| Summary: | 碩士 === 國立臺灣海洋大學 === 通訊與導航工程學系 === 104 === The purpose of this thesis is to apply position calculation and performance evaluation of using radar for resilient positioning. E-Navigation is an International Maritime Organization (IMO) led concept based on the communication and exchange of maritime information onboard and ashore by electronic means, enabling maritime navigation to be safer and more reliable. Accuracy of positioning is an important element of e-navigation. According to the World Wide Radio Navigation Plan of International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA), positioning systems is divided into two categories- satellite based and terrestrial based. When Global Positioning System (GPS) can not support availability of positioning, we expect Aids to Navigation (AtoN) system can provide effective positioning information by using radar systems from shipboard and ground-based stations.
The thesis developed a positioning simulation tool in Java as the test platform for performance analyses and evaluation. When ships sail at different locations, status and conditions, we can leverage radar and e-Compass to get the range, bearing, and coordinates of the location and direction information. Geospatial functions provided by an open source GIS Toolkit, GeoTools, are then utilized to complete position calculation of ships automatically, for example the LineBuffer of Rho-Theta, Polygon of AOA and RingBuffer of TOA. Through the geometry operations, we can generate estimated positioning error range by using different positioning methods. Via the geometry of error range, we can easily understand, analyze and explore the characteristics, strengths, weaknesses and problems of the positioning methods. During the voyage, system can select the best positioning methods to get the best positioning accuracy.
The final simulation results show that selection of positioning method along the route is often limited by the availability of source measurement data for positioning. The uncertainty of resilient positioning results indicated as geometries can be used as a reference for the selection of positioning methods during the voyage. The simulation tool developed in this thesis as well as the evaluation results can assist in the site selection of base stations in the future.
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