Measurement and Monitoring of Frequency of Ambient Vibration using PVDF Piezofilm Sensor

Abstract

Measurement of frequency of ambient vibration, especially at low range is challenging.From practical point of view,the sensing of frequency of ambient vibration below 70 Hz is extremely important for real applications. Unfortunately, the amplitude of the source of vibration is extremely small at low range of vibration frequencies and thus possesses additional challenge in the measurement. Two types of mass loaded PVDF piezofilm sensors are used to capture minute vibration with a special arrangement of the sensors for better efficiency. A signal conditioning circuit consisting of a buffer and comparator is investigated for processing the analog output from the active sensors. An artificial vibrator is used to simulate the ambient vibration and the frequency of which is measured by means of optical sensor independently. The output signals from the signal conditioning circuit and optical sensor are compared to measure the frequency of vibration of the source. It is found that at the very low frequency range up to 50 Hz, the sensor of low resonance frequency performs better whereas the performance of the sensor of comparatively higher resonance frequency is better in the frequency range of 50–70 Hz. Our system is able to measure low vibration frequency as low as 28 Hz with a high degree of repeatability.