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Wayne ChenGavin WuKyuho ChaEdward Chan

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Overview

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

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Background

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

Spinal Cord Injury (SCI) Study- In 2007, approximately 225,702 people suffer from SCI

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 MotivationAllow Better Blood Flow Circulation

Height Control System

- Beneficial for the muscles and blood flow

- Allow user to have equal eye level communication.

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

- Relieve pressure and stress from buttocks area.

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Our SolutionInnovative, 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 ControlsTactile switch buttons

Up

Down

Memory

Stop

-Up, Stop, Down, Memory

-sitting to standing trasistion

-standing to sitting transistion

-stop all transition

-memorizes the current position

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Mainboard

Butterfly

Motor control

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Tilt Sensor/Accelerometer

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

Sensor

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Mechanical DesignLinear 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

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

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

Final Position

Customizable Trajectory

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Safety ComponentsUpper Body Harness/Seat belt

-Prevents user from falling forward.

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Safety ComponentsLeg 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

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

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

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

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

Actuator Control

Enhanced Safety, Comfort & Appeal

User Interface

Customizable

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Project Finances

ITEM Cost

Electronic Components

Total $475.04

Metals

Total $144.87

Bolts/Misc Components

Total $146.79

Fabrication

Total $1780.80

Sub Total $2547.50

Prototype Production Cost Prototype FundingWighton Engineering Development Fund

Cover all prototype costs

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Actual CostsProduct 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

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

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

C500vs Series

EasyStand Ovation Strap Stand

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Business Opportunities

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

- 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.

Possible Usage

Incentives

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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

What We Learned- Mechanical system design and fabrication.- Technical knowledge of different components- Integration techniques of mechanical and electronic components.

- Team environment and management.

Successful Completion of GoalsScheduled Deadline

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Questions?

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Motor ControllerSoftware: Main Function Flow ChartSoftware: Timer ISRMain BoardAVR ButterflyTilt SensorSensor Circuitry – 1Sensor Circuitry -2Max Weight CalculationsAluminumFabricationTechnical Drawings

Technical Information

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Vcc: 12VLogic one from butterfly : 3.3V

β of the npn: 100Ic =xxmA

Ib = Ic/ βR1 = (3.3-0.7)/IbR1 = (3.3-0.7)/Ib

Relay Coil:12V75mA160 ohms

Absolute maximum for transistor:200mA

Motor controller

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Software: Main Function Flow Chart

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Software: Timer ISR

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MainboardComponents- Protection

- Fuses

- Voltage regulators- 3.3V (butter) 5V (sensor)

- Debug- LEDs

- Relay- Actuator control

- Butterfly- Sensor input

- Bottom tilt sensor

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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

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Tilt sensor/AccelerometerOperating 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 Back

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Sensor Circuitry-1

Vss

Vss

Vss

Vss

Vdd

Vout

Sensor

Ro

C2

C1

Sensor output

5V

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Sensor Circuitry-2

Rf = 2.2 KohmRa = 1 KohmR1 = 1 KohmS = 1Rs = 2.2 KohmRx = 3.7 KohmRy = 1.3 Kohm

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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/s^2 = 539.16 NMoment from Weight at Position A = 539.16N * 82 = 44210.92

Limitation Force at Position B = 44210.92/30 = 1473.70Max Weight at Position B = 150.22 Kg

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Aluminum

CheapEasy to machineWeather resistanceLow density compared to other metals- Density, 2.70 g·cm−3

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Fabrication

Out sourced fabricationPrecise fabrication

-CNC, Milling machine, on site welding

Bought own materials-1 1/4 inch square aluminum tubes.

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Technical Drawings Back

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Technical Drawings Back

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Technical Drawings Back

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Technical Drawings Back