• 한국항해항만학회지
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• 제40권5호
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• pp.241-247
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• 2016

The tracking filter plays a key role in the accurate estimation and prediction of maneuvering a vessel's position and velocity when attempting to enhance safety by avoiding collision. Therefore, in order to achieve accurate estimation and prediction, many oceangoing vessels are equipped with the Automatic Radar Plotting Aid (ARPA) system. However, the accuracy of prediction depends on the tracking filter's ability to reduce noise and maintain a stable transient response. The purpose of this paper is to derive the optimal values of the gain parameters used in tracking a High Dynamic Warship. The algorithm employs a ${\alpha}-{\beta}-{\gamma}$ filter to provide accurate estimates and updates of the state variables, that is, positions, velocity and acceleration of the high dynamic warship based on previously observed values. In this study, the filtering coefficients ${\alpha}$, ${\beta}$ and ${\gamma}$ are determined from set values of the damping parameter, ${\xi}$. Optimization of the damping parameter, ${\xi}$, is achieved experimentally by plotting the residual error against different values of the damping parameter to determine the least value of the damping parameter that results in the optimum smoothing coefficients leading to a reduction in the noise corruption effect. Further investigation of the performance of the filter indicates that optimal smoothing coefficients depend on the initial and average velocity of the target.

• 수산해양기술연구
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• 제44권3호
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• pp.229-238
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• 2008

This paper describes on the consolidation of AIS and ARPA radar positions by comparing the AIS and ARPA radar information for the tracked ship targets using a PC-based ECDIS in Busan harbor, Korea. The information of AIS and ARPA radar target was acquired independently, and the tracking parameters such as ship's position, COG, SOG, gyro heading, rate of turn, CPA, TCPA, ship s name and MMSI etc. were displayed automatically on the chart of a PC-based ECDIS with radar overlay and ARPA tracking. The ARPA tracking information obtained from the observed radar images of the target ship was compared with the AIS information received from the same vessel to investigate the difference in the position and movement behavior between AIS and ARPA tracked target ships. For the ARPA radar and AIS targets to be consolidated, the differences in range, speed, course, bearing and distance between their targets were estimated to obtain a clear standards for the consolidation of ARPA radar and AIS targets. The average differences between their ranges, their speeds and their courses were 2.06% of the average range, -0.11 knots with the averaged SOG of 11.62 knots, and $0.02^{\circ}$ with the averaged COG of $37.2^{\circ}$, respectively. The average differences between their bearings and between their positions were $-1.29^{\circ}$ and 68.8m, respectively. From these results, we concluded that if the ROT, COG, SOG, and HDG informations are correct, the AIS system can be improved the prediction of a target ship's path and the OOW(Officer of Watch) s ability to anticipate a traffic situation more accurately.

• 수산해양기술연구
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• 제45권3호
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• pp.177-187
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• 2009

This paper describes a automatic video surveillance system(AVSS) with long range and 360$^{\circ}$ coverage that is automatically rotated in an elevation over azimuth mode in response to the TTM(tracked target message) signal of vessels tracked by ARPA(automatic radar plotting aids) radar. This AVSS that is a video security and tracking system supported by ARPA radar, CCTV(closed-circuit television) camera system and other sensors to automatically identify and track, detect the potential dangerous situations such as collision accidents at sea and berthing/deberthing accidents in harbor, can be used in monitoring the illegal fishing vessels in inshore and offshore fishing ground, and in more improving the security and safety of domestic fishing vessels in EEZ(exclusive economic zone) area. The movement of the target vessel chosen by the ARPA radar operator in the AVSS can be automatically tracked by a CCTV camera system interfaced to the ECDIS(electronic chart display and information system) with the special functions such as graphic presentation of CCTV image, camera position, camera azimuth and angle of view on the ENC, automatic and manual controls of pan and tilt angles for CCTV system, and the capability that can replay and record continuously all information of a selected target. The test results showed that the AVSS developed experimentally in this study can be used as an extra navigation aid for the operator on the bridge under the confusing traffic situations, to improve the detection efficiency of small targets in sea clutter, to enhance greatly an operator s ability to identify visually vessels tracked by ARPA radar and to provide a recorded history for reference or evidentiary purposes in EEZ area.

• 수산해양기술연구
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• 제45권3호
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• pp.165-176
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• 2009

The process of berthing/deberthing operations for entering/leaving vessels in Busan northern harbor was analyzed and evaluated by using an integrated VTS(vessel traffic service) system installed in the ship training center of Pukyong National University, Busan, Korea. The integrated VTS system used in this study was consisted of ARPA radar, ECDIS(electronic chart display and information system), backup(recording) system, CCTV(closed-circuit television) camera system, gyro-compass, differential GPS receiver, anemometer, AIS(automatic identification system), VHF(very high frequency) communication system, etc. The network of these systems was designed to communicate with each other automatically and to exchange the critical information about the course, speed, position and intended routes of other traffic vessels in the navigational channel and Busan northern harbor. To evaluate quantitatively the overall dynamic situation such as maneuvering motions for target vessel and its tugboats while in transit to and from the berth structure inside a harbor, all traffic information in Busan northern harbor was automatically acquired, displayed, evaluated and recorded. The results obtained in this study suggest that the real-time tracking information of traffic vessels acquired by using an integrated VTS system can be used as a useful reference data in evaluating and analyzing exactly the dynamic situation such as the collision between ship and berth structure, in the process of berthing/deberthing operations for entering/leaving vessels in the confined waters and harbor.

• 대한기계학회논문집A
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• 제36권10호
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• pp.1171-1179
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• 2012

본 논문에서는 선박운동제어를 위한 제어시스템 설계문제에 대해 고찰한다. 특히 강인한 추종성능을 가진 2자유도 서보계 설계법을 이용하여 선박의 위치 및 자세제어를 위한 제어기를 설계하고, 실험 등의 실제적인 제어시스템 구축시 센서로부터 모든 정보를 획득할 수 없으므로 이에 필요한 상태를 추정하기 위한 관측기 설계 문제에 대해 고려하고 있다. 그래서 본 논문에서는 실제 상태정보와 추정된 상태정보와의 오차를 최소화하도록 $H_{\infty}$ 오차 바운드를 설정하는 기법으로 관측기의 이득을 구한다. 특히 $H_{\infty}$ 오차 바운드를 만족하는 관측기가 존재하기 위한 조건을 LMI형식으로 변환하여 표현함으로써 관측기 이득 계산을 효율적으로 수행하여 최적의 이득을 구할 수 있음을 보이고 시뮬레이션을 통해 그 유용성을 확인한다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제36권12호
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• pp.967-976
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• 2009

본 논문에서는 CT 및 CT 혈관 조영 영상에서 강체 정합 및 뼈 소거법을 이용한 하지 혈관 자동 추출 방법을 제안한다. 첫째, 뼈의 부분적인 움직임을 반영하기 위하여 해부학 정보를 바탕으로 하지를 자동 구역화하고, 둘째, CT와 CTA 영상간 움직임을 산정하기 위하여 거리지도 기반의 강체 정합을 수행한다. 셋째, CTA 영상에서 복잡한 구조를 갖는 뼈를 제거하고 뼈에 인접한 혈관이 깎이는 것을 방지하기 위하여 뼈 소거법과 혈관 마스킹 기법을 제안한다. 넷째, 정합오차 및 연골 등의 잡음을 줄이기 위하여 혈관 추적 기반의 후 처리 과정을 통하여 보정한다. 제안 방법의 평가를 위해 육안 평가와 정확성 평가 그리고 수행시간을 측정하였다. 육안 평가를 위해 차감 기법, 정합 후 차감 기법, 제안 방법을 적용한 결과를 볼륨렌더링과 최대 강도 투영영상을 사용하여 비교하였다. 정확성 평가를 위해 CTA 영상과 차감 기반 기법 및 제안 방법을 적용한 결과의 밝기값 분포도를 분석하였다. 실험 결과 뼈는 제거되고 가는 혈관 및 다른 조직의 손실 없이 혈관이 정확하게 추출되었음을 볼 수 있었고, 13명의 환자 데이터 전채에 대한 전체 수행시간은 약 40포 정도로 측정되었다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.273-277
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• 2005

본 논문에서는 양식어장을 보호하기 위한 어장 탐지 시스템에 있어서 칼만필터의 적용기법에 대해 논의하였다. 어장탐지시스템(FDS)은 어장에 침입하는 도전선박을 실시간으로 식별하고 어장의 위치변동 등을 파악하고자 하는 것이다. 본 연구에서는 양식어장으로의 접근 물체 중에서 F-AIS를 탑재하지 않은 의심선박에 대해 추적(tracking)을 하기 위해 칼만필터 기법을 적용하고자 한다. 백색잡음을 동반한 가속도계의 대상물에 대하여 위치 및 속도판독을 위한 시뮬레이션을 행하고 트랙킹 시스템으로의 적용 가능성에 대해 살펴본다.

• 한국항해항만학회지
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• 제41권5호
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• pp.297-302
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• 2017

The tracking filter plays a key role in accurate estimation and prediction of maneuvering the vessel's position and velocity. Different methods are used for tracking. However, the most commonly used method is the Kalman filter and its modifications. The ${\alpha}-{\beta}-{\gamma}$ filter is one of the special cases of the general solution provided by the Kalman filter. It is a third order filter that computes the smoothed estimates of position, velocity, and acceleration for the nth observation, and predicts the next position and velocity. Although found to track a maneuvering target with good accuracy than the constant velocity ${\alpha}-{\beta}$ filter, the ${\alpha}-{\beta}-{\gamma}$ filter does not perform impressively under high maneuvers, such as when the target is undergoing changing accelerations. This study aims to track a highly maneuvering target experiencing jerky motions due to changing accelerations. The ${\alpha}-{\beta}-{\gamma}$ filter is extended to include the fourth state that is, constant jerk to correct the sudden change of acceleration to improve the filter's performance. Results obtained from simulations of the input model of the target dynamics under consideration indicate an improvement in performance of the jerky model, ${\alpha}-{\beta}-{\gamma}-{\eta}$ algorithm as compared to the constant acceleration model, ${\alpha}-{\beta}-{\gamma}$ in terms of error reduction and stability of the filter during target maneuver.

• Journal of Power Electronics
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• 제18권1호
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• pp.251-265
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• 2018

To enable a master-slave control independent microgrid system (MSCIMGS) to supply electricity continuously, the microgrid inverter should perform mode transfer between grid-connected and islanding operations. Transient oscillations should be reduced during transfer to effectively conduct a seamless mode transfer. This study uses a typical MSCIMGS as an example and improves the mode transfer strategy in three aspects: (1) adopts a status-tracking algorithm to improve the switching strategy of the outer loop, (2) uses the voltage magnitude and phase pre-synchronization algorithm to reduce transient shock at the time of grid connection, and (3) applies the hybrid-sensitivity $H_{\infty}$ robust controller instead of the current inner loop to improve the robustness of the controller. Simulations and experiments show that the proposed strategy is more practical than the traditional proportional-derivative control mode transfer and effective in reducing voltage and current oscillations during the transfer period.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.314-324
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• 2020

Due to the nonlinearity and environmental uncertainties, the design of the ship's steering controller is a long-term challenge. The purpose of this study is to design an intelligent autopilot based on Extended Kalman Filter (EKF) trained Radial Basis Function Neural Network (RBFNN) control algorithm. The newly developed free running model scaled surface vessel was employed to execute the motion control experiments. After describing the design of the EKF trained RBFNN autopilot, the performances of the proposed control system were investigated by conducting experiments using the physical model on lake and simulations using the corresponding mathematical model. The results demonstrate that the developed control system is feasible to be used for the ship's motion control in the presences of environmental disturbances. Moreover, in comparison with the Back-Propagation (BP) neural networks and Proportional-Derivative (PD) based control methods, the EKF RBFNN based control method shows better performance regarding course keeping and trajectory tracking.