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This is the first paper in a new series to present a coherent theory of sensing frontal crashes, define the characteristics of future airbag sensor systems and to present examples of how this theory can be implemented. After summarizing the relevant conclusions from the authors' previous papers, this paper concludes that future systems should contain: crush zone sensors which sense relevant impacts to all portions of the vehicle front; an occupant position sensor as an input to the sensing system; and a mechanical safing/arming sensor having a long dwell. It is further concluded that cars should be designed so that only impacts involving the front of the vehicle need be sensed for the deployment of frontal protection airbags. This series of papers has the main goal of determining an overall theory of frontal crash sensing and the resulting desirable properties of sensor systems. A second goal is to give examples of how this theory can be realized in real sensor systems.

Crash sensors for use in deploying air bags operate in an environment of severe vibrations, not only along the longitudinal axis of the sensor, but also in the transverse vertical and lateral axes. These vibrations can have a detrimental effect on some crash sensor designs. Various methods using Fourier analysis have failed to provide a characterization of cross-axis vibrations. This is due, in part, to phase shifts in the cross-axis oscillations. A technique using shock spectrum analysis has been developed which can be used to characterize these vibrations. This work has led to the development of a specification for laboratory testing of the sensitivity of a sensor to cross-axis vibrations. This paper presents the underlying theoretical basis for the shock spectrum technique, the results of applying this technique to a library of crash data, and a recommended specification for laboratory sensor testing for sensors mounted in the crush zone and non-crush zone.

THROUGH THE USE of the VODS computer simulation model, the authors have designed driver side airbag systems for the 1980 Series Ford LTD, the Dodge Diplomat, and the Chevrolet Impala. These cars were then retrofitted with a Breed all-mechanical airbag system tailored for each car, and barrier crash tested at 30 mph by NHTSA. System performance results were excellent, and predicted versus actual 50th percentile driver dummy injury measures were in excellent agreement differing by less than 15%. THE MODEL was then used to predict airbag system dummy injury measures in 665 NHTSA crashes. In all but two of these crashes, the injury measures stayed below 80% of those allowed by FMVSS 208. Predicted airbag results for the 1984 NCAP crash tests are presented in detail.