Wayne Chen Gavin Wu Kyuho Cha Edward Chan

1. Wayne Chen Gavin Wu Kyuho Cha Edward Chan

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

3. 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)

4. 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.

5. 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 5

6. System Overview 6

7. System Overview 7

8. 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 8

9. Mainboard Butterfly Motor control 9

10. 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. 10

11. 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. 11

12. 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 12

13. Safety Components • Upper Body Harness/Seat belt • -Prevents user from falling forward. 13

14. Safety Components • Leg Supports • - Keeps the leg in place so that the person is kept from sliding forward. • - Cushion for knee area support. 14

15. 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. 15

16. Project Finances • Prototype Production Cost • Prototype Funding Wighton Engineering Development Fund • Cover all prototype costs 16

17. 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. 17

18. 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) 18

19. 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. 19

20. Timeline 20

21. 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 21

22. 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. 22

23. Questions? 23

24. 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 24

25. Motor controller Vcc: 12V Logic one from butterfly : 3.3V β of the npn: 100 Ic =xxmA Ib = Ic/ β R1 = (3.3-0.7)/Ib R1 = (3.3-0.7)/Ib Relay Coil: 12V 75mA 160 ohms Absolute maximum for transistor: 200mA • Back 25

26. Software: Main Function Flow Chart • Back 26

27. Software: Timer ISR • Back 27

28. Mainboard • Components • - Protection • - Fuses • - Voltage regulators • - 3.3V (butter) 5V (sensor) • - Debug • - LEDs • - Relay • - Actuator control • - Butterfly • - Sensor input • - Bottom tilt sensor • Back 28

29. 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 29

30. 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 30

31. 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 • Back 31

32. Sensor Circuitry-1 • Back 32

33. 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 33

34. Max User Weight Force at Position A = (45.89 Kg + 9.07 Kg)* 9.81m/s^2 = 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 34

35. Aluminum • Cheap • Easy to machine • Weather resistance • Low density compared to other metals • Back - Density, 2.70 g·cm−3 35

36. Fabrication • Out sourced fabrication • Precise fabrication • CNC, Milling machine, on site welding • Bought own materials • 1 1/4 inch square aluminum tubes. • Back 36

37. Technical Drawings • Back 37

38. Technical Drawings • Back 38

39. Technical Drawings • Back 39

40. Technical Drawings • Back 40