Any way to analyze EDR data skewed by vehicle rotation?

Topics related to collision & Trajectory analysis formerly on our 'Registrants only' area however which we get asked about frequently so believe shoud be in the open forum too
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MSI
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Any way to analyze EDR data skewed by vehicle rotation?

Post by MSI » Sat Feb 13, 2016 11:54 am

Q: In an eccentric collision the EDR data likely gets skewed along with the vehicle rotation. It seems to me that this would be a great application for the collision phase of SMAC, something that would get from the vehicle based reference frame of the EDR to a Global or ground based reference frame. Basically, input vehicle specs and EDR accel or dV data and output a ground based dV. Initially I was thinking of putting together an Excel spreadsheet to do this. Then I thought this is a SMAC application. Any thoughts?

A: Over the years many have has issues with good test results due to the differences in accelerometer readings (also w/r to EDR readings) when not at the CG (which they rarely are due to differences in vehicle loading and other factors!)
The differences are more dramatic when either a lot of rotation and/or a secondary collision is involved.
We discussed these issues in our paper on re-evaluation of the RICSAC full scale tests:
  • You’ll find in our SAE paper the steps that you can use for an excel spreadsheet and what information is needed/required. Checking/verifying with simulation results provides a more detailed correlation with full scale tests and ability to refine the more simplified excel spreadsheet analysis.
msmac & msmac3D have had the ability to monitor the accelerations and evaluate the results for locations other than the CG for years. Of course EDR’s are mainly looking at the slope (jerk) of acceleration to say fire/no-fire. Their sampling vs recording times may vary (generally record at 10 ms increment) and therefore do not record in as great detail as accelerometers. Differences will occur.
See FMVSS 563 and the summary page below for what data elements you may be able to get, however depending on make, model and most importantly year, the EDR you are evaluating may not this information.
  • For example, many early EDR’s stopped recording once the airbag fire command was issued
I appreciate your idea of a direct ‘compare with EDR readings’ option
  • We currently that have in our smacthp option which simply asks for the accelerometer/EDR location and then provides time history (in charts and csv output) of accelerometer, deltaV and PDOF. However without mentioning EDR folks probably don’t realize that it can be used for a comparison.
[attachment=0]563 EDR Requirements.png[/attachment]
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