Measurement of Occupant Pocketing Kinematics During Whiplash Assessments

This study documents a method developed for dynamically measuring occupant pocketing during various low-speed rear impact, or “whiplash” sled tests. This dynamic pocketing measurement can then be related to the various test parameters used to establish the performance rating or compliance results. Consumer metric and regulatory tests discussed within this paper as potential applications of this technique include, but are not limited to, the Insurance Institute for Highway Safety (IIHS) Low Speed Rear Impact (LSRI) rating, Federal Motor Vehicle Safety Standard (FMVSS) 202a, and European New Car Assessment Program (EURO-NCAP) whiplash rating. Example metrics are also described which may be used to assist in establishing the design position of the head restraint and optimize the balance between low-speed rear impact performance and customer comfort. This paper builds upon the results of a Design for Six Sigma (DFSS) project optimizing seat parameters influencing low-speed rear impact performance using an application of Principle Component Analysis (PCA). The DFSS studies and follow-up testing identified a number of related seat design factors which play major roles in the seat's overall performance in the various low-speed rear impact assessment tests. These factors include seat frame dimensions, content packaging, and other design factors that influence how the occupant translates rearward, or “pockets”, into the seatback. The technique described in this paper provides a means of directly measuring this pocketing behavior and relating it to the relevant low-speed rear impact test results.