Abstract
Vehicular positioning in urban environments has become a research hotspot in recent years, and global navigation satellite system/inertial navigation system (GNSS/INS) tightly coupled positioning is a commonly used method. With the broadcast of BDS-3 and Galileo four-frequency signals, the multi-frequency and multi-system tightly coupled positioning method provides more possibilities for vehicular positioning in urban environments. At present, most of the studies on multi-frequency and multi-system mainly focus on static or baseline solutions, and there are few studies on the urban dynamic environment. In this paper, based on the triple-frequency GPS/BDS-2/INS tightly coupled positioning model, the BDS-3 four-frequency observation is introduced to conduct a preliminary study on the performance of GPS/BDS-2/BDS-3/INS tightly coupled positioning. Taking into account the positioning accuracy and calculation efficiency of the tightly coupled positioning, single epoch extra-wide-lane/wide-lane (EWL/WL) observation is used to participate in the modeling of tightly coupled positioning. The EWL/WL ambiguity is solved by the geometry-free (GF) method, in which triple-frequency carrier ambiguity resolution (TCAR) and four-frequency carrier ambiguity resolution (FCAR) are used for triple-frequency and four-frequency observations, respectively. Finally, the positioning performance of the tightly coupled method in this paper is evaluated through vehicular experiment. The experimental results show that in the urban dynamic environment, due to the higher quality of the linear combination of BDS-3 four-frequency, the positioning accuracy of the BDS-3/INS tightly coupled was slightly better than that of the triple-frequency BDS-2/INS. Compared with GPS/BDS-2/INS, the GPS/BDS-2/BDS-3/INS tightly coupled positioning accuracy increased by 29.1% and 58.7% in horizontal and vertical directions, respectively, which can realize decimeter positioning accuracy in urban environments.
Highlights
With the demands of applications such as mobile measurement, autonomous driving, and intelligent transportation increasing, vehicular positioning in urban environments has attracted much attention in recent years [1,2,3]
To evaluate the positioning performance of the multi-frequency global navigation satellite system (GNSS)/inertial navigation system (INS) tightly coupled after using the BDS-3 four-frequency observations in urban environments, a land vehicular test of the integrated navigation system was carried out in Nanjing, China on
The global positioning system/BeiDou navigation satellite system (GPS/BDS)-2/BDS-3/INS tightly coupled positioning can achieve decimeterlevel positioning accuracy in the horizontal and vertical directions, respectively, which is in line with theoretical expectations
Summary
With the demands of applications such as mobile measurement, autonomous driving, and intelligent transportation increasing, vehicular positioning in urban environments has attracted much attention in recent years [1,2,3]. In complex environments such as tree occlusion, urban canyon, viaduct, and tunnel, it will cause global navigation satellite system (GNSS). It is difficult to obtain reliable high-precision positioning results in complex environments such as urban canyons only by relying on GNSS [4,5]. The combination of GNSS and INS is the most common and has a wide range of applications, mainly including the loosely coupled and the tightly coupled integration. Compared with the loosely coupled architecture, the tightly coupled solution has distinctive advantages in positioning accuracy and reliability [10]. Considering the cost and the stability of the technical solution, the tightly coupled integration is more suitable for vehicular positioning in urban environments
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