Sliding Variable Structure Control For Cruise Missile With Direct Force/Aerodynamices Combination

Cruise missile, being an important number of tactical missiles, is facing manychallenges since the combat environment is getting more complicated. As a result,some new tasks are put forward for developing the cruise missile, including: how toenlarge the ?ight airspace and improve the maneuverability to meet the new charac-ter of operational goal; how to implement concealed trajectory, avoidance and pen-etration to improve the survivability; how to save the engine fuel, increase availableloading and enlarge fight radius to improve the integral performance of the missile.Under this background, we proposed the method of compound control with the directforce/aerodynamic. Based on this idea, in this thesis, we give some theoretical resultsaccording to sliding mode variable structure control of missile compound control byusing direct force/aerodynamic. The main contents include:Firstly, according to the effect of direct force control moment and aerodynamiccontrol moment, we give the analysis and verification from the theorem and simula-tion. Based on this, we propose the control strategy of instruction decomposition. Thisstrategy, mainly depending on aerodynamic control, applies single aerodynamic con-trol under the situation of low altitude ?ight with high air density. With the increase of?ight altitude, since the aerodynamic moment provided by pitch rudder can not main-tain the balance of missile body, we apply the engine thrust control, providing directforce compensation. This kind of control strategy transforms the coordination controlproblem of two kind of control variables into simple single control problem. Hence,it is simple and easy to be applied by engineering. Based on this strategy, we proposethe indirect design method of direct force control. By using this indirect method, wecan give analysis and design for direct force/aerodynamic compound missile controlas for conventional cruise missile.Secondly, we present a linear multi-sliding mode recursive variable structurecontroller design method. This method designs multiple transitional sliding surfaceout of target sliding surface, such that the system state move gently when it enterssliding surface from reaching stage. When applying sliding mode variable structurecontroller with single sliding surface, the increase of the ?ight height and the decrease of the air density will bring pneumatic efficiency. As a result, the actuator will saturateuntimely. Our proposed method can overcome this defect.Thirdly, we present a sliding mode variable structure control method based oncontrol parameterization enhancing technique. In order that the real overload signalis able to follow the instruction overload quickly, and the response velocity can beimproved, the reaching stage of the sliding mode variable structure control is dividedinto three segments: acceleration accessing segment; speed-keeping segment; deceler-ation buffer segment. Under this decomposition, on the one hand, the system state canreach the sliding surface quickly; on the other hand, the saturation problem is avoidedwhen the system state is moving to sliding surface. However, this decomposition alsochange the original system into switched system with the switching time unknown.It is difficult to solve the optimal control problem of the switched system with theunknown switching times by using existing optimization routine directly. Thus, usingthe control parameterization enhancing technique, the variable switching time is con-verted into fixed time, and the original problem is transformed into a standard optimalparameter selection problem, which can be solved by existing optimization technique.Furthermore, according to the characteristic of mathematical model for missilelarge airspace maneuvering, by designing the sliding mode equation, the uncertaintyof dip angle resulted from the missile space maneuvering is changed into the parame-ter perturbation of the system matrix. Thus the sliding variable structure controller isused to keep the performance of the system due to its perturbation invariance.Finally, for the sliding parameter of sliding mode variable structure controller,we give the gain scheduling design method. This method first apply the design lawof fuzzy controller and adjust the sliding parameter of sliding mode variable structurecontroller according to different system state. Then, the characteristic point is takenfrom characteristic function of fuzzy control law to form characteristic set and thecharacteristic points are interpolated on the characteristic set, obtaining the gain lawof sliding parameter. In addition, by using Ajjzerman stability method, we prove thestability of the proposed controller. Under this controller, the system has the fastresponse speed without the dithering, which can not be eliminated.