This paper describes the electric pressure sensor-based abdominal injury measuring method employed in the Japan's CRS assessment program.

The CRS assessment program was launched in 2001 in Japan[1]·D The objective of this program is to assess usability of CRSs for infants and toddlers and the systems' safety in frontal collision.

This assessment has started due to recent increase of casualties among minor passengers and to introduction of the mandatry use of CRSs for six-year-old or younger passengers.

The safety assessment test determines performance of CRSs by evaluating behavior of dummies and the target CRSs as well as damage caused by the CRS. It also investigates whether or not the CRS is constraining vulnerable parts of the child's body. In the initial plan, high-speed photography was to be used for determining the scale of the injury caused by restraining gear such as a harness on a child's body. It was found, however, that images from high-speed photography are not suited for determining degrees of compression on the abdomen, the most vulnerable part of the body. In order to solve this problem, we have started an investigation for an alternative method capable of quantitatively measuring abdominal compression.

Throughout the study, the electric pressure sensor-based method was employed for determining abdominal compression from the CRS assessment in 2003. This method allows for quantitatively observing the ever-changing pressure distribution on the abdomen. This approach first calculates abdominal loads from the pressure data collected from the area corresponding to the child's abdomen, and then selects the maximum load among them for use in the actual assessment. We have derived children's resistibility to abdominal load by scaling the relation between the waist belt and Abbreviated Injury Scale (AIS) among adults to the children's physique.