Solar Powered Fire Fighting Robot

The risk of uncontrolled fire exists anywhere, anytime, and it can cause both loss of human lives and huge financial losses. Human firefighters usually can successfully cope with fires, but sometimes it is too dangerous for them to reach some areas, and then fire fighting robots prove themselves to be very useful.

Also, mobile fire fighting robots can patrol in some area for 24 hours a day, scanning for unnatural heat, smoke or other issues, and providing a "constant watch" for dangers that humans may not be able to detect.

Models of firefighting robots

Although the day when firefighting robots could save a lot of lives has yet to come, research efforts in this field pushes things further every year.
There are robotic devices that can already be used for firefighting purposes. These include robots that can be thrown into the fire site to inspect the situation, as well as large remote controlled fire extinguishers. Here are some models that are already in use:

Despite its heavy armor and robust look, it measures only 12.5 centimeters in diameter and weighs 2 kilograms.
This robotic device can be thrown into a building on fire and operate there for 30 minutes. As it can withstand temperatures up to 320F (160C), firefighters can explore the environment and plan their actions accordingly using this remote controlled robot.

This robot can ascend and descend stairs, it is waterproof and has a cooling system in order to enable it to work in high temperatures.
It weighs 450 kilograms and it travels 20km/h and its operating time is 2 hours. It is also capable of independent fire-fighting.

The robot was developed based on the vision of a self-propelled fire hose that can crawl into a burning building and extinguish a fire on its own without putting human fire fighters at risk. The idea behind the robot is to equip a fire hose with water hydraulic actuators that enable it to move like a biological snake. This idea is clever in that the energy that the robot needs in order to move is already available inside the fire hose in the form of pressurized water. Water will actually have three functions in the envisioned system:
- Fire extinguishing (by extinguishing the fire with water).
- Cooling (by cooling the robot with water).
- Hydraulic actuation (by moving the joints of the robot with pressurized water).

Designed by Ryland Research Limited, is also among firefighting robots that weigh around 450 kilograms. This robot is also remote controlled (up to 300 meters); it can endure high temperatures as well as extinguish fire using either water or foam. The robot is also equipped with four color cameras that together provide a panoramic view and one infrared camera steerable in horizontal plane. Also, it should be noted that this robot has articulated tracks to ensure better surface travel capabilities.

Standing on two legs, it is about the size of an adult man, measuring 1.8 meters tall and weighing about 64 kilograms.
The robot has three ways of seeing the world: a stereo camera with two lenses that allow it to see with binocular vision (like a human), a thermal imaging camera that enables it to detect heat and see through smoke, and a laser range finder that allows it to map out the distance between itself and an object. Without falling or stopping, the robot can grasp a fire hose and blast the flames with water.

How it was before and the advantages of solar power

In most cases, robots are powered by rechargeable batteries. When the batteries are low, they have to be replaced and recharged. The advantage of solar power is that the robots can be powered as long as there is light. The downside is that they require a lot of light to run continuously so even if we have a panel big enough to power the robot, there is no guarantee the sun is out. Furthermore, even if the sun is out, the earth’s orbit makes it appear to move across the sky, meaning the voltage generated will fluctuate.
  The best way is the robot to be powered both by solar panel and the batteries. When there is light, robot would be powered by solar panel, and the excessive energy would be used to recharge the batteries. When there is no light, robot would use batteries to work.
  Solar cells are layers of semiconductive materials that create an electrical current when exposed to light. A solar cell is a piece of photovoltaic material, usually crystalline silicon. Solar cells are often connected into groups on a support structure, and these are called panels.
Solar cells are rated for direct current (DC) output and because of that, an inverter is needed in order to run household appliances.

Simple Solar Circuit with a Rechargeable Battery Back-Up

  Assuming the solar panel has excess capacity at various times (either because the target device is not consuming its peak power or because the solar panel is receiving extra light) it would be useful to store the extra power. To do so, we simply add one more diode (D3) and a path from the solar source to the rechargeable source.
 Schematic of a simple solar panel charger circuit
The solar panel provides power to the device through D1, or the battery provides power through D2, depending on which power source has a higher voltage. When the solar panel has the higher voltage, solar power flows through diode D1 to power the device and through diode D3 to recharge the battery pack.
A simple direct solar charging circuit works safely only if the solar panel is significantly less powerful than the battery. That ensures the solar power is never too much to overcharge the battery and thus doesn’t need to be electronically monitored to disconnect when the battery is full.

How to build small firefighting robot

Here is an example of small homemade firefighting robot.

It detects and extinguishes fire autonomously. It uses flame sensor for detection and arduino board for processing. Fire extinguisher along with electronic valve (actuator) is used to extinguish the detected fire.
The robot rotates while actively scanning for fire. This scanning is performed by sensors placed on the sides. When a fire is detected, it moves in the direction of fire and stops 30 cm in front of it and triggers the extinguisher to turn out the fire.

Components used:
- 1 Arduino board
- 3 Flame sensor modules
- 2 DC motor driver
- 1 Electronic valve (linear actuator)
- 4 DC gear motor
- 1 Fire extinguisher
- 4 Wheels
- 4 Motor clamps
- Switch, wire, screws
Tools required:
- Soldering iron
- Multimeter

Arduino Board
  Basic description of the board can be seen in the picture.
Flame sensor
 It has a positive supply pin, which must be provided with a +5v supply. GND pin must be grounded. This module provides both analog as well as digital outputs. Only digital output is used in this project.

Motor driver and motor
  Since the arduino board can supply only 5v which is insufficient for driving motor, motor driver is used.
With the help of motor driver, clockwise and anticlockwise rotation of motor can be easily achieved. Motor driver must be supplied with a supply voltage of 5v -9v. Ground must be connected to the ground pin of arduino board.
Since this robot needs to carry a fire extinguisher, dc gear motor having enough torque must be selected. Here i have used metallic gear motor with 60rpm, having 10-12kg/cm torque.

Fire extinguisher and valve

General fire extinguishers are heavier and difficult to be transported or triggered. A spray type one will be most convenient and affordable. In case of general type, an electronic valve should be used to release the gas or foam.
For the spray type, electronic actuator can be used. In this project, i have used spray type extinguisher an instead of actuator, a cam mechanism is used to apply pressure on the nozzle. Cam mechanism consists of a metallic cam connected to a gear motor. It presses the nozzle knob as it rotates. A separate motor driver is used to drive this motor.

Building the robot

Choose a board of convenient size and strength to carry the extinguisher. Use either metal plate board or plywood board. Drill out holes for connecting motor clamps. Place the motor to the chassis with the help of clamp and connect wheels. Short the wires of the motor on the same side such that they rotate in the same direction. Connect each motor pair to the motor driver. Place the flame sensors in the front side of chassis 5-6cm apart, such that the sensor in middle is placed at the center of chassis. Sensitivity of sensors on the sides must be adjusted to detect fire far away. Sensitivity of the center sensor is reduced to detect fire 30cm away. Digital outputs of sensors are connected to pin 2, 3, and 4 of the arduino board. Connect and led to pin 10 so that it glows when fire is detected. Inputs to the motors on left side are obtained from pins 5 and 6 and that for motors on right side is obtained from pin 7 and 8. Pin 11 used to trigger the valve or actuator (pin 11 and12 for cam arrangement). Fire extinguisher must be place on the top of the chassis, inclined at an angle so that it release towards fire. Adjust sensitivity of the center sensor and position or angle of the extinguisher to match the triggering.

The code can be downloaded here - code.ino

How to incorporate solar panel into the robot

 This way the motors can be powered either by the batteries or solar panel, depending on which can provide the most power. The solar panel is also recharging the batteries when there is the sun. This allows the robot to be run by the sun, but not be entirely reliant upon it.

Solar panel



Solder two diodes together such that the cathodes are connected (the side of the diode with the stripe).

Build the circuit

The circuit has two schottky diodes connected cathode-to-cathode with one diode connected to the solar panel and one to the batteries. This setup allows either the batteries or the solar panel to be providing power to the motors, depending on which can provide the most current.
Since the batteries are also rechargeable, there is a third schottky diode connected from the solar panel directly to the battery back. This allows electricity to flow to the batteries and recharge.
Using shrink tube or electrical tape, insulate the wiring to prevent it from shorting.

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