A Computational Method for Astro Fixing: The SOFT Method

• Main Authors: Gong, Wei-Ting, 龔韋婷
• Other Authors: Chen, Chi-Li
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/23348044283293864260

碩士 === 國立臺灣海洋大學 === 商船學系 === 102 === A computational method, namely Sailing-Oriented Fix Thinking (SOFT), is proposed to solve the problem of the astronomical vessel position (AVP). Since most conventional methods to determine the AVP are based on circles of position concept (from viewpoint of the celestial body), they are too complicated to be easily used for the navigator. To improve the disadvantage of those conventional methods, the SOFT method adopts the lines of position concept (from viewpoint of the observer), which can determine the AVP by two straight lines instead of two curves. Because the SOFT method implies the characteristic of “trial-and-error”, “idea of dead reckoning position replacing assumed position” and “the iteration method” can be used in this SOFT method. In addition, the running fix concept is adopted to tackle the problem of different observing time. Importantly, those used formulae in the SOFT method are derived by using three geometrical properties, perpendicular, parallel, and symmetry for the mean latitude sailings of pilotage. Thereafter, a program, AVP-SOFT, with Graphic User Interface is developed from the SOFT method for the navigator. Finally, several benchmark examples are conducted to show that the SOFT method is simple and accurate.