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Wayne Chen Gavin Wu Kyuho Cha Edward Chan. Overview. Background Motivation Our Solution System Overview Future Development Business Case Finances Final Thoughts. Background. Spinal Cord Injury (SCI) Study. In 2007, approximately 225,702 people suffer from SCI. - PowerPoint PPT Presentation
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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
Back
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Software: Main Function Flow Chart
Back
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Software: Timer ISR
Back
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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
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/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
Back
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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
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/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
Back
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Aluminum
CheapEasy to machineWeather resistanceLow density compared to other metals- Density, 2.70 g·cm−3
Back
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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.
Back
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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