Feasibility of frequency-modulated wireless transmission for a multi-purpose MEMS-based accelerometer.

Alessandro Sabato,Maria Feng

doi:10.3390/s140916563

Abstract

Recent advances in the Micro Electro-Mechanical System (MEMS) technology have made wireless MEMS accelerometers an attractive tool for Structural Health Monitoring (SHM) of civil engineering structures. To date, sensors' low sensitivity and accuracy—especially at very low frequencies—have imposed serious limitations for their application in monitoring large-sized structures. Conventionally, the MEMS sensor's analog signals are converted to digital signals before radio-frequency (RF) wireless transmission. The conversion can cause a low sensitivity to the important low-frequency and low-amplitude signals. To overcome this difficulty, the authors have developed a MEMS accelerometer system, which converts the sensor output voltage to a frequency-modulated signal before RF transmission. This is achieved by using a Voltage to Frequency Conversion (V/F) instead of the conventional Analog to Digital Conversion (ADC). In this paper, a prototype MEMS accelerometer system is presented, which consists of a transmitter and receiver circuit boards. The former is equipped with a MEMS accelerometer, a V/F converter and a wireless RF transmitter, while the latter contains an RF receiver and a F/V converter for demodulating the signal. The efficacy of the MEMS accelerometer system in measuring low-frequency and low-amplitude dynamic responses is demonstrated through extensive laboratory tests and experiments on a flow-loop pipeline.

Highlights

In recent decades, a great deal of attention has been given to the possibility of measuring physical quantities using Micro Electro-Mechanical System (MEMS) sensors and transmitting data wirelessly.In general, the wireless transmission of sensor signals, compared to its wired counterpart, is preferable due to its absence of triboelectric noise and elimination of the requirement for cumbersome cabling.The fast growth of the wireless technology piezoelectric based applications, such as ElectroMechanical Impedance (EMI) and Micro electro-mechanical systems, is changing the way civil structures and mechanical systems are monitored, controlled, and maintained
This paper presents the design of a prototype of the MEMS accelerometer system and its experimental evaluations
The wireless MEMS accelerometer system was deployed on a pipe to measure and analyze its flow-induced vibration

Summary

Introduction

The wireless transmission of sensor signals, compared to its wired counterpart, is preferable due to its absence of triboelectric noise and elimination of the requirement for cumbersome cabling. Mechanical Impedance (EMI) and Micro electro-mechanical systems, is changing the way civil structures and mechanical systems are monitored, controlled, and maintained. The SHM applications require the MEMS accelerometers to be accurate for measuring a wide range of structural vibration: from ambient vibration (in the order of 10−2 ms−2) to severe earthquake (in the order of 10 ms−2). Sensor systems able to accurately measure such low-frequency signals are required. Currently available low-cost wireless sensor boards mounted with MEMS accelerometers are characterized by low frequency sensitivity and high noise-density, and, are suited for measuring only high-amplitude vibration (nearly 10−1 m·s−2) [14]

Methods

Results

Conclusion