Dependence of frequency response on different velocity sensitivities of laser Doppler vibrometer

Nozato, Hideaki; Shimoda, T.; Kokuyama, Wataru

doi:10.1016/j.measen.2021.100301

Cited by 3 publications

(2 citation statements)

References 9 publications

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“…However, the accelerometer signals

have a positive delay resulting from varying sensor bandwidth ( Section 4.1 ) as well as internal delays of the sensors, amplifiers, and transmission lines. Figure 7 c shows the total hardware delay

of all individual measurements as well as its estimate of

s and its uncertainty of

s. While the use of a non-contact back wall sensor, such as an additional LDV, is expected to cause a decrease in signal-to-noise ratio, it could provide a reduced hardware delay uncertainty since it provides a flat frequency response over a wide range of frequencies [ 59 ].…”

Section: Results and Discussionmentioning

confidence: 99%

Development of an Accurate and Robust Air-Coupled Ultrasonic Time-of-Flight Measurement Technique

Bühling

Küttenbaum

Maack

et al. 2022

Sensors

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Ultrasonic time-of-flight (ToF) measurements enable the non-destructive characterization of material parameters as well as the reconstruction of scatterers inside a specimen. The time-consuming and potentially damaging procedure of applying a liquid couplant between specimen and transducer can be avoided by using air-coupled ultrasound. However, to obtain accurate ToF results, the waveform and travel time of the acoustic signal through the air, which are influenced by the ambient conditions, need to be considered. The placement of microphones as signal receivers is restricted to locations where they do not affect the sound field. This study presents a novel method for in-air ranging and ToF determination that is non-invasive and robust to changing ambient conditions or waveform variations. The in-air travel time was determined by utilizing the azimuthal directivity of a laser Doppler vibrometer operated in refracto-vibrometry (RV) mode. The time of entry of the acoustic signal was determined using the autocorrelation of the RV signal. The same signal was further used as a reference for determining the ToF through the specimen in transmission mode via cross-correlation. The derived signal processing procedure was verified in experiments on a polyamide specimen. Here, a ranging accuracy of <0.1 mm and a transmission ToF accuracy of 0.3μs were achieved. Thus, the proposed method enables fast and accurate non-invasive ToF measurements that do not require knowledge about transducer characteristics or ambient conditions.

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“…However, the accelerometer signals

have a positive delay resulting from varying sensor bandwidth ( Section 4.1 ) as well as internal delays of the sensors, amplifiers, and transmission lines. Figure 7 c shows the total hardware delay

of all individual measurements as well as its estimate of

s and its uncertainty of

Section: Results and Discussionmentioning

confidence: 99%

Development of an Accurate and Robust Air-Coupled Ultrasonic Time-of-Flight Measurement Technique

Bühling

Küttenbaum

Maack

et al. 2022

Sensors

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show abstract

“…In the following, as a case study, a full metrological approach has been applied to a mechanical sensor with digital output (DUT), to provide the actual sensitivity (and related metrological attributes), toward the actualization of a true 'phygital sensor', at INRIM. At present day, on the basis of a literature survey, only four National Metrology Institutes (NMIs) worldwide, are involved to develop calibration methods for vibration of mechanical sensors with digital output, in static and dynamic conditions, namely at NIST (USA) [10] , NMIJ (Japan) [15][16][17], PTB (Germany) [18][19][20][21], and at INRIM (Italy) [22] - [25].…”

Section: The Metrological Approachmentioning

confidence: 99%

Metrology for next generation “Phygital Sensors”

Schiavi

Mazzoleni

Facello

et al. 2023

2023 IEEE International Workshop on Metrology for Industry 4.0 &Amp; IoT (MetroInd4.0&IoT)

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Commonly speaking a 'sensor' is a device that produces an output signal quantitatively related to a certain physical phenomenon; if the output signal is provided in a digital form, it is referred in terms of 'digital sensor'. As is known, these devices are produced in the order of million/week and are widely used for the management of "smart systems" now commonplace in everyday life, such as automotive, domotics, smart-industry, cooperative robotics ("cobots"), robotic assisted surgery, as well as for advanced monitoring of infrastructures and ecosystems; moreover, digital sensors are the foundation of the "digital twins" technology development, and support the actualization of the "Digital Earth" purposes. However, in many cases, since these sensors manage interaction processes with humans (e.g., driver assistant control, physiological data, remote surgery, environmental hazard…), their technological performance must be actually recognized as safe and trustworthy. Recently, both manufacturers and end users have begun to question the actual reliability of sensors used in particularly complex applications, and see value in traceable chain to calibration and accreditation national laboratories. Indeed, the methods applied for metrological calibration of measuring instruments, against primary or secondary standards, can allow to accurately quantify the performance of these sensors, with respect to traceable physical quantities, providing certified statements of the effective 'sensitivity' (and related uncertainties), as the ratio between the digital output (reaction) and the physical input (stimulus). In that meaning, once calibrated, a digital sensor can be properly considered as a physical-digital sensor, i.e. a device, interfacing the physical world, sensitive to a specific variation of a known physical quantity, and able to convert it into a digital signal output (with known accuracy, precision and reliability), readable for an observer, exploitable by interconnected instruments, and for actuators control. Currently, although no pertinent Standards are yet available for the calibration of 'physical-digital sensors', some National Metrology Institutes are putting into practice appropriate calibration procedures and methods to fill this important lack, as described in this paper.

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Development of Band-Limitless Demodulation Method for Sinusoidal Phase Modulation Interferometry (Evaluation of Noise Floors, Maximum Measurement Speeds and Resolutions)

HIGUCHI,

KATAGIRI,

NAKAGAWA

et al. 2024

Journal of the Japan Society for Precision Engineering

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Dependence of frequency response on different velocity sensitivities of laser Doppler vibrometer

Cited by 3 publications

References 9 publications

Development of an Accurate and Robust Air-Coupled Ultrasonic Time-of-Flight Measurement Technique

Development of an Accurate and Robust Air-Coupled Ultrasonic Time-of-Flight Measurement Technique

Metrology for next generation “Phygital Sensors”

Development of Band-Limitless Demodulation Method for Sinusoidal Phase Modulation Interferometry (Evaluation of Noise Floors, Maximum Measurement Speeds and Resolutions)

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