Research On Missile-borne SINS/GPS/SAR Integrated Navigation Algorithms

Cruise missiles have played an increasingly important role in modern warfare since the Gulf War.The core of missile technology is precise guidance technology,and accurate guidance information is the key to precise guidance.The single navigation system has been difficult to meet the requirements of missile for high precision performance,so the missile integrated navigation system has become the main development direction of missile guidance technology.In this paper,the filtering algorithms of SINS/GPS/SAR integrated navigation system and integrated navigation system are studied in the background of cruise missile.The navigation principles of SINS,GPS and SAR and the working principles of SINS/GPS/SAR integrated navigation system are introduced.The mathematical model of SINS/GPS/SAR integrated navigation system is established.For data fusion of multi-sensor output,centralized filtering structure and federated filtering structure are introduced.According to the advantages of federated filter structure,such as small computation and strong fault tolerance,a federated filter structure without feedback is designed for Missile-borne SINS/GPS/SAR integrated navigation system.The essence of integrated navigation system is non-linear.In this paper,Cubature Kalman Filter(CKF)is used to filter and estimate the output data of navigation system.In view of the singularity of error covariance matrix in the iteration process of CKF algorithm,the error covariance matrix is decomposed by QR to form Square-root Cubature Kalman Filter(SCKF),which guarantees the positive definiteness and symmetry of error covariance matrix.The Strong Tracking Filter(STF)algorithm is combined with SCKF algorithm to enhance the robustness of the system when the system state is prone to mutation and the system model does not match the reality.In view of the fact that the fading factor easily affects the estimation accuracy of the strong tracking algorithm in the normal state of the system,this paper proposes an improved Strong Tracking Square Cubature Kalman Filter(ISTSCKF)algorithm by improving the calculation method and parameter selection of the fading factor.Under normal circumstances,the error probability of strong tracking algorithm can improve the estimation accuracy of filtering algorithm.Through the design of missile trajectory generator,the SINS system,SINS/GPS integrated navigation system,SINS/SAR integrated navigation system and SINS/GPS/SAR integrated navigation system are simulated,and the simulation results are compared and analyzed.The results show that the SINS/GPS/SAR integrated navigation system can improve the navigation accuracy as a whole compared with the single navigation system and the two combined navigation systems.Aiming at the sudden change of SINS/GPS/SAR integrated navigation system state and the mismatch of system model,SCKF,STSCKF and ISTSCKF algorithms are used to simulate respectively.The validity of the proposed filtering algorithm is verified by comparing and analyzing the error curves of missile speed,position and attitude.