Traceability of digital 3-axis MEMS accelerometer: simultaneous determination of main and transverse sensitivities in the frequency domain

Abstract

Traceability of digital sensors is a metrological challenge, as well as a present priority, as stated within the emerging metrology requirements for the future in the Strategy 2017 to 2027 document of the Consultative Committee for Acoustics, Ultrasound, and Vibration of BIPM. From this perspective, in this paper, a calibration system for 3-axis digital MEMS accelerometers is described, in order to simultaneously evaluate the main and transverse sensitivities in the frequency domain (from 5 Hz up to 3 kHz) and in static conditions, together with a proper sensitivity parameter for digital outputs, thus providing the required metrological traceability. The procedure, based on the comparison to a reference transducer, involves a single-axis excitation of inclined planes. Experimental results are expressed in terms of exploitation and sensitivities matrices. Overall expanded uncertainties of the main terms are in the order of 2%, in dynamic conditions, and 1%-2% in static conditions. The feasibility of this system can be exploited for the development of manufacturers' in-line control systems and for the investigation of large-scale calibration procedures.

Evaluation and correction of systematic effects in a simultaneous 3-axis vibration calibration system

“…Standard uncertainties associated to the amplitude of the spurious components, u(ax',syst), u(ay',syst), u(az',syst), are considered as type B uncertainty contributions with an average error of 0.0025 m s -2 , from three repeated measurements, and a uniform rectangular distribution. Standard uncertainties associated to the phase difference due to the spurious components, u(φx',syst), u(φy',syst), u(φz',syst), are considered as type A uncertainty contributions with a maximum standard deviation of 2° from five repeated measurements, as shown in [14].…”

“…Traceability of digital 3-axis MEMS accelerometer: simultaneous determination of main and transverse sensitivities in the frequency domain. Metrologia, 57(3), 035013" [14], which shows the detailed extension of the determination of the systematic effects of the calibration system.…”

“…Traceable calibration methods for digital sensors, and smart sensors, in metrological terms [11 -13], including sensitivity parameter and an appropriate uncertainty evaluation, are necessary in order to consider low-cost and low-power consuming accelerometers as actual measurement devices in frequency domain [14].…”

“…The calibration system, developed at INRiM, allows to simultaneous evaluate the main and the transverse sensitivity, in frequency domain, of 3-axis accelerometers, by means of a single-axis vibration excitation, by using inclined planes rigidly fixed to the vibrating table [14,15]. The calibration procedure is based on the comparison to a reference transducer (in analogy to ISO 16063-21 [16]).…”

Use of MEMS sensors for condition monitoring of devices: discussion about the accuracy of features for diagnosis

“…The output signals range ±(2 16 À1) = ±32768 Decimal 16-bit-signed , where the digit unit is a signed 16-bit sequence converted into a decimal number. Then, the sensitivity of the digital MEMS accelerometer is expressed in linear units of Decimal 16bit-signed /(m s À2 ) [20,21].…”