Development of a Deflection Measurement System for the Hybrid III Six-Year Old Biofidelic Abdomen

Despite advancements in automotive safety, motor vehicle collisions remain the leading cause of unintentional death for children ages 5 to 14. Enhancement of child occupant protection depends on the ability to accurately assess the effectiveness of restraint systems. Booster seat design and proper belt fit require evaluation using child anthropomorphic test devices, yet biofidelity of the abdomen and pelvis of the current anthropomorphic test device, the Hybrid III 6-year-old, needs improvement. Further, measurement of abdominal deflection is needed for quantification of the degree of submarining and associated potential injury risk.

A biofidelic abdomen for the Hybrid III 6-year-old dummy is being developed by the Ford Motor Company. A practical measurement system for the biofidelic abdominal insert has been developed and demonstrated for three dimensional determination of abdominal deflection. Quantification of insert deflection is achieved via differential signal measurement using electrodes mounted within a conductive medium. Signal amplitude is proportional to the distance between the electrodes. A microcontroller is used to calculate distances between ventral electrodes and a dorsal electrode in three dimensions.

This system has been calibrated statically, as well as evaluated dynamically. Its performance has also been demonstrated in a series of sled tests. Deflection measurements from the instrumented abdominal insert showed clear differences between two booster seat designs, yielding an average peak anterior to posterior displacement of the abdomen of 1.0 ± 3.4 mm and 31.2 ± 7.2 mm for the seats, respectively. Implementation of a 6-year-old abdominal insert with the ability to evaluate submarining potential will likely advance the effectiveness of booster seat design and restraint performance, and help mitigate child occupant injury severity in automobile collisions.