近年來消費型多旋翼無人機的盛行，吸引各國公司的大量投資，如大疆、Intel等，現今，不論新聞採訪、地型探勘，亦或者空拍娛樂，都能看見無人機的蹤影。其中無人機在室外的懸停導航，多半以GNSS衛星定位扮演引導的重要角色；美中不足的是，衛星信號在傳遞的過程中遭受大氣層干擾與低成本衛星接收器的接收品質欠佳，因而造成公尺級的定位誤差，這些誤差所帶來的影響，導致無人機在室外飛行的過程容易因此發生危險，同時難以勝任航行智慧自動化的任務，限縮了無人機在工業4.0的發展。

根據此議題，本研究為提升無人機的飛行定位精準度，初步探討定位修正機制，而後以測量技術中的即時動態定位機制(RTK)提高衛星定位精準度至公分級，同時有別於傳統RTK的運作方式，本研究基於日本東京大學高須知二的開放原始碼RTKlib專案，透過嵌入式技術即時給予無人機精確的定位資訊；此外，評估現今主流的開源飛控韌體，選擇由蘇黎聯邦世理工學院Lorenz Meier等人開發具優異的軟體機制、學術價值較高並且尚具發展性的PX4飛行控制專案，進行整合實作。

本研究首先建立RTK-GPS定位系統，並且分析PX4的GPS驅動架構抽象層，進而針對輸出的NMEA標準傳輸協定設計並開發於一套GPS裝置驅動程式於PX4。透過抽象介面進行硬體配對與接收流程設計，流程以解析NMEA訊息，而後將導入必要定位資訊於PX4 Publish-Subscribe軟體機制中的Topic，利於導航工作採用定位資訊。同時，就PX4的安全性，將其改為主動式Dual-GPS，補足Single-GPS的缺點。

最後逐一驗證系統，根據實驗結果，本研究在高比例的Fixing-Ratio下，RTK靜止實測誤差僅10公分內；而據無人機的基本航行實測結果，在低空與高空懸停飛行的實驗下，分別為30公分與70公分的方均根誤差值，確實達到公分級的成效。

Quadcopter is a typical kind of Unmanned Aerial System(UAS). In many outdoor scenarios, it is important to get the exact position of the Quadcopter to do further applications. Unfortunately, in outdoor navigation, Quadcopters are generally installed with low-cost single frequency Global Navigation Satellite System(GNSS) receiver like GPS, which only offers a positioning accuracy of a few meters, and is not always reliable. If these problems can be solved, the safety and effectiveness of the applications of Quadcopter can be ensured.

In the field of geodesy, a kind of techniques to reduce positioning error is Real-Time Kinematic(RTK), which used the technique of differential GPS(DGPS). This thesis will first describe the implementation of RTKLIB, a package of open-source RTK algorithms. Then, it will deliberate on the architecture of PX4 flight stack and the integration of an on-board RTK-GPS. Next, the thesis will propose a flight stack by designing a GPS device driver for NMEA protocol, a general GPS transmission standard. Furthermore, this thesis will propose the extension of active Dual-GPS in PX4 for safety reasons.

Finally, the performance of the precise positioning system will be verified in a practical way. In such matter, PX4 flight control firmware in Quadcopter can be navigated by RTK-GPS in centimeter-level accuracy while flying.

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