Calibration of tri-axial MEMS accelerometers in the low-frequency range – Part 1: comparison among methods

Giulio D'Emilia,Antonella Gaspari,Fabrizio Mazzoleni,Emanuela Natale,Alessandro Schiavi

doi:10.5194/jsss-7-245-2018

Abstract

Abstract. Two alternative experimental procedures for the calibration of tri-axial accelerometers have been compared with traditional methods, performed according the procedures stated in the standard ISO 16063-21. Standard calibration is carried out by comparison with a laser Doppler vibrometer (LDV), used as a primary reference transducer. The main sensitivities have been investigated and, where applicable, also transverse ones. Many aspects have been evaluated: the hypotheses about transverse sensitivities, the simplicity of the procedure, the number of measurements needed, and the effect of typology of transducer, depending on electrical and geometrical contributions. Two different accelerometers have been tested, a piezo-electric accelerometer and a capacitive MEMS accelerometer. A low-frequency range of vibration has been investigated, 3 and 6 Hz, with amplitude of acceleration ranging from 2 to 20 ms−2. A satisfactory reproducibility of methods has been verified, with percentage differences less than 2.5 %. Anyway, pros and cons of each method are also discussed with reference to their possible use for easy and quick calibration of low-cost tri-axial accelerometers.

Highlights

In recent years, there has been a growing interest in microelectro-mechanical system accelerometers (MEMS), due to their low cost, the possibility of embedding these devices within wireless sensor networks, and the capability of detecting low-amplitude and low-frequency vibrations, operations which are not always feasible with the conventional low-cost sensor boards (Batista et al, 2011; Sabato et al, 2017)
Low-frequency vibration measurements are of great interest in many different fields such as, for instance, energy production (Ripper et al, 2017), structural health monitoring (SHM) of buildings and of civil infrastructures (Sabato et al, 2017; Ranieri et al, 2013), and geotechnical applications (Czech and Gosk, 2017) in the field of human vibration and bio-dynamics (Griffin, 2014), mainly because of the increasing development of MEMS embedded in mobile devices (Halim and Park, 2013) and in applications in the field of the Internet of Things (IoT) (Borgia, 2014)
The sensitivity components are expressed in millivolt per metre second squared, for the piezoelectric accelerometer, while they are dimensionless for the MEMS accelerometer, since the digital output values are directly expressed in metres per second squared (m s−2)

Summary

Introduction

There has been a growing interest in microelectro-mechanical system accelerometers (MEMS), due to their low cost, the possibility of embedding these devices within wireless sensor networks, and the capability of detecting low-amplitude and low-frequency vibrations, operations which are not always feasible with the conventional low-cost sensor boards (Batista et al, 2011; Sabato et al, 2017). It should be considered that MEMS accelerometers, in comparison to high-performance piezo-electric transducers, exhibit lower accuracy in consumer grade applications; in the context of extensive applications, such as large sensor networks, in which high accuracy on a wide range of frequency and amplitude is not needed, the technical performances of these accelerometers are considered adequate (Schiavi et al, 2015).

Methods

Results

Discussion

Conclusion