• Journal of the Korean Society for Precision Engineering
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• 제29권8호
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• pp.906-912
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• 2012

This paper presents the new method for a six-degree-of-freedom (DOF) motion measurement and those dynamic characterizations in an ultraprecision linear stage using angle sensor-implemented grating interferometry. It consists of a diffractive optical element, a corner cube, four separate two-dimensional position sensitive detectors, four photodiodes and auxiliary optics components. From the previous study, it was confirmed that the proposed optical system could measure a six-DOF motion error in a linear stage. In this article, six-DOF motion dynamic characteristics of the stage were investigated through the step response and with respect to the conditions with a different speed of a slide table. As a result, the natural frequency and damping ratio according to a six-DOF direction was obtained. Also, it was seen that the speed of slide table had an significant effect on a six-DOF displacement motion, especially, X, which was considered as the effect of friction mechanism and local elastic mechanical deformation in a slide guide.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.325.2-325
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• 2002

A new methodology is presented for the multi-degree-of-freedom vibration absorber for an elastically suspended rigid body with the planes of symmetry in general motion. Unlike the common single degree-of-freedom vibration absorber, the presented methodology makes use of both linear and rotational properties of the absorber. It is suggested that an absorber is designed separately for the in-plane and out-of-plane axes of vibration and combined the two cases for a six-degree-of-freedom absorber. (omitted)

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1110-1115
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• 2004

Water covers two-thirds of the earth and has a great influence on the future existence of all human being. Thailand has extensive coastline and near shore water that contain vast biological and mineralogical resources. The rivers and canals can be found around the country especially in the Bangkok, which once called the Venice of the East. Autonomous underwater robot (AUR) will be soon a tool to help us better understand water resources and other environmental issues. This paper presents the design and basic control of a six-degree of freedom AUR "Chalawan", which was constructed to be used as a testbed for shallow. It is a simple low cost open-frame design, which can be modified easily to supports various research areas in the underwater environment. It was tested with a conventional proportional-integral-derivative (PID) controller. After fine-tuning of the controller gains, the results showed the controller's good performances. In the future, the dynamic model of the robot will be analyzed and identified. The advanced control algorithm will be implemented based on the obtained model.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.10-13
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• 1987

The main work of this paper are the manufacture of six degree of freedom industrial robot control hardware of 16 bit CPU and the development of five motion control software. The work would draw on KIT of Robotics Laboratory whose extensive experience in these areas; in particular the 68000 assembler and Modula-2 languages, and existing robot control systems. We found that this controller is good for the robot controller of PID types. But, for the use of self-tuning algorithms and real time calculations we need 32 bit CPU robot controller such as MC 68020 microprocessor.

• Journal of Institute of Control, Robotics and Systems
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• 제5권3호
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• pp.288-296
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• 1999

A force-reflecting hand controller can provide the kinesthetic information obtained from a slave manipulator to the operator of a teleoperation system. The goal is to construct a compact hand controller that can provide large workspace and good force-reflecting capability. This paper presents the design and the analysis of a 6-degree-of-freedom force-reflecting hand controller using fivebar parallel mechanism. The forward kinematics of the fivebar parallel mechanism has been calculated in real-time using three pin-joint sensors in addition to six actuator position sensors. A force decomposition approach is used to compute the Jacobian. To evaluate the characteristics of the fivebar parallel mechanism, it has been compared with the other three parallel mechanisms in terms with workspace and manipulability measure. The hand controller using the fivebar parallel mechanism has been constructed and tested to verify the feasibility of the design concept.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권4호
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• pp.320-329
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• 2016

An implicit method of solving the six degree-of-freedom rigid body motion equations based on the second order Adams-Bashforth-Moulten method was utilised as an improvement over the leapfrog scheme by making modifications to the rigid body motion solver libraries directly. The implementation will depend on predictor-corrector steps still residing within the hybrid Pressure Implicit with Splitting of Operators - Semi-Implicit Method for Pressure Linked Equations (PIMPLE) outer corrector loops to ensure strong coupling between fluid and motion. Aitken's under-relaxation is also introduced in this study to optimise the convergence rate and stability of the coupled solver. The resulting coupled solver ran on a free floating object tutorial test case when converged matches the original solver. It further allows a varying 70%-80% reduction in simulation times compared using a fixed under-relaxation to achieve the required stability.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제33권11호
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• pp.1347-1352
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• 2009

Magnetic force driven six degree-of-freedom active vibration isolation system is developed. The velocity sensor using an electromagnetic principle that is commonly used in the vibration control is investigated since its phase lead characteristic causes an instability problem for a low frequency vibration. A lag-type compensator is adopted to reduce the phase lead and the stability test is performed by using a Bode analysis. The performance of the AVIS is validated by comparing with the passive isolation system by using the frequency responses.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 한국방송∙미디어공학회 2021년도 추계학술대회
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• pp.189-192
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• 2021

three degree of freedom (3DoF), three degree of freedom plus (3DoF+), six degree of freedom(6DoF) 등 몰입형 비디오의 높은 몰입감을 제공하기 위해 다중 비디오 영상을 효율적으로 처리하는 기법이 활발히 연구되고 있다. 이를 위해 원본의 몰입형 비디오가 입력되면 기본 시점 영상과 추가 시점 영상에서의 중복을 제거하고 기본 시점(basic view)에서는 보이지 않지만 추가 시점(additional view)에서는 보이는 영역을 추출하는 프루닝 과정이 이뤄지는 부호기에서의 부호화 모드 결정은 매우 중요하다. 본 논문은 test model for immersive video (TMIV)의 모드 중 하나인 MPEG immersive video (MIV) view mode 를 통해 만들어진 프루닝 (pruning) 그래프에서 선택된 시점들을 활용하여 뷰 간 중복성을 제거할 수 있는 효율적인 부호화 구조로 클러스터를 기반으로 병렬적으로 부호화하는 클러스터 기반 정렬 기법을 제안한다. 선택된 시점들을 인덱스 순서에 따라 부호화하는 기존 방법에 비해 제안하는 방법은 peak signal-to-noise ratio (Y-PSNR)에서 평균 3.9%의 BD-rate 절감을 보여주었다. 본 연구는 또한 더 객관적인 품질 측정을 위해 immersive video peak signal-to-noise ratio (IV-PSNR)에 의한 비교 결과도 함께 제공하며, 참조 순서에 맞게 정렬한 프루닝 기반 정렬 기법과의 비교도 함께 제공한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.653-657
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• 1990

Since linearized equations of notion have much modelling errors, robust controller for disturbances and noises Is necessary for autopilot. In this paper, notion equations for underwater vehicle with six degree-of-freedom are derived and linearized. And robust autopilot for this system is designed by using LQG/LTR methodology.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.115-124
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• 2017

In this paper, a different technique to predict the effects of soil-structure interaction (SSI) on seismic response of building systems is investigated. The technique use a machine learning algorithm called Support Vector Regression (SVR) with technical and analytical results as input features. Normally, the effects of SSI on seismic response of existing building systems can be identified by different types of large data sets. Therefore, predicting and estimating the seismic response of building is a difficult task. It is possible to approximate a real valued function of the seismic response and make accurate investing choices regarding the design of building system and reduce the risk involved, by giving the right experimental and/or numerical data to a machine learning regression, such as SVR. The seismic response of both single-degree-of-freedom system and six-storey RC frame which can be represent of a broad range of existing structures, is estimated using proposed SVR model, while allowing flexibility of the soil-foundation system and SSI effects. The seismic response of both single-degree-of-freedom system and six-storey RC frame which can be represent of a broad range of existing structures, is estimated using proposed SVR model, while allowing flexibility of the soil-foundation system and SSI effects. The results show that the performance of the technique can be predicted by reducing the number of real data input features. Further, performance enhancement was achieved by optimizing the RBF kernel and SVR parameters through grid search.