Fast Pressure Based Sensing Systems for Side Impact Restraint Systems

This paper describes the application and the algorithm concepts of a high volume product for a very fast side impact detection system. To activate a side airbag the inner-door air pressure is measured by the sensing system. Specific characteristics of this pressure signal reflect different crash modes and, in conjunction with intelligent algorithms, very short activation times for side impact restraint systems are reached. These deployment times are typically faster than those of acceleration based sensing systems æ usually less than 5ms in all legal test modes. In addition to this the system is very robust during real world driving conditions such as crossing railroad tracks and potholes or more generally in events which do not compress the air of the inner-door cavity. Result tables of firing times to compare the acceleration- and the pressure-based system are included for several platforms.

Finally, an example of a combined acceleration- and pressure-based system is given as a proposal to discriminate all real world crash conditions in an appropriate response time.