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 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 Data logger Uniaxial Measures up to 40G peak acceleration 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 Description Data logger worn on belt Accelerometer wired to logger Data 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 belt Self 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 Amplifier Analog 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 logger Decide on an accelerometer Order components Construct prototype Testing Make adjustments if necessary Any Questions References http www tekgear com index cfm pageID 90 prodid 227 section 73 nodelist 1 73 functi on 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
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