Bomb-Sniffing Robot Final Report May 3, 2011

1. Bomb-Sniffing RobotFinal ReportMay 3, 2011 Lahar Gupta Hieu Nguyen Kirtan Patel John Walthour

2. Overview • Design Problem • Design Implementation • Testing and Evaluation • Time Constraints • Cost Constraints • Safety Features • Ethical Concerns • Recommendations

3. Scope and Purpose • Present details design and evaluation of the Bomb-Sniffing Robot prototype • This presentation covers the period from January 18, 2011 through May 3, 2011

4. Design Problem • To save men and women from dying preventable deaths in combat. • Each year hundreds of men and women die in combat due to un-detected bombs and chemical exposure. http://news.bbc.co.uk/2/shared/spl/hi/in_depth/baghdad_navigator/

5. Design Solution • Proof-of-concept prototype called the Bomb-Sniffing Robot • Designed for military personnel and civilian bomb squads to allow the remote detection of hazardous conditions and substances • Unmanned vehicle controlled wirelessly from a laptop with a gamepad • Sensors on the robot send information about hazardous chemicals to the operator

6. Specifications

7. Hardware • Remote controlled robot • Chemical Sensors • GPS Tracking • Video Camera • Laptop with Graphical User Interface (GUI) • USB gamepad controller

8. Laptop Interface • National Instruments LabVIEW GUI • Gather control information from gamepad • Process sensor signals • Display video feed • Display GPS location information • Battery and connection status • Configuration menu • Technical support information

9. Microcontroller Software • PIC32 programmed in C with Microchip MPLAB IDE • Drivers required for design solution: • UART • SPI • ADC • PWM • Custom TCP server to communicate with LabVIEW • Leverage Microchip TCP/IP Application Library

10. Implementation • Data flow diagrams • Software design • Microcontroller • LabVIEW • Hardware components

11. Operational Block Diagram Video Feed Controller Users GPS Wi-Fi Gas Sensors Motor Control LabVIEW GUI Robot Laptop

12. LabVIEW Block Diagram Output Input

13. Graphical User Interface • Multiple tabs to separate main display from auxiliary data • Main Display • Video • Sensor Data • Battery Life • Connection Status • Location Tracking • Configuration • Video Settings • Network Settings • Tech Support • FAQ • Manual

14. Gamepad Controller • Simple and intuitive control • Gamepad has two joysticks • Camera pan and tilt control • Vehicle motion • Started with Joystick Input Device Control LabVIEW module • Modified the module for use with Logitech USB Gamepad • Read data from the gamepad controller

15. Embedded Software • Interrupt Driven Input/Output • SPI interface for Ethernet controller • UART serial interface for GPS • ADC sampling • Output Compare and Timerinterrupts for PWM outputs • Cooperative Multitasking Loop • Debugged and tested to verify that all functions have no critical sections

16. Microcontroller SoftwareBlock Diagram Foreground Interrupts Storage

17. Network Protocol Network Protocol • TCP used for reliable data transfer • TCP messages are strings with values separated by commas • Packet Types • Control Data CameraX,CameraY,MotorDirection,MotorVelocity<CR> ex. “3650,3725,2278,4502<CR>” • Sensor Data Header,Methane,LPG,CO,Battery<CR> ex. “SD,13,0,508,1011<CR>” • GPS Data • Format defined by NEMA Header,NMEA Message<CR> ex. “GD,$GPRMC,053740.000,A,2503.6319...<CR>” • Keep-Alive ex. “KA<CR>”

18. Robot Hardware

19. Microcontroller • DigilentCerebot 32MX4 • Based on Microchip PIC32MX460F512L • 80 MHz • 512K Flash • 32K RAM • Compatible with Microchip’s TCP/IP application library • 16 channel 10-bit ADC for sensor sampling • 1 million samples per second • 5 Pulse Width Modulation outputs • 2 SPI Interfaces • 2 UART Interfaces

20. Wireless Network • Linksys WRT54GS provides wireless link between laptop and robot • Installed DD-WRT open source firmware • > 100 Meter range • 54 Mbps • 802.11B/G • Microchip ENC28J60 connects the microcontroller to the router • 10Base-T • SPI Interface • Compatible with Microchip’s TCP/IP application library

21. Motor Controller and Motors • Dimension Engineering Sabertooth 2X25 • Dual channel motor controller • 25A continuous current per channel • 50A burst current • Thermal protection • Overcurrent protection • Lithium battery under-voltage cutoff • Direction and velocity selected with PWM • Signal inputs VOH = 5V, so 3.3V output of PIC converted using 7407 IC • Controls two PD27M DC motors • 12V, 5A (35A Stall) • 300 RPM • 694 oz-in torque (4.9Nm)

22. Robot Sensors • Hanwei MQ-4 Methane Gas Sensor • Detects 200 – 10000 ppm • 150mA • Hanwei MQ-7 Carbon Monoxide Gas Sensor • Detects 20 – 2000 ppm • 150mA • LocosysLS20031 GPS Unit • 66 channel • 10 Hz update rate • Battery backup • LVTTL UART interface

23. Video Camera • Asante Voyager I IP Camera • 640x480 Resolution @ 30 Frames Per Second • Wireless or Ethernet connectivity • Infrared night-vision • Audio recording • ActiveX control for interfacing to LabVIEW • LynxmotionBPT-KT Pan and Tilt • Includes two Hitec HS-422 servo motors • Provides 180º by 110º camera movement

24. Power System • 12V Switching Regulator • 2.5A maximum current • Supplies power to camera and wireless router • Over-current and over-voltage protection • Based on the National Semiconductor LM3488 • 5V Switching Regulator • 2A maximum current • Supplies power to the microcontroller, servos, and sensors • Over-current and over-voltage protection • Based on the National Semiconductor LM22676 • 10 Ah of battery power • Provided by two 3-cell Lithium-Polymer packs • One battery supplies the voltage regulators • The other battery powers the DC motors

25. Custom PCB • Created with Advanced Circuits PCB Artist • Combines several systems onto single PCB • 12V Switching Regulator • 5V Switching Regulator • Two Gas Sensors and Filtering • Battery Monitor • GPS Interfacing • Ethernet Controller • 3.3V to 5V Level Shifter for Motor Controller

26. Chassis • Made from acrylic plastic and aluminum • 2 polyurethane treads from Lynxmotion • 3 platforms to hold components • Weighs 12 lbs. with components • 14”L x 12”W x 10”H

27. Testing and Evaluation

28. Wireless Range Testing • Specification: Wireless range greater than 100 meters • Test Results • Lost video feed at 168 meters • The response time became greater than 500ms at 182 meters • All response times less than 100ms within 100 meters

29. Robot Weight Testing • Specification: Weighs less than 48 lbs. • Test Results • Robot weighs 12 lbs. • Laptop weighs 6.4 lbs. • Total weight of 18.4 lbs.

30. Battery Life Testing • Specification: Battery life greater than one hour • Test Results • Starting voltage of 12.55V • During the open house, continuous motion for three hours • Ending voltage • Battery 1 = 11.38V • Battery 2 = 11.30V • Estimated total run-time of six hours

31. Gas Detection Testing • Specification: Detect unknown quantities of methane and carbon monoxide • Natural gas from a stove used to test the methane sensor • Smoke from a burning piece of paper used to test the carbon monoxide sensor • The test was repeated five times for each sensor and the results were all similar to the graphs shown

32. Vehicle Mobility Testing • Specification: The robot should be able to climb a 30º incline • Test Result: The robot can climb a 35º incline • The center of gravity, not torque, is the limiting factor

33. Interface Testing • Specification: Likert survey results of agree or higher. • 1 = Strongly Disagree • 2 = Disagree • 3 = Neutral • 4 = Agree • 5 = Strongly Agree • Test Result: An averagescore of 4.2 was given • Change resulting from survey • Location tracking enlarged • Time zone taken into account

34. Cost Constraints • Total budget of $1500 • Budget did not allow the purchase of actual bomb-detecting sensors • Removed radiation detector due to cost • Built chassis from scratch to save money • Causes the frame to shake, which lowers the video feed quality • Current Project Cost = $1,263.66

35. Safety Features • Protection Mechanisms • Zener diodes to avoid over-voltage and fuses to avoid over-current • Guards to protect the user • Microcontroller monitors the battery level to perform an auto shutdown before the batteries become depleted • Hazards • Remove the batteries before recharging

36. Ethical Concerns • Recyclable plastics and metals for the chassis • Restriction of Hazardous Substances (RoHS) certified lead-free components for the electronics • Lithium Ion batteries are the most hazardous components of the robot • Production model should offer an end-of-life recycling program at no charge • Invasion of privacy concerns

37. Ver 2.0 Recommendations • Proposed Changes • Get access to new nano-technology research currently increasing the sensitivity of bomb detection • Construct the chassis from aluminum to increase strength and durability • Increase the ground clearance of the robot. Currently, on rough terrain, the robot can become stuck on rocks or fallen branches. • Successes • DigilentCerebot32MX4 • TCP/IP Library from Microchip • Wireless router to establish communication link between the robot and laptop • National Instruments’ LabVIEW for data processing and user interfacing

38. Wrap up and Q&A • Topics Discussed: • Design Problem • Design Implementation • Testing and Evaluation • Time Constraints • Cost Constraints • Safety Features • Ethical Concerns • Recommendations