Dynamic metrics to differentiate booster performance

The purpose of this research was to explore candidate booster performance metrics that may have the potential to identify less effective booster systems, because current FMVSS No. 213 booster performance requirements can be met without a booster.

To provide a more realistic test environment, dynamic testing was performed using a surrogate seat belt retractor on the most recent preliminary design update proposed for the FMVSS No. 213 seat assembly. Given that field data show that belt-positioning boosters are effective at reducing injury risk, potential testing measures were assessed relative to data collected for the no-booster condition. Eleven booster products were evaluated, as well as the no-booster condition, with 6 tests performed using the Hybrid III 10-year-old and 33 tests run with the Hybrid III 6-year-old.

Possible metrics associated with good anthropomorphic test device (ATD) kinematics (no submarining or rollout) were the difference between knee and head excursion, maximum torso angle, lumbar spine Moment Z, and lumbar spine Force Y.

When testing boosters under more realistic dynamic conditions, the proposed metrics would allow better discernment of less effective boosters, because they differentiate performance relative to the no-booster condition.