1. Field Measurement of Running Impacts Team: Chelsea Wanta, Amanda Feest, Matt Kudek, Nicole Daehn, Lindsey Carlson BME 201 March 9, 2007 Client: Dr. Bryan Heiderscheit, PhD, PT Advisor: Paul Thompson

2. Overview Problem Statement Background Design Requirements Proposed Designs Design Matrix Future Work Questions

3. Problem Statement Design a portable system to measure tibial accelerations. This system would incorporate the use of an accelerometer and a data logger.

4. Background Tibial stress fractures  One of the most serious running injuries Tibia absorbs force of impact instead of muscle Greater forces on tibia may increase risk of stress fracture Knee contact angle also has an effect on severity of impact

5. Current Methods Patient runs on a force plate in lab Accelerometer is directly connected to PC  Hard-wired through room This system requires extensive wiring Limited testing for different running surfaces

6. Design Requirements Portable system Lightweight accelerometer worn on leg  Uniaxial  Measures up to 40G peak acceleration Data logger  Sampling rate of 1,000-2,000 Hz  Multiple analog inputs  Supply power to accelerometer(s) Design should not affect runner’s gait Prototype completed for use this summer

7. Proposed Design #1: Wired Device Description  Data logger worn on belt  Accelerometer wired to logger  Data logger provides power to accelerometer

8. Proposed Design #1 Pros  Reliable signal  Only one power source needed  Good design to evaluate feasibility of a portable system Cons  Wires on leg may be bothersome  Belt with logger may be bulky

9. Proposed Design #2: Wireless Device Description  Bluetooth communication between components  Data logger worn on belt  Self-powered accelerometer

10. Proposed Design #2 Pros  No wires  Potential to download directly to a PDA or watch Cons  Signal can be unreliable at times  Increased weight of accelerometer  Difficult to manufacture  Belt with logger may be bulky

11. Proposed Design #3: Microcomputer Device Description  Entire device worn on leg  Accelerometer attached to microcomputer Microcomputer analyzes/stores data Downloads later to a PC  One power source for entire system AccelerometerAmplifier Analog to Digital Converter Microcomputer

12. Proposed Design #3 Pros  Compact device worn completely on leg  Reliable signal  One power source Cons  Not feasible within time constraints of course  Requires advanced knowledge of circuits  Unknown if device would alter runner’s gait

13. Design Matrix WiredWirelessMicrocomputer Signal Reliability (40) 10 7 Feasibility (30) 1063 Lightweight on leg (20) 976 Comfort (10) 678 Total (100)946169

14. Future Work Finalize purchase of data logger  Decide on an accelerometer Order components Construct prototype Testing Make adjustments, if necessary

15. Any Questions? http://www.tekgear.com/index.cfm?pageID=90&prodid=22 7&section=73&nodelist=1,73&function=viewproducts www.sparkfun.com/commerce/product_info.php?products _id=254 http://www.bluetooth.com/bluetooth/ http://www.pcb.com/searchresults.asp?searchcriteria=352 a24 http://www.mie-uk.com/datalogger/index.html References