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Wheelchair Dynamic Center of Gravity (D-COG)

Wheelchair Dynamic Center of Gravity (D-COG). Kyle Mobley, BME Garrett Spiegel, BME Andrew Lossing, ChBE Advisor: Dr. Mark Richter, President. Lossing , Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/ D-COG Senior Design 2009-10. Background.

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Wheelchair Dynamic Center of Gravity (D-COG)

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  1. Wheelchair Dynamic Center of Gravity (D-COG) Kyle Mobley, BME Garrett Spiegel, BME Andrew Lossing, ChBE Advisor: Dr. Mark Richter, President Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  2. Background • 1.6 – 2.2 million American wheelchair users1 • 146.8% increase in wheelchair related injuries from 1991 to 20031 Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  3. Background (cont’d) • Most users cannot climb hills greater than 8% grade for more than 30 feet 2 • Necessitates user folding to maintain stability. Leads to discomfort and greatly increased effort. Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  4. Basic Design Questions Seat or Axle movement? How will it move? How is the movement controlled? How far does it need to move? How will it stay in place? How is it designed? Feasibility - upgrade possibility Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  5. Seat or Axle Movement? • Axle Movement necessitates overcoming weight at wheels’ point of contact • Seat Movement is much more feasible • Similar to movement of driver or passenger seat in a car Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  6. How will it move? • Use of pre-existing HiRoller Elevating Wheelchair ™ technology • Roller-track movement technique Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  7. How is the movement controlled? • Spring loaded to be biased in forward direction • Moves COG forward, in front of rear axle • Rear wheel propulsion naturally resets COG to original position Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  8. How far does it need to move? • Choosing tippiness is a “compromise between risk of rearward instability and the ability to propel and maneuver easily”.3 • Shorter wheelbase = more tippy = COG backwards • Longer wheelbase = less tippy = COG forwards Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  9. How far does it need to move? (cont’d) Determinations: 20% COG change necessary for desired effect 4 inches of axle movement Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  10. How will it stay in place? • Spring-loaded locking pins • Two sets of pins to simplify user operation • Each set designates different setting • User controlled through lever placed on side of seat Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  11. How is it designed? • Altering pre-existing HiRoller base design to conform to our specifications • Dimensional constraints • Pin placement Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  12. Future Directions • Get assistance with AutoCAD • Build prototype • Welding, Metalwork, Construction • Test/Revise prototype Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

  13. References 1. H Xiang, A-M Chany, G A Smith. 2006. “Wheelchair related injuries treated in US emergency departments”. Injury Prevention. 12:8–11. 2. “ADA Wheelchair Ramp Specifications”.Mobility Advisor. http://www.mobility-advisor.com/wheelchair-ramp-specs.html 3. “Guidance on the Stability of Wheelchairs”. March, 2004. MHRA. DB2004(02). Lossing, Mobley, Spiegel http://www.bme.vanderbilt.edu/srdesign/2009/group5/D-COG Senior Design 2009-10

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