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  • 學位論文

地面動態載台GNSS相對定位品質評估

Evaluating the Quality of Relative GNSS Position for Terraintial Mobile platforms

指導教授 : 韓仁毓

摘要


全球導航衛星系統(Global Navigation Satellite System, GNSS)因軍事活動興起,發展至今已逐漸成熟,由於該技術可以快速獲取點位資訊,近年來時常與慣性導航系統(Inertial Navigation System, INS)結合,廣泛應用於各種動態載台的即時定位,除了民生應用的導航外,也逐漸應用在精度需求較高的測量領域中,諸如地形測繪、動態光達資料蒐集等,因此對於GNSS之定位精度的要求也隨之提高。為了要提升移動載台的定位品質,在施測的過程中利用地面基站配合差分定位消除單點定位的系統性誤差,但精度卻受載台的移動導致的基線長度變化而影響。另外過去在GNSS精度評估過程中,僅利用簡單遮罩角模擬固定單點的地形遮蔽狀況及衛星可視性分析,已不能滿足動態載台的使用需求,且隨著載台的移動,載台跟衛星、與基站、以及與地形之間的關係皆隨著移動而不斷改變,導致之間所產生的相互影響更加複雜且顯著。另一方面隨著測量科技的進步,高品質的數值地形模型(Digital Terrain Model)產製技術日益成熟,若能事先取得施測地區的地形資料,便能在事先分析測區中各種因素的相互關係進而獲得可靠的定位品質評估,對於施測前的規劃將有實質的幫助。本研究利用數值地形模型模擬地形遮蔽狀況,並以改良式非等間隔取樣法進行地形遮蔽分析,不僅能更真實地呈現現地情況,相較於傳統的等間隔取樣法,能在精度規範之下有效減少約80%的取樣間隔數目,進而使運算時間減少約77%,分析的成果相較於傳統遮罩角具有更好的穩定性。此外,在本研究中利用定位品質指標針對固定路徑,考量各種影響GNSS定位精度的因素做整體的精度評估工作,並透過實地試驗驗證本方法之應用效能與可靠度,對於提升動態載台之事前的衛星品質評估有具體的助益。

並列摘要


Global Navigation Satellite System (GNSS) is well developed these days. It can rapidly get three-dimensional spatial information, and is usually coupled with an Inertial Navigation System (INS) to provide positional, and orientation solutions for a moving platform in real-time. However, the relationship between satellites, receivers, base stations, and topographic obstructions are more complicated because the platform moves across time. As a consequence, current static approaches for the evaluation of the quality of a GNSS surveying are not applicable for such applications. This study aims to develop an approach that considers all major factors affecting the GNSS positioning quality of a moving platform. Results from case studies reveal that, by using the improved adaptive topographic sampling algorithm, the sampling intervals along the path and the computing time are reduced by 80% and 77%, respectively. Furthermore, by incorporating digital terrain data, the predicted number of satellites and DOP values become more reliable than using flat terrain model. It illustrates that the topographic effect should be an essential consideration in the quality assessment of a satellite surveying. Finally, an accumulative positioning quality index (APQI) is proposed in the analysis, providing an explicit quality indication so that a GNSS surveying for a moving platform can be better planned.

參考文獻


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被引用紀錄


張郁翎(2017)。以Google Street View影像進行地面動態載台衛星可視性分析〔碩士論文,國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342%2fNTU201702032
羅建台(2014)。應用自適應動態轉換模式於移動載台之定位誤差改正〔碩士論文,國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342%2fNTU.2014.00749

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