Research On Key Technologies Of PPP/INS Integrated System

Precise point positioning is a hotspot in the field of global navigation satellite systems in the 21 st century.It does not require reference stations,has a larger coverage,and is another technological revolution that followed RTK and network RTK.However,due to the limitation of ambiguity convergence time and other factors,PPP is still in the stage of research and development.Based on the characteristics of INS short-term high accuracy,PPP/INS integrated system is a feasible solution for PPP's convergence time,application accuracy,reliability and other issues.In this paper,PPP/INS integrated system and its application are discussed in detail based on the research of PPP and INS.And the INS-aided cycle slip detection and repair methods are proposed.The main innovation of the thesis is the use of INS-aided cycle slip detection method,to eliminate the impact of INS accumulative errors and rapidly recover PPP ambiguities.The main research contents of this thesis include strapdown INS,PPP,PPP/INS integrated system and INS-aided cycle slip detection and repair.Some experiments about static,dynamic,vehicle-borne are carried out.It can be summarized as follows:(1)Stapdown Inertial Navigation System.It compares the differences between strapdown and platform INS,describes some concepts such as the shape and the radius of curvature of the earth,defines the common coordinate system and attitude angles,and analyzes the strapdown INS mechanical arrangement.It specifically elaborates the algorithms of stapdown INS in e-system,including posture update,speed update and location update,and makes in-depth discussions on the initialization,coarse and fine alignment of the INS.(2)Precise Point Positioning.It elaborates various error sources and corresponding correction methods in PPP,and introduces three common models,i.e.ionospheric-free(IF)combination,semisum combination and non-difference non-combination,which are based on the mathematical model of PPP.By linearizing the PPP observation equation,it analyzes how to process in Kalman filtering.Combined with the self-developed PPP post-processing software,the IGS station data were processed statically and dynamically,and the precision can be reached to dynamic decimeter level and static centimeter level.(3)PPP/INS Integrated System.On the basis of stochastic models such as white noise,random constants,random walks and first-order Markov processes,the least-squares estimation and discrete Kalman filtering methods are discussed in detail.And PPP/INS loose and tight combination models in e-system are analyzed based on the INS space error and device error equation.It also elaborates the state and measurement equations of the combination models.(4)INS-aided Cycle Slip Detection and Repair.It utilizes high-precision INS information instead of a pseudorange to remove the satellite-receiver geometric range in the wide-lane(WL)and IF phase combinations and creates two INS-aided models.The models have a short-term high accuracy and can identify various types of small cycle slips.By fixing WL cycle slips,the method evaluates and removes the inertial accumulation error from the cycle slip detection models.It can recover the ambiguity within one epoch after a long-term GPS interruption.