Team 1617: Autonomous Firefighting Robot Contest Katherine Drogalis, Electrical Engineering Zachariah Sutton, Electrical Engineering Chutian Zhang, Engineering.

Team 1617: Autonomous Firefighting Robot Contest

Katherine Drogalis, Electrical EngineeringZachariah Sutton, Electrical Engineering

Chutian Zhang, Engineering Physics

Advisor: Professor John Ayers

Overview

• 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

• 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

• 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

• No rigid corners to bump walls• Electrical insulating property• Strong; Will not crack when cut• Threaded rod for support• Levels: Top to Bottom

o Start button; LED; mic; kill-power plug; handleo Flame detection sensors; extinguishero Microcontroller; laser scannero 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 positiono Draws current to maintain position - waste of battery power

• Option 2: Servomotorso Similar to Steppero Consumes power as rotates to position then rests - better, wastes less power!o Angle of rotation is limited to 180o (or so) back and fortho 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• 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

○ 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○ 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○ 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)○ “r” coordinate useful in finding wall discontinuities○ Need to convert to cartesian for SLAM

• 2000 samples per second○ 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 Sensoro produce a map of heat valueso able to pick up the difference 1.5m awayo low power consumptiono 16 x 4 = 64 pixelso FOV: 60º horizontal, 16.4º verticalo 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

Candle in total field of view

Experimental Flame Sensor Heat Map

Routing/Navigation

• SLAM (Simultaneous Localization and Mapping)• Find current location in a map of landmarks

○ 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 2560o 256 kB of Flash Memoryo 8 kB of SRAMo 4 kB of EEPROM o 7 to 12 Voltso Highly versatileo Many available open source librarieso Programmable in C++

• Raspberry Pi (possible addition)o Helps the speed of processingo All real-time calculations with scanner data must be accomplished within 500 uso Will add if unable to make Arduino code this efficient

Flame Extinguishing

• Realistic: Compressed gas (CO2)o Best option for large-scale fire - bonus points!o Cartridge at the back of the roboto Extended nozzle at the front aligned with the sensorso Pointed directed at the candle flame

• Unrealistic: Fano Will make a large-scale fire worse!o Controlled by Arduinoo Fallback option

Power Supply and Other Requirements

• Rechargeable DC batterieso Two sets - use one while charging other - save time!o 4 separate cells - option to pull power from individual cellso Max 14.8 Vo 5500 mAho 532.2 grams

• Other requirementso Start button: green backgroundo LEDs: white backgroundo Microphone: blue backgroundo Kill-power plug: yellow backgroundo Handle

Budget

Questions?