Bomb-Sniffing RobotFinal Report

May 3, 2011Lahar GuptaHieu NguyenKirtan PatelJohn Walthour

Overview

Design Problem Design Implementation Testing and Evaluation Time Constraints Cost Constraints Safety Features Ethical Concerns Recommendations

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

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/

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

Specifications

Specification Range

Response Time < 500 Milliseconds

Wireless Range > 100 Meters

Battery Life > 1 Hour

Weight < 48 Lbs.

Budget $1,500

Hardware

Remote controlled robot Chemical Sensors GPS Tracking Video Camera

Laptop with Graphical User Interface (GUI)

USB gamepad controller

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

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

Implementation

Data flow diagrams Software design

Microcontroller LabVIEW

Hardware components

Operational Block Diagram

Video Feed

GPS

Gas Sensors

Motor Control

Wi-Fi

LabVIEW GUI

ControllerUsers

Laptop Robot

LabVIEW Block Diagram

LabVIEWGUI

Sensor Graphs

Video screen

Google Location Map

Robot Path Map

USB Gamepad

TCP Receive

Gas Sensor

GPS

Video Camera

TCP Transmit

Controller Data

Input Output

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

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

Embedded Software

Interrupt Driven Input/Output SPI interface for Ethernet

controller UART serial interface for GPS ADC sampling Output Compare and Timer

interrupts for PWM outputs Cooperative Multitasking

Loop Debugged and tested to verify

that all functions have no critical sections

Microcontroller SoftwareBlock Diagram

Custom TCP

Server (TCP/IP Library)

FIFO Queue

Ethernet (SPI)

Motor Control Values

PWM Driver

ADC Samples

ADC Driver

GPS Location

Data

UART Driver

Foreground

Interrupts

Storage

Network ProtocolNetwork Protocol

TCP used for reliable data transfer TCP messages are strings with values separated by commas Packet Types

Control DataCameraX,CameraY,MotorDirection,MotorVelocity<CR>ex. “3650,3725,2278,4502<CR>”

Sensor DataHeader,Methane,LPG,CO,Battery<CR>ex. “SD,13,0,508,1011<CR>”

GPS Data Format defined by NEMAHeader,NMEA Message<CR>

ex. “GD,$GPRMC,053740.000,A,2503.6319...<CR>” Keep-Alive

ex. “KA<CR>”

Robot HardwarePart ModelMicrocontroller Digilent Cerebot 32MX4

Wireless Router Linksys WRT54GS

Video Camera Asante Voyager I

Camera Pan and Tilt Lynxmotion BPT-KT

GPS Unit Locosys LS20031

Methane Sensor Hanwei MQ-4

Carbon Monoxide Sensor Hanwei MQ-7

Ethernet Controller Microchip ENC28J60

Motor Controller Dimension Sabertooth 2x25

Motors Hennkwell PD51M

Batteries Turnigy T5000.3S.25

Custom PCB Advanced Circuits

Microcontroller

Digilent Cerebot 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

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

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)

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

Locosys LS20031 GPS Unit 66 channel 10 Hz update rate Battery backup LVTTL UART interface

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

Lynxmotion BPT-KT Pan and Tilt Includes two Hitec HS-422 servo motors Provides 180º by 110º camera movement

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

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

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

Testing and Evaluation

Test Performed ResultWireless Range Passed

Robot Weight Passed

Battery Life PassedGas Detection Passed

Vehicle Mobility Testing Passed

Interface Ease and Usability Passed

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

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.

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

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

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

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

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

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

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

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 Digilent Cerebot 32MX4

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

Ver 2.0

Wrap up and Q&A

Topics Discussed:

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