Study On Elastic Properties And Control Of The Flexible Missile

The slender trend of missile makes the airframe structure's flexible feature becoming increasingly evident, amplitude of vibration becoming larger and attenuation time becoming longer. And all of these will deteriorate the working environment of missile precision instruments. While the bending vibration of airframe structure will change the aerodynamics suffered by the structure, and the changing Aerodynamic further affect the missile body vibration., and occurring the phenomenon of so-called aeroelastic. Meanwhile, the sensors installed on the missile makes the coupling of vibration and control systems, and aeroservoelastic instability may occur. All these factors will affect the system's instability and control precision. Therefore, researches on flexible missile have important theoretical and practical significance.This article views the flexible missile as a free-free beam with end rocket thrust, and builds the beam vibration model. Then the change law of the bending vibration modes due to the change of thrust and length-to-diameter ratio is studied, and the unstable point of the bending flutter is found. On this basis, the effort of aeroelasticity on the vibration stability is discussed, and the trend of critical stability point is revealed. The simulation results show that aeroelasticity weakens the system's stability, narrows down the interval of stability, and with increasing length-to-diameter ratio, this phenomenon become more serious. Furthermore flexible deformation is simulated, and the relation of amplitude with thrust and length-to-diameter ratio is given by using curve fitting.An integrated model of flexible missile containing rigid motion and elastic vibration is derived by the small perturbation theory, and based on this model, an two-degree-of-freedom controller for trajectory tracking and vibration attenuation is designed. Simulation results show that this algorithm not only can achieve tracking control, and avoid large extent and long time vibration but also solves the closed loop stability problem due to the aeroservoelasticity stability.