Research On High Precision Navigation Technology Based On Multiple Civilian GPS Data Fusion

With the development of science and technology,more and more requirements have been put forward on the reliability,fault tolerance and accuracy of navigation system.For a navigation system,GPS positioning technology plays a vital role and is a key factor in determining navigation accuracy.For general civil GPS systems,a single GPS has the problem of low navigation and positioning accuracy.Therefore,it is of great significance to apply multiple low-cost GPS data fusion to obtain high-precision positioning and navigation accuracy.On the other hand,the navigation system may generate a fault due to factors such as changes in the external environment during operation,which will degrade the navigation accuracy of the system or make the system invalid.Therefore,how to study an effective fault detection technology,which can predict the occurrence of faults in advance and take countermeasures to improve the fault-tolerant performance of the navigation system is very important.This article focuses on the navigation problems of unmanned platforms such as unmanned aerial vehicles(UAV)and small robots.Multiple civilian GPS receivers and multi-source information fusion technology are used to design an optimal asynchronous fusion algorithm to improve the positioning of low-cost GPS receivers.At the same time,in order to further improve the positioning accuracy of the UAV navigation system,a dual GPS/SINS integrated navigation positioning system based on a federated filter is designed.Aiming at the problem of increased system failure rate caused by the increase in the number of sensors,this paper designs a fault-tolerant integrated navigation system,which can detect the fault of the sensor subsystem.The main research contents of this article are as follows:(1)First,a brief overview of the research background of UAV navigation and the current research status at home and abroad is given.Then,under the requirement of low cost,aiming at the problems of low positioning accuracy and serious data drift of a single GPS receiver,an optimal asynchronous fusion algorithm based on Kalman filter is proposed by installing multiple GPS receivers on the UAV,which can make full use of the positioning data of multiple GPS receivers to reduce the phenomenon of data drift,thereby improving the positioning accuracy of the UAV.The experimental verification shows the effectiveness of the algorithm.(2)To further improve the positioning accuracy of the UAV navigation system,inertial navigation is introduced based on satellite navigation.By analyzing the error of the inertial navigation system and taking advantage of the high short-term accuracy of inertial navigation system,a dual GPS/SINS navigation and positioning system based on a federated filter with strapdown inertial navigation system as the public subsystem is designed.The adaptive adjustment of the distribution coefficient improves the positioning accuracy of the system.(3)To reduce the influence of sensor faults on navigation accuracy and improve the robustness of the navigation system,an adaptive fault-tolerant algorithm based on the maximum likelihood criterion is designed.This algorithm uses the residual Chi-square test to detect sudden faults and uses the Boole decision-maker in the fault detection module to set the fault subsystem to realize the isolation of sudden fault subsystem.Aiming at the problem that slow-changing faults are difficult to be detected in the early stage,by feeding back the global optimal estimation of the system to the subsystem,the true residual of the subsystem is constructed.By using the sliding window technique and maximum likelihood criterion,the residual variance of the subsystem is estimated,and the estimator of subsystem measurement noise variance is obtained.Through the correction of the measurement noise in the subsystem,the slow-changing faults in the subsystem are suppressed,thereby improving the fault tolerance and robustness of the entire system.Finally,through the dual GPS/SINS integrated navigation test,the positioning accuracy of the system and the performance of the fault-tolerant algorithm are verified,which shows the feasibility of the algorithm.