Guidance Laws Of Homing Missiles Based On Dynamic Surface Control

New endo-atmospheric interceptor missiles are required to intercepte stealthfighters, great dive attacked guided bombs, hypersonic cruise missiles and other fastand maneuvering targets. The autopilot dynamics of endo-atmospheric missiles is animportant factor to cause the final miss distance. In this dissertation, some homingguidance laws are designed based on dynamic surface control method with consid-eration of the autopilot dynamics.In practical applications, the autopilot dynamics can be approximated as secondorder dynamics. The model of a guidance system accounting for the second-orderdynamics of missile autopilot is established in plane. Based on this model, a newguidance law accounting for the second-order dynamics of missile autopilot is de-signed using the dynamic surface control method. Furthermore, based on the targetand the missile dynamics in three dimensional coordinate, a three dimensionalguidance model accounting for the second-order dynamics of missile autopilot isestablished. A new three dimensional guidance law accounting for second-orderdynamics of missile autopilot is then designed using the dynamic surface controlmethod. The above two guidance laws avoid the occurrence of high-order deriva-tives of line of sight angle in their expressions such that they are easy to implementin practical applications. Simulation results show the guidance laws are effective incompensating for the bad influence of the autopilot dynamics on guidance accuracy.They ensure exact guidance results for intercepting both non maneuver targets andmaneuvering targets, even if a target escapes in a great and fast maneuver and themissile autopilot has a relatively large lag.In order to destroy some specific targets, two guidance laws with terminal im-pact angle constraint are designed. Under the condition that the terminal flight pathangles of the target can be predicted, the control of terminal impact angle wastransformed into the control of the final line of sight angle and then a guidancemodel with terminal impact angle constraint is established. Based on this model, asliding mode guidance law is designed to intercept maneuvering targets with termi-nal impact angle constraint under the assumption of an ideal missile autopilot. Thesliding mode guidance law ensures that the line of sight angle and its rate of theguidance system converge to the sliding mode in finite time. The line of sight angleexponentially converge to a desired value and line of sight angular rate exponen-tially converge to zero after entering the sliding mode at the final time of the guid-ance process. This guidance law can be used to cases where the missile autopilot has a fast response. Furthermore, accounting for the second-order dynamics of missileautopilot, a new guidance law with terminal impact angle constraint is designed us-ing the dynamic surface control method. Simulation results show that this guidancelaw is effective in intercepting maneuvering targets and compensating for the mis-sile autopilot dynamics. It is able to guide a missile to intercept a maneuver targetwith a desired angle and a small miss distance. Because there is no occurrence ofhigh-order derivatives of the line of sight angle in the expression of the guidancelaw, it is apt to be implemented in practical applications.Since a missile’s jerk cannot be directly measured in practice, two ob-server-based guidance laws accounting for the missile autopilot as second-orderdynamics and observer-based guidance law with impact angle constraint are de-signed using the dynamic surface control method and observer design theory. Sta-bility of the guidance system with such a guidance law is proved. Simulation resultsshow that the proposed guidance law is effective in intercepting both non maneu-vering targets and maneuvering targets, and compensating the dynamics of the mis-sile autopilot. The proposed guidance law is able to guide a missile to accuratelyintercept targets with great maneuvers in the presence of a large autopilot lag. Theguidance law does not use the high-order derivatives of the line of sight angle.Based on the relative motion equation of missile and target in plane and thesecond-order missile autopilot dynamics, through properly selecting the slidingmode, a guidance law with finite time convergence is designed using the slidingmode control method and finite time convergence control theory. Stability of theguidance system with the proposed guidance law is analyzed. The guidance systemconverges to the sliding mode in finite time, and then the states of system in thesliding mode exponentially converge to zero. Simulation results show that the pro-posed guidance law is effective in intercepting non maneuvering targets and ma-neuvering targets, and compensating the dynamics of the missile autopilot. Theguidance system converges in finite time before the final time of the guidance proc-ess. The high-order derivatives of the line of sight angle are avoided in the expres-sion of guidance law such that it can be implemented in practical applications.