The first tool enabling measurement of forces transmitted to the test dummy abdomen by the seat belt in submarining was developed by the LPB-APR in 1979. Thar tool was a cantilever beam attached at the iliac crest level and sensitive to shearing loads. The instrument, known as A-Transducer, was subjected to evaluation tests both at the LPB-APR and in other laboratories. Transducer response failings were observed, especially during tests with violent submarining and major pelvic rotation.
To remedy these failings, a number of improvements were defined. These improvements led to the development of a new instrument incorporating a pair of two-dimensional sensors. Each sensor consists of two instrumented beams which can measure forces transmitted to the abdomen in the A-P and I-S directions respectively. This paper contains a detailed description of the instrument components. The instrument's performance is analyzed in dynamic tests with especially violent submarining (force transmitted to the abdomen in the I-S direction: 2000 N).