Self -Guided Wheelchair

SelfSelf--Guided WheelchairGuided WheelchairDesign Review PresentationDesign Review Presentation

Student Members:Margaret ShangleVee Shinatrakool

Tara SpodenJohn Volkens

Brian Yauk

Faculty Advisor:Dr. Nicola Elia

Client:National Instruments

AgendaAgenda

� Introduction� Functional Requirements� General Solution� Detailed Design� Summary

Presentation OverviewPresentation Overview

IntroductionIntroduction

� Self-guided wheelchair• Capable of autonomously moving through

environment while avoiding any obstacles• Selectable starting points/final destinations• Based on motorized wheelchair• Programmed with LabVIEW Embedded 8.2• Sponsored by National Instruments

Project DescriptionProject Description

DefinitionsDefinitions

LabVIEW Embedded…. graphical programming language developed by National Instruments for implementation on OEM hardware

RF……………………….. (radio frequency) frequency that lies in the range within which radio waves may be transmitted, from about 10 kilohertz per second to about 300,000 megahertz.

Transponder…………… radio transmitter-receiver activated for transmission by reception of a predetermined signal. An RF reader/transmitter sends a signal via radio waves in order to detect transponders designed to read that reader’s particular frequency signal.

VI………………………… (virtual instrument) file containing subroutines or subfunctions created in LabVIEW

Project TerminologyProject Terminology

Functional RequirementsFunctional Requirements

� Medical hospital setting� Operation on a single floor level� Free of stairs or similar large drop-offs� Common hospital floor type

• Tile• Hardwood• Short carpet

Operating EnvironmentOperating Environment

Functional RequirementsFunctional Requirements

� Primary User• Provides location information for the system input• Shape recognition and basic literacy• Medical staff or guardian

� Secondary User• Passenger that will be transported • Able to maintain a seated position within the

confines of the chair dimensions• Patient

Intended Users and UsesIntended Users and Uses

General SolutionGeneral SolutionEnd Product DescriptionEnd Product Description

9%90%10%Path calculation

9%90%10%Obstacle detection

35%100%35%LabVIEW Embedded controlled operation

4.75%95%5%User-selectable starting and ending points

91.75%100%Total

100%

100%

50%

80%

Evaluation Score

10%

15%

5%

4%

Resultant Score

10%Turn control with 5% accuracy

15%Speed control (forward, reverse, stop)

10%Location recognition

5%Obstacle avoidance

Relative ImportanceFunctionality


Inputs Processing Outputs

Starting position/final destination

Current location

Distance to obstacles

Magnetic orientation

Gyroscope orientation

Calculate path from start to end

Determine critical obstacles

Recalculate path from current

location

Left/right wheel control for intended

speed/turn

Left/right wheel control

Sensor stimuli

Input information (interfacing)

Location information (debugging)


[0:7]

12Vreg

24V Battery

Joystick

Left/Right5.9V ± 0.9V

5.9V ± 0.9VForward/Reverse

[0:7]ADC

ADC

DB15

Motor Control Box

RS232

Controller

RFIDReader

Gyroscope

Compass

Sonar Array(x13)

Echo[0:12]

9Vreg5Vreg

Trigger[0:12]

LCDDisplay

USB

USB Keypad

ADC

ADC


1 Controller2 LCD3 Keypad4 Compass5 Gyroscope6 Modified joystick7 Motor Control Box8 Batteries9 Sonar10 RFID Reader

12

3

4

59

7

8

10

6

Detailed DesignDetailed Design

� Controller & Software - John

� Sensors• Ranging Modules• Orientation

� Motor Control� Localization� Power Management� User Interface

OverviewOverview


� VIA EPIA-EN12000EG Mini-ITX• 1.2GHz VIA C7 Fanless

Processor• DDR2 533 SDRAM (up to 1 GB)

• Full range I/O including USB & Serial

� Full PC capabilities• XP and LabVIEW Embedded

• Expandable

� Multiple Peripheral I/O

Controller & SoftwareController & Software


� Operating System• Windows XP Embedded

○ RFID Reader

� Software• LabVIEW Embedded

○ All calculations, algorithms○ VIs for I/O to sensors

� Program Flow…

Controller & SoftwareController & Software

Detailed DesignDetailed DesignController & SoftwareController & Software

Detailed DesignDetailed DesignController & SoftwareController & Software


� Controller & Software� Sensors - Brian

• Ranging Modules• Orientation


OverviewOverview


• Uses:○ Navigation

○ Obstacle detection

• Operation:○ Sends out a sonar pulse

○ Calculates distance to nearest object based on reflection time

○ 55°Angular Resolution

Ranging ModulesRanging Modules

� Ultrasonic SRF04 Sonar Sensors


� Mounting• Front:

○ Obstacle Detection

○ Mapping

• Sides:○ Wall Tracking

○ Hallway Detection

• Rear:○ Backing up

Ranging ModulesRanging Modules


• Uses:○ Find heading relative to

Earth’s magnetic field

• Operation:○ Pulse width modulated

○ 1-37ms

○ Accuracy: 3-4°

Orientation SensorsOrientation Sensors

� Devantech R117 Magnetic Compass


• Uses:○ Gyroscope

○ Measures rate of turning

• Operation:○ Detects up to 150°/s

Orientation SensorsOrientation Sensors

� ADXRS150 Angular Rate Sensor


� Controller & Software� Sensors


� Motor Control - Tara

� Localization� Power Management� User Interface

OverviewOverview

� Operation based on potentiometers• Forward / Reverse• Right / Left

� 5.9V ± 0.9V DC signal� D/A converters

• Output from controller• 8-bits per speed, direction

○ Step Size = Span / 2n ≈ 7mV

Detailed DesignDetailed DesignMotor ControlMotor Control

Detailed DesignDetailed DesignMotor ControlMotor Control




� Motor Control� Localization - Margaret

� Power Management� User Interface

OverviewOverview


• Uses:○ Identify current location

relative to onboard map

○ Identify start/end point

• Operation:○ High Freq (13.56MHz)

○ Sends RF signal to transponders/tags

○ Passive tags return ID

LocalizationLocalization

� APSX RW-310 RFID Reader and Transponders


� Mounting• Reader/Antenna

○ Bottom of chair

○ 4” reading range

• Tags○ Floor

○ Span critical intersections, starting points/destinations

� Connection○ RS232 -> USB

LocalizationLocalization





OverviewOverview

� Power requirements:

� Testing will rely on individual power supplies� Not a priority for prototype design


• 24VDC○ Wheelchair

• 12VDC○ Mini-Itx Controller*

• 9VDC○ RFID Reader

• 5VDC○ Ultrasonic Sonar

○ Gyroscope○ Compass

• USB (5VDC)○ Keypad

○ LCD

Power ManagementPower Management


� Individual systems:• Wheelchair, controller, RFID reader

� 5VDC system:

Power ManagementPower Management




� Motor Control� Localization� Power Management� User Interface - Vee

OverviewOverview


• Uses:○ Gather inputs

○ Display selected and current locations

○ Debugging

• Operation:○ 2x20 character display

• Connection:○ USB

User InterfaceUser Interface

� Mini-box picoLCD


• Uses:○ Gather inputs○ Select starting location

and final destination○ Initiate travel○ Emergency stop

• Operation:○ 19-key

• Connection:○ USB

User InterfaceUser Interface

� Targus USB Numeric Keypad

Other ConsiderationsOther Considerations

� Economic/Environmental• RoHS compliant controller, wheelchair non-compliant (1991)• Localization system comparatively inexpensive

� Social/Political/Ethical• N/A

� Health/Safety• System not designed for environments with large drop-offs• Obstacle avoidance critical to passenger safety

� Manufacturability/Sustainability• Prototype design – not designed for manufacture• Proof of concept only

SummarySummary

� LabVIEW Embedded controlled operation• Path calculation• Obstacle avoidance algorithm

� User-selectable starting and ending points• Keypad, LCD

� Obstacle detection• Sonar

� Location recognition• RFID reader and tags

� Motor speed control• D/A Converter

� Turn control• Gyroscope, compass

QuestionsQuestions

Self -Guided Wheelchair

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