Research And Software Implementation Of Key Technologies For PPP/INS Integrated Navigation In Urban Harsh Environment

In today’s society,emerging industries such as autonomous driving and mobile robots have shown explosive growth,leading to an increasing demand for highprecision and high-reliability positioning services,particularly in rapidly developing urban areas where high-precision positioning technologies are needed to support the construction of smart cities and intelligent logistics.However,the complexity of urban environments presents challenges to the accuracy and reliability of single navigation and positioning methods,such as Global Navigation Satellite System(GNSS).As a result,the fusion of information from multiple navigation systems has gradually received attention and research from relevant professionals.Against this background,this thesis aims to improve the accuracy and reliability of navigation information in harsh urban environments,and conducts in-depth research and discussion on the integration of precise point positioning(PPP)and inertial navigation system(INS)under vehicle environments technology.The main research contents are as follows:(1)Theoretical models related to inertial navigation and precise point positioning were derived in detail.Based on two observation models of PPP,a multi-system PPP/INS loosely coupled model(LC-PPP/INS),a multi-system ionosphere-free PPP/INS tightly coupled model(IF-PPP/INS),and a multi-system undifferenced and uncombined PPP/INS tightly coupled model(UC-PPP/INS)were constructed.The positioning performance of the constructed models was verified and analyzed using actual vehicle-mounted data.The experimental results show that: 1.The positioning accuracy of the multi-system PPP/INS model is significantly higher than that of the single-system PPP/INS model;2.Thanks to the mutual assistance of GNSS and INS in error correction,the positioning accuracy of PPP/INS tightly coupled is slightly better than that of loose combination in open environments;3.Under the same satellite system participation,the IF-PPP/INS model has the same positioning accuracy as the UC-PPP/INS model.(2)To address the problem of decreased positioning accuracy and stability of PPP/INS coupled navigation systems in urban harsh environments,this thesis constructed a partially integrity-constrained PPP/INS tightly coupled model and proposed an improved Sage-Husa adaptive filtering algorithm based on PDOP values.The constructed PPP/INS enhancement model was verified and analyzed using actual vehicle-mounted data with poor observation conditions.The experimental results show that: 1.When the satellite is briefly out of lock for 60 s,the PPP/INS enhancement model based on non-integrity constraints can still ensure meter-level positioning accuracy and effectively suppress the error accumulation of the combination navigation system during the out-of-lock period.2.Compared with the traditional Sage-Husa adaptive filtering algorithm,the position accuracy is improved by 62.0% by using the PDOP-based Sage-Husa improved adaptive algorithm proposed in this thesis,and the overall stability of the filter is better.(3)A multi-system PPP/INS coupled navigation processing software,MPINav,was designed and developed.The software is based on the theoretical models and algorithms constructed in the previous sections and incorporates forward-backward filtering and smoothing algorithms.The main functions of the software include static PPP solution,dynamic PPP solution,multi-system PPP/INS loosely coupled solution,multi-system PPP/INS tightly coupled solution,and result visualization analysis.The software has good scalability,maintainability,and human-computer interaction experience.Finally,the positioning performance of the software was tested and verified using a set of static data and a set of dynamic vehicle-mounted data.