• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2004년도 International Conference on Digital Policy & Management
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• pp.185-202
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• 2004

Recent development in wireless computing and GPS technology cause the active development in the application system of location information in real-time environment such as transportation vehicle management, air traffic control and location based system. Especially, study about vehicle location tracking system, which monitors the vehicle's position in a control center, is appeared to be a representative application system. However, the current vehicle location tracking system can not provide vehicle position information that is not stored in a database at a specific time to users. We designed a vehicle location tracking system that could track vehicle location using mobile interface such as PDA. The proposed system consist of a vehicle location retrieving server and a mobile interface. It is provide not only the moving vehicle's current location but also the position at a past and future time which is not stored in database for users.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1122-1123
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• 2008

This paper proposes a the high efficiency tracking system regarding power loss when operating a tracking system for environment variable such as a rapidly changing insolation and shadow effect to improve the power of PV tracking system. To reduce the power loss, this paper proposes a novel control algorithm of the tracking system. And paper suggests a method controlling an altitude for length which is received the shadow influence of PV array. The paper is analyzed efficiency about conventional PV tracking method, comparing proposed algorithm with high performance method.

• 대한전자공학회논문지SP
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• 제41권5호
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• pp.1-11
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• 2004

본 논문에서는 비정형 객체를 능동형태 모델을 사용하여 실시간으로 추적하기 위한 방법을 제시하였다. 객체를 추적 할 때, 가려진 부분의 윤곽을 추정해 낼 수 있는 능동형태 모델을 사용하였으며, 비디오의 각 프레임에서 처리과정의 시간을 줄이기 위해서 영상을 계층적으로 분리하여 실시간 처리를 가능하게 하였다 또한 다음 입력영상의 초기 윤곽을 효율적으로 찾기 위해서 칼만필터(Kalman filter)를 사용하여 특징점을 예측하였고, 블록 정합(block matching) 기법을 추가하여 예측 안정성을 향상시켰다. 비 계층적 방법, 비 예측 방법 등과 비교 실험을 통해서 제안된 계층적, 예측형 방식이 수렴속도 증가와 모델링의 정확도에서 모두 개선된 효과를 얻을 수 있음을 확인하였다.

• International Journal of Control, Automation, and Systems
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• 제1권4호
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• pp.495-502
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• 2003

This paper focuses on the implementation of an efficient tracking method of a moving object using optimal representative blocks by way of a pan-tilt camera. The key idea is derived from the fact that when the image size of a moving object is shrunk in an image frame according to the distance between the mobile robot camera and the object in motion, the tracking performance of a moving object can be improved by reducing the size of representative blocks according to the object image size. Motion estimations using Edge Detection (ED) and Block-Matching Algorithm (BMA) are regularly employed to track objects by vision sensors. However, these methods often neglect the real-time vision data since these schemes suffer from heavy computational load. In this paper, a representative block able to significantly reduce the amount of data to be computed, is defined and optimized by changing the size of representative blocks according to the size of the object in the image frame in order to improve tracking performance. The proposed algorithm is verified experimentally by using a two degree-of- freedom active camera mounted on a mobile robot.

• 제어로봇시스템학회논문지
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• 제13권7호
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• pp.711-717
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• 2007

Location information will become increasingly important for future Pervasive Computing applications. Location tracking system of a moving device can be classified into two types of architectures: an active mobile architecture and a passive mobile architecture. In the former, a mobile device actively transmits signals for estimating distances to listeners. In the latter, a mobile device listens signals from beacons passively. Although the passive architecture such as Cricket location system is inexpensive, easy to set up, and safe, it is less precise than the active one. In this paper, we present a passive location system using Cricket Mote sensors which use RF and ultrasonic signals to estimate distances. In order to improve accuracy of the passive system, the transmission speed of ultrasound was compensated according to air temperature at the moment. Upper and lower bounds of a distance estimation were set up through measuring minimum and maximum distances that ultrasonic signal can reach to. Distance estimations beyond the upper and the lower bounds were filtered off as errors in our scheme. With collecting distance estimation data at various locations and comparing each distance estimation with real distance respectively, we proposed an equation to compensate the deviation at each point. Equations for proposed algorithm were derived to calculate relative coordinates of a moving device. At indoor and outdoor tests, average location error and average location tracking period were 3.5 cm and 0.5 second, respectively, which outperformed Cricket location system of MIT.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권6호
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• pp.1166-1191
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• 2011

This paper presents an adaptive active tracking system with sector based scanning for a single PTZ camera. Dividing sectors on an image reduces the search space to shorten selection time so that the system can cover many targets. Upon the selection of a target, the system estimates the target trajectory to predict the zooming location with a finite amount of time for camera movement. Advanced estimation techniques using probabilistic reason suffer from the unknown object dynamics and the inaccurate estimation compromises the zooming level to prevent tracking failure. The proposed system uses the simple piecewise estimation with a few frames to cope with fast moving objects and/or slow camera movements. The target is tracked in multiple steps and the zooming time for each step is determined by maximizing the zooming level within the expected variation of object velocity and detection. The number of zooming steps is adaptively determined according to target speed. In addition, the iterative estimation of a zooming location with camera movement time compensates for the target prediction error due to the difference between speeds of a target and a camera. The effectiveness of the proposed method is validated by simulations and real time experiments.

• International Journal of Precision Engineering and Manufacturing
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• 제5권1호
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• pp.27-35
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• 2004

In the field of machine vision using a single camera mounted on a mobile robot, although the detection and tracking of moving objects from a moving observer, is complex and computationally demanding task. In this paper, we propose a new scheme for a mobile robot to track and capture a moving object using images of a camera. The system consists of the following modules: data acquisition, feature extraction and visual tracking, and trajectory generation. And a single camera is used as visual sensors to capture image sequences of a moving object. The moving object is assumed to be a point-object and projected onto an image plane to form a geometrical constraint equation that provides position data of the object based on the kinematics of the active camera. Uncertainties in the position estimation caused by the point-object assumption are compensated using the Kalman filter. To generate the shortest time trajectory to capture the moving object, the linear and angular velocities are estimated and utilized. The experimental results of tracking and capturing of the target object with the mobile robot are presented.

• 한국통신학회논문지
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• 제29권11C호
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• pp.1551-1563
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• 2004

여기는 본 논문에서는 움직이는 물체 추적을 위한 윤곽선 및 형태 파라미터 추출을 위해 웨이블릿 변환을 이용한 능동형태모델의 계층적인 접근방법에 대해 제안한다. 능동형태 모델의 여러 단계 중 지역구조 모델링은 비정형 객체의 형태를 추출하기 위해 가장 중요한 비중을 차지한다. 제안한 알고리듬은 웨이블릿을 이용하여 계층적인 접근은 물론 지역구조 모델링단계를 웨이블릿 대역 분할을 이용하여 복잡한 환경에서의 객체를 강건하게 추적할 수 있도록 하였다. 또한 비정형객체를 실시간 비디오 추적에 이용하기 위해 웨이블릿을 이용한 계층적 움직임 추정방법을 적용하여 객체의 움직임을 예측, 보정하는 효과적인 방법을 제시하였다. 제안하는 알고리듬은 객체 추적에 대한 성능을 평가하기 위해 다양한 실험영상을 통해 우수함을 확인하였다.

• Journal of Astronomy and Space Sciences
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• 제30권4호
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• pp.279-290
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• 2013

Due to the continuous space development by mankind, the number of space objects including space debris in orbits around the Earth has increased, and accordingly, difficulties of space development and activities are expected in the near future. In this study, among the stages for space debris removal, the implementation of a vision-based approach technique for approaching space debris from a far-range rendezvous state to a proximity state, and the ground test performance results were described. For the vision-based object tracking, the CAM-shift algorithm with high speed and strong performance, and the Kalman filter were combined and utilized. For measuring the distance to a tracking object, a stereo camera was used. For the construction of a low-cost space environment simulation test bed, a sun simulator was used, and in the case of the platform for approaching, a two-dimensional mobile robot was used. The tracking status was examined while changing the position of the sun simulator, and the results indicated that the CAM-shift showed a tracking rate of about 87% and the relative distance could be measured down to 0.9 m. In addition, considerations for future space environment simulation tests were proposed.

• 한국정보통신학회논문지
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• 제8권3호
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• pp.694-701
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• 2004

본 논문에서는 능동카메라 환경에서 카메라의 움직임에 의해 유발되는 광역움직임(global motion)과 이동물체에 의해 발생하는 지역움직임(local motion)을 분리한 후, 카메라 팬틸트를 제어하여 물체를 추적하는 특징기반의 추적 시스템을 제안했다. 제안한 시스템은 블록기반 움직임 계측을 통해 연속한 2 프레임 사이의 이동 움직임을 찾고, 이 움직임에서 카메라의 움직임으로 인한 광역 움직임을 제거함으로써 전경물체의 지역 움직임만을 추적한다. 이때, 배경만의 움직임만으로 카메라 움직임을 강건하게 계측하기 위하여, 블록기반 움직임에서 배경움직임을 분류하기 위한 지배적인 움직임 추출방법을 제시한다. 또한 분리된 지역움직임으로부터 잡음물체의 움직임을 제거하기 위하여 꼭지점 특징의 추적궤적 속성에 따른 군집화 알고리즘을 제안한다. 제안한 추적시스템은 여러가지 실험에서 좋은 결과를 보였다.