Hirotsugu Wake

An image ranging system at sea

In a current experimental automatic navigation system, the Automatic Radar Plotting Aids (ARPA) is a device to acquire navigational information about ships in radar visibility. The authors are developing image processing techniques for calculating the distance to a target ship based on processing scenery pictures, which have been originally obtained from visual images and used as navigational information by ship operators. This scheme is realized by measuring a minute angle between the horizon and the waterline in a scenery image and computing the distance to a target. In the paper, the authors describe: 1) the derivation of theoretical equations for calculating the distance to a target by means of the computed minute angle, 2) the verification for the efficiency of the Mouse Pointer Ranging System, and 3) the development of a semi-automatic system helped by image processing techniques, that is named the Semi-automatic Image Ranging System. The authors have tested the accuracy of their calculations by applying 148 pictures and 214 images to the ranging systems. It is possible for both image ranging systems to measure distances at an error rate of less than 11 or 13 percent of ARPA radar distances. The accuracy is good enough for practical use in order to apply to ship handling for avoidance.<<ETX>>

Support system for planning of navigation schedule by using tidal current in inland seas

There are many inland seas where have international and domestic sailing routes in the world. They have complicated lay of lands and tidal current. We propose Support System for Planning of Navigation Schedule (SUSPANSE), that utilizes current in these inland seas. SUSPANSE bears the least fuel consumption of ships. The least fuel consumption realizes the preservation of natural environment in these inland seas. In this paper, the objective sea area is the Inland Sea Of Japan (ISJ). The width of ISJ is 30 miles from North and South, and 240 miles from East and West. ISJ has about 3,000 islands, which are scattered, and the current is complicated. Besides, main sailing routes of Japan exist in the ISJ. The estimation of current set and velocity in ISJ is generally to carry out by using Tide Tables of Japan Maritime Safety Agency (JMSA). 13 standard points and 212 semi-standard points of tidal current are prepared in ISJ. However, they are not useful for calculation of tidal current velocity at optional points and time in ISJ. For supplement these lack, JMSA publishes Stream Charts of each sea area in ISJ. Tidal current database is prepared by utilizing the Stream Charts. The tidal current database is made from tidal current information and geographical information, and they are piled up together in the database. Tidal current calculation system (TCCS) can estimate the current velocity at optional point and time in ISJ. When sailing route and departure time are input to SUSPANSE, ships hours under way is calculated in accordance with the sailing route. SUSPANSE recommends the optimal departure time in this day for shortest hours under The effective of SUSPANSE is confirmed by making comparison between actual hours under way and the output of SUSPANSE.