Kinematic Comparison of Pediatric Human Volunteers and the Hybrid III 6-Year-Old Anthropomorphic Test Device.

The Hybrid III 6-year-old ATD has been benchmarked against adult-scaled component level tests but the lack of biomechanical data hinders the effectiveness of the procedures used to scale the adult data to the child. Whole body kinematic validation of the pediatric ATD through limited comparison to post mortem human subjects (PMHS) of similar age and size has revealed key differences attributed to the rigidity of the thoracic spine. As restraint systems continue to advance, they may become more effective at limiting peak loads applied to occupants, leading to lower impact environments for which the biofidelity of the ATD is not well established. Consequently, there is a growing need to further enhance the assessment of the pediatric ATD by evaluating its biofidelity at lower crash speeds. To this end, this study compared the kinematic response of the Hybrid III 6 year old ATD against size-matched male pediatric volunteers (PVs) (6-9 yrs) in low-speed frontal sled tests. A 3-D near-infrared target tracking system quantified the position of markers at seven locations on the ATD and PVs (head top, opisthocranion, nasion, external auditory meatus, C4, T1, and pelvis). Angular velocity of the head, seat belt forces, and reaction forces on the seat pan and foot rest were also measured. The ATD exhibited significantly greater shoulder and lap belt, foot rest, and seat pan normal reaction loads compared to the PVs. Contrarily, PVs exhibited significantly greater seat pan shear. The ATD experienced significantly greater head angular velocity (11.4 ± 1.7 rad/s vs. 8.1 ± 1.4 rad/s), resulting in a quicker time to maximum head rotation (280.4 ± 2.5 ms vs 334.2 ± 21.7 ms). The ATD exhibited significantly less forward excursions of the nasion (171.7 ± 7.8 mm vs. 199.5 ± 12.3 mm), external auditory meatus (194.5 ± 11.8 mm vs. 205.7 ± 10.3 mm), C4 (127.0 ± 5.2 mm vs. 183.3 ± 12.8 mm) and T1 (111.1 ± 6.5 mm vs. 153.8 ± 10.5 mm) compared to the PVs. These analyses provide insight into aspects of ATD biofidelity in low-speed crash environments.