Research On The Key Techniques Of Tight Integrated CDGPS/SINS Navigation System

The integration of GPS and SINS can effectively improve the shortcomings of each subsystem and enhance the performance of integrated navigation system.It is a high-precision and real-time navigate mode.With respect to pseudo-range measurements,GPS carrier phase measurements have higher accuracy,the combination of GPS carrier phase and SINS is bound to enhance the accuracy of the integrated navigation system.Differential technique can effectively eliminate the unnecessary interference terms during the process of navigation solution.And the differential carrier phase measurements(Carrier Phase Differential,CDGPS)combined with SINS is also a hot spot of GPS/SINS tight combination.Carrier phase differential measurement between epochs is a high-precision observation,the error terms are eliminated using differential technology and then combined with SINS,which can improve the availability of GPS carrier signal,and enhance the reliability of the system.On the base of GPS carrier phase differential between epochs and SINS tight combination system,this paper focuses on the following aspects:The traditional carrier phase differential technique is achieved by using the position relationship between the satellite and the receiver,while GPS carrier phase differential between epochs has no need to build base stations,it can be used as a raw GPS observation to fuse with other navigation information.This paper analyzes the observe equations of carrier phase in differential in various ways,mathematical equation of epoch-differential carrier phase(EDCP)is deduced,Taking the advantage of its high-accuracy and it has no need solve integer ambiguity,the combination with SINS and its solution relation with carrier speeds are established.In order to ensure the accuracy of carrier phase measurements,cycle slip detection and repair have to be done.For the object of this study,that is,GPS epoch-differential carrier phase,this paper analyzes the corresponding cycle slip solution.For independent single-frequency receivers,a method using receiver autonomous integrity monitoring(RAIM,Receiver Autonomous Integrity Monitoring)is presented to detect cycle slip,using carrier epoch-differential the statistical test measurement is constructed,least squares residual differential method is derived,then the repair is made by polynomial fitting,and the algorithm is verified by experiments.On the other hand,the residuals which contain cycle slip and noise can be established for EDCP.And it can detect the cycle slip and calculate the size directly.The error of carrier phase epoch-differential position is analyzed,and the positioning equation is derived.The localization results of different modes of motion are studied.Contrast with the conventional general and cumulative scheme,a circular cumulative scheme is designed,the geometry deviation during the location process using epoch-differential carrier phase is reduced effectively.The positioning accuracy is enhanced.Filter technique is a necessary mean to achieve GPS/SINS Integration.The improvement of the accuracy of filter methods can reduce the cost of hardware and enhance the performance of system.For non-linear model under large misalignment angles,the CubatureKalman filter(CKF)is introduced to integrated navigation.The basic principle of CKF is expounded.Using the Taylor series,the mean and variance of CKF is analyzed in the mathematical sense and compared with EKF.Aiming at the non-Gaussian model and negative definite covariance matrix situation,an improved scheme of CKF is made and bring it into the bicyclical framework filter,the combination of epoch-differential carrier phase and SINS is completed.Receiver capture technology has been studied,the factors affecting the performance of capture and the key indicators in the process of capture are analyzed.Based on the analysis of the importance of determinating the Doppler frequency shift,the SINS information is introduced to assist receiver to capture the satellite signal,the superiority of the algorithm is analyzed theoretically.Meanwhile,using epoch-differential to assist receiver capture is proposed and the corresponding experiments and analysis are given.