Research Of SINS/CNS/SAR Integrated Navigation Technology

In modern warfare,The need for high-precision strike weapons is growing and becoming more and more important.As the cornerstone of high-precision combat weapons,Navigation system can provide navigation information for the tactical strategic missile to improve the accuracy of the weapon played an important role.However,because of the shortcomings of various navigation systems and the complexity of the combat environment considerations,a single navigation guidance system is far from being able to match the long-range ballistic missiles of high precision,high reliability,autonomy and other needs.Therefore,in order to make full use of the advantages of different integrated navigation systems,an Integrated navigation system suitable for medium and long-range ballistic missiles is designed.the way and algorithm of integrated navigation system are studied in the present and the future for a long time.In this paper,the basic working principle of the strap down inertial navigation system,the astronomical navigation system,the synthetic aperture radar system and the UKF nonlinear filtering algorithm are introduced.After introducing the basic working principle of each system and its error analysis,the estimation model of strap down inertial navigation and star sensor based on quaternion and the estimation model of strap down inertial navigation and synthetic aperture radar are established respectively.Then,in the framework of the optimal filtering theory,the extended Kalman filter is applied to different integrated navigation systems to analyze and compare the results,then provide the basis for further optimization of the combination method and filtering algorithm.For the ballistic missile in the flight process,at different stages of the force and the environment in which their flight process is complex and varied,so the design of three-stage ballistic missile flight trajectory.According to its different force conditions,the track is divided into active segment,free flight segment,re-entry of three parts.Due to the active section of the engine work and shorter working hours,so the use of pure strap down inertial guidance can be,the error does not diverge too much;because of the free flight segment work in the atmosphere,the external interference is small,so SINS/CNS combination The navigation system guides the segment and obtains high accuracy attitude angle information.Because the reentry section enters the atmosphere again,the force is complex and the speed is high.Finally,the target needs to be locked and attacked.SAR with radar altimeter integrated navigation guidance of the missile,and ultimately get a high degree of accuracy of thelocation information.In this paper,an improved UKF nonlinear filtering algorithm is proposed for the non-linearity of the integrated navigation process and the measurement characteristics of the missile-borne SAR.This algorithm overcomes the non-uniform interval characteristics and the measurement lag characteristics of the SAR during the measurement of the missile-borne SAR,so that the measurement information of the SAR can be corrected at the right time to ensure the correctness of the strap-down inertial navigation system Both SAR output and non-measured information output can be correctly identified and processed,which greatly contributes to error reduction and precision improvement.Meanwhile,SINS / CNS can not get the same interval and measurement delay,so the traditional UKF filtering algorithm can get the desired result.