Modeling And Application Of Structured Multipath Error For Pseudolite Indoor Positioning

In indoor positioning,pseudolite positioning system has the advantages of flexible layout,low cost,compatible with GNSS satellite positioning system,and can also solve the problem of GNSS satellite signal missing in indoor.However,the indoor positioning of Pseudolite will encounter the interference of multi-path signal,resulting in multi-path error.The short distance between the station and the satellite will lead to linearization error in the traditional positioning method,which will further amplify the multi-path error and affect the positioning accuracy.In view of the above problems,this paper studies and proposes a structural multipath error modeling method for pseudolite indoor positioning.This method mainly extracts and analyzes the multipath error in pseudolite indoor positioning.Next,according to the characteristic analysis results,this paper uses the appropriate nonlinear regression algorithm to build the pseudolite indoor multipath error model,and on this basis,analyzes the pseudolite indoor linear error model The error characteristics are reduced by using unscented Kalman filter algorithm.Finally,the multipath error model in pseudo satellite room is used to suppress multipath error.The main research work of this paper is as follows:(1)The multipath error characteristics of Pseudolite indoor positioning are extracted and analyzed.This paper studies the pseudo range multipath error extraction method and carrier multipath error extraction method based on static ambiguity initialization algorithm.Then,according to the theoretical analysis,simulation experiments and some measured experiments,the relationship between multipath error and time,carrier to noise ratio,geometric position and reflection coefficient of reflector is analyzed.It is concluded that multipath error is affected by geometric position of receiver and reflection coefficient of reflector,and carrier multipath error is more stable in time domain.(2)A structural multipath error modeling method for pseudolite indoor positioning is proposed.In order to construct an accurate structural multipath error model for pseudolite indoor positioning for multipath error suppression,according to the analysis results of multipath error characteristics,this paper selects the receiver coordinates as the input variables and the carrier double difference multipath error as the output variables to construct the structural multipath error model.In order to select the optimal nonlinear regression modeling method,this paper compares the modeling effect of different nonlinear regression algorithms,and tests the mathematical model with the measured data.The final results show that the indoor structured multipath error model of Pseudolite based on radial basis function support vector regression algorithm optimized by LOO method has the highest accuracy.(3)The linearization error of Pseudolite indoor positioning is analyzed.Through theoretical analysis,it can be found that the distance between the pseudolite transmitter and the receiver and the error of the receiver coordinates will affect the linearization error,and the linearization error will amplify the multipath error.This paper uses the pseudolite indoor positioning data to verify that when the receiver coordinate error is larger and the distance from the satellite to the receiver is smaller,the linearization error is larger;when the receiver coordinate error is relatively larger,the convergence speed and overall accuracy of the product free Kalman filter algorithm are better than the extended Kalman filter algorithm.(4)The multipath error suppression method of Pseudolite indoor positioning is studied.In order to solve the problem of multipath error in pseudolite indoor positioning,this paper proposes a pseudolite indoor fingerprint positioning method and a pseudolite indoor positioning method considering structural multipath error correction.The experimental test of indoor measured data shows that the pseudolite indoor positioning method based on carrier to noise ratio and carrier double difference fingerprint database is slightly better than the pseudolite indoor positioning method based on carrier double difference fingerprint database Although the fingerprint positioning method is relatively stable,the error is too large,which is not suitable for indoor positioning of pseudolites with less training sample points;the multipath error model based on radial basis function support vector regression algorithm optimized by LOO method has the best multipath error suppression effect,and the positioning accuracy is higher than other nonlinear regression algorithm models.Finally,using the pseudo satellite indoor positioning algorithm considering the structural multipath error correction,the corresponding pseudo satellite data quality analysis software is designed and developed.