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
General SolutionGeneral SolutionEnd Product DescriptionEnd Product Description
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)
General SolutionGeneral SolutionEnd Product DescriptionEnd Product Description
[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
General SolutionGeneral SolutionEnd Product DescriptionEnd Product Description
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
Detailed DesignDetailed Design
� 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
Detailed DesignDetailed Design
� 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 Design
� Controller & Software� Sensors - Brian
• Ranging Modules• Orientation
� Motor Control� Localization� Power Management� User Interface
OverviewOverview
Detailed DesignDetailed Design
• 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
Detailed DesignDetailed Design
� Mounting• Front:
○ Obstacle Detection
○ Mapping
• Sides:○ Wall Tracking
○ Hallway Detection
• Rear:○ Backing up
Ranging ModulesRanging Modules
Detailed DesignDetailed Design
• 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
Detailed DesignDetailed Design
• Uses:○ Gyroscope
○ Measures rate of turning
• Operation:○ Detects up to 150°/s
Orientation SensorsOrientation Sensors
� ADXRS150 Angular Rate Sensor
Detailed DesignDetailed Design
� Controller & Software� Sensors
• Ranging Modules• Orientation
� 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 Design
� Controller & Software� Sensors
• Ranging Modules• Orientation
� Motor Control� Localization - Margaret
� Power Management� User Interface
OverviewOverview
Detailed DesignDetailed Design
• 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
Detailed DesignDetailed Design
� Mounting• Reader/Antenna
○ Bottom of chair
○ 4” reading range
• Tags○ Floor
○ Span critical intersections, starting points/destinations
� Connection○ RS232 -> USB
LocalizationLocalization
Detailed DesignDetailed Design
� Controller & Software� Sensors
• Ranging Modules• Orientation
� Motor Control� Localization� Power Management� User Interface
OverviewOverview
� Power requirements:
� Testing will rely on individual power supplies� Not a priority for prototype design
Detailed DesignDetailed Design
• 24VDC○ Wheelchair
• 12VDC○ Mini-Itx Controller*
• 9VDC○ RFID Reader
• 5VDC○ Ultrasonic Sonar
○ Gyroscope○ Compass
• USB (5VDC)○ Keypad
○ LCD
Power ManagementPower Management
Detailed DesignDetailed Design
� Individual systems:• Wheelchair, controller, RFID reader
� 5VDC system:
Power ManagementPower Management
Detailed DesignDetailed Design
� Controller & Software� Sensors
• Ranging Modules• Orientation
� Motor Control� Localization� Power Management� User Interface - Vee
OverviewOverview
Detailed DesignDetailed Design
• Uses:○ Gather inputs
○ Display selected and current locations
○ Debugging
• Operation:○ 2x20 character display
• Connection:○ USB
User InterfaceUser Interface
� Mini-box picoLCD
Detailed DesignDetailed Design
• 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
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