Autonomous Fire-Fighting Robot

An Arduino-based robot that autonomously scans its environment for fire, identifies the direction of the flame, aims a water pump at it, and extinguishes it all without human intervention.

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Project Overview

This project was developed during my SIWES (Students' Industrial Work Experience Scheme - Nigeria's national internship program) internship at Hub360 Circuits Ltd, Abuja, Nigeria. It demonstrates the integration of embedded systems, servo motor control, sensor interfacing, and basic autonomous decision-making on a microcontroller platform.

The robot continuously scans its surroundings using a flame sensor mounted on a rotating servo. Upon detecting fire, it locks onto the direction, aims a second servo-mounted water pump nozzle at the source, and activates a relay-controlled pump to dispense water. After extinguishing the fire, it resumes scanning automatically.

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Objectives

• Design a low-cost, autonomous fire detection and suppression system
• Implement servo-based directional scanning for 360° situational awareness (within a configurable arc)
• Develop state-machine logic to transition between Scan Mode and Extinguish Mode
• Control a water pump via relay based on sensor feedback
• Validate the system's ability to detect and extinguish a small open flame

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Components & Hardware

Component	Quantity	Purpose
Arduino Uno	1	Main microcontroller
IR Flame Sensor	1	Detect presence of fire (mounted on scan servo)
SG90 Servo Motor (Scan)	1	Sweeps flame sensor across the environment
SG90 Servo Motor (Pump)	1	Aims the water pump nozzle toward detected fire
5V Relay Module	1	Switches the water pump on/off
Mini Water Pump (DC)	1	Dispenses water to extinguish the flame
Water Reservoir (container)	1	Stores water for the pump
Silicone tubing	-	Channels water from pump to nozzle
Jumper wires, breadboard	-	Wiring and prototyping
9V / USB Power Supply	1	Powers the Arduino and peripherals
Note: All components share a common ground (GND) to ensure stable signal communication between the sensors, servos, and the Arduino.

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System Architecture

The system operates as a finite state machine (FSM) with two primary states:

┌─────────────────────────────────────────────────────────────────┐
│                         SYSTEM START                            │
│               Servos initialized, pump OFF                      │
└────────────────────────────┬────────────────────────────────────┘
                             │
                             ▼
┌─────────────────────────────────────────────────────────────────┐
│                      STATE 1: SCAN MODE                         │
│  • Scan servo sweeps from 10° → 170° and back in 5° steps      │
│  • Flame sensor polled at each position                         │
│  • Sensor reads LOW = fire detected                             │
└────────────────────────────┬────────────────────────────────────┘
                             │
                     Fire Detected?
                      (LOW signal)
                             │
                             ▼
┌─────────────────────────────────────────────────────────────────┐
│                   STATE 2: EXTINGUISH MODE                      │
│  • Record angle of detection                                    │
│  • Aim pump servo to same angle                                 │
│  • Activate relay → pump ON for 3 seconds                      │
│  • Re-check sensor after pump stops                             │
│  • If fire gone → return to SCAN MODE                           │
│  • If fire remains → continue pumping                           │
└─────────────────────────────────────────────────────────────────┘

Pin Assignments

Arduino Pin	Connected To	Mode
D2	IR Flame Sensor (OUT)	INPUT
D8	Relay Module (IN)	OUTPUT
D9	Scan Servo (Signal)	PWM OUTPUT
D10	Pump Servo (Signal)	PWM OUTPUT

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⚙️ How It Works — Step by Step

1. Initialization: On power-up, the scan servo moves to 10° (start position), the pump servo centers at 90°, and the relay is set LOW (pump off).

2. Scanning: The scanForFire() function moves the scan servo in 5° increments from 10° to 170° and back, pausing 100ms at each position to poll the flame sensor.

3. Fire Detection: The IR flame sensor outputs LOW when it detects infrared radiation characteristic of a flame. Upon detection, the current servo angle is stored as fireDetectedAngle.

4. Aiming: The pump servo is immediately commanded to rotate to fireDetectedAngle, aligning the nozzle with the detected fire source.

5. Suppression: The relay activates (pump ON). The pump runs for PUMP_DURATION (3 seconds by default, configurable).

6. Verification: After the pump cycle, the sensor is re-read. If the flame is gone, the system resets to scan mode. If the fire persists, the pump reactivates and continues suppressing.

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Software & Code

Language: C++ (Arduino)
IDE: Arduino IDE 2.x
Libraries Used:

• Servo.h — Standard Arduino servo control library (built-in)

Key Configurable Parameters

const int SCAN_MIN_ANGLE = 10;    // Leftmost scan position (degrees)
const int SCAN_MAX_ANGLE = 170;   // Rightmost scan position (degrees)
const int SCAN_STEP = 5;          // Angular resolution of scan
const int SCAN_DELAY = 100;       // Pause per step (ms) — allows sensor to stabilize
const int PUMP_DURATION = 3000;   // Pump run time per cycle (ms)

The full source code is available in fire_fighting_robot.ino.

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Results & Observations

Test Condition	Outcome
Candle flame at ~30 cm distance	Detected and extinguished within ~2 sec
Flame at extreme angles (near 10° / 170°)	Successfully detected; servo reached target position
Fire already extinguished after first pump cycle	System correctly resumed scan mode
Fire persisting after first pump cycle	System correctly ran a second suppression cycle

Observations:

• The 100ms scan delay was critical — reducing it caused false negatives due to sensor settling time
• Servo alignment between the scan angle and pump aim angle was accurate to ±5°
• The system was sensitive to ambient bright light (fluorescent/sunlight), which could cause false positives — a shielded sensor housing would improve robustness

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Setup & Replication

1. Wire all components according to the pin assignments table above
2. Clone this repository:

   git clone https://github.com/YOUR-USERNAME/fire-fighting-robot.git

3. Open fire_fighting_robot.ino in Arduino IDE
4. Select Board: Arduino Uno, Port: your COM port
5. Click Upload
6. Open Serial Monitor at 9600 baud to observe system status messages

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🚀 Potential Improvements

• Add a chassis and wheels for a mobile fire-fighting robot
• Replace IR flame sensor with UV/IR dual-spectrum sensor for outdoor use
• Add a water level sensor to prevent dry pump operation
• Implement wireless alerting (ESP8266/GSM) to notify a remote operator
• Use a PID controller for smoother servo tracking of a moving flame
• Multi-sensor array for faster and more reliable flame triangulation

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Project Context

Detail	Info
Programme	SIWES (Industrial Training)
Organization	Hub360 Circuits Ltd, Abuja, Nigeria
Year	2024/2025
Developer	Raphael Ebubechi Efita
Institution	Federal University of Technology, Minna
Department	Mechatronics Engineering

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License

This project is licensed under the MIT License — see the LICENSE file for details.
Feel free to use, modify, and build upon this work with attribution.

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Connect

Raphael Ebubechi Efita
Mechatronics Engineering | Embedded Systems | IoT
Federal University of Technology, Minna, Nigeria