Reliable partial ambiguity resolution for single-frequency GPS/BDS and INS integration

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• 作者：Houzeng Han ; Jian Wang ; Jinling Wang ; Alberto Hernandez Moraleda
• 关键词：GPS ; BDS ; INS ; Tightly coupled ; Single ; frequency ; Partial ambiguity resolution
• 刊名：GPS Solutions
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：21
• 期：1
• 页码：251-264
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geophysics/Geodesy; Atmospheric Sciences; Space Sciences (including Extraterrestrial Physics, Space Exploration and Astronautics); Automotive Engineering; Electrical Engineering;
• 出版者：Springer Berlin Heidelberg
• ISSN：1521-1886
• 卷排序：21

文摘

Correctly fixing carrier phase integer ambiguities is a prerequisite to achieve high-precision positioning solutions from global navigation satellite system (GNSS). However, for the single-frequency dynamic users, a low ambiguity resolution (AR) success rate is usually associated with the small number of visible satellites. It is expected that the instantaneous single-frequency AR performance will be significantly improved by combining the observations from both global positioning system (GPS) and Chinese BeiDou navigation satellite system (BDS) for enhanced geometric strength. We develop an inertially aided AR technique using single-frequency GPS/BDS observations. With the addition of inertial navigation system (INS) measurements, a highly reliable fixing of ambiguities right after the GNSS signal blockages is possible because of the improved accuracy of the float ambiguities based on the calibrated inertial navigation solutions before the GNSS signal blockages. In addition, a new partial ambiguity resolution (PAR) technique is proposed, which is of great benefit when full ambiguity resolution fails under challenging conditions. The subset of ambiguities is ordered according to the maximum rounding fixing rate ordering method. An a priori decorrelation procedure is applied to the original observations that aim to obtain an optimal subset ordering. A further AR procedure is conducted to resolve the remaining unfixed ambiguities using the ambiguity-fixed phase observations, with the objective of improving the probability of fixing more ambiguities. In order to test the proposed algorithm, a field vehicular test was performed. The results show the availability and reliability of ambiguity resolution for the INS-aided single-frequency GPS/BDS using PAR technique are significantly improved compared to that of GNSS-only, and a success rate greater than 90 % can be obtained for the single-GNSS/INS system as well as combined GPS/BDS/INS system. In terms of positioning accuracy, the best performance is achievable for the single-frequency GPS/BDS/INS system, the RMSs for position difference stay below 1 cm for GPS/INS and GPS/BDS/INS single-epoch solutions; however, the worst positioning performance is from the BDS/INS system. In terms of INS bridging capability, a fast ambiguity recovery within 5 s becomes feasible for a 19-s outage using INS-aided PAR scheme after a long calibration period.