PRESENTED BY:
Myles Durkin
Kevin McHugh
Ryan Ehid
Brian Lepus
Stephen Kropp

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Problem Statement
The robot that this team is proposing to build must be capable of performing many tasks. The robot must be able to search a two story, three bedroom house in under 15 minutes. In addition the robot must be able to identify victims and deliver an air tank, fire blanket and homing beacon to their location in order to extend their lives while the firefighters attempt to control the blaze. In order to be able to exist in such harsh conditions the robot must be heat resistant and water resistant. To make the robot more maneuverable the weight of this robot has been limited to 150 pounds and the width of the robot has been limited to two feet to accommodate doorways. The main goal of this project is to save lives. If the robot can successfully aid in the rescue of victims who would have otherwise perished in a fire this groups goals have been met.
I. Introduction
Historically, fire has been one of mans greatest fears. Fire has the ability to destroy all in its path regardless if on land or on sea. In the present day fire, while not as substantial of a fear as in previous centuries, is still a legitimate cause of death in the United States. It is estimated that someone dies in a fire once every 162 minutes and someone injured by fire every 32 minutes. As such, the goal is to create a robot which can travel through a burning home, recognize and identify any persons within, and extinguish a fire to allow for said person to exit the building safely. A robot such as this could also be sent into a burning building ahead of firefighters to assess the risks of sending a human being inside. Integrating robotics into life threatening these life threatening situations can help save countless lives while not putting the lives of the firefighters at risk.
This device would be able to overcome obstacles such as stairs, fallen tables or chairs and reach a stranded person. It follows that this robot must have some type of infrared detection system or rudimentary video camera to allow for the recognition of victims and fire hazards. Also this robot must be capable of extinguishing a small fire using some fire quenching material. While the initial idea for this project stems from an actual robotics competition sponsored by Trinity College, our finished product would be radically different. We plan to build a marketable and useful device which could be employed in any situation where fire hinders human search and rescue efforts. Traditionally fires that are out of control must be put out or controlled before firefighters can begin searching for survivors inside a structure. With the integration of this robot, the search and rescue operation can begin immediately and simultaneous to efforts to control the blaze from the outside of the structure. This robot could be used by fire departments but also by military branches looking for a safe and effective way to extinguish fires especially in enclosed areas like ships.
While there are naturally many versions of firefighting robots which are used in the aforementioned competition this project differs quite substantially. In the competition an entirely autonomous robot is created which can traverse a predetermined path and extinguish a candle however, our robot will be built with a control system which will allow a team member to guide the robot through an unknown building and put out a fire. This control system will require a great deal of programming, circuitry, and mechanical knowledge as well as a guidance system to assist the driver through an ostensibly smoke filled room. This robot will also be capable of putting out a larger flame than that in the competition, and as such our robot must be impervious to flames so as to withstand the possible dangers which come from fire rescue. The robot must also be able to withstand the large amounts of water that will be pouring into the structure from the firefighter’s efforts on the outside. A water or fire extinguishing system of some type must also be incorporated into the design; possibilities include a simplistic water hose as well as a normal fire extinguisher. The human operator will be in control of this and will be able to engage/disengage as well as aim the extinguishing material toward the blaze. A further control which we would like to incorporate is the ability of the robot to transport a fire proof blanket to protect any person who is trapped in the burning building as well as some type of device which allow people trapped to know help is on the way. This would require an additional set of controls so that the blanket would be protected from damage while the robot is traveling through the home as well as allowing it to be distributed by either the controller or trapped individual.
It will be necessary to examine the materials used to determine if they are fire proof so as to design a robust robot. As in any life-threading situation, time is of the essence and the speed of the robot and the efficiency with which it navigates the building is paramount. Varying gear trains must be examined as with wheels or possible treads to determine which would be best for this project. It will be required that the motor powers be evaluated so as to determine the most efficient method to power the robot (battery, solar power, etc.). As mentioned above this robot cannot be tethered to the control board thus it is necessary to implement a communication system between the robot and the controller. It is also required that the control of this robot be streamlined to allow any person to use it regardless of their occupation.
Ultimately the goal of this project is to integrate all of the advantages of robots with all of the advantages of having a human being on scene. Humans can react faster to changing scenarios than can robots, however robots are capable of maneuvering where humans cant, are able to lift heavier objects, are able to maneuver better in limited visibility and can withstand much higher levels of heat. A robot such as this could be used in scenarios varying from a house fire to high-rise fires and could even make disaster rescues similar to 9/11 happen with much greater efficiency and with much less loss of life on the part of the rescuing parties.

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FIRE FIGHTING ROBOT SYSTEM
ABSTRACT
This paper describes the design and construction of a small autonomous robot for entry in the 1998 Fire Fighting Robot Competition. At the heart of the system is the 68HC12 microcontroller by Motorola. Program code to control the fire fighting robot is written in 68HC12 native assembly language. The system controls two optically isolated stepper motors for precision movement. Furthermore, the robot performs analog to digital conversion on 6 infrared sensors: 4 for wall proximity detection, one to detect floor markings, and one for candle detection. The 4 proximity sensors utilize heterodyne modulation of the IR signals to reduce the effects of ambient lighting. The extinguishing system is comprised of a large fan salvaged from a toy hovercraft, and a 3.5kHz tone decoder circuit is used to start the robot and gain bonus points.
INTRODUCTION
The annual Fire Fighting Robot Competition sponsored by Trinity College has been an exciting event for several years. Robot hobbyists and professionals of all ages from all parts of the world gather to compete and show off their creations. The goal of the event seems simple: Navigate a model house floorplan, find a lit candle, and extinguish it. As simple as this may sound, it is an intricate process to construct a device which can accomplish such a task. There are a vast number of design options and operating techniques that can be explored.
As the contest’s web page states, a primary purpose of the contest is to "provide an incentive for the robotics community to develop what will be a practical application for a real-world robot". Although the contest is merely a simulation of a real-world scenario, it requires the designers to use practical techniques to create useful designs. The competition serves as an example of what robots can do on a larger scale.
In the first year of competition, there were only a few robots that were able to successfully find and extinguish the candle reliably. The more recent events, however, have yielded a larger number of successful entries. It appears, that the designs are becoming more sound as the robotics community learns which approaches work and which fail. Because of these improvements, the event has a higher level of competition. An entry that strives to perform well must be fast and reliable. This designers of this project aim to accomplish both these tasks.
OVERVIEW OF ROBOT SYSTEM
Figure 1 is a functional block diagram of the robot system. At the heart of the robot is the 68HC12 microcontroller from Motorolla. The microcontroller is responsible for sending signals to and receiving signals from the robot hardware. First, the 68HC12 receives input from the calibration button before each run. This allows the user to align the robot at a specific distance from the desired wall to be followed. Once this has occured, the 68HC12 waits for a logic low from the tone-decoder. Then, the controller outputs to the optoisolators to control the motor driver circuits. The controller also reads values from the IR phototransistors in order to detect walls and search for the candle.
STEPPER MOTORS AND STEPPER DRIVER CIRCUIT
When deciding how to move the robot through the house, the designers realized that precision movement would be necessary in order to avoid touching the walls and receiving penalties. In order to achieve the required precision in movement, it was decided that the robot would utilize stepper motors.
The main benefit of stepper motors is that they are able to turn a specific number of degrees for every step. A four phase stepper motor has four coils that, when energized in a specific sequence, rotate a driving magnetic field which, consequently, rotates a set of permanent magnets. These permanent magnets are attached to a rotor which drives an output shaft. Thus, by pulsing the coils in a certain sequence, a clockwise or counterclockwise movement can be attained.
A change in the coil states (ie. changing from state 2 to state 3 as shown above) results in a single step of the motor shaft. Direction is easily controlled by running through the above sequence either forward or backward. It should also be noted that the coils A and A' are always oppositely charged, as are coils B and B'. By inverting the signals going to coils A and B, the corresponding signals A' and B' can be attained. Thus, only two control lines are required to place the motor into any one of the 4 possible states. Even though this is an important consideration for certain applications, the controller used in this implementation has a sufficient number of lines to control each coil. Furthermore, because two of the coils are always energized at any given time, the rotor is held into place by the two magnetic fields and hence will not easily slip -- even when the motor is not turning. This is another benefit of stepper motors. Figure 2 provides an internal diagram of a typical four phase stepper motor.
The stepper motors used for this project were salvaged from surplus Epson printers. The steppers are designed to provide 1.8 degrees per step (or 200 steps per revolution) and supply a sufficient amount of torque. However, the current requirements of almost any motor are more than a digital output can provide. Because of this requirement, a transistor circuit is needed to drive the motor coils.
The circuit shown in Figure 3 is used to drive the motor coils. Because there are a total of eight motor coils in the robot, eight of these circuits are needed. The circuit functions by receiving a digital input from the microcontroller. This signal is fed to an optoisolator in order to separate the low-voltage, low-current microcontroller from potentially dangerous signals in the motor driver circuit. In other words, the optoisolator allows the 68HC12 to control the motors without any physical connection to the driver circuit. The output side of the optoisolator then drives the base of the TIP112 driver transistor. Just as the stepper motors were, the TIP112 transistors were salvaged from the Epson printers. The TIP112 power transistors are able to supply 50 watts of power, which is more than sufficient to drive the stepper motor coils.