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

Overview

Problem Statement Background Design Requirements Proposed Designs Design Matrix Future Work Questions

Problem Statement

Design a portable system to measure tibial accelerations. This system would

incorporate the use of an accelerometer and a data logger.

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

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

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

Proposed Design #1: Wired Device

DescriptionData logger worn on belt Accelerometer wired to loggerData logger provides power to accelerometer

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

Proposed Design #2: Wireless Device Description

Bluetooth communication between components

Data logger worn on beltSelf-powered accelerometer

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

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

Accelerometer AmplifierAnalog to Digital

Converter Microcomputer

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

Design Matrix

Wired Wireless Microcomputer

Signal Reliability (40) 10 7 10

Feasibility (30) 10 6 3

Lightweight on leg (20)

9 7 6

Comfort (10) 6 7 8

Total (100) 94 61 69

Future Work

Finalize purchase of data loggerDecide on an accelerometer

Order components Construct prototype Testing Make adjustments, if necessary

Any Questions?

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

References