Research On Key Technology Of Adaptive Fault-tolerant And Accuracy Enhancement Of INS/GNSS Integrated Navigation

In recent years,the INS/GNSS integrated navigation system has made great progress in both military and civil field,because of the increasing multiple constellations,high dynamic performance and accuracy of inertial sensor and improved INS/GNSS integration mechanism.Following the updated need of precise navigation under complicated circumstance and the development of new type high dynamic aircraft,higher requirements of precision and reliability of INS/GNSS integrated navigation system are demanded.The integration mechanism of INS/GNSS system has been gradually developed from loose integration,tightly-coupled integration to deep integration.In these integration systems,the INS is mainly assisted and corrected by GPS based on observations of pseudorange,pseudorangrate and carrier phase,which cannot fully avoid the effects of satellite clock drift,signal transmission distortion and loss-of-lock under complex circumstance.Therefore,the high-precision INS/GPS adaptive fault-tolerant integrated navigation system is essential for guaranteeing the accuracy and reliability performance of INS/GNSS integration under complicated condition.Aiming at improving the accuracy and reliability performance of INS/GNSS integrated navigation system under complex environment,the research on new type of scheme,theory and algorithms of adaptive fault-tolerant INS/GNSS high-precision integrated navigation has been developed in this dissertation.The higher capacity of obtaining stable and reliable navigation information,fast fault detection and isolation,adaptive judgment and optimization of observation under high dynamic and complicated environment are expected on the basis of research work in this dissertation and finally the precise and reliable navigation performance can be realized.The research contents include: fast fault detection method of INS/GNSS integration based on LSSVM,multiple fault detection,isolation and remodeling method of INS/GNSS integration based on subset p-value test,adaptive robust integrated navigation method based on smoothing pesudorange and online noise modelling,fault-tolerant INS/GNSS-PPP integrated navigation algorithm based on dynamic cycle-slip compensation.Detecting slowly growing fault in real-time is critical to improve reliability of INS/GNSS integrated system.Autonomous integrity monitoring by extrapolation(AIME)method is usually used for slowly growing fault.However,innovation of navigation filter used for calculating test statisticsthe in AIME is affected by error tracking effect,which will bring time delay of fault detection.IV To improve the realtime ability of slowly growing fault detection,Least Square Support Vector Regression(LSSVR)belongs to data driven method is used in this paper.To avoid error tracking of filter,a forecast filter innovation regressed by LSSVR is used for test statistics calculation in AIME,which work with system filter in parallel mode.Simulation results show that the proposed mtheod can improve real-time ability of slowly growing fault.Along with rapid expansion of gloabal navigation satellite system in the world,on orbit satellite numbers increase greatly.In the same time,the probability of multiple outliers simultaneous happen in observations of INS/GNSS integrated navigation system will increase.How to detect,isolate multiple faults in observations of INS/GPS integrated system and evaluate observe quality is important to imprve system reliability.A new fault detection method based on subsets P-value test is proposed for the purpose of detecting multiple faults.Quality value of observations can be obtained by the proposed method.Based on quality value,fault observation can be isolated faults and non-fault observation quality affected by faulty ones can be evaluated.After that,the INS/GNSS system reconfiguration scheme is proposed to improve precision more.To improve navigation precision of the INS/GPS tightly-couple integrated system,high precision observation is needed.Aiming at resolving the probloms that pseudorange observation has high-level noise and integer ambiguity calculation is needed in carrier phase observation,a new kind of adptive robust INS/GPS integrated algorithm based on carrier phase smoothing pseudorange is proposed in this paper.The system model of carrier phase smoothing pesedorang observation by time differential is built and the navigation system scheme is designed.Furthermore,for smoothing pesudorange observation has strong non-Gaussion characteristics at the beginning of smoothing,the noise characteristics has been analyzed and modeled to online estimati nosie parameters in system filter.Combining noise model with robust weight factor,system filter can realize robust estimation in the condition of interference or cycleslip.The feasibility of INS integrating with Precise Point Positioning(PPP)is researched in this paper.The system model of INS/GPS-PPP has been built up and the performance of INS/GPS-PPP integrated system is tested and analyzed.Furthermore,a self-repairing adaptive filter especially for the condition of cycle slip happens in carrier phase observation is also proposed.The cycle slip is introduced as state variable in system fliter model which is corrected by filter feebback loop.Meanwhile,a parallel filter used for cycle slip estimation is run for parameter adjustment.Test and simulation show that the proposed system has higher precision and reliability.Based on the above theoretical research for precision enhancement and reliability enhancement of INS/GPS integrated integrated navigation system,this paper investigates digital simulation testing system and experiments vehicle running test.The propose system scheme and algorithms are tested both in simulation and experiments.The research work of this paper are helpful for aircraft flight naviation,which have important theoretical meaning and engineering valure.