Designing Fully Autonomous Firefighting Robot for Trinity International Robot Contest

1. Team 1617: Autonomous Firefighting Robot Contest Katherine Drogalis, Electrical Engineering Zachariah Sutton, Electrical Engineering Chutian Zhang, Engineering Physics Advisor: Professor John Ayers

2. Overview • Project Overview & Contest Background • Mechanical Design & Layout • Sensors& Routing • Microcontroller • Flame Extinguishing • Power Supply • Budget

3. 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

4. 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

5. Test Arena

6. 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 • Start button; LED; mic; kill-power plug; handle • Flame detection sensors; extinguisher • Microcontroller; laser scanner • Driving motors; control circuit; batteries

7. Two Motors Independently Driving Two Wheels • Can turn different angles simultaneously • Take commands from microcontroller • Option 1: Stepper Motors • Position controlled: constant input voltage drives motor to specific position • Draws current to maintain position - waste of battery power • Option 2: Servomotors • 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

8. 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 • 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)

9. 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

10. 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

11. Video of Laser Range Sensor

12. Experimental Data

13. Flame Sensor • RoBoard RM-G212 16X4 Thermal Array Sensor • 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

14. Experimental Setup

15. Experimental Flame Sensor Heat Map Heat measurements at distance of 0.2 m Heat measurements at distance of 1.5 m

16. Experimental Flame Sensor Heat Map Candle in total field of view

17. 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

18. Routing/Navigation

19. Microcontroller • Arduino Mega 2560 • 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) • Helps the speed of processing • All real-time calculations with scanner data must be accomplished within 500 us • Will add if unable to make Arduino code this efficient

20. Flame Extinguishing • Realistic: Compressed gas (CO2) • 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 • Will make a large-scale fire worse! • Controlled by Arduino • Fallback option

21. Power Supply and Other Requirements • Rechargeable DC batteries • 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 • Start button: green background • LEDs: white background • Microphone: blue background • Kill-power plug: yellow background • Handle

22. Budget

23. Questions?