This paper investigates the effect of sensor module motion on the output and functionality of MEMS crash accelerometers. Short duration and high amplitude shock pulses generated by a crash event may excite a large vibration on sensor module and cause undesirable sensor output and system failure. A series of vibration and shock tests are carried out to characterize the dynamic response of four commercial crash satellite sensor modules in the sensitive axis of MEMS sensor. It is found that most modules have natural frequencies below 5 kHz and Q-factors are generally high. Due to very stiff PCB structure in this direction, the difference between PCB response and module response is very small. A single degree of freedom vibration model is used to simulate vibration on sensor module during crash event or shock test. The simulation data from this model is input to the MEMS sensor behavior model to simulate its output in vehicle crash tests. It is found that neglecting module effect on MEMS sensor output may lead to large discrepancy between sensor simulation results and sensor test data. It is also found that the peak acceleration output of MEMS sensor may be reduced by module vibration due to complex sensor design.

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