Key Technologies' Improvement Of GPS/INS Ultra-tightly Integrated Navigation System

At present,the scope of navigation applications is becoming more and more extensive,and persons' requirements on the navigation system's accuracy,dynamic performance and robustness continue to increase.High positioning accuracy of GPS(Global Positioning System),but it is easy to make the loop to lose lock when high dynamic moving.INS(Inertial Navigation System)has high dynamic performance and good frequency characteristics,while its errors accumulate over time.GPS/INS integrated navigation technology not only can enhance the robustness of the GPS receiver,but also can correct the cumulative error of inertial navigation system well,so it has become a hot topic in the field of navigation.This paper described the research status of the development of GPS/INS ultra-tight integrated navigation system,listed basic structures and characteristics of GPS/INS combination models,analyzed the data fusion method in the integrated navigation system,and deduced state equations of the ultra-tight integrated system,then this paper introduced the process of GPS ambiguity resolution,which laid the foundation for the research of key technologies of GPS/INS ultra-tight integrated navigation.According to the typical architecture and problems of GPS/INS ultra-tight integrated navigation system,this paper improved some key technologies in it.Firstly,a designed method of combination filter based on filter update was proposed and simulated by matlab,simulation results showed that observed output value agreed well with estimated value.Secondly,aiming at reducing accumulation errors of the inertial navigation system,an optimization algorithm based on the low speed motion state of inertial navigation parameter detection was proposed in this paper,And the fitting algorithm was applied to the elimination of the singular points generated by the inertial solution.Through simulation and actual tests,it was shown that this paper's optimization measures can effectively reduce the inertial accumulation errors.Finally,the setting rule of Ratio-value in GPS ambiguity recognition was explored,summed up and generated a query table of Ratio set value by using the method of statistical analysis.Through actual tests,it was shown that the Ratio value obtained in the query table,which was applied to the solution of GPS ambiguity,can reduced initial time of GPS effectively and has some practical application value.According to above improvements,this paper integrated a hardware test platform of GPS/INS ultra-tight integrated navigation system in order to verify the rationality and effectiveness of the improved work.Testing results proved that data static errors of the hardware platform were less than 50 cm,and low-speed dynamic errors were less than 2.5 m,so this test platform achieved the goal of improving the work effect,and had certain practical application value.