MADYMO & Occupant Simulation Reconstruction IMPORTANT issues

Subjects related to ATB & ATB clones & the reconstruction and simulation of Occupants in vehicles and Pedestrians struck by vehicles
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MSI
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MADYMO & Occupant Simulation Reconstruction IMPORTANT issues

Post by MSI »

Q: Do you use or have you evaluated any MADYMO applications in litigation cases?

A: I do not use MADYMO but I have been hired to evaluate MADYMO applications used in litigation. In one case in particular, from a few years ago, we evaluated an expert report who used the MADYMO occupant simulation program to evaluate injury potential in a low speed collision.
This post is to demonstrate that ANY and ALL occupant simulation needs to be carefully evaluated.
EVERY HUMAN is different!
  • For any case specific application of ANY occupant simulation approach:
    • Use and/or evaluate with extreme caution!
Occupant simulation models come in several flavors, however ALL are based on or direct derivatives of the ATB program:
  • What is ATB?
    • Explanation of the origins of the ATB with links to papers on it including two papers we wrote in response to 'experts' using ATB to 'reconstruct occupant movements in a crash' and then trying to sell simple silly changes in the inputs as 'design changes' to prove that their proposed design changes produced 'mitigation' of the injuries. Total garbage. And to generalize out main quote
      • "Any results or conclusions drawn from arbitrary and speculative occupant simulations related to individual crashes which experts claim produce detailed occupant kinematics involve so many approximations, estimates, and assumptions that they must be recognized as not being compatible with sound engineering practices and principles and, therefore, not scientifically supportable.
  • MADYMO program:
    • Includes important research which has improved vehicle safety however not applicable to individual crash reconstructions
  • pc-crash Multi_body option
    • this is a version of the ATB hidden as the 'multi-body' option, the references they cite are NOT for occupant simulation programs and for some reason they pretend it is NOT ATB. IT IS ATB! NOT applicable to individual crash reconstruction
  • pc-crash simplified MADYMO option
    • This is such a stripped down version of MADYMO it doesn't have ability to customize the interior to match and/or other severe limitations and of course NOT applicable to individual crash reconstruction
  • GATB
    • this is a version of the ATB and NOT applicable to individual crash reconstruction
  • Virtual CRASH
    • They use a version of the ATB for their pedestrian and passenger simulations
Here are the conclusions from the case where we evaluated a MADYMO application (Note NAMES AND DATES REDACTED):
  • Summary and Conclusions
    In summary, the authors of the EXPERT report did not properly perform a scientific investigation or reconstruction of the subject accident. They provided arbitrary and speculative opinions based on limited and incomplete information, they did not use or reference any current techniques to reconstruct a collision like the subject accident, they included arbitrary calculations of impact duration and range of speed with no scientific basis.
    The authors of the EXPERT report then used their opinions as the basis to perform a 3D occupant simulation of OCCUPANT in the subject collision.
    The authors of the EXPERT report utilized the MADYMO 3D simulation model with the following deficiencies:
    • They did not properly create an acceleration substantially similar to the acceleration in the subject accident.
    • They did not properly create and include any provisions for the interior of the Jeep with seat, floor, dash, center console, B pillar and side glass substantially similar to the vehicle at the time of the collision.
    • They did not properly create a 3-point restraint system substantially similar to the belt in the vehicle at the time of the accident.
    • They did not properly create inputs to model OCCUPANT and place her in a position and orientation for their MADYMO simulation that was substantially similar to the position and orientation of OCCUPANT at the time of the impact (i.e., turned to left in preparation for making a right turn).
    Any results or conclusions drawn from their arbitrary and speculative MADYMO 3D occupant simulation related to detailed occupant kinematics involve so many approximations, estimates, and assumptions that they must be recognized as not being compatible with sound engineering practices and principles and, therefore, not scientifically supportable.
and here's the original report: For additional related information Please see:
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MSI
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Posts: 1479
Joined: Thu Jun 18, 2009 12:37 pm

Re: MADYMO & Occupant Simulation Reconstruction IMPORTANT issues

Post by MSI »

Today on the NAPARS Facebook page They posted about
  • "IRCOBI", pronounced "er-COE-bee", in my experience, but perhaps anyone who knows better can chime in. Anyway, it stands for the "International Research Council on Biomechanics of Injury" As you might guess, their conference papers are rife with squishy research of all sorts, but human injury from car crashes is clearly part of their ouvre. The reference tidbit for today is that IRCOBI papers appear to be ALL online and free - there's a lot of reading there: http://ircobi.org/wordpress/proceedings/
And a response to the post included:
  • In my humble opinion, most in this "field" are advocates. I have never found anybody to explain or understand that each and every human being is different and averages do NOT work for an individual.
To which we responded with:
  • I agree that averages do not apply since all individual humanoids are different (unlike car models!!)
    However
    Dismissing all research to try to help understand and improve occupant safety is not good.
    In the words of the late Don Heulke after receiving an SAE award for distinguished speaker said
    • ‘after watching some of these presentations perhaps we need to add an SAE award for the other end’

    There are advocates who publish but not all who publish are advocates.
    See my critiques on the rash of occupant and pedestrian simulations in reconstruction as if you can use in individual cases.
    You can not!!!
We included a link to this forum topic.
In reviewing the topic I also made a few minor edits and adjustments to links on this topic.
Question? Comment? Please email forum@mchenrysoftware.com. Also see the McHenry Forum Index
Visit McHenrySoftware.com for technical information & software.
(c) McHenry Software, Inc ALL Rights Reserved.
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