On Guidance Law Of Air Defense Missile Based On Sliding Mode Variable Structure Control

With the continuous development of air defense missiles, the problem on control of air defense missile becomes more and more important, and there are more and higher requirements of stability and pointing accuracy problem of air defense missile. The guidance system of missile plays an important role in missile system. Since the classical guidance law can not satisfy the more and more complicated conditions in air intercept, so it is a meaningful work to design a precision terminal guidance law.The thesis deals with the guidance law of air defense missile in the sliding mode variable structure control, which has excellent robustness to system uncertainties and external disturbance. This thesis accepts universal approximation of adaptive fuzzy systems to get the guidance law which is not easy to achieve on engineering applications. This general design of a guidance law with constrained angle in the intercept course achieved accurate interception of target. The main work includes:The necessary coordination systems and the transformation relations among them are given. The characteristics of control method are described and the traditional geometric relationship of missile guidance law is analyzed, the mathematical model relay to kinematics in used in guidance law is deduced.Based on the context of knowledge, first, according to the characteristic of the air to air missile, for the accuracy and engineering application, robustness of the sliding-mode variable structure guidance law is designed. Take the maneuvering of target as an external disturbance, so it is unnecessary to know the trajectory of target. According to the rate of change of line of sight angular, the problem of seeker technology is resolved.Second, taking into account the controller is complex of the general system, using fuzzy adaptive systems universal approximation coordinate with sliding mode features of the advantages of robust, the ideal controller is designed. Simulation results show that the controller approach works well, and presents a good dynamic performance of output, which can meet the requirements of air defense missile design.Then, considering when the missile hit the target, the influence of incident angle effects lethality, this thesis uses sliding mode variable structure control theory to design a kind of angle constraints with a terminal guidance law. Based on the robustness of global sliding mode variable structure control through the full process, the sliding mode variable structure guidance law is designed. The simulation results show that the design have achieved the desired effect. At last, summarize the works of this thesis, and point out the direction for further research.