Midcourse Guidance Strategy And Method Of High Speed Maneuvering Target Interception Based On Intercept Geometry

With the increasing maturity of the technology of scramjet engine, the special strategic value of near space has received wide attention. And as a precision strike weapon, near space hypersonic aircraft has been developed rapidly. So it is of great importance to develop the defense technology of hypersonic aircraft. There are three main difficulties in the defense of hypersonic aircraft.(1) The high speed of hypersonic aircraft has reduced the detection probability of early warning system and placed higher demand on the speed of the interceptor.(2) The uncertain maneuverability of hypersonic aircraft has brought great difficulty to the interception system.(3) Optical detection faces complex aero optical effect in near space and aerodynamic heating effect can also be generated when the interceptor is flying at high speeds, which have increased the detection difficulty of hypersonic aircraft. Therefore, the intercept geometry which is formed by all possible intercept points is derived in this paper by considering all possible velocity directions of the target. In order to improve the interception accuracy of hypersonic targets, the midcourse and terminal guidance handover conditions of the interceptor are analyzed based on the intercept geometry and the midcourse guidance law is designed using Gauss pseudospectral method. The main research of this paper contains the following aspects:Firstly, according to the relative motion between the missile and target, the all possible intercept points which form the intercept geometry are derived by considering all possible velocity directions of the target. The establishment of the intercept geometry can lay the foundation for the analysis of the midcourse and terminal guidance handover conditions of the hypersonic target interceptor.Secondly, the midcourse and terminal guidance handover conditions of the hypersonic target interceptor are analyzed based on intercept geometry. According to the research of the intercept geometry, the precondition for intercepting the hypersonic targets which is called the interception condition is given. In order to intercept the target successfully or meet the requirements of the miss distance, the position condition and angle condition to be satisfied at the handover from the midcourse to terminal guidance are derived. And the method is verified by simulation.Thirdly, the midcourse guidance law of the hypersonic target interceptor is designed based on Gauss pseudospectral method. The design of midcourse guidance law of the interceptor can be transformed into an optimal control problem by considering the midcourse and terminal guidance handover angle condition, handover distance, LOS angular rates as the constraints and the integral of the squared control input multiplied by reciprocal of time-to-go to the power of n as the performance criterion. The optimal control problem can be transformed into a nonlinear programming problem by adopting Gauss pseudospectral method and the solution of the optimal control problem can be derived by solving the nonlinear programming problem. The effectiveness of the midcourse guidance law is verified by simulation. In the actual guidance process, the guidance command of midcourse guidance law is required to be the discrete value that can be output by the trajectory control engine. In this paper, we put forward two methods which are the direct method and the threshold method respectively based on the consideration of the characteristics of the trajectory control engine. The effectiveness of the two methods is verified by simulation.Finally, aiming at different forms of target maneuver, the simulation analysis is carried out on the whole process of the midcourse guidance and the midcourse and terminal guidance handover. In the process of simulation, the midcourse guidance process of the interceptor is divided into two kinds of situations, which are without consideration of the characteristics of the trajectory control engine and considering the characteristics of the trajectory control engine. The simulation results show that the hypersonic target interception scheme proposed in this paper can ensure the interceptor intercept the target successfully or meet the requirements of the miss distance.