Research And Implementation Of Indoor Positioning Method Based On Beidou Pseudolite

GNSS navigation and positioning systems can provide continuous and reliable high-precision positioning and navigation services in outdoor environments,but users cannot normally receive satellite navigation signals in complex indoor environments.Pseudolites,as an effective extension of GNSS positioning in a GNSS sheltered environment,it can provide continuous and reliable indoor high-precision positioning services.Therefore,indoor pseudolite positioning technology has become one of the effective ways to achieve seamless indoor and outdoor positioning requirements.With the completion and use of the Beidou system,the Beidou pseudolite indoor positioning technology has also become a research hotspot.Based on the established indoor Beidou pseudolite positioning system,this paper proposes a pseudolite positioning algorithm based on the combination of carrier phase ranging and observation fingerprint matching,which can achieve high-precision positioning in indoor environments.The main research contents are as follows:(1)Aiming at the ambiguity problem of indoor pseudolite carrier phase positioning,this paper analyzes the indoor pseudolite carrier phase positioning process and ambiguity fixation algorithm in detail.In order to solve the static and dynamic positioning problems of indoor pseudolites,this paper proposes a fixed ambiguity algorithm based on known initial points.Experimental test results show that,given high-precision initial coordinates,the pseudolite static positioning results can reach centimeter-level accuracy,and dynamic positioning can reach decimeter-level accuracy.Positioning accuracy and reliability are mainly affected by distance.(2)Aiming at the problem that indoor pseudolites are seriously affected by multipath effects and lead to unstable positioning,this paper proposes a fingerprint matching positioning method based on pseudolite observations.This article first analyzes and evaluates the characteristics of the observation information provided by the satellite receiver.At the same time,the fingerprint database is created using the observational sample data collected in the offline stage as fingerprint features.Finally,the online matching positioning algorithm is used to calculate the position coordinates.The experimental results show that,without high-precision initial coordinates,only the observation fingerprint matching algorithm can be used to achieve sub-meter positioning accuracy,and the positioning stability is better.(3)Aiming at the problem that indoor pseudolite carrier phase ranging positioning accuracy is high but the stability is poor,and characteristic fingerprint matching positioning is fast and stable but the accuracy is general,this paper proposes a combination of Beidou pseudolite carrier phase ranging positioning and observable characteristic fingerprint matching positioning.Positioning method.The core idea is to use the pseudolite observation and measurement characteristic fingerprint matching positioning result to initialize the initial value of the carrier phase ranging positioning method,and to constrain the positioning result generated by the combined positioning.Experimental results show that,in the absence of precise initial point coordinates,the combination of pseudolite observation fingerprint and carrier phase ranging positioning can achieve continuous stable positioning at the static centimeter level and dynamic decimeter level.In summary,the combined positioning method based on carrier phase ranging positioning and observable feature fingerprint matching positioning proposed in this paper solves the problem that Beidou pseudolite indoor positioning results are excessively dependent on the indoor positioning environment.To a certain extent,the accuracy and stability of Beidou pseudolite indoor positioning results are improved.Compared with the traditional method,the algorithm in this paper can realize the fixed ambiguity of the whole circle without precise initial coordinates,and the dynamic positioning result is stable,which provides a certain research foundation for high-precision indoor location services.