A Methodology for Generating Objective Targets for Quantitatively Assessing the Biofidelity of Crash Test Dummies

A set of analysis tools and a procedure are presented for generating objective biofidelity targets derived from post-mortem human subject (PMHS) test response data and quantitatively assessing the biofidelity of crash test dummies. Using response time history data from PMHS tests (Maltese et al., 2002), this paper presents a methodology for creating PMHS response targets that have a statistical basis and then using those targets for quantitative evaluation of crash dummy biofidelity. The first step in the methodology is to normalize the response data to remove variation associated with anthropometric differences and match the size of the dummy to be assessed (e.g., 50th percentile male). After the data are normalized the phase differences are minimized for all responses using the cross-correlation functions and the Lagrange Multiplier technique. The resulting phase-adjusted set of time histories can be averaged, point by point, to obtain a “typical” response. The average phase shift is utilized to locate the mean PMHS response in time. The typical response, or mean curve, can then be bracketed with plus and minus one standard deviation curves resulting in a biofidelity target specification for a dummy response. A single average standard deviation value is used to encompass the mean curve rather than using the point by point standard deviation values, which eliminates “necking” at crossing points. To quantitatively determine the quality of the dummy biofidelity, each dummy response is evaluated for biofidelity in terms of shape and magnitude (SM) and phase (P). First, phase differences between the dummy and mean PMHS response are minimized by using the cross-correlation function to find the phase shift, or lag, that minimizes the squared difference between the two curves. Then the difference between the phase-minimized dummy response and the target mean is measured using a cumulative variance ratio (DCV/CCV) to describe the response shape and magnitude biofidelity. In addition, the dummy phase response biofidelity is assessed utilizing a ratio of the minimizing lag (dummy phase shift) divided by a standard acceptable lag. The acceptable lag is found by shifting the PMHS mean curve in time with respect to itself and determining the lag between the shifted and unshifted PMHS mean curves that results in a DCV/CCV equal to 1.0. The values for shape and magnitude biofidelity (SM) and phase biofidelity (P) are combined using a root mean square (RMS) methodology (the resultant or orthogonal vector addition) to provide a sense of the total biofidelity quality of each channel time history. The RMS values for each response measurement are averaged for each test condition to obtain the test condition rank; the test condition ranks are averaged to obtain the body region rank; and the body region ranks are averaged to obtain the External or Internal Biofidelity Rank; the External and Internal Biofidelity Ranks are then averaged to obtain the Overall Biofidelity Rank. Results consist of example PMHS biofidelity targets for lateral sled impact tests and two side impact dummies are ranked using this revised BioRank system.

Language

  • English

Media Info

  • Media Type: Web
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 14p
  • Monograph Title: 23rd International Technical Conference on the Enhanced Safety of Vehicles (ESV): Research Collaboration to Benefit Safety of All Road Users

Subject/Index Terms

Filing Info

  • Accession Number: 01569489
  • Record Type: Publication
  • Report/Paper Numbers: 13-0138
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jul 14 2015 1:22PM