Research On The Information Fusion Algorithm Of Ultra-Tightly Coupled Integrated GPS/SINS Navigation System

With the development of science and technology, all kinds of high speed and high dynamic aircraft appear layer upon layer without end, problems of how to better solve aircraft navigation and positioning in high dynamic conditions attract worldwide attentions. At present, GPS (Global Positioning System) and SINS (strapdown inertial navigation system) are two kind of commonly used navigation system. But the anti-interference ability of GPS is poor in the high dynamic environment, the tracking loop of receiver is easy to lose lock and lose the navigation ability under the infuluence of Doppler frequency shift and Doppler frequency shift rate. SINS also has problems of the increased error with time and the initial alignment. Given the complementary characteristics of both, using the navigation technology to combine them can raise the overall navigation accuracy and performance of the navigation system and meet the navigation demand under dynamic conditions.Under the National Natural Science Fund, this paper mainly make some study on the information fusion algorithm of the ultra tightly coupled integrated GPS/SINS navigation system. First of all, the paper starts from the structure of integrated navigation system, it describes the structure of several kinds of the integrated navigation system and the basic principle in detail, and has completed the work of modeling on the basis of it. On the basis of the analysis of ultra tightly coupled integrated GPS/SINS navigation system, this paper design and analyze the inertial velocity aided GPS receiver tracking loop, and finally gives the Doppler frequency shift algorithm that use satellite ephemeris, inertial position and velocity information to calculate.Then this paper propose a system framework for simulation of the ultra tightly coupled integrated GPS/SINS navigation system, develope a trajectory generator, a SINS signal simulator and GPS IF signal simulator, build the simulation platform for high dynamic integrated GPS/SINS navigation system. The paper also study on the satellite selection process which is a necessary process of GPS signal simulation process, propose a fuzzy satellite selection algorithm based on the fuzzy algorithm, this algorithm can help the simulator to select the best combination of satellites efficiently among the visible satellites.Because of the strong nonlinearity of the ultra tightly coupled integrated GPS/SINS navigation system in high dynamic conditions, this paper has conducted the research on the adaptative information fusion algorithm, do analysis and comparison between the present commonly used nonlinear filtering algorithms like EKF (extended Calman filter), UKF (unscented Calman filter) and PF (particle filter), and propose the fixed matrix square root UKF based on UKF algorithm and UPF algorithm which is combined with the advantages of PF, finally compare the performance according to the nonlinear examples and related data analysis, and choose the relatively best information fusion algorithm to apply in the ultra tightly coupled integrated navigation system.Finally, this article verify the availability and the effectiveness of the algorithm separately from the process of simulating signal and real signal collected.