Effects of Excitation Voltage on Piezoresistive and Resistive Sensor Output Characteristics

In laboratory car crash tests, Anthropomorphic Test Devices (ATD) are equipped with piezoresistive and resistive sensors for occupant injury assessment. Accelerometers are inertial transducers that convert acceleration into electrical output which can be easily recorded by a Data Acquisition System (DAS). For an accelerometer, this electrical output mainly depends upon subjected acceleration, sensitivity of the accelerometer, excitation voltage and gain provided. Before use in testing, accelerometers are calibrated at a standard excitation (manufacturer decided) voltage to determine characteristics like Sensitivity, Sensitivity per unit excitation voltage, Zero Measurand Output (ZMO), Transverse Sensitivity etc. It is observed that these characteristics are highly dependent on the excitation voltage. In testing, due to limitations of DAS and/or other unwanted noise in the excitation voltage, these accelerometers are sometimes used at a different excitation voltage. This paper studies the behavior and characteristics of various accelerometers used in impact testing with respect to changes in excitation voltage and thus predict the inconsistencies in the injury data measurement.