1. Instrumented Wheel For Wheelchair Propulsion Assessment. Jacob Connelly Andrew Cramer John Labiak

2. Dr. Mark Richter – Project Advisor  Owner and Director of R&D  Stanford Graduate  Wheelchair Propulsion Research Handrim Biomechanics – Flexrim  Product design to maximize the mobility of inidividuals with disability.

3. Problem Statement Manual wheelchair users are at considerable risk of developing upper extremity overuse injuries.  Upper extremities are primary means of mobility.  Extensive upper extremity use in seating transfer.  Upper extremity function is injury level dependent. Need to quantify effect of propulsion biomechanics.  Propulsion assessment.  Properly seat user.  Train user.

4. Project Goals Develop an inexpensive instrument capable of measuring applied resultant force in order to analyze propulsion techniques of manual wheelchair users. Lower instrument cost $5-6K  SmartWheel (3rivers) ~ $25K  Load cell propulsiometer > $10K

5. Market Outlook Spinal Cord Injury Hospitals and Rehabilitation Centers: 50 – 60 in U.S. Seating and Training Clinics: 50 – 100 http://www.sci-info-pages.com/rehabs.html Research Labs: ~50 Product will be sold as a pair of wheels  Only 1 wheel will be instrumented.  Same size diameter and same inertial effects. Construction Cost: Below $2K Price of Pair: $5K

6. Solution Strain gauges used to measure resultant force. ΔV  calculate strain  calculate resultant force. Create ΔV vs. Force standard curve. 6 push-rim attachments. This is variable.

7. Initial Solution Voltage divider circuit.  1mV change with a 4V offset result in 1.25mV sensitivity. Contingencies involve instrumentation amplifier design. 8-Pin DAQ unit. Bluetooth wireless transceiver (USB compatible) T C

8. Completed Work Initial prototype completed.  Strain gauges attached and wired to DAQ.  Power supply active.  Connections Insulated in rubber coating. Data recorded in LabVIEW.  Low CMRR. 10 mV noise > signal  Low Pass Filter ineffective.

9. Current Work Adapt current prototype.  Decrease from 6 attachements to 3.  Hope the handrim will not be as rigid as before. Determine and order parts for new circuits.

10. 5.0 V DAQ TENSION COMPRESSION 5.0 V

11. Future Work If no mechanical or physical change help  new circuit design including amplifiers  Order circuit parts to test them and ensure we are obtaining accurate results  Have circuit board printed and order the remaining parts Clean up all of the wiring on second prototype.  Run all of the wiring prior to strain gauge attachment.

12. Future Work Obtain acceptable change in voltage data Analyze trends in the strain data Calibrate the strain data to form a resultant force curve Incorporate other possible tab designs Design the hub to house the electronics of the wheel