Design and Development of an Autonomous Fire Extinguishing Robot Using Arduino Mega and Dry Powder Extinguisher for Class B Fires

Firefighting is one of the most dangerous occupations, with firefighters frequently facing extreme heat, toxic smoke, explosions, and structural collapse. These adverse conditions lead to numerous injuries and fatalities each year. Although robotic systems have been proposed to reduce human exposure, many existing designs rely on remote control, use water or fans that are ineffective for flammable‑liquid fires, or suffer from limited detection ranges and slow response times. This study addresses these gaps by designing and fabricating an autonomous fire-extinguishing‑ robot specifically targeting Class B fires (flammable liquids and gases). The robot employs an Arduino Mega 2560 microcontroller as the central processing unit, three flame sensors (left, forward, right) for fire localization within a range of 10 cm to 90 cm, four ultrasonic distance sensors for obstacle detection and avoidance, and a 1 kg dry‑powder extinguisher actuated by a 12 V solenoid valve. A servo motor sweeps the nozzle from 50° to 130° and back to distribute the extinguishing agent over a calculated area of 113.1 cm². The drive system consists of four 9 V DC gear motors controlled via an H‑bridge driver, with speed ramped linearly from 0 to a maximum PWM value of 180 (achieving a measured maximum velocity of 0.030 m/s). The obstacle avoidance algorithm compares left and right distances; if an obstacle is closer than 25 cm in front, the robot turns toward the clearer side. Testing on a 1 m² test area with controlled alcohol‑based fires demonstrated that the robot reliably detects fire at up to 90 cm, navigates around obstacles, and completely suppresses the fire within a single continuous run. The flame sensor output decays nonlinearly with distance, following an inverse‑square trend, which allows approximate distance estimation but limits resolution beyond 70 cm. Across five repeated trials, mean fire detection time was 2.1 ± 0.3 s and mean extinguishing time was 11.8 ± 0.8 s, with a 100% extinguishing success rate. Results confirm that the autonomous system performs consistently without human intervention, offering a scalable, low-cost solution to reduce firefighter casualties. Future improvements should focus on larger chassis, onboard battery integration, and autonomous extinguisher replacement.