Auto-Navigation of unmanned helicopter to extinguish forest fire using wireless sensor networks (WSN). The prototype was made using an RC helicopter, thermostat and IRIS motes for WSN.

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Auto-navigation of Unmanned Helicopter to
Detect and Extinguish Forest Fire
University of Maryland Baltimore County
December 17, 2010
Jerome Stanislaus
(sjerome1@umbc.edu)
Abstract
A Wireless Sensor Network application has been presented that is capable of detecting forest fires
by using fire sensors. When there is an event sensed, the sensor communicates with the base
station, which then sends control signals to a helicopter. The helicopter will go to the particular
sensor and extinguish the fire.
1. Introduction
A Wireless Sensor Network (WSN) consists of spatially distributed autonomous sensors to
cooperatively monitor physical or environmental conditions, such
as temperature, sound, vibration, pressure, motion or pollutants [1]. Recent advancements in
wireless sensor networks have made them grow beyond the military applications that they were
initially designed for to the world where humans work and live: buildings, cars, homes, etc. The
biggest advantage gained from these advancements has been the fact that the sensor networks are
now able to work with very little human intervention.
This advantage has been utilized in our project wherein forest fires are detected automatically by
deploying fire sensors that operate wirelessly. If one of the sensors detects a fire it sends a signal
to the computer. The computer then controls the helicopter and sends it to the particular sensor.
Thus, with minimal human intervention the fire is extinguished.

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2. Overview
Consider a forest where sensors are randomly deployed all over the region using any random
deployment method. Now, if a forest fire is detected the sensors send a signal to the command
node which is connected to a computer via USB. This command node and the computer together
serve as a base station. The computer then sends out signals via its parallel port to control a
helicopter, which is directed towards the fire. The helicopter may be equipped with fire
fighting tools that will help subdue the forest fire.
Fig. 1. Diagrammatic representation of the application
3. Implementation
Our project implements a Wireless Sensor Network that can also be extended to a large scale
implementation. The wireless network is created by separate motes or nodes which are equipped
with a sensor board. When activated, the sensor node is able to communicate to the computer.
This communication takes place in a multi-hop fashion. The motes used are manufactured by
Crossbow Technology and are called the Crossbow IRIS motes. The sensor boards are the MDA
100 boards, also manufactured by Crossbow.
So, the entire network can be represented as shown in Figure 2.

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Fig. 2. Project representation
The sensors are programmed individually first and then deployed (the source code for the same
is attached at the end of this report). A location map is created of the sensors. The computer
knows which sensor is activated so it is able to point the helicopter in the right direction. After
the deployment, we wait for a sensor to trigger the signal to the helicopter. When a signal is
received, the chopper flies towards the particular sensor node.
We have created a circuit that is connected to the parallel port of a computer. The circuit is
shown in Figure 3. The transistors Q1 and Q2 are 2N3053, n-p-n transistors.
Fig. 3. Circuit to interface with parallel port

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Inside the helicopter’s remote control, the directional control stick works based on two separate
variable resistors. The first variable resistor controls the front-back movement and the second
variable resistor makes the helicopter turn clockwise. For example, considering the variable
resistor that controls the back propeller of the helicopter (i.e. front-back movement), we observed
that the chopper moves forward when the resistor is at its minimum position and stays stationary
when the resistance is maximum. So, by bypassing the variable resistor, we apply either a low
resistance or a high resistance across the terminals. We used a BJT as a switch in the circuit. A
BJT switches according to the voltage applied at its Base terminal. The Collector and Emitter are
connected to the ends of the variable resistor. So, when +5V is applied to the Base of the BJT,
there is a connection between the Collector and Emitter terminals. This provides a path of least
resistance between the Collector and Emitter terminals, implying a low resistance is found on the
variable resistor. Hence, the chopper moves forward. When 0V is applied at the Base, there is no
connection between the Collector and Emitter. This provides the high resistance that’s required.
So, the chopper stops moving forward. To reduce the Base current, so as to save power, we
added a heavy resistor on the Base terminal. Two data ports from the parallel port of the
computer supply the voltages.
4. Simulation
For the simulation, the time the helicopter takes to traverse 10 feet was recorded. This was done
to know how long the parallel port must send logic “one” (i.e. +5V) to the Base. The helicopter
is first controlled manually to take it to a steady position and height after which the sensor is
activated. The computer gets the signal from the sensor via multi-hop following which it
calculates the distance the helicopter must travel. It then sends the corresponding signals to the
Bases of the transistors mentioned previously.
5. Future work
In the future, we propose that the application be automated further and the helicopter be entirely
controlled by the computer. The sensor network could be formed in a different manner so as to
optimize the coverage of the nodes.

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6. References
[1] Definition of WSN.http://en.wikipedia.org/wiki/Wireless_sensor_network
[2] Image of laptop. http://blog.loaz.com/timwang/index.php
[3] Image of Motes. http://neo.lcc.uma.es/staff/guillermo/index_files/investigacion/redes