Studies on the Control Aspects of Human Pilots and the Expert System for Automatic Navigation.

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At the present, ships are maneuvered by human operators in harbors. A berthing maneuver of ships is one of the most sophisticated controls conducted by human operators. In this berthing maneuver, a pilot has to take firstly maneuvering safety into consideration. It is very important to control maneuvering motion accurately, because the final berthing speed has to be kept under 5 cm/sec. Therefore a pilot has to predict the maneuvering motion which is executed by his operation under relatively large disturbances. For ships have large mass but they have only equipped with relatively small control power. Then there are many practices which enable a pilot to keep maneuvering safety.In collision avoidances in narrow waterways, the situation is about similar. As a pilot has to estimate correctly the relative motions among own ship and encountered ships, he has to predict the paths of target ships, taking traffic rules, mariners' practices and so on into consideration.In order to realize a co … More mputer aided maneuvering system for such complicated maneuvers, It is necessary to analyze maneuvering motions of ships in harbors and collision avoidance actions which are conducted bypilots.In the present report, firstly an attempt is made to design and to construct a ship maneuvering simulator which can realize real time maneuvering simulations by human pilots. The Harbor Kaneuverins Simulator of Hiroshima University has been established, constructing a mockup of the wheelhouse with conventional navigational aids, developing a visual display system of computer generated imagery type, building up a mathematical models of ship motions, environmental situations in a computer. The reality of the simulations has been assured by many professional pilots of the Japan Pilots Association.At the second, maneuvers of course keeping, changing, berthing and berthing are simulated and analyzes with special emphasis on the maneuvering safety problems such as the allowable limit of ship maneuverability. The allowabLe limits in course-keeping and -changing have been evaluated. Those are important for realizing a computer aided maneuvering system.Finally, the expert system has been developed for the maneuvers at confused and narrow waterways with regulated traffic routes. The Knowledge base with hierarchy structures is built. The knowledge base contains the rules of reasoning control, decision making after prediction, sub-decision making and elementaL knowledge. Traffic simulations have been carried out by the expert system for checking the maneuvering performance and improving the knowledge base. The expert system has been confirmed to work well for collision avoidance maneuvers and passing maneuvers through traffic routes. Less