Presentation on theme: "FIRE FIGHTING ROBOT ELECTRO-MECHANICAL SYSTEMS TERM PROJECT 1"— Presentation transcript:
FIRE FIGHTING ROBOT ELECTRO-MECHANICAL SYSTEMS TERM PROJECT 1 http://www.engr.mun.ca/~burt/
TEAM FIREFIGHT! Mark BurtJoe TraverseBrent Pomroy 2
PROJECT OBECTIVES 3 For this Term Project our fundamental goal was to design and manufacture an electromechanical device that would be able to locate and extinguish a flame. This goal was reached through the integration of light sensors, stepper motors, H-bridge, and a pic micro-controller.
Device Components 4 Two 1.8” Stepper Motors (8.4V, 0.56A) 12V Brushless DC Fan (0.15A)
Device Components 5 Two Light Sensors Two 3 3/4” Diameter Aggressive Tread RC Wheels
Device Components 6 Free rotating dolly wheel
Device Components 7 16F877 PIC Microcontroller and “H” bridge
Device Components 8 Two 12 volt DC batteries
Design 9 Frame: The frames is made of Lexan Ecstatically pleasing Lightweight, Strong “bullet proof” easily machined and workable Flame retardant It should also be noted that Lexan is widely used in power tools, electrical appliances, communications equipment, business machines, safety equipment and aircraft components. Wheels: The Aggressive Tread RC Wheels were chosen mostly due to the fact that if any obstacles were to get in the way of the robots motion then it would have no trouble climbing over the obstacle.
Design 10 Motion: It was decided to use two stepper motors as the motion devices and incorporate a dolly wheel at the rear to allow the device to pivot more easily. This would allow the robot to have near perfect rotation and permit straight forward motion.
Design 11 Type of Sensor: A Photoresistor is an electronic component whose resistance decreases with increasing incident light intensity. This type of sensor was selected in comparison to Heat Sensors due to the fact that a candle produces very little heat compared to the amount of light created. For our prototype light sensors were more efficient and made more sense to design and implement.
Design 12 How Sensors were located: The light sensors where positioned on the front of our robot just inside the two large front wheels. The purpose of this was so that the wheels would accurately guide the light sensors. Wherever the wheels turned, the sensors would follow until both sensors recorded an equal value. Once the two sensors received the same amount of light within a predetermined range, the robot would begin to go in a straight motion untill the value received by both sensors is greater then a set voltage, at which time the robot will stop and extinguish the flame. Photoresistors
Design 13 A sensor divider was installed between the two sensors to decrease the amount area that would produce equal sensor readings in part increasing the accuracy of the robot. With this addition the fire will have to be directly in front of the sensors to produce an equal sensor reading.
Integration of Device 14 The code implementation for this project was done in a step by step process: First one stepper motor was wired up and code was written to run the lone motor by itself Next we hooked an “H” bridge to the PIC microcontroller which allowed us to add a second motor. Our code was adjusted run both motors simultaneously. Then the first senor was hooked in to Port A0 and the programmed was attuned so that the motors were dependant on the sensor input values. We then used hyper terminal to read the values from the phototransistor sensor which aided with the tweaking of the programming values which in turn enabled us to control the motion of the motors when the light intensity of the senor changed. Finally the second senor was added and code was written to implement a multiple candle search possibility for our robot which would have been impossible with just one sensor.
Program Flow Chart 15
Design Trade Offs 16 By having the fan switched on at all times, this allows are mechanical device to be smaller. In order for the fan to have been turned on when it has reached the desired distance from the light. It would have required more wiring and another electrical board. Lighter batteries could have been used. The two 12 V batteries used add unwanted excessive weight to the robot. Cooling fan or an aluminium heat sink could have been installed to cool steppers. Two 12 Volt Batteries
Design Trade Offs 17 Due to the fact that we were un-able to alter the shafts of the stepper motors, we used a set screw to couple the wheels to the drive shafts. This dramatically reduces the amount of torque the steppers were able to output due to slippage. Machined part that attaches the wheel to the steeper motor using a set screw so that the wheel is attached securely. Hollow end which slides over the stepper motor
18 Problems Encountered Through out the course of the project some problems were encountered. The Universal Pic Boards have been used and abused the over past few years, some of the connections are lose and caused many headaches as we found out, having to replace three boards during the build ! Like the Pic Board, our “H” bridge also had a lose connection which caused some down time until the problem was rectified and fixed. The fact that the shafts of the stepper motors could not be machined caused a problem with slipping. If the shafts could be machined the stepper motors could produce a lot more torque and also a lot more speed.
19 Problems Encountered Major Problems occurred from the use of single strand solid wires. These wires were used to connect the PIC to the stepper motors. With the continuous assembly and disassembly of the robot these wires would bend back and forth eventually break off where there were connected to the port on the board. Re-occurring Broken wire
Pics from the build 20
Primary Environment 22 Primary Fire Fighting Conditions
Application 23 The Fire Fighting Robot could be used to fight fires in hazardous location, which firefighters cannot access safely. The Robot could be used to enter small spaces that are impossible to be accessed by a person. Did you know that forgotten candle are the # 1 cause of house fires! This robot could be use to extinguish candles and prevent these tragedies.