Field Measurement of Running Impacts

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 Analog to Digital Converter Microcomputer Accelerometer Amplifier

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

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

15. Any Questions? References • http://www.tekgear.com/index.cfm?pageID=90&prodid=227&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=352a24 • http://www.mie-uk.com/datalogger/index.html