• Journal of Power Electronics
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• 제8권3호
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• pp.268-274
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• 2008

This paper presents a proposed position controller for a vector controlled induction motor. The position controller design depends on the rotational motion equations and a classical speed controller (CSC) performance. The CSC is designed to have the ability to track variable reference inputs and to provide a predefined system performance. Standard position controller in industry is presented to analyze its performance and its drawbacks. Then the proposed position controller is designed, based on the well defined rotational motion equations. The proposed position controller and the CSC are applied to control the position and speed of the vector controlled induction motor with different ratings. Simulation results at different operating conditions are presented to evaluate the proposed controllers' performance. The results show that the CSC can drive the motor with a predefined speed performance and can track a variable reference speed with an approximately zero steady state error. The results also show that the proposed position controller has the ability to effect high-precision positioning in a limited time and to track a variable reference position with a zero steady state error.

• 로봇학회논문지
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• 제11권3호
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• pp.127-132
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• 2016

For a practical mobile robot team such as carrying out a search and rescue mission in a disaster area, the localization have to be guaranteed even in an environment where the network infrastructure is destroyed or a global positioning system (GPS) is unavailable. The proposed architecture supports localizing robots seamlessly by finding their relative locations while moving from a global outdoor environment to a local indoor position. The proposed schemes use a cooperative positioning system (CPS) based on the two-way ranging (TWR) technique. In the proposed TWR-based CPS, each non-localized mobile robot act as tag, and finds its position using bilateral range measurements of all localized mobile robots. The localized mobile robots act as anchors, and support the localization of mobile robots in the GPS-shadow region such as an indoor environment. As a tag localizes its position with anchors, the position error of the anchor propagates to the tag, and the position error of the tag accumulates the position errors of the anchor. To minimize the effect of error propagation, this paper suggests the new scheme of full-mesh based CPS for improving the position accuracy. The proposed schemes assuring localization were validated through experiment results.

• 한국산학기술학회논문지
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• 제7권2호
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• pp.213-218
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• 2006

본 논문에서는 자동차 에드혹망에서의 위치기반 라우팅 프로토콜과 비위치기반 라우팅 프로토콜의 성능을 비교하고 분석하였다. 여러 가지 성능평가 요소로 분석되어진 프로토콜들은 위치기반 라우팅 프로토콜의 GPSR (Greedy Perimeter Stateless Routing)과 비위치기반 라우팅 프로토콜의 AODV (Ad-hoc On-Demand Distance Vector)과 DSR (Dynamic Source Routing) 프로토콜들이다. 패킷 전송율, 접속시 첫 번째 패킷의 지연, 그리고 거리에 따른 평균 홉수의 3가지 프로토콜 특성들을 비교하였다. 시뮬레이션의 결과로 AODV는 DSR 보다 우수한 성능을 보였다. 그러나, 자동차 에드혹망의 높은 이동성 때문에 위치기반 라우팅 프로토콜인 GPSR이 AODV와 DSR과 같은 비위치기반 라우팅 프로토콜들보다 우수한 성능을 보여주었다.

• 로봇학회논문지
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• 제2권2호
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• pp.129-136
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• 2007

This paper introduces a position-based robust visual servoing method which is developed for operation of a human-like robot with two arms. The proposed visual servoing method utilizes SIFT algorithm for object detection and CAMSHIFT algorithm for object tracking. While the conventional CAMSHIFT has been used mainly for object tracking in a 2D image plane, we extend its usage for object tracking in 3D space, by combining the results of CAMSHIFT for two image plane of a stereo camera. This approach shows a robust and dependable result. Once the robot's task is defined based on the extracted 3D information, the robot is commanded to carry out the task. We conduct several position-based visual servoing tasks and compare performances under different conditions. The results show that the proposed visual tracking algorithm is simple but very effective for position-based visual servoing.

• Journal of Information Processing Systems
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• 제18권5호
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• pp.614-627
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• 2022

Aspect-based sentiment analysis is to discover the sentiment polarity towards an aspect from user-generated natural language. So far, most of the methods only use the implicit position information of the aspect in the context, instead of directly utilizing the position relationship between the aspect and the sentiment terms. In fact, neighboring words of the aspect terms should be given more attention than other words in the context. This paper studies the influence of different position embedding methods on the sentimental polarities of given aspects, and proposes a position embedding interactive attention network based on a long short-term memory network. Firstly, it uses the position information of the context simultaneously in the input layer and the attention layer. Secondly, it mines the importance of different context words for the aspect with the interactive attention mechanism. Finally, it generates a valid representation of the aspect and the context for sentiment classification. The model which has been posed was evaluated on the datasets of the Semantic Evaluation 2014. Compared with other baseline models, the accuracy of our model increases by about 2% on the restaurant dataset and 1% on the laptop dataset.

• 한국항해항만학회지
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• 제38권2호
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• pp.89-96
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• 2014

This paper presents an improvement for calculating method of astronomical ship position based on circle of equal altitude equation. In addition, to enhance the accuracy of ship position achieved from solving equation system, the authors used singular value decomposition (SVD) in least square method instead of normal decomposition. In maths, the SVD was proved more numerically stable than normal decomposition. Therefore, the solution of equation system will be more efficient and the result would be more accurate than previous methods. By proposal algorithm, a computer program have been developed to help the navigators in calculating directly ship position when the modern equipment has failure. Finally, some of experiments are carried out to verify effectiveness of proposed algorithm, the results show that the accuracy of ship position based on new method is better than the intercept method.

• 한국정보과학회논문지:데이타베이스
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• 제34권4호
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• pp.343-356
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• 2007

센서 네트워크, 위치 기반 서비스 등의 기술 발전에 따라, 최근의 이동객체 위치정보는 연속적이고 끊임없이 변경되는 스트림 데이타 형태를 가지게 되었다. 본 논문에서는 이와 같이 스트림 형태로 발생하는 이동객체의 위치정보를 제한된 메모리에 저장하고, 과거 위치를 추정하는 효율적인 방법을 제안한다. 이를 위하여, 우선 제한된 메모리 양으로 지속적으로 추가되는 이동객체의 과거 위치 이력을 저장하기 위한 위치정보의 점진적 추출(incremental extraction) 개념을 제시한다. 점진적 추출이란 새로운 위치정보가 추가될 때마다, 시스템이 관리해야 할 과거 위치정보를 기존 위치정보와 새로운 위치정보를 바탕으로 점진적으로 추출하는 방법을 의미한다. 그런 다음, 이러한 점진적 추출 개념을 적용하여 스트림 환경에서 위치정보를 저장 및 추정하는 전체적인 프레임워크를 제시한다. 그리고, 제안한 프레임워크 하에서 추정위치를 계산하는 방법으로 다항식을 이용한 직선기반과 곡선기반 방법을 제시한다. 다음으로, 점진적 추출 개념을 사용하여 과거 위치를 추출하는 방법으로 균등 간격 추출, 기울기 기반 추출. 그리고 최근 시점강조 추출의 세 가지 방법을 제시한다. 실험 결과, 제안한 점진적 추출 방법은 적은 비율(0.1%)의 위치정보를 저장함에도 불구하고 과거 위치추정에 있어 비교적 높은 정확도(오차율 3% 이내)를 나타냈다. 특히, 곡선기반의 점진적 추출 방법은 전체 위치 데이타의 0.1% 만을 저장하면서도 오차율 1.5% 미만의 높은 정확도를 나타내었다. 이러한 결과로 볼 때, 제안한 방법은 스트림 환경에서 이동객체의 위치정보를 저장하고, 과거 위치를 추정하는 우수한 연구결과라 사료된다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.340-342
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• 2003

Location based services based on positions of moving objects are expanding the business area gradually. The location is included all estimate position of the future as well as the position of the present and the past. Location based routing service is active business application in which the position information of moving objects is applied efficiently. This service includes the trajectory of past positions, the real-time tracing of present position of special moving objects, and the shortest and optimized paths combined with map information. In this paper, we describes the location based routing services is extend in distributed web GIS environment. Web GIS service systems provide the various GIS services of analyzing and displaying the spatial data with friendly user - interface. That is, we propose the efficient architecture and technologies for servicing the location based routing services in distributed web GIS environment. The position of moving objects is acquired by GPS (Global Positioning System) and converted the coordinate of real world by map matching with geometric information. We suppose the swapping method between main memory and storages to access the quite a number of moving objects. And, the result of location based routing services is wrapped the web-styled data format. We design the schema based on the GML. We design these services as components were developed in object-oriented computing environment, and provide the interoperability, language-independent, easy developing environment as well as re - usability.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.253-256
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• 1997

This paper proposes a control strategy of position and force control in the same direction based on hybrid position/force control. In order to control position and force in the same direction, a weighting matrix is introduced instead of a selection matrix suggested by Raibert and Craig. The major part of the controller output comes from the position controller when a position control error is large, from the force controller when a position control error is large. The proposed algorithm is implemented by the simulation and experiment focusing on the peg-in-hole task where friction exist significantly and is not constant. It also adopts and event control scheme for more efficient performance.

• Journal of Positioning, Navigation, and Timing
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• 제11권1호
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• pp.35-44
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• 2022

In this paper, a dual foot (DF)-PDR system is proposed for the fusion of integration (IA)-based PDR systems independently applied on both shoes. The horizontal positions of the two shoes estimated from each PDR system are fused based on a particle filter. The proposed method bounds the position error even if the walking time increases without an additional sensor. The distribution of particles is a non-Gaussian distribution to express the lateral error due to systematic drift. Assuming that the shoe position is the pedestrian position, the multi-modal position distribution can be fused into one using the Gaussian sum. The fused pedestrian position is used as a measurement of each particle filter so that the position error is corrected. As a result, experimental results show that position of pedestrians can be effectively estimated by using only the inertial sensors attached to both shoes.