Wayne Chen

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Wayne Chen Gavin Wu Kyuho Cha Edward Chan
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Overview

• Background
• Motivation
• Our Solution
• System Overview
• Future Development
• Business Case
• Finances
• Final Thoughts

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Background

• Spinal Cord Injury (SCI) Study

• In 2007, approximately 225,702 people suffer
• from SCI

• Estimated annual SCI is approximately 12,000
  
• new cases each year.

• Types of Disability Proportions

• 34.1 incomplete tetraplegic (weak control
• over upper lower body muscles)

• 23 are complete paraplegic (no control over
• lower body movement)

• 18.5 are incomplete paraplegic (weak lower
• body movement)

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Design Motivation

• Allow Better Blood Flow Circulation

• Beneficial for the muscles and blood flow

• Relieve pressure and stress from buttocks
• area.

• Height Control System

• Allow user to have equal eye level
• communication.

• Increase range of height, ease of access to
• shelf top, switches etc.

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Our Solution

• Innovative, Reliable Cost Effective Device

• A system that can be retrofitted on to existing
• power wheelchair designs and be able to
• transfer an user effortlessly from a sitting to
  a
• standing position.

• Goals

• Safe and secure transfer for the user

• Manual button controls for user

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System Overview
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System Overview
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Button Controls

• Tactile switch buttons

• -Up, Stop, Down, Memory

• Up

• -sitting to standing trasistion

• Down

• -standing to sitting transistion

• Stop

• -stop all transition

• Memory

• -memorizes the current position

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Mainboard
Butterfly
Motor control
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Tilt Sensor/Accelerometer

• Bottom of the seat
• Detects the angle between the frame and the seat.
• Allows the micro-controller to monitor the
  position of the seat.

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Mechanical Design

• Linear Actuators

- Controls the bottom and top frame movement.

• Light-weight Aluminum Frame

- Allows minimum change to actual wheelchair.

• Strong and secure foundation for
• user.

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Trajectory of Motion

• Final Position

• - 70 Degrees incline
• - Users have weak joints that
• does not allow for max movement

• Customizable Trajectory

• - Movement range changes with the
• mounting position/size of the actuators

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Safety Components

• Upper Body Harness/Seat belt
• -Prevents user from falling forward.

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Safety Components

• Leg Supports
• - Keeps the leg in place so that the person is
  kept from sliding forward.
• - Cushion for knee area support.

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Future Development

• Actuator Control

• - Control both actuator at the same time.
• - Put a safety function to detect interference of
  actuator motion.

• Enhanced Safety, Comfort Appeal

• - Attach higher quality safety harness to improve
  comfort and safety.
• - Improve visual appeal and design of frame and
  components

• User Interface

- Sip n-puff (ideal for quadriplegic people).

• Customizable

• - Customize frame to fit the needs of various
  body type.
• - Use different size actuators to control the
  trajectory of the frame.

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Project Finances

• Prototype Production Cost

• Prototype Funding

Wighton Engineering Development Fund
ITEM Cost
Electronic Components Electronic Components
Total 475.04
Metals Metals
Total 144.87
Bolts/Misc Components Bolts/Misc Components
Total 146.79
Fabrication Fabrication
Total 1780.80
Sub Total 2547.50

• Cover all prototype costs

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Actual Costs

• Product Cost

• Fabrication costs were a major portion of our
  project budget. If mass
• production occurs, partnership can be made with
  fabrication shop and may
• be able to lower a large portion of the project
  costs.

• Unused Parts

• Extra and additional parts were sourced in for
  quick replacement if parts
• are damaged along the testing phases.

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Competition

• C500vs Series

• - High Cost 30,000 - 40,000
• - Built as all-in-one unit
• - Able to select the features you want
• for customization

• EasyStand Ovation Strap Stand

- No mobility - Separate unit - Large
and bulky (Robust)
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Business Opportunities

• Possible Usage

• Assist with standing process for people with
  weaker leg strength.
• - Transfer the user to a position suitable for
  urination

• Incentives

• - Not all disabled people have the same needs.
• - Minimize cost by reuse/upgrade existing
  wheelchair.
• - Could become a part of rehabilitation
  process.
• - Allow better blood flow to the legs
• - Decrease work load for nurses/doctors to
  stand a person up.

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Timeline
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Acknowledgements

• GF Strong Rehabilitation Center

• Ian Denison (Physiotherapist)
• Charles Martin (Wheelchair Technician)

• Peter Borwein

• Patrick Leung
• Jason Lee
• Jamie Westell
• Andrew Rawicz
• Steve Whitmore
• Carlo Menon

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Conclusion

• Successful Completion of Goals

• Scheduled Deadline

• What We Learned

• Mechanical system design and fabrication.
• Technical knowledge of different components
• Integration techniques of mechanical and
  electronic components.
• - Team environment and management.

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Questions?
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Technical Information

• Motor Controller
• Software Main Function Flow Chart
• Software Timer ISR
• Main Board
• AVR Butterfly
• Tilt Sensor
• Sensor Circuitry 1
• Sensor Circuitry -2
• Max Weight Calculations
• Aluminum
• Fabrication
• Technical Drawings

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Motor controller
Vcc 12V Logic one from butterfly 3.3V ß of
the npn 100 Ic xxmA Ib Ic/ ß R1
(3.3-0.7)/Ib R1 (3.3-0.7)/Ib Relay
Coil 12V 75mA 160 ohms Absolute maximum for
transistor 200mA

• Back

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Software Main Function Flow Chart

• Back

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Software Timer ISR

• Back

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Mainboard

• Components
• - Protection
• - Fuses
• - Voltage regulators
• - 3.3V (butter) 5V (sensor)
• - Debug
• - LEDs
• - Relay
• - Actuator control
• - Butterfly
• - Sensor input
• - Bottom tilt sensor

• Back

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Butterfly

• Operating voltage
• - 2.7V to 5.5V (we chose 3.3V)
• Supply current
• - 2.3mA to 4mA
• CPU speed
• - 8MHz, factory set by software to 2MHz to save
  button battery life.
• ADC
• - 10-bit (0-3.3V ADC range)
• - Changed reference voltage to 1.1 to increase
  ADC sensitivity
• Timer
• - 16-bit timer counter with 64 prescaler
• - Timer interrupt is set to 0.08s

• Back

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Butterfly

• I/O
• - PortB, PortD, JTAG/PortF (ADC)
• - PortB used for button control and bottom
  actuator control
• - PortD used for LEDs to output current stage for
  debugging purposes, PortD also used for
  controlling back actuator
• Temperature range
• - (-40C to 85C)
• LCD
• - PortD, turned off to avoid conflict between
  output function and LCD display
• Absolute maximum ratings
• - Operating voltage, 6.0V
• - DC current per I/O pin 40.0mA
• - DC current Vcc and GND pins 200.0mA

• Back

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Tilt sensor/Accelerometer

• Operating voltage
• - 4.75V to 5.25V
• Single Axis
• - Z axis
• Sensitivity
• - 750mV/g
• - 2.5g sensing range
• Temperature range
• - (- 40C) to (105C)
• Supply current
• - 1.1 to 3mA
• Self protection mechanism
• - 2kV ESD protection circuitry

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Sensor Circuitry-1

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Sensor Circuitry-2
Rf 2.2 Kohm Ra 1 Kohm R1 1 Kohm S 1 Rs
2.2 Kohm Rx 3.7 Kohm Ry 1.3 Kohm

• Back

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Max User Weight
Component Weight Position
Battery (x2) 45.89 Kg A
Motor 9.07 Kg A
User X Kg B
Force at Position A (45.89 Kg 9.07 Kg)
9.81m/s2 539.16 N Moment from Weight at
Position A 539.16N 82 44210.92 Limitation
Force at Position B 44210.92/30 1473.70 Max
Weight at Position B 150.22 Kg

• Back

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Aluminum

• Cheap
• Easy to machine
• Weather resistance
• Low density compared to other metals

• Back

- Density, 2.70 gcm-3
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Fabrication

• Out sourced fabrication
• Precise fabrication

• CNC, Milling machine, on site welding

• Bought own materials

• 1 1/4 inch square aluminum tubes.

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Technical Drawings

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Technical Drawings

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Technical Drawings

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Technical Drawings

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