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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/55799
標題: | 單音束測深機音鼓姿態效應與測深誤差之相關性研究 The Study of Transducer Attitude Bias of the Single Beam Echo Sounder related with Sounding Error |
作者: | Ming-Yi Hsu 徐明誼 |
指導教授: | 宋國士 |
關鍵字: | 單音束測深,姿態參數,誤差, single-beam bathymetry,attitude,error, |
出版年 : | 2014 |
學位: | 碩士 |
摘要: | 水深測量大多使用單音束測深儀和多音束測深儀的方式進行。其誤差來源會包括儀器誤差、定位誤差、姿態誤差、聲速誤差等。現今近岸的精密測量多使用多音束測深儀,因為它在於水深資料分布上具有相當完整的覆蓋率,測深精度也因為聲波束寬較小,較易達到做地形差異工作的精度需求。但在水深淺到數公尺的時候,其效率會變越差,因為要達成覆蓋率,則需要較密的航線,而且因為音鼓價格昂貴,在水深過淺時,因觸底的風險高,測量者對於在岸區使用多音束測深儀的意願會很低。所以為顧及成本和業者意願,使用單音束測深機往往在所謂的環境變異調查的項目中,其使用仍為主流。使用單音束測深儀,其資料的代表性,最主要問題來自地形解析能力的不足,除聲波束寬較大,隨測區區域變深會讓地形解析快速放大外,另外,測線間的聲波束印分布,會使資料對目標沒有完整的覆蓋率;本研究主要就架設音鼓時,當音鼓面非垂直水面往海床方向安裝而產生指向差的效果做分析。另外,我們也會討論當動態感測器與音鼓面並非擺在同一水平面上對測值精度的影響,上述兩項因素會導致船體受浪搖擺的角度值會出現據偏差的測值,再如果動態感測器的輸出量沒經過離心力的修正,當船隻轉向或換線施測時,都會造成一些不可預期的測深誤差。本研究就以上問題提出解決方案,方法是利用去改良測線間資料分布的差異性,我們可以推算音鼓面偏離水平的角差量,進而改良測值的精準度。 For the bathymetry, using single beam echo sounder and multi-beam echo sounder is the most common approach. Its source of errors include positioning, vehicle’s attitude, acoustic speed variation, and some others. Recently, by reason of quite full coverage for bathymetric data and making it easier to achieve the accuracy requirements for topographic differences works, multi-beam echo sounder is the popular way in the nearshore areas. Nevertheless, at shallow depths less than several meters, reaching complete coverage needing denser survey lines, and the high risk of multi-beam’s transducers colliding with the ocean bottom due to high-priced of the transducers, which are the reason that surveyors are the lower willingness in using a multi-beam sounder in the nearshore areas. Consequently, to take into account the costs and businesses will, single beam echo sounder is still the mainstream for variation in the environment of the project. The main problem of bathymetry by using single beam echo sounder for representation of data is from the lack of resolution capabilities of topography. In addition to the larger sound beam width, the resolution will deteriorate with the survey area becoming deeper, and distribution of the sounding beams will not make data complete coverage. For the survey work in the nearshore areas, survey vessels often change, and the instrument will need to reinstall for each survey vessel. There are the expected measuring errors due to the fact that setting up from human factors. This study is to analyze that the installation of transducer without pointing form surface to the seabed vertically produce poor results. Besides, we will discuss how influence of accuracy affects when dynamic motion sensor and transducer are not put the same level. Therefore, these two factors will cause the bias of the angle of ship by the wave swing. Then, the output data of dynamic motion sensor is not corrected by the centrifugal, which caused the unpredictable sounding errors in the turning of the vessel or changing the survey line. In this study, we propose the solution to the above problems, and the method is to improving the differences in survey lines of the distribution of data. Thereby, it is improved the accuracy of the measured values by calculating the bias of angle between the transducer surface and horizontal plane. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/55799 |
全文授權: | 有償授權 |
顯示於系所單位: | 海洋研究所 |
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