — simulate circuits and run code in-browser without hardware.

Frequently Asked Questions

What types of fires can this robot handle?

This prototype handles small, open-flame fires (candles, small paper fires, alcohol flame — typical in competition arenas). It cannot handle: large fires (insufficient water pressure/volume), electrical fires (water dangerous — need CO2), kitchen grease fires (water causes explosive steam), or fires in confined spaces with toxic smoke. For realistic firefighting robots, use CO2, dry powder, or foam extinguishing agents appropriate for the fire class.

Introduction