An Estimation Algorithm For Target’s Line-of-sight Rate Considering Exo-atmospheric Kill Vehicle Body Vibration

Line of sight(LOS) rate has a direct effect on terminal guidance’s accuracy of exo-atmospheric kill vehicle(EKV), which is of great importance when interceptor uses proportional guidance law. To estimate target’s inertial LOS rate, this dissertation focuses on vibration of missile body, reconstruction of inertial LOS angle and estimation algorithm of LOS rate. The main results achieved are summarized as follows:Elastic vibration modeling of missile body is studied 1) A finite element model(FEM) is constructed according to simplified EKV structure and the model is properly compartmentalized. 2) Modal analysis and transient response analysis are carried on based on the FEM of EKV. By dynamic response analysis, the response data of vibration is obtained when interceptor is shocked by lateral thrusters. 3) Frequency response analysis is conducted based on the FEM of EKV. The transfer function of vibration is built, whose validity is verified in time domain.The reconstruction methods of LOS angle and LOS rate are investigated. 1) Based on transformation of coordinates, the nonlinear mapping relation between body LOS and inertial LOS angles is built up. 2) Elastic body’s attitude, the very point where strap-down seeker is mount on the body, can be updated in real time by the method put forward in the dissertation. 3) Taking full advantage of body’s attitude, the methods of inertial LOS angle and LOS rate’s reconstruction are built up based on the nonlinear mapping relation.Estimation algorithm of LOS rate is studied. 1) Virtual measurement information is introduced when filtering. Observation equation and covariance matrix are constructed based on virtual measurement information. 2) Using spline function to describe inertial LOS change with time, estimation algorithm of LOS rate is studied based on spline filtering. 3) Spline filtering under the frame of Interacting Multiple Model(IMM) algorithm is applied in estimation of inertial LOS rate with target non-maneuvering and maneuvering respectively.The main error factors estimating LOS rate are analyzed. 1) Taking transient response of missile body into account, the influence of interceptor body vibration on the reconstruction of inertial LOS is studied. 2) Assuming the body LOS angles of terminal guidance are very small, measurement error propagation can be described by the approximate formula, whose accuracy is verified by Monte-Carlo simulation. 3) The effectiveness of algorithm to estimate LOS rate is evaluated by Mean Square Error Lower Bound(MSELB), and the main error factors which have an effect on estimation are analyzed.The study is based on body LOS angles,which is obtained by strap-down seeker directly. In the light of characters of EKV body vibration, the method of estimating target’s inertial LOS rate is proposed by associating spline filtering and Interacting Multiple Model algorithm. The achievements of the dissertation are valuable whether in theoretical research or engineering application.