Research On Estimation And Application Of LOS Rates For Strapdown Seekers

The exploration vehicles with strapdown seekers(EKV)use the seekers to explore the target and approach it in the termina l phase by a guidance law,and as an important constituent part of the guidance law,the line of sight(LOS)rates are of great significance to the guidance performance while their estimation precision are improved.Based on a strapdown seeker of the exploration vehicle,this dissertation focuses on the estimation and application of the LOS rates in the endgames.The estimation algorithm design of one exploration vehicle,the LOS rates reconstruction and estimation of two cooperative exploration vehicles,and the 6-DOF modelization and simulation of the terminal guidance are studied in this thesis.The main works are summarized as follows:The LOS rates estimation algorithm based on the Current Statistical Model(CS)and Interacting Multiple Model(IMM)for one exploration vehicle is proposed.1)The body LOS angles measured are decoupled to get the inertial LOS angles as the virtual measurements when filtering,and then the virtual observation equation as well as the observation covariance matrix are constructed.2)The Constant Acceleration Model(CA)and the CS Model are introduced as the state equations of the LOS rates estimation,and the two parameters in the CS model are modified based on the analysis of the model tracking performance.3)The LOS rates estimation algorithm based on the IMM model composed of CA and CS models is proposed to eatimate the LOS rates,and the filtering performance of the proposed algorithm as well as other algorithms are tested by comparations in the simulation scenarios of maneuvering and nonmaneuvering target.The LOS rates reconstruction and estimation of two cooperative exploration vehicles are studied.1)The distribution relative to the target and the data fusion strategy of two cooperative exploration vehicles are determined.2)Based on the established relative vehicle-target motion model and the extremum principle,the rough position expression of the target is derived and the position error is analyzed via simulations.3)The rough position of target is used to reconstruct the new inertial LOS between target and vehicles.Then the new LOS angles are filtered and the LOS rates estimation is compared with that of only one exploration vehicle in the scenarios of exploring target,from which the improvement of the LOS rates estimation accuracy is studied.The 6-DOF modelization and simulation of the terminal guidance are conducted.1)The 6-DOF missile system with the heart,the measurement system and the guidance and control system,is established.The attitude decoupling a nd control strategy is studied.2)The ZEM calculation method is introduced and the major factors which impact on the ZEM uncertainty are analyzed.3)The simulations of attitude controling and ZEM in endgames are conducted.The guidance precision of one o nly exploration vehicle and two cooperative exploration vehicles are analyzed and compared based on the simulation results.This dissertation focuses on the estimation and application of the LOS rates in the endgames to the exploration vehicles with strapdown seekers.The estimation algorithms of only one exploration vehicle and two cooperative exploration vehicles are proposed and studied,respectively.The attitude controling and guidance precision for exploration vehicles in terminal phase are simulated and analyzed.The achievements of this dissertation are valuable whether in theoretical research or engineering application.