• 한국정밀공학회지
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• 제16권7호
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• pp.119-124
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• 1999

A method to find the line of sight ray in space which corresponds to a point in an image plane is presented. The line of sight ray is defined by two points which are the intersections between the two calibration planes and the sight ray. The intersection point is found by the oblique coordinate mapping between the image plane and the calibration plane in the space. The proposed oblique coordinate mapping method has advantages over the transformation matrix method in the required memory space and computation time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.934-937
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• 2003

In this paper, authors use a stereo vision system based on the visual model of human and establish inexpensive method that recognizes moving distance using characteristic points around the robot. With the stereovision. the changes of the coordinate values of the characteristic points that are fixed around the robot are measured. Self-displacement and self-localization recognition system is proposed from coordination reconstruction with those changes. To evaluate the proposed system, several characteristic points that is made with a LED around the robot and two cheap USB PC cameras are used. The mobile robot measures the coordinate value of each characteristic point at its initial position. After moving, the robot measures the coordinate values of the characteristic points those are set at the initial position. The mobile robot compares the changes of these several coordinate values and converts transformation matrix from these coordinate changes. As a matrix of the amount and the direction of moving displacement of the mobile robot, the obtained transformation matrix represents self-displacement and self-localization by the environment.

• Journal of Power Electronics
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• 제18권5호
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• pp.1347-1356
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• 2018

In a three-phase system, three-phase AC signals can be translated into two-phase DC signals through a coordinate transformation. Thus, the PI regulator can realize a zero steady-state error for the DC signals. In the control of a three-phase grid-connected inverter, the phase angle of grid is normally detected by a phase-locked loop (PLL) and takes part in a coordinate transformation. A novel control strategy for a three-phase grid-connected inverter with a frequency-locked loop (FLL) based on coordinate transformation is proposed in this paper. The inverter is controlled as a current supply. The grid angle, which takes part in the coordinate transformation, is replaced by a periodic linear changing angle from $-{\pi}$ to ${\pi}$. The changing angle has the same frequency but a different phase than the grid angle. The frequency of the changing angle tracks the grid frequency by the negative feedback of the reactive power, which forms a FLL. The control strategy applies to non-ideal grids and it is a lot simpler than the control strategies with a PLL that are applied to non-ideal grids. The structure of the FLL is established. The principle and advantages of the proposed control strategy are discussed. The theoretical analysis is confirmed by experimental results.

• 한국측량학회지
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• 제27권2호
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• pp.281-288
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• 2009

수치지도를 최신의 데이터로 갱신하기 위한 방법론 중 건설도면을 이용하는 경우 CAD 데이터에서 필요한 객체를 추출하는 과정이 필요하다. 하지만 건설도면에 존재하는 가상좌표로 이루어진 연속객체를 활용하기 위해서는 선결조건으로 각 도면마다 분리되어진 객체를 접합하고 좌표를 부여하는 과정이 필요하다. 이를 위해서는 합리적으로 도면의 신축보정 및 축척 간 접합 등을 처리할 수 있는 기법의 개발과 CAD 좌표에서 실좌표로 변환하기 위한 방법론의 개발이 무엇보다 중요한 과정이라 할 수 있다. 본 연구는 SOC 건설 도면 중 준공도면으로 이루어진 도면 특히, 가상좌표계로 구성되어진 도로의 종평면도에 존재하는 객체들의 변환 및 활용을 위한 도면 간 접합을 2차원 등각사상변환방법과 부등각사상변환방법을 도입하여 수행하였다. 이를 위해, 도면간 이음선과 좌표경계선의 교차점을 접합점으로 하여 2차원 변환계수를 추출하고 이를 접합한 후 도면에 명시된 기준점을 이용 CAD좌표계에서 실좌표계로의 좌표변환방법을 시도하였다. 그 결과 도면접합에는 2차원 등각사상변환방법이 좋은 결과를 나타내었으며 실좌표계로의 변환은 2차원 부등각사상변환이 좋은 결과를 보여주었고, 변환 후 위치오차는 수치지도 작성내규를 만족하였다. 따라서 본 연구를 통하여 개발된 방법론은 추후 건설도면을 이용한 수치지도 갱신에 있어 활용가능성이 높을 것으로 기대된다.

• 전기전자학회논문지
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• 제24권4호
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• pp.954-960
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• 2020

본 논문은 단상 영구자석 동기전동기의 속도 가변형 비례공진 전류제어 기법을 제안한다. 단상 영구자석 동기전동기는 전자기적 특성상 고정자 전류와 역기전력의 위상차에 따른 부토크 및 영토크가 발생하며 센서리스 운전 시 낮은 고정자 저항과 인덕턴스로 인해 과전류 제한이 필요하다. 이러한 조건하에서 전류제어를 위해 3상 교류 전동기에 사용되는 벡터 제어를 이용할 경우, 좌표변환, 역좌표변환 및 가상의 dq축 성분을 생성하는 과정이 필요하다. 하지만, 단상 영구자석 동기전동기의 자기적 특성을 고려하여 제안한 속도 가변형 비례공진 전류제어 기법은 3상 교류 전동기에 사용되는 좌표변환 과정이 필요하지 않다. 본 논문에서는 가변 비례공진 전류제어 기법을 이용하여 안정적인 기동 성능을 확인하며 일정 속도 도달 시 위치 센서 없이 단상 영구자석 동기전동기의 수학적 모델 기반 센서리스 제어로 제안한 전류제어 기법의 효용성을 다수의 실험을 통해 검증하였다.

• 제어로봇시스템학회논문지
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• 제19권12호
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• pp.1145-1151
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• 2013

Kinematic modeling is a prerequisite for motion planning and the control of mobile robots. In this paper, we proposed a new method of kinematic modeling for a type of mobile robot based on differential motion transformation. The differential motion implies a small translation and rotation in three-dimensional space in a small time interval. Thus, transformation of the differential motion gives the velocity relationship, i.e., Jacobian between two coordinate frames. Since the theory of the differential motion transformation is well-developed, it is useful for the systematic velocity kinematic modeling of mobile robots. In order to show the validity for application of the differential motion transformation, we obtained velocity kinematic models for a type of exemplar mobile robot including spherical ballbots.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.285-286
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• 2002

The lubricating characteristics of negative pressure slider were performed by using divergence formulation method with the coordinate transformation method. This method makes it possible to deal with an arbitrary configuration of a lubricated surface. The pressure profile of the slider is calculated. These results are compared to that from direct numerical method. The steady-state, including minimum film thickness, pitching and rolling angle are calculated by multi-dimensional Newton-Rapson method. The stiffness and damping characteristics are also calculated.

• 한국멀티미디어학회논문지
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• 제17권7호
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• pp.806-817
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• 2014

The extraction of lip region is essential to Lip Reading, which is a field of image processing to get some meaningful information by the analysis of lip movement from human face image. Many conventional methods to extract lip region are proposed. One is getting the position of lip by using geometric face structure. The other discriminates lip and skin regions by using color information only. The former is more complex than the latter, however it can analyze black and white image also. The latter is very simple compared to the former, however it is very difficult to discriminate lip and skin regions because of close similarity between these two regions. And also, the accuracy is relatively low compared to the former. Conventional analysis of color coordinate systems are mostly based on specific extraction scheme for lip regions rather than coordinate system itself. In this paper, the method for selection of effective color coordinate system and chromaticity transformation to discriminate these two lip and skin region are proposed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.629-632
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• 1999

In this paper, color coordinate system transformation based visual servo controller has been considered. Mobile robot always has a position error and an orientation error resulted from wheel slipping etc.. Even more, the errors have accumulative properties. So feedback from environments is important. In this paper, by using color model faster land mark extraction can be achieved. And the global position and the orientation of mobile robot can be known by only two land marks positions in image coordinate system. Finally, the adoption of visual information in path tracking problem makes visual servo control.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.591-595
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• 2000

In this paper color coordinate system transformation based visual servo controller has been considered Mobile robot always has a position error and an orientation error resulted from wheel slipping etc.. Even more, the errors have accumulative properties. So feedback from environments is important. In this paper by using color model faster land mark extraction can be achieved. And the global position and the orientation of mobile robot can be known by only two land mark positions in image coordinate system. Finally, the adoption of visual information in path tracking problem makes visual servo control.