论文中文题名: | 抗差部分模糊度固定的RTK高精度定位方法及地质灾害监测应用 |
姓名: | |
学号: | 21210226059 |
保密级别: | 公开 |
论文语种: | chi |
学科代码: | 085215 |
学科名称: | 工学 - 工程 - 测绘工程 |
学生类型: | 硕士 |
学位级别: | 工程硕士 |
学位年度: | 2024 |
培养单位: | 西安科技大学 |
院系: | |
专业: | |
研究方向: | GNSS数据处理与应用 |
第一导师姓名: | |
第一导师单位: | |
论文提交日期: | 2024-12-24 |
论文答辩日期: | 2024-11-30 |
论文外文题名: | RTK high—precision positioning method with robust partial ambiguity fixing and its application in geological disaster monitoring |
论文中文关键词: | |
论文外文关键词: | GNSS ; RTK ; Robust estimation ; Partial ambiguity is fixed ; Geological disaster monitoring |
论文中文摘要: |
地质灾害的监测和预警是防灾减灾的重要前提。GNSS(Global Navigation Satellite System)因具有全天候、测站间无需通视、提供实时三维位置信息等优势,被广泛应用于监测工作。RTK(Real-time Kinematic)技术因具有出色的实时性和监测精度而广泛用于地质灾害监测预警中。但在复杂的地质灾害环境中,由于大气条件活跃,同时受山地、植被遮挡等因素影响,GNSS信号极易受多路径效应干扰,特别是新出现观测卫星时,卫星信号较弱,容易出现粗差,形变序列会出现监测不连续、异常值多等问题,难以获取可靠的监测结果。针对以上在地质灾害监测过程中遇到的问题,本文提出一种抗差部分模糊度固定的RTK方法,该方法利用抗差技术和部分模糊度固定策略,能够同时提升模糊度固定率和RTK定位精度,此外,利用第五代大气再分析数据集(ECMEF Reanalysis v5,ERA5)进一步削弱大高差背景下对流层延迟对RTK定位高程方向的影响,保证地质灾害监测的定位精度、鲁棒性和可靠性。本文的主要研究内容如下: (1)针对GNSS不同系统不同频率的监测精度不同,基于信噪比、多路径效应开展数据质量分析,并对不同频率、不同系统进行组合,获取地质灾害背景下精度最高的RTK监测结果。受限于RTK定位精度随基线长度增加而下降的特点,导致只有短基线条件下能达到mm级精度。因此,基于地质灾害监测数据,从定位精度、模糊度固定率、卫星可见数、精度衰减因子(Dilution of precision,DOP)进行分析,得到不同基线长度下精度最优组合。结果表明,单系统下BDS(B1+B3)定位精度优于GPS(L1+L2)和BDS(B1+B2),组合系统GPS(L1+L2)+ BDS(B1+B3)可以进一步提高定位精度,弥补RTK技术在地灾监测过程中受环境影响导致精度不足。 (2)针对多路径误差干扰RTK定位精度及固定率,采用不同抗差方法和部分模糊度固定方法改善RTK定位结果,并生成抗差部分模糊度固定算法。对伪距单点定位进行抗差处理,采用IGGIII等价权函数和零速约束的卡尔曼滤波提高伪距单点定位精度。进一步对相对定位中卡尔曼滤波分先验后验进行二次抗差处理,分别采用IGGIII、IGGI、Huber、Hample、Andrew等价权函数进行抗差,并对同一等价权函数选取不同阈值进行对比,结果表明:Huber等价权函数对精度提升最为明显,随着阈值增加,抗差后RTK定位精度提升,模糊度固定率提升。采用基于卫星高度角的部分模糊度固定算法和基于成功率和Ratio为指标的部分模糊度固定算法进一步提高RTK定位模糊度固定率,并与全模糊度固定算法进行对比。结果表明,2种部分模糊度算法固定率均在95%以上,基于成功率和Ratio为指标的部分模糊度固定算法在短基线拥有更好地精度提升效果,基于卫星高度角的部分模糊度固定算法不受基线长度影响,在10km以上基线的定位结果仍能保证精度。最后将抗差和部分模糊度相结合,形成抗差部分模糊度固定算法,基线长11.8km时,采用该算法精度较抗差方法在E、N、U三个方向上分别提高了19.6%,14.1%,8.6%,较部分模糊度方法在E、N、U三个方向上分别提高了34.9%,29.3%,49.7%,该方法模糊度固定率较传统RTK方法从21.8%提升到了100%。 (3)采用ERA5大气再分析资料计算RTK对流层延迟,并与抗差部分模糊度固定算法结合,生成一种ERA5约束的抗差部分模糊度固定RTK算法。结果表明,ERA5约束后RTK对流层湿延迟在高差为140m、189m、229m分别提升了82.2%,90.5%,94.8%,高程方向精度分别提升了2.3%,5.8%,10.7%。将ERA5约束的抗差部分模糊度固定RTK方法应用在地质灾害监测上,结果表明,该方法可以有效提升定位精度,当基线为6km,高差为140m时,传统RTK方法8小时解算水平和高程方向能达到mm级精度,本文方法6小时就可以达到mm级精度,提高了RTK在地质灾害监测领域的精度和可用性。 |
论文外文摘要: |
The monitoring and early warning of geological disasters is an important prerequisite for disaster prevention and mitigation. GNSS (Global Navigation Satellite System) is widely used in monitoring work because of its advantages of all-weather, no inter-station visibility, and real-time three-dimensional position information. RTK (Real-time Kinematic) technology is widely used in geological disaster monitoring and early warning because of its excellent real-time performance and monitoring accuracy. However, in the complex geological disaster environment, due to the active atmospheric conditions and the influence of factors such as mountains and vegetation occlusion, GNSS signals are easily interfered by multipath effects. Especially when new observation satellites appear, satellite signals are weak and prone to gross errors. Deformation sequences will have problems such as discontinuous monitoring and many outliers, and it is difficult to obtain reliable monitoring results. In view of the above problems encountered in the process of geological disaster monitoring, this paper proposes a robust partial ambiguity fixing RTK method. This method uses robust technology and partial ambiguity fixing strategy to improve the ambiguity fixing rate and RTK positioning accuracy at the same time. In addition, the fifth generation of atmospheric reanalysis data set (ECMEF Reanalysis v5, ERA5) is used to further weaken the influence of tropospheric delay on the elevation direction of RTK positioning under the background of large height difference, and ensure the positioning accuracy, robustness and reliability of geological disaster monitoring. The main research contents of this paper are as follows : (1) Based on the signal-to-noise ratio and multipath effect, the data quality analysis is carried out, and different frequencies and different systems are combined to obtain the RTK monitoring results with the highest accuracy under the background of geological disasters. Limited by the fact that RTK positioning accuracy decreases with the increase of baseline length, mm-level accuracy can be achieved only under short baseline conditions. Therefore, based on the monitoring data of geological disasters, the optimal combination of accuracy under different baseline lengths is obtained by analyzing the positioning accuracy, ambiguity fixed rate, satellite visibility and dilution of precision (DOP). The results show that the positioning accuracy of BDS (B1 + B3) under single system is better than that of GPS (L1 + L2) and BDS (B1 + B2). The combined system GPS (L1 + L2) + BDS (B1 + B3) can further improve the positioning accuracy and make up for the lack of accuracy caused by the environmental impact of RTK technology in the process of ground disaster monitoring. (2) Aiming at the multipath error interference RTK positioning accuracy and fixed rate, different robust methods and partial ambiguity fixing methods are used to improve the RTK positioning results, and a robust partial ambiguity fixing algorithm is generated. The robust processing of pseudo-range single point positioning is carried out, and the IGGIII equivalent weight function and zero-speed constraint Kalman filter are used to improve the accuracy of pseudo-range single point positioning. Further, the Kalman filter in the relative positioning is divided into a priori posterior for secondary robust processing. The IGGIII, IGGI, Huber, Hample, and Andrew equivalent weight functions are used for robustness, and the same equivalent weight function is selected. Different thresholds are compared. The results show that the Huber equivalent weight function has the most obvious improvement in accuracy. As the threshold increases, the RTK positioning accuracy after robustness is improved, and the ambiguity fixed rate is improved. The partial ambiguity fixing algorithm based on satellite elevation angle and the partial ambiguity fixing algorithm based on success rate and Ratio are used to further improve the ambiguity fixing rate of RTK positioning, and compared with the full ambiguity fixing algorithm. The results show that the fixed rates of the two partial ambiguity algorithms are all above 95 %. The partial ambiguity fixing algorithm based on success rate and Ratio has better accuracy improvement effect on short baselines. The partial ambiguity fixing algorithm based on satellite elevation angle is not affected by baseline length, and the positioning results of baselines above 10 km can still ensure accuracy. Finally, the robust and partial ambiguity are combined to form a robust partial ambiguity fixing algorithm. When the baseline length is 11.8 km, the accuracy of the algorithm is 19.6 %, 14.1 %, and 8.6 % higher than that of the robust method in the E, N, and U directions, respectively. Compared with the partial ambiguity method, it is increased by 34.9 %, 29.3 %, and 49.7 % in the E, N, and U directions, respectively. The ambiguity fixing rate of this method is improved from 21.8 % to 100 % compared with the traditional RTK method. (3) The tropospheric delay of RTK is calculated by ERA5 atmospheric reanalysis data, and combined with the robust partial ambiguity resolution algorithm to generate an ERA5 constrained robust partial ambiguity resolution RTK algorithm. The results show that the tropospheric wet delay of RTK after ERA5 constraint is increased by 82.2 %, 90.5 % and 94.8 % respectively at 140 m, 189 m and 229 m, and the accuracy in elevation direction is increased by 2.3 %, 5.8 % and 10.7 % respectively. The robust partial ambiguity fixed RTK method constrained by ERA5 is applied to geological disaster monitoring. The results show that this method can effectively improve the positioning accuracy. When the baseline is 6km and the height difference is 140m, the traditional RTK method can achieve mm-level accuracy in the horizontal and elevation directions in 8 hours. The method in this paper can achieve mm-level accuracy in 6 hours, which improves the accuracy and availability of RTK in the field of geological disaster monitoring. |
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中图分类号: | P228 |
开放日期: | 2024-12-24 |