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Position Measurement System for an Automated RTGC
Hideki Kawai,Young-Bok Kim,Yong-Woon Choi 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
This paper describes a camera-based position measurement system for automatic tracking control of a rubber Tired Gantry Crane (RTGC). An automatic tracking control of RTGC depends on the ability to measure its displacement and angle from a guide line that the RTGC has to follow. The measurement system proposed in this paper is composed of a camera and a PC that are mounted on the right upper between front and rear tires of the RTGC’s side. The measurement accuracy of the system is affected by disturbances such as cracks and stains of the guide line, shadows, and halation from the light fluctuation. To overcome the disturbances, both side edges of the guide line are detected as two straight lines from an input image taken by the camera, and parameters of the straight lines are determined by using Hough transform. The displacement and angle of the RTGC from the guide line can be obtained from these parameters with the robustness against the disturbances. From the experiments with the disturbances, we found the accurate displacement and the angle from the guide line that have the standard deviations of 0.95 pixels and 0.22 degrees, respectively.
Distance Measurement System Based on Image Sensors for Automatic Berthing of Ships
Hideki Kawai,Junpei Sakamoto,Young-Bok Kim,Yongwoon Choi 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10
This paper describes a distance measurement system based on image sensors for automatic berthing of ships. An automatic berthing system is a solution to relieve psychological and physical strains on the operator in berthing maneuvering that is the most difficult and delicate phase. Usually, a sensor system for the automatic berthing system should accommodate ship movements such as rolling, pitching, and yawing, in order to continuously measure the relative distance from the ship to a dock in a port. For acquiring the accommodation to the ship movements, the proposed measurement system is composed of two movable image sensors, and measures the relative distance by detecting and tracking a target on the dock. Additionally, a template matching method robust to light fluctuation in outdoor environment, named the vector code correlation, is employed to the movable image sensor for the target detection. From the experimental results performed in an outdoor environment where lighting condition was varied, we confirmed that the measurement system could continuously measure the relative distance under 3.1m of absolute errors in the measuring range of 100m to 5m. Especially, high accuracy within ±1.0m was accomplished from 40m to 5m of the relative distance.
Anti-sway system with image sensor for container cranes
Hideki Kawai,김영복,최용운 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.10
High speed and efficiency are highly important factors in handling cargo at ports. The ability to handle cargo at high speed strongly depends on the anti-sway system employed. However, it is not easy to realize a high-performance antisway control system due to a number of problems. High-speed operation of container cranes is continuously required for crane operators who work as cargo handlers at ports. Undesirable motion can lower the work efficiency due to the prolonged strain to which operators are subjected. To overcome this problem, we propose an anti-sway system with an image sensor for container cranes. In this system, the image sensor is used for measuring the motion of the spreader, and the measured data are fed back to the controller in real time. The applied image processing technique is a kind of robust template matching method referred to as vector code correlation (VCC), which was devised in order to consider real environmental conditions. The anti-sway system proposed in this paper is a mass damper type system in which a movable mass is installed on the spreader. The actuator acting on the movable mass applies inertial force to the spreader, which results in suppressing undesirable sway motion. The system is simple and can be easily applied to any crane system. In this regard, the useful features and the performance of the proposed anti-sway system are experimentally verified.
실외 주행환경을 고려한 카메라 기반의 RTGC 위치계측시스템 개발
Hideki Kawai,김영복(Young Bok Kim),최용운(Yong Woon Choi) 제어로봇시스템학회 2011 제어·로봇·시스템학회 논문지 Vol.17 No.9
This paper describes a camera-based position measurement system for automatic tracking control of a rubber Tired Gantry Crane (RTGC). An automatic tracking control of RTGC depends on the ability to measure its displacement and angle from a guide line that the RTGC has to follow. The measurement system proposed in this paper is composed of a camera and a PC that are mounted on the right upper between front and rear tires of the RTGC’s side. The measurement accuracy of the system is affected by disturbances such as cracks and stains of the guide line, shadows, and halation from the light fluctuation. To overcome the disturbances, both side edges of the guide line are detected as two straight lines from an input image taken by the camera, and parameters of the straight lines are determined by using Hough transform. The displacement and angle of the RTGC from the guide line can be obtained from these parameters with the robustness against the disturbances. From the experiments with the disturbances, we found the accurate displacement and the angle from the guide line that have the standard deviations of 0.95 pixels and 0.22 degrees, respectively.
Skew Measurement Technique for Container Crane Spreader using a Camera
Hideki-Kawai,Young-Bok Kim,Yong-Woon Choi 제어로봇시스템학회 2010 제어로봇시스템학회 합동학술대회 논문집 Vol.2010 No.6
Precise steering of ship motion at low and very low speed in the harbor area is one of the most important operations, requires a set of adequate thrust devices with commonly taken into account surge, sway and yaw motion. However, effectiveness of actuators is nominal in this condition, so using tugboat for ship berthing assistance is necessary. With the constraints of control allocation problem by using tugboats, a new algorithm based on redistributed pseudo inverse matrix is presented. The main goal of this method is to minimize power consumption supplied to tugboats and increase their controllability. Particulars of CybershipⅠ that is a model ship (scale 1:70), is used to evaluate the efficiency of proposed method through Matlab simulation.
카와이 히데키(HIDEKI KAWAI),김영복(YOUNG-BOK KIM),최용운(YONG-WOON CHOE),양주호(JOO-HO YANG) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.4
In general, the swing motions of a crane are controlled and suppressed by controlling the trolley motion. In many of our previous studies, we suggested a new type of anti-sway control system for a crane. In this proposed control system, a small auxiliary mass (moving-mass) is installed on the spreader and moving this auxiliary mass controls the swing motion. The actuator reaction against the auxiliary mass applies inertial control forces to the container in order to reduce the swing motion in the desired manner. However, measuring systems based on a laser sensor or other means are not veryuseful in real-worldapplications. So, in this paper, animage sensor is used to measure the motions of the spreader and the measured data are fed back to the controller in real time. The applied image processing technique is a kind of robust template matching method called Vector Code Correlation (VCC), which was devised to consider real environmental conditions. The H∞ based control technique is applied to suppress the swing motion of the crane. Experimental results showed that the proposed measurement and control system based on a image sensor is useful and robust to disturbances.
Hardware Design of Vector Code Correlation Method for High-Speed Template Matching
Masaki Yoshimura,Hideki Kawai,Taketoshi Iyota,Yongwoon Choi 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
Template matching has been applied to the image processing of the fields such as security and robot vision to recognize a target from images. The method used in those fields requires the high-speed processing and robustness to illumination change or occlusion. To accommodate this, we employ a method, named the vector code correlation (VCC) that codes the gradient of intensity change, but the method on software is not enough in aspect of image processing time. Therefore, the purpose of this study is to achieve the template matching in real-time by designing hardware to implement the VCC method at high speed. The hardware design consists of five modules doing pipeline processing and is able to realize in relatively small scale. In the present paper, experimental results of 60 fps obtained with the designed hardware and its configuration are shown.
( Satoshi Hiyama ),( Hideki Iijima ),( Syoichiro Kawai ),( Akira Mukai ),( Eri Shiraishi ),( Shuko Iwatani ),( Toshio Yamaguchi ),( Manabu Araki ),( Yoshito Hayashi ),( Shinichiro Shinzaki ),( Tsuneka 대한장연구학회 2016 Intestinal Research Vol.14 No.4
Background/Aims: Peyer`s patches (PPs) are aggregates of lymphoid follicles that are mainly located in the distal ileum; they play a major role in mucosal immunity. We recently reported that patients with ulcerative colitis (UC) have alterations in PPs that can be detected using narrow-band imaging with magnifying endoscopy (NBI-ME). However, the usefulness of NBI-ME in UC treatment as a whole is still unknown. Methods: We collected NBI-ME images of PPs from 67 UC patients who had undergone ileocolonoscopy. We evaluated changes in the villi using the “villi index,” which is based on three categories: irregular formation, hyperemia, and altered vascular network pattern. The patients were divided into two groups on the basis of villi index: low (L)- and high (H)-types. We then determined the correlation between morphological alteration of the PPs and various clinical characteristics. In 52 patients who were in clinical remission, we also analyzed the correlation between NBI-ME findings of PPs and clinical recurrence. Results: The time to clinical recurrence was significantly shorter in remissive UC patients with Htype PPs than in those with L-type PPs (P <0.01). Moreover, PP alterations were not correlated with age, sex, disease duration, clinical activity, endoscopic score, or extent of disease involvement. Multivariate analysis revealed that the existence of H-type PPs was an independent risk factor for clinical recurrence (hazard ratio, 3.3; P <0.01). Conclusions: UC patients with morphological alterations in PPs were at high risk of clinical relapse. Therefore, to predict the clinical course of UC, it may be useful to evaluate NBI-ME images of PPs. (Intest Res 2016;14:314-321)