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measuring impact forces with accelerometry

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  • measuring impact forces with accelerometry

    hello everyone.

    Does anyone have ny insight on how to obtain impact forces using accelerometers? I am trying to measure ball heading forces in soccer using a wireless accelerometer

    thank you

    Ali

  • #2
    Re: measuring impact forces with accelerometry

    Ali -- This is a non-trivial task:

    (1) Use a rigid, free body assumption. (2) Measure subject head circumference. (3) Look up literature on head mass and moments of inertia as function of circumference and calculate. (4) Ensure your accelerometer(s) have appropriate bandwidth and sensitivity. (5) Include measurements of angular velocity and angular acceleration using appropriate bandwidth and sensitivity. (6) Quantify relative motion between your sensors and the skull (the scalp will move during headers). (7) Calculate rigid body head center of gravity linear acceleration. (8) Calculate vector rho from CG to impact point on surface of rigid body. (9) Calculate force as a function of (3), (7), (8). (10) Add an uncertainty calculation to your measurements so that you know if you report 100N force, whether its +/- 1N, +/-10N, +/-100N.

    Good luck!
    Adam Bartsch, Cleveland Clinic

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    • #3
      Re: measuring impact forces with accelerometry

      Hi Ali,

      I have a couple of minor points to follow up on Adam's very good response:

      (1) If you haven't already, you might want to look up some work from around a decade ago by Guy Genin and Phil Bayly at Washington University. I don't recall who was the first author (one of their students, I think) but I know that they rigged up an accelerometer on a headband configuration. If I remember correctly, they also did some work with accelerations of cadaver specimens using the in vivo data as a guide, followed by MRI scans to detect damage.

      (2) A great resource for the head mass and moments of inertia that Adam suggested is the ANSUR anthropometric database, produced as a technical report by a couple of U.S. military laboratories. The 1988 edition is frequently cited (McConville is first author), and there may have been a followup study within the last several years. Feel free to contact me directly if you have any trouble finding this report.

      Good luck!

      Dave

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