• Title, Summary, Keyword: Displacement

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The Tip Position Measurement of a Flexible Robot Arm Using a Vision Sensor (비전 센서를 이용한 유연한 로봇팔의 끝점 위치 측정)

  • Shin, Hyo-Pil;Lee, Jong-Kwang;Kang, E-Sok
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.8
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    • pp.682-688
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    • 2000
  • To improve the performance of a flexible robot arm one of the important things is the vibration displacement measurement of a flexible arm. Many types of sensors have been used to measure it, The most popular has been strain gauges which measures the deflection of the beam,. Photo sensors have also been for detecting beam displacement and accelerometers are often used to measure the beam vibration. But the vibration displacement can be obtained indirectly from these sensors. In this article a vision sensor is used as a displacement sensor to measure the vibration displacement of a flexible robot arm. Several schemes are proposed to reduce the image processing time and increase its accuracy. From the experimental results it is seen that the vision sensor can be an alternative sensor for measuring the vibration displacement and has a potential for on-line tip position control of flexible robot systems.

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Retrieving the Time History of Displacement from Measured Acceleration Signal

  • Han, Sangbo
    • Journal of Mechanical Science and Technology
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    • v.17 no.2
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    • pp.197-206
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    • 2003
  • It is intended to retrieve the time history of displacement from measured acceleration signal. In this study, the word retrieving means reconstructing the time history of original displacement signal from already measured acceleration signal not just extracting various information using relevant signal processing techniques. Unlike extracting required information from the signal, there are not many options to apply to retrieve the time history of displacement signal, once the acceleration signal is measured and recorded with given sampling rate. There are two methods, in general, to convert measured acceleration signal into displacement signal. One is directly integrating the acceleration signal in time domain. The other is dividing the Fourier transformed acceleration signal by the scale factor of - $\omega$$^2$and taking the inverse Fourier transform of it. It turned out both the methods produced a significant amount of errors depending on the sampling resolution in time and frequency domain when digitizing the acceleration signals. A simple and effective way to convert the time history of acceleration signal into the time history of displacement signal without significant errors is studied here with the analysis on the errors involved in the conversion process.

Evaluation of Displacement Measurement Technique Using Laser Speckle and Digital Image Correlation Method (레이저 스페클과 디지털 화상관련법을 이용한 변위 측정방법의 평가)

  • 강기주;이정현;전문창
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.6
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    • pp.47-54
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    • 2003
  • As a tool for strain measurement to work with screw driven or hydraulic material test systems, in which mechanical vibration is inherent, SSDG (Speckle Strain/Displacement Gage), ESP (Electronic Speckle Photography) and its 3-dimension version SDSP are evaluated for the theory and practical appliance. Through tension test of steel strips, their validity and shortcomings are examined. As the results, it has been shown that, although SSDG and ESP provide direct measurement of in-plane strain in one direction, they are so sensitive to the out-plane displacement. On the other hand, SDSP which is aided with DIC (Digital Image Correlation) technique to trace the movement of the speckles provides not only in-plane 2-dimensional displacement field, but also out-of-plane displacement simultaneously. However, because the DIC is time-consuming, not automated yet and it needs post-processing to evaluate strain from the displacement field, SDSP appears to be not adequate as a real time sensor.

Changes in Selected Electrolyte Concentrations in Dairy Cowe with Abomasal Displacement (제사위전위증유우에 있어서 몇가지 혈청전해질 농도에 관한 조사연구)

  • Lee Sa-Kyun;Cheong Chang-Kook
    • Journal of Veterinary Clinics
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    • v.2 no.1
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    • pp.143-150
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    • 1985
  • The concentrations of serum calcium, inorganic phosphorus, sodium and potassium from 24 cows with left displacement of abomasum and 21 cows with right displacement of abomasum on pre and postoperation were determined. 1. The preoperative levels of serum calcium in left and right displacement of abomasum were below normal and returned to normal levels postoperatively. 2. The preoperative levels of serum inorganic phosphorus in left and right displacement of abomasum showed slight increase preoperatively and consistent slight rise postoperatively. 3. The preoperative levels of serum sodium in left and right displacement of abomasum were slightly below normal and maintained low levels postoperatively. 4. The preoperative levels of serum patassium in left and right displacement of abomasum were low normal limit and increased to upper normal limit postoperatively.

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Temperature-Compensative Displacement Sensor based on a Pair of Fiber Bragg Gratings Attached to a Metal Band

  • Kim, Kwang Taek;Kim, Dong Geun
    • Journal of Sensor Science and Technology
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    • v.27 no.2
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    • pp.82-85
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    • 2018
  • This paper proposes a new temperature-compensative displacement sensor with a pair of fiber Bragg gratings (FBG) attached to the inner and outer surfaces of an elastic metal band. The sensor can be also used as a temperature sensor with high sensitivity. The FBG pair shifted Bragg wavelengths in the same direction according to changes in the temperature. However, because the pressure of the metal band shifted a pair of Bragg wavelengths in the opposite direction, the displacement sensor could compensate for the effect of the temperature change in the proposed FBG pair. Results of the experiments showed that the two FBG displacement sensors responded linearly and symmetrically with respect to the displacement, and the displacement could be obtained using the difference between the two Bragg wavelengths.

Multi-Degree-of-Freedom Displacement Measurement of a Rigid Body Using a Diffraction Grating as a Cooperative Target (회절 격자 표식을 이용한 강체의 다자유도 변위 측정)

  • Kim, Jong-Ahn;Bae, Eui-Won;Kim, Kyung-Chan;Kim, Soo-Hyun;Kwak, Yoon-Keun
    • Proceedings of the KSME Conference
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    • pp.415-419
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    • 2000
  • Multi-degree-of-freedom (MDOF) displacement measurement Is needed In many application fields: precision machine control, precision assembly, vibration analysis, and so on. This paper presents a new MDOF displacement measurement method using a laser diode (LD), two position-sensitive detectors (PSDs), and a conventional diffraction grating. It utilizes typical features of a diffraction grating to obtain the information of MDOF displacement. MDOF displacement is calculated from the independent coordinate values of the diffracted ray spots on the PSDs. Forward and inverse kinematic problems were solved to compute the MDOF displacement of a rigid body. Experimental results show maximum absolute errors of less than ${\pm}10$ micrometers in translation and ${\pm}30$ arcsecs in rotation.

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Force per unit Displacement according to the Shape of a Clasp Arm and Flexibility of the Material (Clasp arm의 형상과 재료 탄성에 따른 단위 변위에 대한 힘)

  • Lim, Dong-Chun
    • The Journal of Korean Academy of Dental Technology
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    • v.23 no.2
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    • pp.171-177
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    • 2002
  • The purpose of this study is to evaluate force per unit displacements according to the shape of a clasp arm and flexibility of the material. Effect of four shape parameters of a clasp, base width and thickness and tip width and thickness, on tip displacement and force per unit displacement was investigated to get the fact that displacement and force per unit displacement at the tip increase as thickness and width of clasp arm increase just as expected. But force per unit displacement is much more affected by the change in thickness than by change in width. So it is effective to increase the thickness rather than width in order to increase the force at the tip using the same amount of the material.

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A Study of Micro Displacement Measurement of Micro System using the Laser Interferometer (레이저 간섭계를 이용한 마이크로 시스템의 미소변위 측정에 관한 연구)

  • Choi, Kyung-Hyun;Kim, Chang-Jong;Cho, Su-Jeong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.5 no.2
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    • pp.22-26
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    • 2006
  • This paper addresses the development of a laser interferometer to measure micro displacement for a micro system. The laser interferometer is able to measure micro displacement during a few micro seconds with non-contact. In order to employ the interferometer, the displacement calibration experiment should be required. For the experiment, a laser probe installed on the optical table with optical devices and a micro stage. The velocity decoding board is also added to calculate doppler shift frequency directly. The output signal is processed by LabView. Finally experiments are found out the relation between displacement and output signal.

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A Study on the Displacement Measuring Method of High-rise Buildingas using LiDAR (라이다를 이용한 고층 건물의 변위 계측 기법에 관한 연구)

  • Lee Hong-Min;Park Hyo-Seon
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.151-158
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    • 2006
  • Structural health monitoring is concerned with the safety and serviceability of the users of structures, especially for the case of building structures and infrastructures. When considering the safety of a structure, the maximum stress in a member due to live load, earthquake, wind, or other unexpected loadings must be checked not to exceed the stress specified in a code. It will not fail at yield, excessively large displacements will deteriorate the serviceability of a structure. To guarantee the safety and serviceability of structures, the maximum displacement in a structures must be monitored because actual displacement is a direct assessment index on its stiffness. However, no practical method has been reported to monitor the displacement, especially for the case of displacement of high-rise buildings because of not to easy accessive. In this paper, it is studied displacement measuring method of high-rise buildings using LiDAR The method is evaluated by analyzing accuracy of measured displacements for existing building.

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Case Study of Estimate the Response Displacement for the Seismic Design of Shaft Cable Tunnel (수직전력구 내진설계를 위한 응답변위 산정에 대한 사례 조사)

  • Kim, Yong-Min;Jeong, Sang-Seom;Kim, Young-Ho;Kwon, Young-Ki
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.634-639
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    • 2009
  • The response displacement method is the most frequently used method for the seismic design of underground structures. Underground structures under seismic loading will tend to deform with the surrounding ground, and thus the structure is designed to accommodate the free-field deformation without loss of its structural integrity. This method is pseudo-static method, and response displacement of surrounding ground are most important steps. In this study, the single cosine method and the equivalent linear analysis are applied to estimate the response displacement of the real sites, and the results of the each method are compared. Response analysis was also performed with respect to bedrock depth. As a results, Equivalent linear analysis result was larger than single cosine method. And, the relative displacement becomes lager according to depth of the bedrock.

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