Transcript Design Review Presentation

Team 1617: Autonomous
Firefighting Robot Contest
Katherine Drogalis, Electrical Engineering
Zachariah Sutton, Electrical Engineering
Chutian Zhang, Engineering Physics
Advisor: Professor John Ayers
Overview
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Project Overview & Contest Background
Mechanical Design & Layout
Sensors & Routing
Microcontroller
Flame Extinguishing
Power Supply
Budget
Design a Fully Autonomous Robot to Find &
Extinguish a Flame
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Trinity International Robot Contest (April 1-3, 2016)
User initiated, autonomous start & navigation
Search for and extinguish burning candle
Design can be extended to real life situations
Trinity International Robot Contest
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8x8’ plywood maze
Arbitrary start position
Competing in 2 of 3 levels
Timed trials
Unique robot
31x31x27 cm robot
Level 1 Arena
Level 2 Arena
Test
Arena
Round Polycarbonate Body
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No rigid corners to bump walls
Electrical insulating property
Strong; Will not crack when cut
Threaded rod for support
Levels: Top to Bottom
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Start button; LED; mic; kill-power plug; handle
Flame detection sensors; extinguisher
Microcontroller; laser scanner
Driving motors; control circuit; batteries
Two Motors Independently Driving Two Wheels
• Can turn different angles simultaneously
• Take commands from microcontroller
• Option 1: Stepper Motors
o Position controlled: constant input voltage drives motor to specific position
o Draws current to maintain position - waste of battery power
• Option 2: Servomotors
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Similar to Stepper
Consumes power as rotates to position then rests - better, wastes less power!
Angle of rotation is limited to 180o (or so) back and forth
Complicated setup with PWM tuning
Best Option: DC Motor w/ Encoder
• Velocity controlled: constant input voltage drives motor to specific velocity
• Can control position by applying velocity commands over a certain time
o Pulse-Width Modulation signal
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FAST - 100 rpm
12V - perfect for battery operation
Count wheel rotations with encoders
64 counts per rotor revolution (6400 counts per wheel revolution)
Need to Sense: Walls/Obstacles & Flame
• Range sensing options
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Ultrasonic: cheap, easy to use, low interference, low resolution
Infrared: cheap, range limited, interference prone, low resolution
Laser: expensive, long range, low/no interference, processing required, high res
• Flame sensing options
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Look for presence of both light and heat
Light: photoresistors/photodiodes, subject to external interference
Heat: IR non-contact sensing, must work at range of ~1 m
Choice: 360o Laser Scanner by RoboPeak
• Scanner vs. Stationary
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Stationary: cheaper, would need to be mounted on scanning platform
Scanner: set sample rate, configurable scan speed, built-in angular encoder
• Measurements in body reference frame polar coordinates (heading = 0º)
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“r” coordinate useful in finding wall discontinuities
Need to convert to cartesian for SLAM
• 2000 samples per second
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Vary scan speed to control angular distance between samples
Get ~1 sample per degree with 5.5 Hz scan rate
Video of Laser Range Sensor
Experimental Data
Flame Sensor
• RoBoard RM-G212 16X4 Thermal Array Sensor
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produce a map of heat values
able to pick up the difference 1.5m away
low power consumption
16 x 4 = 64 pixels
FOV: 60º horizontal, 16.4º vertical
0.02 Degree Celsius uncertainty
• Can find center of candle at close range
• Have a particular pixel act as target location
• May be unecessary to add light sensing
Experimental Setup
Experimental Flame Sensor Heat Map
Heat measurements at distance of 1.5 m
Heat measurements at distance of 0.2 m
Experimental Flame Sensor Heat Map
Candle in total field of view
Routing/Navigation
• SLAM (Simultaneous Localization and Mapping)
• Find current location in a map of landmarks
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Use laser to pick out corners and terminal points in walls
Predict next position from current position and a given control command
Compare prediction with sensor result after command is executed
Correct based on previous reliability of sensor measurements and predictions
• Adaptive
Routing/Navigation
Microcontroller
• Arduino Mega 2560
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256 kB of Flash Memory
8 kB of SRAM
4 kB of EEPROM
7 to 12 Volts
Highly versatile
Many available open source libraries
Programmable in C++
• Raspberry Pi (possible addition)
o Helps the speed of processing
o All real-time calculations with scanner data must be accomplished within 500 us
o Will add if unable to make Arduino code this efficient
Flame Extinguishing
• Realistic: Compressed gas (CO2)
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Best option for large-scale fire - bonus points!
Cartridge at the back of the robot
Extended nozzle at the front aligned with the sensors
Pointed directed at the candle flame
• Unrealistic: Fan
o Will make a large-scale fire worse!
o Controlled by Arduino
o Fallback option
Power Supply and Other Requirements
• Rechargeable DC batteries
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Two sets - use one while charging other - save time!
4 separate cells - option to pull power from individual cells
Max 14.8 V
5500 mAh
532.2 grams
• Other requirements
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Start button: green background
LEDs: white background
Microphone: blue background
Kill-power plug: yellow background
Handle
Budget
Questions?