http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Development of a flap-type mooring-less wave energy harvesting system for sensor buoy
Joe, Hangil,Roh, Hyunwoo,Cho, Hyeonwoo,Yu, Son-Cheol Elsevier 2017 ENERGY Vol.133 No.-
<P><B>Abstract</B></P> <P>To reduce deployment and maintenance costs, a novel wave energy converter (WEC) is proposed for mooring-less sensor buoys. The design concept is based on a small size WEC capable of harvesting wave energy without mooring, which can reduce the installation cost. The proposed wave energy converter consists of a submerged and a floating body, and the submerged body is a self-rectifying wave-induced turbine that uses the rise and fall of waves to turn a rotor. The rotor of the turbine has flap-type blades, which allows a self-rectifying rotation with rising and falling of waves. In this paper, the dynamics of the system is modeled by hydrodynamic equations, and simulations are carried out based on the dynamic model to determine the optimal design parameters of the system. In addition, the power generation in regular and irregular wave conditions and efficiency in irregular waves of the system are estimated. To verify the results of the simulation, a prototype of the system is implemented and tested in a sea trial. The results demonstrate the feasibility of the proposed wave energy converter.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A flap-type mooring-less wave energy converting system is proposed. </LI> <LI> Hydrodynamic model of the proposed system and the results of a series of simulations are presented. </LI> <LI> Optimal design parameters and theoretical power generation are presented. </LI> <LI> Indoor tank test is conducted to verify the simulation results, and field feasibility is verified in sea trial. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
3D Reconstruction Using Two Sonar Devices in a Monte-Carlo Approach for AUV Application
Hangil Joe,Jason Kim,Son-Cheol Yu 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.3
We propose a sequential method to extract 3-dimensional information for mapping by using sensor fusion of two sonar devices. The 3D reconstruction using sonar images from forward-looking multibeam sonar (FLMS) is an ill-posed problem due to the loss of elevation angle; thus we used an additional sonar and its complementary information. Our approach is to utilize geometric constraints between the installation of two sonar devices and complementary characteristics such as a different angle of the acoustic beams and data acquisition method. The fusion process proceeds in three stages. The first stage is to build a likelihood map using geometric constraints of the installation between two sonar devices. The second stage is to calculate the feasible elevation angle of the FLMS. The elevation angle of FLMS is limited by its vertical beam spreading angle, which can be represented by particles. The third stage is Monte-Carlo experiment using the generated particles by computing the weight, and correct the data of FLMS. To verify the proposed method, we applied the proposed method in simulations and experiments in engineering basin with an AUV.
웨이브 글라이더 메커니즘을 이용한 이동형 파력발전 시스템의 성능 테스트와 최적 설계에 관한 연구
조한길(Hangil Joe),유선철(Son-Cheol Yu) 한국해양공학회 2018 韓國海洋工學會誌 Vol.32 No.5
This paper reports a novel mobile-type wave energy harvesting system. The proposed system adopts a wave glider’s propulsion mechanism. A wave glider’s blades were mounted on a circular layout and generated a rotational motion. Combining the wave converting system with the wave glider, a mobile floating-type robotic buoy system was developed. It enabled the relocation of the buoy position, as well as station-keeping for long term operation. It had a small size and could efficiently harvest wave energy. A feasibility study and modeling were carried out, and a prototype system was constructed. Various tank tests were performed to optimize the proposed wave energy harvesting system.
Byeongjin Kim,Hangil Joe,Son-Cheol Yu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.9
This study proposes a method for generating a high-precision three-dimensional (3D) map using twodimensional (2D) sonar images from an imaging sonar installed on an autonomous underwater vehicle (AUV). The 2D sonar image sequence was analyzed pairwise to estimate the amount of displacement and used to create a 2D mosaic sonar image. The mosaic sonar map contains intensity information in a wide area and precise shape information but has no height information. To overcome this limitation, we can generate a 3D point cloud from 2D sonarimage sequences. This method takes advantage of the mobility of the AUV to reconstruct the height information and partially solves the ambiguity issues in the imaging sonar’s elevation angle. The height map generated from the 3D point cloud contains height information of a wide area, but the shape information is inaccurate. By fusing two maps to complement each other’s imperfections, we can generate a precise 3D sonar map. This map enables the AUV to estimate the pose and recognize the surrounding environment. We verified the proposed method by conducting experiments in an indoor water tank. After placing various objects on the floor, the AUV with the imaging sonar scanned the floor and objects to generate a 3D sonar map. We analyzed the estimated AUV trajectory and the accuracy of the 3D sonar map. This study proposes a method for generating a high-precision three-dimensional (3D) map using twodimensional (2D) sonar images from an imaging sonar installed on an autonomous underwater vehicle (AUV). The 2D sonar image sequence was analyzed pairwise to estimate the amount of displacement and used to create a 2D mosaic sonar image. The mosaic sonar map contains intensity information in a wide area and precise shape information but has no height information. To overcome this limitation, we can generate a 3D point cloud from 2D sonar image sequences. This method takes advantage of the mobility of the AUV to reconstruct the height information and partially solves the ambiguity issues in the imaging sonar’s elevation angle. The height map generated from the 3D point cloud contains height information of a wide area, but the shape information is inaccurate. By fusing two maps to complement each other’s imperfections, we can generate a precise 3D sonar map. This map enables the AUV to estimate the pose and recognize the surrounding environment. We verified the proposed method by conducting experiments in an indoor water tank. After placing various objects on the floor, the AUV with the imaging sonar scanned the floor and objects to generate a 3D sonar map. We analyzed the estimated AUV trajectory and the accuracy of the 3D sonar map.
Jongkyoo Kim,Hangil Joe,Son-cheol Yu,Lee, Jin S.,Minsung Kim IEEE 2016 IEEE transactions on industrial electronics Vol.63 No.2
<P>This paper presents an enhanced time-delay controller (TDC) for the position control of an autonomous underwater vehicle (AUV) under disturbances. A conventional TDC performswell when the involved data acquisition rate is fast. However, in AUV control applications that use a Doppler velocity log (DVL) navigation system, we cannot keep the data acquisition rate sufficiently fast because a DVL sensor generally supplies data at a slow acquisition rate, which degrades the performance of the TDC. To overcome this problem, we propose an integral sliding-mode controller to be supplemented to the conventional TDC to improve the control precision even if the DVL navigation system is in operation. The proposed controller is computationally simple and robust to unmodeled dynamics and disturbances. We performed computer simulations and experiments with the Cyclops AUV to demonstrate the validity of the proposed controller.</P>
Lidar SLAM Comparison in a Featureless Tunnel Environment
Iulian Filip,Juhyun Pyo,Meungsuk Lee,Hangil Joe 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11
Simultaneous Localization and Mapping (SLAM) algorithm consists a vital part of decision-making process of autonomous robot platforms. Many lidar-based SLAM methods have been proposed for indoor and urban environments. However, a few studies are reported in a featureless tunnel environment. In this paper we consider recent lidar SLAM frameworks and test their performance in a tunnel environment. Our dataset is collected by a four-wheeled ground vehicle that is equipped with a lidar sensor used for mapping and feature detection and an IMU sensor used for odometry tracking information. The performance of seven different lidar SLAM algorithms is tested and as a result, in corridor environment LIO-SAM and SC-LIO-SAM frameworks show the lowest trajectory and point cloud error, respectively. On the other hand, LIO-SAM and FAST-LIO2 displays the best trajectory accuracy in the tunnel environment with addition of artificial landmarks and without them, respectively. The results obtained during the performance of seven different lidar SLAM algorithms can contribute to the development of a SLAM framework in a featureless tunnel environment.