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GNSS精密單點定位及非差模糊度快速確定方法研究

發(fā)布時間:2018-07-28 08:42
【摘要】:GPS精密單點定位(Precise Point Positioning,簡稱PPP)是上世紀九十年代末發(fā)展起來的一種新的GPS定位技術,它集成了GPS標準單點定位和GPS相對定位的技術優(yōu)勢,是GPS定位技術中繼RTK/網(wǎng)絡RTK技術后出現(xiàn)的又一次技術革命。歷經(jīng)十多年的快速發(fā)展,GPS精密單點定位的基本理論與實踐問題已經(jīng)得到了比較好的解決,目前正在朝工程化應用方向邁進。但是,現(xiàn)階段能工程化應用的PPP技術仍然以PPP浮點解為主,PPP固定解尚處于研究和發(fā)展階段。特別是實時PPP中的快速模糊度固定問題仍然是當前的一個研究難點。 本論文系統(tǒng)深入地研究PPP的數(shù)學模型,分析傳統(tǒng)PPP模糊度無法固定為整數(shù)的本質(zhì)原因,進而提出一套新的非差模糊度整數(shù)解方法。詳細研究了PPP模糊度無法快速固定為整數(shù)的原因,提出了實時PPP快速初始化和快速重新初始化的新方法。融合網(wǎng)絡RTK與PPP技術的優(yōu)勢,建立一套完整的統(tǒng)一的精密定位服務系統(tǒng),為實時PPP技術的廣泛應用奠定理論與實踐基礎。論文的主要工作和貢獻如下: (1)詳細介紹了精密單點定位的常用數(shù)學模型、主要誤差項以及參數(shù)估計方法。為了滿足實時PPP的需要,提出并開發(fā)了高采樣率精密衛(wèi)星鐘差快速估計和更新算法。討論了其解算效率及精度,估計的鐘差與IGS最終鐘差吻合較好,其相對偏差大多數(shù)在0.1ns以內(nèi);開發(fā)了一套基于因特網(wǎng)的實時精密單點定位服務系統(tǒng),實驗結(jié)果表明:該實時系統(tǒng)可取得平面方向5厘米,高程方向10厘米左右的實時定位精度。同時,針對非差相位觀測值數(shù)據(jù)預處理中小周跳難探測、難修復的問題,提出了一種新的實時PPP中的周跳固定與修復方法,該方法精細分離各項誤差,并引入LAMBDA方法搜索周跳值。 (2)從GNSS觀測的基本數(shù)學模型出發(fā),分析了傳統(tǒng)PPP模型中模糊度無法固定為整數(shù)的原因,基于此提出了非差模糊度整數(shù)解的新模型與方法。大量的實驗結(jié)果表明PPP模糊度固定可以顯著提高精密定位與定軌的精度。同時,提出了一種利用預報大氣層延遲輔助PPP模糊度快速固定的新方法,該方法充分利用首次初始化完成后生成的精密大氣信息,可實現(xiàn)短時信號中斷后模糊度的單歷元固定,避免了信號中斷所引起的PPP重新初始化的問題。大量實驗結(jié)果表明:使用本文所提出的方法,即使在所有的衛(wèi)星全部短時失鎖的情況下,仍然可以實現(xiàn)PPP單歷元模糊度固定。 (3)提出了區(qū)域增強的PPP方法。充分利用從區(qū)域參考網(wǎng)提取的精密大氣改正數(shù),實現(xiàn)了實時PPP的快速初始化。該方法可以將網(wǎng)絡RTK和實時PPP兩大技術融為一體,集成為一個統(tǒng)一的定位服務。即在沒有區(qū)域增強信息的情況下,可全球范圍內(nèi)實現(xiàn)幾個厘米精度的實時PPP服務,在有區(qū)域信息增強的區(qū)域,則可提供更高精度的快速精密定位服務。同時,基于此開發(fā)了一種分層的GNSS精密數(shù)據(jù)處理策略,可以實現(xiàn)大規(guī)模且疏密不均的參考網(wǎng)的PPP區(qū)域增強。精密軌道和鐘差的生成作為基本的兩層,另外的兩層分別為相位小數(shù)偏差估計和區(qū)域增強改正數(shù)。 (4)針對PPP模糊度初始化時間較長的難題,提出了顧及電離層特征的PPP模型,基于該模型開發(fā)了新的相位小數(shù)偏差估計算法。新模型不僅能改進相位小數(shù)偏差產(chǎn)品的質(zhì)量,而且顯著縮短PPP模糊度的初始化時間。實驗結(jié)果表明:新方法能縮短實時動態(tài)解收斂時間30%,由超過30分鐘縮短為不超過20分鐘;首次模糊度固定時間減少25%,由20分鐘縮短為15分鐘。處理靜態(tài)測站,新方法首次固定時間約為10分鐘,在測站坐標固定為已知值情況下固定時間僅需5分鐘。 (5)對各種定位模型與算法進行深入分析,并經(jīng)過提煉與綜合,提出了一種統(tǒng)一的顧及大氣約束的非差非組合的精密定位模型與算法。即采用非差原始觀測值,將電離層和對流層延遲作為參數(shù)進行估計,并依據(jù)其時空特征以及實時得到的大氣模型或區(qū)域大氣改正數(shù)合理的施加適當?shù)募s束。這對于使用稀疏參考網(wǎng)增強PPP尤為重要,合理的約束大氣延遲參數(shù)可以補償由大的測站間距引起的殘余大氣誤差。這個統(tǒng)一的算法不僅能將PPP和網(wǎng)絡RTK集成為無縫的定位服務,且可將這兩個技術融合為一個統(tǒng)一的模型和算法;趯崟r產(chǎn)品流和統(tǒng)一的處理策略,我們可以提供如下實時動態(tài)定位服務:5-10厘米精度的全球PPP;2-5厘米精度的固定解PPP;1-3厘米精度的區(qū)域增強PPP。
[Abstract]:GPS precision single point positioning (Precise Point Positioning, abbreviated as PPP) is a new GPS positioning technology developed at the end of the 90s of last century. It integrates the technical advantages of GPS standard single point positioning and GPS relative positioning. It is another technical revolution after GPS positioning technology relay RTK/ network RTK technology. After more than 10 years of rapid development. The basic theoretical and practical problems of GPS precision single point positioning have been solved well and are moving towards engineering applications. However, at present, the PPP technology that can be applied in engineering is still based on PPP floating-point solutions, and the fixed solutions of PPP are still in the research and development stages, especially the fast fuzzy fixed questions in real-time PPP. The problem is still a research difficult point at present.
This paper systematically studies the mathematical model of PPP, analyzes the essential reason that the traditional PPP ambiguity can not be fixed as an integer, and then puts forward a new set of non differential integer solution method. The reason why the PPP ambiguity can not be fixed quickly to the integer is studied in detail, and a new method of rapid initialization and rapid re initialization of the real-time PPP is proposed. Combining the advantages of RTK and PPP technology, a complete and unified precision positioning service system is set up, which lays the foundation for the wide application of real-time PPP technology. The main work and contribution of this paper are as follows:
(1) the common mathematical model, main error term and parameter estimation method of precision single point positioning are introduced in detail. In order to meet the needs of real time PPP, a fast estimation and updating algorithm of high sampling rate precision satellite clock difference is proposed and developed. The calculation efficiency and accuracy are discussed. The estimated clock difference is in good agreement with the final clock difference of IGS, and its relative deviation is relatively biased. Most of the difference is within 0.1ns, and a set of real-time precision single point positioning service system based on the Internet is developed. The experimental results show that the real-time system can obtain real-time positioning accuracy of 5 cm in plane direction and 10 centimeters in elevation direction. At the same time, it is difficult to repair and repair the small and medium cycle hops according to the number of non differential phase observations. In this paper, a new cycle skip fixing and repairing method in real-time PPP is proposed. The method extracts the errors accurately and introduces the LAMBDA method to search cycle slips.
(2) starting from the basic mathematical model of GNSS observation, the reason that the fuzzy degree of the traditional PPP model can not be fixed as an integer is analyzed. Based on this, a new model and method for the integer solution of the non difference ambiguity is proposed. A large number of experimental results show that the precision of the precision localization and the orbit determination can be greatly improved by the PPP fuzziness. At the same time, a kind of use is put forward. A new method for predicting the fast fixation of PPP fuzzy degree aided by atmospheric delay is used. This method makes full use of the precise atmospheric information generated after the first initialization, and can realize the single epoch of the ambiguity after short time signal interruption, avoiding the problem of the re initialization of PPP caused by signal interruption. A large number of experimental results show that the use of this paper is used in this paper. The proposed method can achieve PPP single epoch ambiguity even if all satellites are short lost.
(3) a region enhanced PPP method is proposed. The rapid initialization of real-time PPP is realized by making full use of the precision atmospheric correction number extracted from the regional reference network. This method can integrate the network RTK and the real time PPP technology into a unified positioning service. A real-time PPP service with a few centimeter precision can provide a higher precision positioning service in a region with enhanced regional information. At the same time, a hierarchical GNSS precision data processing strategy is developed to achieve the PPP enhancement of a large and unevenly distributed reference network. The generation of precision orbit and clock difference is made. For the basic two level, the other two layers are phase decimal deviation estimation and region enhancement correction.
(4) aiming at the problem of the longer initialization time of PPP ambiguity, a PPP model considering the ionosphere characteristics is proposed. A new phase decimal estimation algorithm is developed based on the model. The new model can not only improve the quality of the phase decimal deviation product, but also significantly shorten the initialization time of the PPP ambiguity. The experimental results show that the new method can be reduced. The short time dynamic solution convergence time is 30%, which is shortened from more than 30 minutes to less than 20 minutes. The first fuzzy fixed time is reduced by 25% and the 20 minute is shortened to 15 minutes. The static station is treated with a fixed time of about 10 minutes for the first time, and the fixed time of the station coordinates is fixed to the known value only 5 minutes.
(5) in depth analysis of various positioning models and algorithms, and after refining and synthesis, a unified model and algorithm for non differential non combinatorial positioning, taking into account of atmospheric constraints, is proposed. That is, using the non differential original observation values, the ionosphere and tropospheric delay are estimated as parameters, and based on their temporal and spatial characteristics and real time results. The atmospheric model or the regional atmospheric correction number is properly constrained. This is particularly important for the use of sparse reference networks to enhance the PPP. The reasonable constraints of the atmospheric delay parameters can compensate for the residual atmospheric errors caused by large station spacing. This unified algorithm can not only integrate PPP and network RTK into seamless location services, but also can be used as a seamless location service. The two technologies are integrated into a unified model and algorithm. Based on real time product flow and unified processing strategy, we can provide the following real-time dynamic positioning services: 5-10 cm precision global PPP; 2-5 cm precision fixed solution PPP; 1-3 cm precision regional enhanced PPP.
【學位授予單位】:武漢大學
【學位級別】:博士
【學位授予年份】:2013
【分類號】:P228.4

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