• 센서학회지
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• 제15권1호
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• pp.40-46
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• 2006

This paper presents a novel fiber optic accelerometer system for monitoring vibration of large-size structures. The system is composed of one (or multiple) sensor head, a light control unit and a signal processing unit. The sensing mechanism of the sensor head is based on a novel integration of the moire fringe phenomenon with fiber optics to achieve a robust performance in addition to its immunity to EM interference, easy cabling, and low cost. In this paper, a prototype of the fiber optic accelerometer system has been developed successfully. A low-cost light control unit has been developed to drive the system's optic and electronic components. A unique algorithm has also been developed to derive the sensor's acceleration from the raw signals of the light control unit; it is implemented via a separate signal processing unit. Finally, the shaking table tests successfully demonstrate the performance and the potential of the moire fringe fiber optic sensor system to monitor the health of civil infrastructures.

• 대한기계학회논문집A
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• 제35권7호
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• pp.791-798
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• 2011

모든 기계 시스템의 변수는 불확실성을 가지고 이는 시스템 성능에 직접적인 영향을 미칠 뿐 아니라 생산성 감소를 야기한다. 특히 MEMS 시스템의 크기는 매우 작으므로 일반적인 기계 시스템에 비해 제조 공차는 상대적으로 커질 수 밖에 없다. 이 제조 공차에 의한 시스템 변수 불확실성은 MEMS 시스템의 성능과 제조 수율에 영향을 미친다. 본 연구에서는 두 가지의 불확실성 해석법을 이용하여 MEMS 가속도계의 시스템 변수 불확실성에 의한 성능의 불확실성 해석을 수행하고 성능분포 및 제조수율을 예측하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.448-452
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• 2007

Many industrial operations require continuous or nearly-continuous operation of machines, which if interrupted can result in significant financial loss. The condition monitoring of these machines has received considerable attention recent years. Rapid developments in semiconductor, computing, and communication with a remote site have led to a new generation of sensor called "smart" sensors which are capable of wireless communication with a remote site. The purpose of this research is the development of smart sensor using which can on-line perform condition monitoring. This system is addressed to detect conditions that may lead to equipment failure when it is running. Moreover it will reduce condition monitoring expense using low cost MEMS accelerometer. This sensor can receive data in real-time or periodic time from MEMS accelerometer. Furthermore, this system is capable for signal preprocessing task (High Pass Filter, Low Pass Filter and Gain Amplifier) and analog to digital converter (A/D) which is controlled by CPU. A/D converter that converts 10bit digital data is used. This sensor communicates with a remote site PC using TCP/IP protocols. Wireless LAN contain IEEE 802.11i-PSK or WPA (PSK, TKIP) encryption. Developed sensor executes performance tests for data acquisition accuracy estimations.

• 인터넷정보학회논문지
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• 제11권1호
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• pp.129-141
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• 2010

본 논문에서는 사람의 행동 모니터링을 위한 멀티 센서 기반의 웨어러블 지능형 디바이스를 제안한다. 다중 행동을 인식하기 위해, 이미지 센서와 가속도 센서를 이용하여 행동 인식 알고리즘을 개발하였다. 멀티 센서로부터 얻은 데이터를 분석하기 위해 그리드 기반 옵티컬 플로우 방법을 제안하고 SVM 분류기법을 이용하였다. 이미지 센서로부터 얻은 모션 벡터의 방향과 크기를 이용하였고, 3축 가속도 센서로부터 얻은 데이터에서 FFT의 축과 크기와의 상관관계를 계산하였다. 실험 결과에서 이미지 센서 기반과 3축 가속도 센서기반의 행동 인식률은 각각 55.57 %, 89.97%를 보였으나 제안한 멀티센서기반의 행동인식률은 92.78% 를 보였다.

• 한국전문물리치료학회지
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• 제23권1호
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• pp.87-93
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• 2016

Background: Posture balance control is the ability to maintain the body's center of gravity in the minimal postural sway state on a supportive surface. This ability is obtained through a complicated process of sensing the movements of the human body through sensory organs and then integrating the information into the central nervous system and reacting to the musculoskeletal system and the support action of the musculoskeletal system. Motor function, including coordination, motor, and vision, vestibular sense, and sensory function, including proprioception, should act in an integrated way. However, more than half of stroke patients have motor, sensory, cognitive, and emotional disorders for a long time. Motor and sensory disorders cause the greatest difficulty in postural control among stroke patients. Objects: The purpose of this study is to determine the effect of visual and somatosensory information on postural sway in stroke patients and carrying out a kinematic analysis using a tri-axial accelerometer and a quantitative assessment. Methods: Thirty-four subjects posed four stance condition was accepted various sensory information for counterbalance. This experiment referred to the computerized dynamic posturography assessments and was redesigned four condition blocking visual and somatosensory information. To measure the postural sway of the subjects' trunk, a wireless tri-axial accelerometer was used by signal vector magnitude value. Ony-way measure analysis of variance was performed among four condition. Results: There were significant differences when somatosensory information input blocked (p<.05). Conclusion: The sensory significantly affecting the balance ability of stroke patients is somatosensory, and the amount of actual movement of the trunk could be objectively compared and analyzed through quantitative figures using a tri-axial accelerometer for balance ability.

• 한국산업융합학회 논문집
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• 제25권5호
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• pp.773-782
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• 2022

Estimation of cable tension through proper measurements is one of the essential tasks in evaluating the safety of cable structures. In this paper, a study on cable tension estimation using the built-in accelerometer and camera in a smartphone was conducted. For the experimental study, visual displacement measurement using a smartphone camera and acceleration measurement using a built-in accelerometer were performed in the cable-stayed bridge model. The estimated natural frequencies and transformed tensions from these measurements were compared with the theoretical values and results from the normal visual displacement method. Through comparison, it can be seen that the error between the method using the smartphone and the normal visual displacement is sufficiently small to be acceptable. It has also been shown that those errors are much smaller than the difference between the values calculated by the theoretical model. These results show that the deviation according to the type of measurement method is not large and it is rather important to use an appropriate mathematical model. In conclusion, in the case of cable tension estimation, it can be said that the visual displacement measurement and acceleration using a smartphone can be a sufficiently applicable method, just like the normal visual displacement method. It is also noteworthy that the smartphone accelerometer has a larger magnitude error and has more limitations such as high-frequency sampling instability compared to the visual displacement method, but shows almost the same performance as the visual displacement method in this cable tension estimation.

• 제어로봇시스템학회논문지
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• 제18권7호
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• pp.632-637
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• 2012

This paper introduces a simple and efficient calibration method for three-axis accelerometers and three-axis gyroscopes using three-axis motion rate table. Usually, the performance of low cost MEMS-based inertial sensors is affected by scale and bias errors significantly. The calibration of these errors is a bothersome problem, but the previous calibration methods cannot propose simple and efficient method to calibrate the errors of three-axis inertial sensors. This paper introduces a new simple and efficient method for the calibration of accelerometer and gyroscope. By using a three-axis motion rate table, this method can calibrate the accelerometer and gyroscope simultaneously and simply. Experimental results confirm the performance of the proposed method.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제2권6호
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• pp.395-402
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• 2013

본 논문에서는 스마트폰 사용자를 위한 가속도 센서 기반의 제스처 인식 방법을 제안한다. 제안하는 제스처 인식 방법에서는 DTW 알고리즘을 적용하여 새로운 시계열 가속도 데이터와 각 제스처별 대표 훈련 데이터간의 유사도를 측정한 뒤, k-NN 알고리즘을 적용하여 제스처를 판별한다. 본 논문에서 제안하는 제스처 인식 방법의 성능을 분석해보기 위해, 안드로이드 스마트폰에서 동작하는 제스처 인식 프로그램과 이것을 활용한 제스처 기반 원격 제어 로봇 시스템을 구현하였다. 사용자-혼합 및 사용자-독립 실험들을 통해, 본 논문에서 제안한 제스처 인식방법과 구현 시스템이 높은 인식 성능과 확장성을 가진다는 것을 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2182-2186
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• 2003

This paper presents the differential type resonant accelerometer (DRXL) and its performance test results. The DRXL is the INS grade, surface micro-machined sensor. The proposed DRXL device produces a differential digital output upon an applied acceleration, and the principle is a gap-dependent electrical stiffness variation of the electrostatic resonator with torsion beam structures. Using this new operating concept, we designed, fabricated and tested the proposed device. The final device was fabricated by using the wafer level vacuum packaging process. To test the performance of the DRXL, a nonlinear self-oscillation loop is designed using describing function technique. The oscillation loop is implemented using discrete electronic elements. The performance test of the DRXL shows that the sensitivity of the accelerometer is 12 Hz/g and its long term bias stability is about $2mg(1{\sigma})$. The turn on repeatability, bandwidth, and dynamic range are 4.38 mg, 100 Hz, and ${\pm}\;70g$, respectively.

• 한국공간구조학회논문집
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• 제16권1호
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• pp.85-94
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• 2016

In this study, an acceleration sensor that has optical fibers to measure the inclination and acceleration of a structure through contradictory changes in two-component FBG sensors was examined. The proposed method was to ensure precise measurement through the unification of the deformation rate sensor and the angular displacement sensor. A high sensitivity three-axis accelerometer was designed and prepared using this method. To verify the accuracy of the accelerometer, the change in wavelength according to temperature and tension was tested. Then, the change in wavelength of the prepared accelerometer according to the sensor angle, and that of the sensor according to the change in ambient temperature were measured. According to the test results on the FBG-based vibration sensor that was developed using a high-speed vibrator, the range in measurement was 0.7 g or more, wavelength sensitivity, 2150 pm/g or more, and the change in wavelength change, $9.5pm/^{\circ}C$.