The Differential – Piezoelectric Accelerometers Used for Environmental Vibration and Human Vibration Measurements

A prototype of a low frequency differential-piezoelectric accelerometer is described. It has the function that the vibration signals can be transformed to a pair of push-pull signals which are out of phase. But for the non-vibration signals, such as the environmental temperature transient sensitivity, the out-puts are all in phase. Owing to the difference in phase, the non-vibration signals can be separated out and thus can be compensated directly. The experimental results show that the temperature transient sensitivity can be reduced to 6.4 times and 9.3 times when the lower limiting frequencies are 0.3 Hz and 0.08 Hz respectively. Combining with other measures, the temperature transient sensitivity of the accelerometer is quite low and therefore it can be neglected in most low frequency vibration measurement applications. After analyzing the compensation of the transverse sensitivity and acoustic sensitivity, it is concluded that these effects are not significant in practical use. Meanwhile, a predicting method for calculating the natural frequency is described. Some experimental products of this structure have been used effectively in the measurements of human vibration and environmental vibration.