Accurate laboratory testing of low-frequency triaxial vibration sensors under various environmental conditions

TL;DR

This paper presents a triaxial environmental testing system (TETS) that integrates a thermostatic chamber with a long-stroke triaxial vibrator to evaluate low-frequency vibration sensors under temperatures from -30 °C to +80 °C. Primary calibration of reference accelerometers is performed inside the chamber using ISO 16063-11 with a laser-interferometer reference outside the chamber, establishing a temperature-dependent complex sensitivity model $S(T,f)=S_{com}(f)\frac{r(T)}{1+i f/f_c(T)}$ and enabling accurate, traceable references. A MEMS accelerometer is demonstrated as a sensor under test (SUT) while three reference Servo accelerometers provide the triaxial reference, achieving an overall measurement uncertainty of about $0.23\%$ and validating seismic observation capabilities across -15 to +56 °C. The approach enables systematic, reliable evaluation of vibration sensing technologies for earthquake monitoring and infrastructure health in harsh environmental conditions, with potential to improve field data reliability. The measured seismic intensity $I_ ext{JMA}=2\log_{10} a+0.94$ under varying temperatures confirms practical applicability for earthquake reconnaissance and monitoring.

Abstract

Triaxial vibration sensor are widely used used in various application. Recently, low-cost sensors based on micro electro mechanical system (MEMS) technology are also becoming more widely adopted. However, their measurement accuracy can be affected by environmental factors such as temperature. In this study, we developed an environmental testing system integrated with a triaxial vibration exciter. The system can reproduce long-stroke, low-frequency triaxial vibrations -- such as those caused by huge earthquakes -- under temperatures ranging from $-30~^\circ\mathrm{C}$ to $+80~^\circ\mathrm{C}$. Using this system, the measurement accuracy of vibration sensors can be evaluated under different environmental conditions. The system provides highly accurate reference measurements using a laser interferometer and reference accelerometers that are primarily calibrated within the system. The overall accuracy of the reference vibration measurement is estimated to be approximately 0.23~\%. Based on these reference measurements, we investigated the accuracy of earthquake observations using a MEMS accelerometer as a demonstration. The system configuration and testing procedures are presented in this paper.

Figures (7)

• Figure 1: Schematic diagram (upper) and photo (lower) of the triaxial environmental test system (TETS).
• Figure 2: A measurement setup of the servo accelerometer for primary calibration.
• Figure 3: Comparison of primary calibration results using existing system Shimoda2023 and TETS for Servo 1 at room temperature (23 $^\circ$C).
• Figure 4: Primary calibration results at various temperatures for three servo accelerometers. The measured values are plotted with open circles, and the fitting results are plotted with dashed lines.
• Figure 5: Temperature dependence of the relative magnitude $r(T)$ and cutoff frequency $f_\mathrm{c}(T)$. The fitting results with a cubic function are shown with dashed lines.