Missile Terminal Guidance Law With Impact Angle Constraint

The rapid development of high-tech put forward higher requirements on missile guidance accuracy.The terminal guidance law as one of the key technologies that influence the precision of guidance gradually become the hot topic of today's research.With the emergence of large maneuvering targets such as hypersonic aircraft,the missile terminal guidance law is required to have certain anti-disturbance performance.In order to improve the killing effect of missile combat,people hope that the missile can hit the target in the desired angle,so in the design of the guidance law we need to consider the impact angle constraint problem.On the other hand,the missile system inevitably has the characteristics of the saturation non-linearity of the actuator and the dynamic delay characteristic of the autopilot.In addition,due to the high maneuverability of the target and the constraint angle of the terminal,it is necessary to lead the seeker beyond the field of view constraint.Thus we also need to consider the seeker field of view constraints.Therefore,it is very important to study the missile guidance law under various disturbance and constraint conditions.The main contents of this dissertation are as follows:Aiming at the problem of missile intercepting maneuvering target and taking the longitudinal interception plane as an example,the relative motion model of the missile target is established under the line of sight coordinate system.The relative distance and the line of sight are used to describe the relative motion position of the missile.The geometric definition of trajectories of the missile and target,the relative distance and the line of sight.Then,the mathematical analysis and assumptions of the impact angle constraint and the acceleration constraint are carried out,while the guidance model under various constraints is established.When considering the problem of impact angle constraint in the process of missile intercepting maneuvering target,the asymptotic convergence guidance law is designed based on state feedback design.When considering that the target maneuver information is often unpredictable,the disturbance upper bound is unknown.Thus the classical nonlinear disturbance observer finite time guidance law is designed with the non-singular terminal sliding mode and the super-twisting disturbance observer.Then the stability of the system is analyzed by Lyapunov stability theory.When considering the problem of impact angle and acceleration constraints in the process of missile intercepting maneuvering target,the adaptive guidance law is designed based on the backstepping theory.The adaptive law is used to estimate the saturation non-linearity and disturbance of the system.The system is asymptotic stability in the presence of acceleration saturation.When considering the dynamic delay of the autopilot,the impact angle constraint and acceleration constraint,the the guidance law is designed by using the command filter backstepping method.Finally,the simulation results show that the proposed guidance law can make the missile accurately hit the target.Further considering the seeker's field of view constraint,the problem of the seeker's field of view constraint is analyzed in detail.The mathematic model of the seeker's field of view constraint is established.The guidance law considering multiple constraints is designed through the relationship between the seeker's look and the acceleration of the missile.Finally,through the simulation,it is proved that the guidance law can ensure that the seeker's look angle is always kept within the field of view during the whole guidance process.