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A Feedback Control of Pump-Controlled Electro-Hydrostatic Actuation System
유재관(Jae-Kwan Ryu),서형태(Hyung-Tae Seo) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.10
This paper presents a position control strategy for a pump-controlled electro-hydrostatic actuator (EHA) using feedforward control with disturbance compensation. As the disturbance observer is used to estimate nonlinear dynamics of EHA, which has valve-opening conditionals, as well as external disturbances, an additional feedforward control is adopted to achieve rapid response. The effectiveness of the proposed control strategy is verified through experiment using an EHA test bench. The proposed controller shows better tracking performance compared with a conventional PID controller.
운용개념 개발 프로세스를 활용한 무인수상정(USV) 탑재 모함의 운용 요구사항 분석
허장완,홍순국,임경한,유재관,Hur, Jang Wan,Hong, Soon Kook,Lim, Kyung Han,Ryu, Jae Kwan 한국시스템엔지니어링학회 2020 시스템엔지니어링학술지 Vol.16 No.1
The South Korean Navy is making efforts to acquire vessels that the new technology of the 4th industry is applied, and as a part of these efforts, it has a plan to mount and operate an Unmanned Surface Vehicle(USV) on a vessel that will be introduced later. However, the recent studies have focused on only development of common platforms and mission equipment for the USV, and have not sufficiently analyzed studies and operatinoal requirements on mother ship that will operate the mounted USV. Hence, this study analyzed and presented requirements of mother ship with the mounted USV in order to operate effectively it when the future medium and large vessels to be acquired by the South Korean Navy intent to operate the USV.
한민석(Min-Seok Han),유재관(Jae-Kwan Ryu),홍순국(Soon-Kook Hong) 한국정보전자통신기술학회 2019 한국정보전자통신기술학회논문지 Vol.12 No.4
본 논문에서는 10m급 무인수상정의 RCS 해석과 함께 RCS 증가 요인을 분석하고 RCS 감소 방안을 도출하였다. 기하학적 형상을 변형시키는 성형기법을 통해 레이다 단면적을 감소시킬 수 있고, 이것을 스텔스 무인수상정 개발에 활용할 수 있음을 확인한다. RCS 감소를 위해 기존의 Top Mast 부분을 함미부분으로 1m 이동시키고 경사각 5도를 준 후 0.5 m 아래로 이동시킨 다음 중앙과 주변 반사 구조물에 대한 영향을 최소화시키기 위해 주변에 Guided Wall을 추가 설치하였다. 기존 모델과의 RCS 해석 값을 비교 분석한 결과 모든 고각에 대해 감소 대책이 적용된 모델이 기존 모델보다 -3.79 dB 이상 낮아진 것을 알 수 있으며, 최대 대푯값은 기존 모델 고각 0도의 12.74 dB에서 6.32dB로 낮아졌다. 특히, 희생각 영역을 제외한 영역에서 강한 산란 현상이 상당부분 제거된 것을 확인할 수 있다. 또한, Guide wall을 추가한 -5m ~ 2 m 부분의 경우 반사되는 신호가 최대 20 ~ 40 dB 이상 개선되어 2D ISAR 영상에 나타나지 않는 것을 알 수 있다. 무인수상정 RCS 분석은 거리방향 프로파일 분석과 ISAR 영상 분석을 통해 문제 위치를 분석, 식별하는 과정을 설명하였으며, 그에 대한 문제를 해결할 수 있는 RCS 감소 방안을 함께 제시하였다. In this paper, the RCS analysis of the 10m unmanned surface vehicles was performed, and the factors of RCS increase were analyzed. Modeling techniques by transforming a geometric shape can reduce the RCS area, which can be used to develop stealth unmanned surface vehicles. In order to reduce the RCS, the existing Top Mast part was moved 1m to the tail part, the 5 degree tilt angle was moved below 0.5 m, and additional guided walls were installed to minimize the influence on the center and surrounding corner reflecting structures. As a result of comparing and analyzing the RCS analysis value with the existing model, it can be seen that the reduced countermeasure model is -3.79 dB lower than the existing model for all elevations. In particular, it can be seen that the strong scattering phenomenon is substantially removed in the region except the sacrificial angle region. In addition, it can be seen that in the case of -5m to 2m where the guide wall is added, the reflected signal is improved up to 20 to 40 dB or more, so that it does not appear on the 2D ISAR image. RCS analysis of unmanned surface vehicles explained the process of analyzing and identifying problem location through distance profile analysis and ISAR image analysis.
무인수상정을 위한 경로선 추종이 가능한 개선된 Dynamic Window Approach
김효곤,윤성조,최영호,이정우,유재관,원병재,서진호,Kim, Hyogon,Yun, Sung-Jo,Choi, Young-Ho,Lee, Jung-Woo,Ryu, Jae-KWan,Won, Byong-Jae,Suh, Jin-Ho 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.5
Recently, autonomous navigation technology, obstacle recognition, and obstacle collision avoidance technology are actively being developed for an unmanned surface vehicle (USV). The path to move from the current location to the destination should be planned, in order for an USV to autonomously operate safely to its destination. The dynamic window approach (DWA) is a well-known navigation scheme as a local path planning. The DWA algorithm derives the linear velocity and angular velocity by evaluating the destination direction, velocity, and distance from the obstacle. However, because DWA algorithm does not consider tracking the path, when using only the DWA algorithm, the ship may navigate away from the path line after avoiding obstacles. In this paper, we propose an improved DWA algorithm that can follow path line. And we implemented the simulation and compared the existing DWA algorithm with the improved DWA algorithm proposed in this paper. As a result, it is confirmed that the proposed DWA algorithm follows the path line better.
구평모(Pyung Mo Ku),유재관(Jae Kwan Ryu),이원희(Won Hee Lee) Korean Society for Precision Engineering 2022 한국정밀공학회지 Vol.39 No.1
This paper proposes a simplified path-following control method for an Unmanned Surface Vessel (USV) considering towed Unmanned Underwater Vehicles (UUV). For dealing with an effective USV dynamic model, 1st order of the linear system with time delay and gain value are applied rather than applying a non-linear dynamic model, and it is identified with real vessel data from several straight and turning experiments. Then, USV attitude and velocity are controlled by multi-loop Proportional-Derivative (PD) and proportional controller. A USV guidance scheme is derived through a UUV guidance scheme to support autonomous navigation for towed UUV, and combination of cross track and Line of Sight (LOS) guidance is presented for adaptive path following. Finally, to validate the performance of the proposed USV path-following control method with respect to the towed UUV guidance scheme, the results of simulations are presented.
Development of a Power Assistive Device Controller with User Intention Detection for Fire Fighters
전광우(Kwang Woo Jeon),이재열(Jae Youl Lee),최재연(Jae Yeon Choi),정구봉(Goo Bong Chung),유재관(Jae Kwan Ryu) Korean Society for Precision Engineering 2019 한국정밀공학회지 Vol.36 No.7
This paper describes the development of a power assistive device controller with user intention detection for fire fighters. In order to detect the intention of users, an F/T sensor frame was designed for the power assistive device controller. Using the numerical approach, each directional strain value of the F/T sensor frame was evaluated singly to determine the optimum point to mount the strain gauge under varying load conditions. The numerical analysis was conducted using the commercial program Ansys v11.0. The finite element model for the F/T sensor frame consisted of 37,547 elements and 157,154 nodes. A sensor bonding device and calibration jig were designed for the F/T sensor frame. In an effort to obtain the decoupling matrix for the F/T sensor frame of the proposed power assist device, calibration tests were conducted in the x-direction, y-direction, z-direction, My-direction and Mz-direction. In addition, the operating system was tested using the power assistive device controller that comprised of the F/T sensor frame.
김태근(Tae-Keun Kim),김휘수(Hwi-Su Kim),송재복(Jae-Bok Song),백주현(Joo Hyun Baek),유재관(Jae-Kwan Ryu) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In recent years, there has been increased need for a surveillance robot used to obtain the information on its environments. The robot consists of a mobile platform which can operate in rough terrain and an arm equipped with a camera for reconnaissance. However, traditional robots have low mobility due to large volume and high center of mass, and their camera view is often unstable while operating in rough terrain. In order to solve these problems, we developed a foldable arm with a stabilization controller. The 4 DOF robot arm was designed so that it could be folded into a designated place to lower the center of mass and to minimize the volume when not in use, thus increasing mobile performance of the robot. Also, we propose a controller for camera view stabilization using an IMU sensor. Through simulations, it was verified that the robot with a stabilization controller can reduce the vibration, which stabilizes the camera view.
Estimation of Walking Intension Using Centroid Variation of Lower Body Area
원인식(Ihn Sik Weon),이순걸(Soon Geul Lee),정제연(Je Yeon Jung),유재관(Jae-Kwan Ryu),문상찬(Sang Chan Moon) Korean Society for Precision Engineering 2017 한국정밀공학회지 Vol.34 No.5
A depth image camera is used for efficient estimation of walking intention of a pedestrian. Three-Dimensional image coordinates of the pedestrian’s joints are obtained from the image data that includes depth information and are converted into the absolute coordinate values. The absolute coordinate data are classified and matched with all 20 joints of a pedestrian and the 9 joints that are corresponding the lower limbs are finally selected. After calculating each three-dimensional area of a triangle that was formed with the adjacent 3 joints of the 9 lower limb joints, the centroid of all triangles along time is obtained. The walking intention, that includes the direction and the speed of walking, can be estimated with the change rate of this centroid. It is experimentally verified by comparing the distance that is measured with inertia moment unit and the distance that the calculated centroid is moving.