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Article type: Cover
1991 Volume 85 Pages
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Published: September 25, 1991
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Article type: Cover
1991 Volume 85 Pages
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Published: September 25, 1991
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Masaaki INAISHI, Hayama IMAZU, Akio M. SUGISAKI
Article type: Article
1991 Volume 85 Pages
1-8
Published: September 25, 1991
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This paper explores a new possibility of building a collision avoidance system using a neural network. The reason using a neural network technique is aimed at parallel processing for many vehicles and at the possibility of making an integrated circuit which stored collision avoidance judgment criteria. As the first step, authors have built a circumstantial judgment sub-system using a neural network. The neural network is composed of two backpropagation neural networks, which are degree of scope network and action level network. The supervised training data is acquired from an expert of a ship operator. The summary of the results are shown below. (1) An output from the networks is in agreement with the expert's decision making when the continuous circumstances change is given in the networks. (2) When unknown data is included in the networks input, the lower correct recognition rate is given. To solve the lower correct recognition rate problem, it is necessary to have an addition to the supervised training data which gives consideration to unknown data pattern. (3) The quality of supervised training data is discussed with randomness scale. (4) The possibility of building a collision avoidance sub-system using a neural network is found.
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Hayama IMAZU, Yujiro MURAYAMA, Kunihiko TANAKA, Nobuo ARIMURA, Masayos ...
Article type: Article
1991 Volume 85 Pages
9-15
Published: September 25, 1991
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A method for critical target's position, the position at which collision is avoidable by give-way vessel's maneuver, has been developed. The method can be cosidered about trajectories were obtained using nonlinear maneuverability theory, error of estimated target's vector and passing conditions. The passing conditions are the minimum distance to keep between these two vessels for safety passing, and the time to spare for avoiding action. The critical target's positions were determined for various speed of vessel and different passing conditions. And the distribution of these positions around give-way vessel (critical position for give-way vessel), and the distribution of these positions around stand-on vessel (critical position for stand-on vessel) were shown. The difference of these two distributions showed that give-way vessel should take avoiding action not only before the critical position for give-way vessel but also before the critical position for stand-on vessel.
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Fujio KANEKO, Yujiro MURAYAMA, Kunihiko TANAKA, Nobuo ARIMURA, Masayos ...
Article type: Article
1991 Volume 85 Pages
17-24
Published: September 25, 1991
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As the level of traffic congestion of sea area and the number of high speed craft has been growing recently in Japan, efficient measures for safety at sea is now required urgently. To establish efficient safety measures, the safety assessment of a ship navigation system with safety measures is needed. For the assessment, experiments by a simulator is useful. In this paper the requisites to the simulator for the safety assessment of ship navigation system and the procedure of the safety assessment using the simulator are discussed. And the present status of our simulator which aimes to the simulator for such purpose is shown.
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Masayoshi NUMANO, Keiko OKUZUMI, Junji FUKUTO, Fujio KANEKO, Kunihiko ...
Article type: Article
1991 Volume 85 Pages
25-31
Published: September 25, 1991
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Marine traffic for passengers and cargoes is highly congested in a cosmopolice such as Tokyo. The water front is also developed both for business and pleasure traffic. To keep navigation safety under such conditions, various navigation aids will be newly developed and various traffic routes will also be designed. Although it is necessary to acquire the social acceptance about their effect on safety, a conventional method of probabilistic approach is not sufficient but the safety assessment from the viewpoint of a potential danger should be needed. In the present paper, the procedure for the safety assessment of ship navigation from the viewpoint of potential danger is proposed and discussed. An analysis on a simulation result of high speed vessel traffic is explained as an example.
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Kiyoshi HARA
Article type: Article
1991 Volume 85 Pages
33-40
Published: September 25, 1991
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Author made a proposal on maneuvering standard to avoid collision among ships based on a fuzzy model of collision avoidance maneuver. As well known there are often different decision makings on the same ship-encounter among navigators and between them on board and VTS operator ashore although they have common traffic rules. First author analyzed and evaluated the assessing process of navigator on collision avoidance maneuver under various encounters among ships using ship handling simulator. Based on the results author constructed a fuzzy reasoning model for subjective risk assessment on collision, SJ. Supposing a safety level, SJ^*, which is an admissible risk level of SJ by a navigator or VTS operator, author proposed to have a common value of SJ^* as an aiming safety level among people concerned in navigation in congested and VTS area. Author studied how the average and variance of subjective assessment value on the risk of collision (SJ) exert influence on the safety of navigation at congested waters and maneuvering load on navigator by making traffic simulation in which the fuzzy reasoning model was installed. Finally the simulation results indicated that each ships in congested waters should be operated based on the common maneuvering standard in order to increase the safety of navigation and share the same maneuvering load among ships concerned. VTS operators should also timely make advice and give information of traffic to vessels based on the same standard.
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Makoto INUI, Kohei OHTSU, Toshio ISEKI, Masanori ISHIZUKA
Article type: Article
1991 Volume 85 Pages
41-50
Published: September 25, 1991
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A ship's abstract log book is a precious data for statistics in which various informations on the individual ship's status under navigation, are included. Nevertheless, it is well kown that the description of abstract log book in a general merchant ship is not always accurate. In this paper, the authors analyze the abstract log of a training ship whose description is comparatively reliable and derive the statistical model of the performance curve and the horse power curve to the relevant variables which are described in the log book. And in building the statistical models, the authors propose throughout adoption of the Minimum AIC Estimate method. As a result, the authors will conclude that the models which were gained by the proposed procedure to analyze a ship's abstract log book, gives a good information about the propulsive characteristic curves, inferencing from the correlation coefficients of the models which were gained by this procedure and other analysis.
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Masao FURUSHO, Shigetoshi KAI, Susumu HASHIMOTO
Article type: Article
1991 Volume 85 Pages
51-62
Published: September 25, 1991
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Nowadays, the speed of ships has increased, and high speed vessels are now being operated, such as the JETFOIL and HOUVER CRAFT which travel at the speed between 30 and 50 knots. We have taken the measurement of the eye-movement of the pilot on board the super speed vessel, JETFOIL, by using an eye-pointer. We have analized the data with the pilot's head fixed forward, and the result is as follows. (1) When the vessel is running on hull-borne in a harbor, the eyes of the pilot move broadly breadthwise. (2) When the vessel is foil-borne on the open sea, the eyes of the pilot move lengthwise in a narrow area.
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Hiroaki KOBAYASHI, Masamichi TAKAYAMA
Article type: Article
1991 Volume 85 Pages
63-69
Published: September 25, 1991
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It is often pointed out that many traffic accidents are caused by human control errors. Human handling characteristics are changed by the vehicle characteristics. So, it is necessary to study the human characteristics taking account of the vehicle characteristics. In this paper, we consider that vehicle characteristics are described as follows, (1) Dimension of movement (2) Number of control factor (3) Type of movement (4) Response time It is the purpose of this study to know the quantitative relation between the human control error and vehicle characteristics. According to this study, the following matters will be cleared; (1) The desirable vehicle characteristics and the limitation of vehicle characteristics for human control. (2) The desirable type of control and the number of control factor. The formulas which are obtained by this study, explain the relation between the human control error and response time of vehicle and the number of control factor.
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Masayoshi KUBO, Kenji ASAKI, Tadahiro ONODA, Atsuki SHIBATA
Article type: Article
1991 Volume 85 Pages
71-81
Published: September 25, 1991
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Oil pollution caused by casualties is becoming a serious public problem. Even if a large quantity of oil spills, there are no any effective countermeasures that seamen can take by themselves. It is very important to know that most of oil spills at the early stage of the accident, and a rough weather condition often continues for several days. Therefore, we cannot expect any other supports just after the accident. It is necessary to have some equipments on board. In this paper, an equipment enclosing the hull with curtains is proposed for the prevention of spilt oil diffusion. It is equipped on board and designed to be set in a few minutes. Some two-dimensional experiments are carried out to study the behavior of the water body around the hull and the curtains by using the circular tank. The experiments show a possibility of preventing the spilt oil diffusion. Furthermore, it is found that the above system is cheaper than any other systems which contain the hull reconstruction.
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Kinzo INOUE, Yoshitaka FUKUO, Tokiko SUGANUMA
Article type: Article
1991 Volume 85 Pages
83-92
Published: September 25, 1991
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It is desirable in the planning of port and harbour facilities that the mariners' intention as the port users is considered into the design process of the layout and the dimensions of the waterway, the harbour-basin and the breakwater. In the present paper, the mariners' subjective criteria are introduced and the application of these criteria to the evaluation of safety of the facilities from the mariners' view on the basis of their sense of safety is discussed. These criteria were obtained through the questionnaires which were distributed to 562 Japanese marine pilots. Based on these criteria, it is capable to evaluate the preference of the design alternatives of the facilities from the view point of the operational safety and to obtain the information that how much percentage of the mariners can accept the designed layout and dimensions of the facilities. The proposed criteria can be also available to the comparison of the similarity and the difference between ports.
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Kuniji KOSE, Shinichiro YAMAMOTO, Shihei NOMURA, Hiroki IWASAKI, Takas ...
Article type: Article
1991 Volume 85 Pages
93-105
Published: September 25, 1991
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The results of the simulator study on an allowable limit of directional instability of ships were presented in the first report. The limit is very important for the maneuverability standards to be discussed at the IMO and the results of further study is now introduced. To estimate the allowable limit of directional instability more clearly further maneuvering simulations were carried out as a cooperated research program between the Japan Pilots' Association and Hiroshima University. The maneuvers by pilots in the narrow channel and the port with complicated external disturbances are now examined carefully and the relation between the maneuverability and the navigational difficulty is estimated. It is finally pointed out that the directional instability is more severe for the maneuvers in the curved narrow channel than the port and the permissible limit is about the instability with the unstable loop width of 7.5 degrees for the ships of 20,000 tons and 12 knots.
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Masayoshi KUBO, Katsuhiko SAITO, Nobuyasu IKOMA, Tsuyoshi OKI
Article type: Article
1991 Volume 85 Pages
107-116
Published: September 25, 1991
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In the previous paper, to prevent the ship separation from a quay wall, we proposed a system where the water pressure resulted from the difference of the water level of both ship's side was utilized. We would like to name the system "the prevention system of ship separation from quay wall". In this paper, we carry out model tests under wave action in order to investigate the behavior of the ship moored by the system. The obtained results are summarized as follows: (1) As the direction of the system's force agree with the sway, the sway becomes small. Moreover, subharmonic motions in sway do not occur because the ship always moves within the fender deflection. In the same reason, roll motions are also small. (2) The direction of the system's force intersect at right angles with heave, the degree of decrease of heave is smaller than the others.
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Naoki KUSHIDA
Article type: Article
1991 Volume 85 Pages
117-126
Published: September 25, 1991
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In this paper, the author proposes a new autopilot which can evaluate as closely as the helmsman's reaction by using the fuzzy controller which can simulate the control action of the helmsman. Although there are some papers about fuzzy autopilot by other researchers, the author proposes a new fuzzy controller which has the following features: (i) From both the interview with the expert helmsman and the consideration for the manoeuvring data of helmsman, the IF〜THEN rules of the fuzzy controller are defined. The membership function of the front condition is the shape of the triangle, and the function of the back condition is the singleton. The MIN-MAX Gravity Method is used in deciding the order of the manipulating value. (ii) Although the way of deciding the parameters has been vague in the past, by taking the real ship's manoeuvring data of the expert helmsman using the Conjugate Gradient Method, carrying out the parameter tuning becomes possible. Moreover, (iii) When the ship's mathematical model is able to linearize during course keeping, the use of the fuzzy controller is terminated, and the self-tuning PID controller, proposed by the authors in the past, is used instead. This proposed controller has the capability of overcoming the bad effect caused by the mismatch of the construction for the mathematical model. Lastly, to confirm the high availability, the digital simulation, which is similar to real ship's motion, and the experiments using a real ship are implemented.
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Masayoshi KUBO, Katsuhiko SAITO
Article type: Article
1991 Volume 85 Pages
127-134
Published: September 25, 1991
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When cargo handling is carried out in a harbor by using a crane on the floating pier, the operation is interrupted as a results of cargo swing caused by severe motions of floating pier. In this paper, the motions of two floating bodies moored along a slope are investigated by using two dimensional boundary integral equation method. A floating container terminal in port Valdez, Alaska, is treated as an example. The cargo swing and relative motions between ship and cargo are calculated. The obtained results are summarized as follows; (1) The property of the two floating bodies motions moored along a slope can be explained qualitatively by the relation , between floating bodies and standing waves along a quay wall. (2) The cargo swing is related with the magnitude and phase of sway and roll of the floating pier and the length of cargo fall. (3) The cargo swing becomes large when the natural period of roll is close to the wave period. So it is important to decide the breadth, center of gravity of floating pier, and the height of crane by considering the predominant waves at the harbor. (4) The cargo handling ability can be improved by the best selection of the distance between slope and floating pier from stand point of two floating bodies motions.
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Hiroyuki SADAKANE, Masanori KANAZAWA
Article type: Article
1991 Volume 85 Pages
135-141
Published: September 25, 1991
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Estimation of the lateral force acting on VLCC moving slowly and laterally in shallow water is an important work for the berth manoeuver by using tug boats. However, since numerical values of the lateral force coefficient C_<wy> shown by some research institutions are remarkably different, it is difficult to estimate appropriately the force mentioned above. In this paper, on the supposition that the difference of C_<wy> values is caused by the blockage effect due to side walls of water tank, C_<wy> is investigated experimentally. From the present studies, following results were obtained: (1) The blockage effect of side walls have clearly influence on C_<wy> especially in shallow water, like the ratio of water depth to ship draft h/d=1.1. (2) In order to avoid the blockage effect, the water tank breadth b is needed to be over 6 times of the model ship length L, namely b/L>6. (3) When being the unrestricted shallow water h/d=1.1, C_<wy> of an oil tanker ship model is about 2.1. This numerical value is approximately equal to the drag coefficient of the flat plate in the two dimensional flow.
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Yuji HAYASHI, Nobukazu WAKABAYASHI, Hirotsugu WAKE
Article type: Article
1991 Volume 85 Pages
143-151
Published: September 25, 1991
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In an experimental automatic navigation system, an ARPA is currently employed as a sensor to obtain navigation information about ships in the radar visibility. Consequently the ARPA is expected to have an equivalent capability to ship operator's eyesight. Some researchers are engaged in developing such an advanced ARPA. However, the advanced ARPA alone can not assure high reliability, simply because it gives us only a single kind of sensor information. From this point of view, we have focused on image understanding techniques for mechanization of ship operator's eyesight, and studied an extraction of navigation information from an image of a ship at sea. In last paper, we described 1) a derivation of theoretical equations for calculating the distance between a target and an own ship using a position of a horizon and 2) a verification of their efficiency with Digitizer Distance Measuring System (OMS). As the next step in developing a practical system, we have implemented semiautomatic distance measuring system, Mouse Distance Measuring System (MOMS). MOMS consists of an engineering workstation (EWS) and an image scanner as the hardware. An input image is fed into the EWS by the scanner and processed for edge detection, binarization and thinning. The coordinates (x, y) of important points are, then, extracted from the processed image on the display by clicking the mouse. In this paper, we explain MOMS in detail and that its accuracy is enough in some practical situations.
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Nobumichi ISHIMURA, Kanemichi KASAHARA, Ikuo INOUE
Article type: Article
1991 Volume 85 Pages
153-160
Published: September 25, 1991
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To make a big step forward in automatic reading of contours on charts, we need to add the function for recognition of the altitude values with contours to its processing. In this paper, therefore, we propose a method to carry out this function efficiently and verify the validity of this method through the experiment using actual chart data. In this method, the altitude reading is executed by two steps. The first step is to cut off only the region where the altitude values are described on chart images. The second step is the recognition of numerical letters that are cut off in the previous step. Although the recognition processing generally puts much load on a computer using many parameters as the features of letters, this recognition is very simple and useful. The reason is that it can be accomplished by only two parameters. Namely, one is the number of pixels composing the digital line drawings. The other is the average of the magnitude of the directional changes per pixel in the trace on a digital line drawing. These parameters are also essential to the classification of line drawings and can be commonly used in it.
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Ken ITANO, Mitsuhiro FUJITA
Article type: Article
1991 Volume 85 Pages
161-168
Published: September 25, 1991
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An ATC (Air Traffic Control) experiment using ETS-V (Engineering Test Satellite V) was conducted. In the experiment, the position of aircraft was measured by CIS (Cooperative Independent Surveillance) and ADS (Automatic Dependent Surveillance). Data communication and voice communication using NBFM and LPC between ground and air was conducted. The result shows that the positioning accuracy of CIS and ADS is enough to minimize present oceanic separation of aircraft. More than 95% of the controllers participated in the experiment evaluated the quality of voice communication using NBFM as bettr than that of present HF communication. Also 81% of them prefer LPC to HF. An error rate of received characters on aircraft through data communication is less than 2×10^<-4>, which shows that the satellite data link has the possibility of improving oceanic ATC capability.
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Sakae NAGAOKA
Article type: Article
1991 Volume 85 Pages
169-177
Published: September 25, 1991
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This paper deals with the feasibility of the aircraft height monitoring systems composed of multiple SSR sensors. Two systems, one is a hybrid system using an SSR interrogator and SSR receivers and another is a passive system using only SSR receivers, are considered. The height estimation accuracy of these SSR-based systems are studied theoretically in terms of VDOP (Vertical Dilution of Precision). The distributions of calculated VDOPs for two systems composed of 4 sensors under the same geometrical configurations are examined and compared each other. The results show that the passive system has higher accuracy than the hybrid system has. Theoretical VDOP obtained for the passive system under the examined geometrical configurations becomes less than 1 when the target aircraft is in a close range from the reference SSR. This suggests that, under some limitted conditions, the absolute height measurement with the accuracy of 15m (1σ) or less may be possible using the proposed system.
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Mitsuo YOSHIDA, Hiroyuki SHIMADA, Takashi KURODA
Article type: Article
1991 Volume 85 Pages
179-186
Published: September 25, 1991
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A social survey measuring images of the sea and ships was conducted among general college students and mercantile marine students in Japan and general college students in the United States. Questionnaire items were examined from the viewpoints of methodological concerns to validate SD (Semantic Differential) method. Response categories were analyzed by investigating (1) distributions of total responses, (2) curve fitting on cumulative percents to investigate neutral category, (3) calculating of sample moments that show the shape of distribution, and (4) comparing factor structures between the two countries. The two samples of both Japan and the US showed reasonable consistency.
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Article type: Appendix
1991 Volume 85 Pages
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Published: September 25, 1991
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Article type: Appendix
1991 Volume 85 Pages
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Published: September 25, 1991
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Article type: Appendix
1991 Volume 85 Pages
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Published: September 25, 1991
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Article type: Appendix
1991 Volume 85 Pages
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Published: September 25, 1991
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Article type: Appendix
1991 Volume 85 Pages
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Article type: Cover
1991 Volume 85 Pages
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Article type: Cover
1991 Volume 85 Pages
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