• Title, Summary, Keyword: Accelerometer

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A Study on the Performance Improvement of the Micromachined Convective Accelerometer (열 대류 가속도계의 성능향상에 관한 연구)

  • Youn, Sung-Kie;Oh, Jun-Seok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.5
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    • pp.570-577
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    • 2007
  • A micromachined convective accelerometer is a recently developed device. Typical micromachined accelerometers use a solid proof mass for measuring acceleration. But a micromachined convective accelerometer does not use a solid proof mass. A micromachined convective accelerometer is composed of a heating resistor and temperature sensors. This device measures acceleration by using convective heat transfer phenomenon. Therefore characteristics of a micromachined convective accelerometer are different as compared with typical micromachined accelerometer. In this research, we analyze the convective accelerometer by using transient convective heat transfer analysis. Based on the results of a convective accelerometer, we propose a new model which has improved performance.

Design of Force Rebalance Loop for Silicon Accelerometer using Parametric Robust Control Technique (변수적 강인해석기법을 이용한 실리콘 가속도계의 재평형루프 설계)

  • Seong, Sang-Gyeong;Lee, Jang-Gyu;Gang, Tae-Sam
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.49 no.3
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    • pp.124-132
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    • 2000
  • In this paper, presented are an active surface-micromachined silicon accelerometer, force rebalance loop using parametric robust control method, and experimental results with a real micromachined accelerometer. And finally, a robust controller of the form of PID compensator was designed to construct force rebalance loop. Through the frequency response analysis, it is shown that the loop guarantees appropriate stability and robustness. Experiments with a real accelerometer demonstrated that the proposed loop effectively controls the position of the accelerometer's proof mass. It also demonstrated that the resolution of the fabricated accelerometer is better than 1mg. Compared with a commercial accelerometer the proposed force rebalance silicon accelerometer showed better performances.

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Natural Vibration Characteristics of Accelerometer (가속도 계측 센서의 고유진동 특성 분석)

  • Kim, Seung-Ki;Kwak, Moon K.;Yang, Dong-Ho;Yang, Dong-Yuk
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.922-924
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    • 2014
  • This paper is concerned with the analysis of natural vibration characteristics of an accelerometer used in power plant. The malfunction of the accelerometer in high-temperature environment may produce erroneous sensor signal and the erroneous signal may cause unpredicted accidents in power plants. Hence, the accelerometer which endures high temperature needs to be developed. In this study, the natural vibration characteristics of the accelerometer were investigated prior to the development of the high-temperature accelerometer. The main mechanical part of the accelerometer is a spiral spring. In this study, the dynamic characteristics of the spiral spring were investigated first by using a commercial finite element code. Numerical results show that the thickness of the spiral spring affects the dynamic characteristics. Numerical investigation on the effect of temperature on the performance of the accelerometer will follow.

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A Simple Analytical Model for MEMS Cantilever Beam Piezoelectric Accelerometer and High Sensitivity Design for SHM (structural health monitoring) Applications

  • Raaja, Bhaskaran Prathish;Daniel, Rathnam Joseph;Sumangala, Koilmani
    • Transactions on Electrical and Electronic Materials
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    • v.18 no.2
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    • pp.78-88
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    • 2017
  • Cantilever beam MEMS piezoelectric accelerometers are the simplest and most widely used accelerometer structure. This paper discusses the design of a piezoelectric accelerometer exclusively for SHM applications. While such accelerometers need to operate at a lower frequency range, they also need to possess high sensitivity and low noise floor. The availability of a simple model for deflection, charge, and voltage sensitivities will make the accelerometer design procedure less cumbersome. However, a review of the open literature suggests that such a model has not yet been proposed. In addition, previous works either depended on FEM analysis or only reported on the fabrication and characterization of piezoelectric accelerometers. Hence, this paper presents, for the first time, a simple analytical model developed for the deflection, induced voltage, and charge sensitivity of a cantilever beam piezoelectric accelerometer.The model is then verified using FEM analysis for a range of different cases. Further, the model was validated by comparing the induced voltages of an accelerometer estimated using this model with experimental voltages measured in the accelerometer after fabrication. Subsequently, the design of an accelerometer is demonstrated for SHM applications using the analytical model developed in this work. The designed accelerometer has 60 mV/g voltage sensitivity and 2.4 pC/g charge sensitivity, which are relatively high values compared to those of the piezoresistive and capacitive accelerometers for SHM applications reported earlier.

A Study on Acoustic and Vibratory Response of a MEMS Resonant Accelerometer (공진형 MEMS 가속도계의 음향가진 반응특성 연구)

  • Lee, Sang Woo;Lee, Hyung Sub;Yu, Myeong-Jong;Kim, Do Hyung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.9
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    • pp.1330-1336
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    • 2015
  • It is necessary to study on acoustic and vibratory response of a MEMS resonant accelerometer before applying to military applications. In this paper, we analyze why the resonant accelerometer reacts to an acoustic wave and a high frequency vibration. And we describe experimental results on acoustic and vibratory response of the accelerometer. The accelerometer consists of a proof mass and a dual ended tuning fork. It is a differential resonant accelerometer with arranging a pair of accelerometers. The mode shape was analyzed to find out the input mode frequency by using a FEM simulation. Some experiments regarding the acoustic noise was carried out by using a tweeter and a microphone in the anechoic room. Results showed that the accelerometer reacted to the acoustic wave and vibration which had the input mode frequency as we had expected. We showed experimentally not only that the susceptibility of the accelerometer to an acoustic wave was 70 dB but also that the effectiveness of applying an acoustic absorber and a metal case was 20 dB, respectively. Also, we could minimize the vibratory response property of the accelerometer by installing a IMU with a silicone rubber mount pad.

Analysis of Braking Response Time for Driving Take Based on Tri-axial Accelerometer

  • Shin, Hwa-Kyung;Lee, Ho-Cheol
    • The Journal of Korean Physical Therapy
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    • v.22 no.6
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    • pp.59-63
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    • 2010
  • Purpose: Driving a car is an essential component of daily life. For safe driving, each driver must perceive sensory information and respond rapidly and accurately. Brake response time (BRT) is a particularly important factor in the total stopping distance of a vehicle, and therefore is an important factor in traffic accident prevention research. The purpose of the current study was (1) to compare accelerometer. BRTs analyzed by three different methods and (2) to investigate possible correlations between accelerometer-BRTs and foot switch-BRTs, which are measured method using a foot switch. Methods: Eighteen healthy subjects participated in this study. BRT was measured with either a tri-axial accelerometer or a footswitch. BRT with a tri-axial accelerometer was analyzed using three methods: maximum acceleration time, geometrical center, and center of maximum and minimum acceleration values. Results: Both foot switch-BRTs and accelerometer-BRTs were delayed. ANOVA for accelerometer BRTs yielded significant main effects for axis and analysis, while the interaction effect between axis and analysis was not significant. Calculating the Pearson correlation between accelerometer-BRT and foot switch-BRT, we found that maximum acceleration time and center of maximum and minimum acceleration values were significantly correlated with foot switch-BRT (p<0.05). The X axis of the geometrical center was significantly correlated with foot switch-BRTs (p<0.05), but Y and Z axes were not (p>0.05). Conclusion: These findings suggest that the maximum acceleration time and the center of maximum and minimum acceleration value are significantly correlated with foot switch-BRTs.

Study on improvement of frequency response characteristics of accelerometer (진동가속도계의 주파수응답특성 개선에 관한 연구)

  • 한응교;조진호
    • Journal of the korean Society of Automotive Engineers
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    • v.3 no.1
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    • pp.61-68
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    • 1981
  • There are three types in frequency response accelerometer; one is lightly damped piezp type, another is oil damping stainguage type and the third is electro induction type accelerometer within electromagnetic damping. The usable frequency range of lightly damped accelerometers is limited to 0.2 of their mounted natural frequency for amplitude distortion of less than 5 percents. There have been situation where the measured motion contains unforeseen high - frequency components, which are regarded as such due to the accelerometer transfer function. There are several way to overcome amplitude distortion of the higher than anticipated frequency components; (I) to make use of the accelerometer with natural frequency three times and more as high as the measured frequency, (II) to establish data-analysis techniques which will account for the amplitude distortion, (III) to set up a notch filter circuit which has a transfer function that is the reciprocal of the accelerometer transfer function, and so on. This paper makes a report of the method as to(III), i. e., set up a few notch filter circuits, it is discussed what happens when the transfer functions, are in discord as to natural frequency of the filter and accelerometer damping vs. filter damping. And especially as for the cantilever strain gauge type accelerometer made by oneself with ease, it was compared and discussed between the ideological value and the experimental value of actual designed circuit in case of the mismatching of the transfer functions, and it was considered whether to be practicable or not, the result of which was as following; the useful frequency range of the accelerometer can be extended to near resonance if (a) the accelerometer mounted natural frequency and the filter center frequency are matched within .+-. 2 percent and (b) the damping ratios are matched within two factors. Therefore, we obtained the good result in improvement for extending frequency response characteristics of accelerometer.

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Model Updating in Small Structural Dynamics Model by Elimination of Mass Loading Effect of Accelerometer (가속도계 영향을 제거한 소형 구조물의 동특성 모델 개선)

  • Lee, Jung Youn
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.1
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    • pp.40-47
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    • 2015
  • Dynamic response of any small structure is always affected by the mass of the attached accelerometer. This paper predicts the natural frequencies and frequency response functions by removing the mass loading effect from the accelerometer. This mass loading is studied on a simple cantilever beams by varying the location of accelerometer. By using sensitivity analysis with iteration method, accelerometer mass and location are obtained. The predicted natural frequencies of the small cantilever beam without the accelerometer's mass show good agreement with the structural re-analysis.

Dynamic Characterization of Sub-Scaled Building-Model Using Novel Optical Fiber Accelerometer System

  • Kim, Dae-Hyun
    • Journal of the Korean Society for Nondestructive Testing
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    • v.31 no.6
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    • pp.601-608
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    • 2011
  • This paper presents the damage assessment of a building structure by using a novel optical fiber accelerometer system. Especially, a sub-scaled building model is designed and manufactured to check up the feasibility of the optical fiber accelerometer for structural health monitoring. The novel accelerometer exploits the moir$\acute{e}$ fringe optical phenomenon and two pairs of optical fibers to measure the displacement with a high accuracy, and furthermore a pendulum to convert the displacement into acceleration. A prototype of optical fiber accelerometer system has been successfully developed that consists of a sensor head, a control unit and a signal processing unit. The building model is also designed as a 4-story building with a rectangular shape of $200{\times}300$ mm of edges. Each floor is connected to the next ones by 6 steel columns which are threaded rods. Basically, a random vibration test of the building model is done with a shaker and all of acceleration data is successfully measured at the assigned points by the optical fiber accelerometer. The experiments are repeated in the undamaged state and the damaged state. The comparison of dynamic parameters including the natural frequencies and the eigenvectors is successfully carried out. Finally, the optical fiber accelerometer is proven to be prospective to evaluate dynamic characteristics of a building structure for the damage assessment.

Development of Fiber Optic Accelerometer for Third-Party Damage Detection (타공사 감시를 위한 광섬유 가속도계의 개발)

  • Park, Ho-Rim;Choe, Jae-Bung;Kim, Yeong-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.10
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    • pp.1551-1558
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    • 2001
  • Recently, a number of underground pipelines have been drastically increased. The integrity of these buried pipelines, especially gas transmitting pipelines, is of importance due to an explosive characteristic of natural gas. The third party damage is known as one of the most critical factor which causes fatal accidents. For this reason, a number of systems detecting third party damage are under development. The major concern in the development of third party damage detection system is to transmit vibration signals out of accelerometer to signal conditioner and data acquisition system without any interference caused by noise. The objective of this paper is to develope a fiber optic accelerometer applicable to third party damage detection system. A fiber optic accelerometer was developed by use of combining principles of one degree of freedom vibration model and an extrinsic Fabry-Perot interferometer. The developed fiber optic accelerometer was designed to perform with a sensitivity of 0.06mVg, a frequency range of less than 6kHz and an amplitude range of -200g to 200g. The developed, accelerometer was compared with a piezoelectric accelerometer and calibrated. In order to verify the developed accelerometer, the field experiment was performed. From the field experiment, vibration signals and the location of impact were successfully detected. The developed accelerometer is expected to be used for the third party damage detection system which requires long distance transmission of signals.