Research On The Fast Positioning Technoique Of Pseudolite RTK In Indoor Dense Multipath Environments

The Pseudolites(Pseudolite,PL)were originally used as a supplement to the GNSS(Global Navigation Satellite System,GNSS)positioning system,mainly used to improve the GNSS spatial layout and improve positioning accuracy.At present,pseudolites are also used for independent network positioning,and indoor positioning is an important application scenario of pseudolites.Indoor pseudolite positioning still faces many challenges,among which multipath effect is an important factor restricting the high precision indoor positioning of pseudolite,especially in indoor dynamic conditions,multipath effect is more likely to cause instantaneous cycle slip of carrier observation value and pseudolite receiver Shortterm lock loss,so how to reduce the impact of multipath effects is the key to achieving highprecision,continuous and reliable indoor positioning.In the application scenario of indoor single-frequency differential carrier phase positioning,in order to solve the problem of how to reduce the impact of multipath effects on positioning applications,this thesis focuses on the dynamic single-frequency cycle-slip detection and repair algorithm and the fast solution of the double-difference cycle after the loop is out of lock.The algorithm of ambiguity and recovery positioning is studied,and then the traditional three-difference algorithm of carrier phase is studied and an improved method is proposed.The performance before and after improvement is analyzed,and the feasibility of applying to indoor positioning is discussed.The specific content is as follows:Aiming at the instantaneous cycle slip of receiver carrier phase observation value caused by multipath effect in the process of indoor dynamic positioning,a dynamic singlefrequency cycle slip detection and repair algorithm is studied by using the method of Doppler constant velocity.Its focus is on the calculation of the integral Doppler prediction value,and the calculation of the prediction value is realized by using the kinematic parameter method and the fitting method respectively.The correctness of the algorithm is verified by simulation,and the simulation results show that both methods can effectively detect and repair cycle slips.Aiming at the situation that the positioning application cannot work continuously and stably due to the short-term loss of lock of the receiver caused by the serious multipath effect in the process of indoor dynamic positioning,a fast positioning algorithm of RTK assisted by inertial navigation is studied by using the method of multi-sensor fusion.Its focus is on double-difference ambiguity settlement on-the-fly and information fusion and update between inertial navigation and receiver.The floating-point solution filter is used to complete the double-difference integer ambiguity on-the-fly,the inertial navigation and pseudolite data are fused through the Kalman filter,and the zero-speed correction is implemented for the inertial navigation.The research results show that under certain conditions,the pseudolite receiver RTK double-difference positioning algorithm using INSassisted loss-of-lock processing can quickly and reliably solve the floating-point solution of the integer ambiguity to quickly restore the positioning application.Aiming at the limitations of the double-difference algorithm in indoor positioning,the analysis and improvement of the indoor triple-difference positioning algorithm are carried out.Referring to the indoor radio positioning model,the pseudolite indoor triple-difference carrier phase algorithm is studied,and the feasibility of the algorithm is verified by simulation.The analysis of the positioning results found that there is a problem of error accumulation in the traditional three-difference algorithm.Aiming at the problems existing in the three-difference algorithm,an indoor three-difference algorithm is improved.Reference for positioning.The research shows that under certain conditions,the improved triple-difference algorithm is used in indoor pseudolite system,which can realize the positioning solution simply and quickly.