Active Vibration Control Of Flexible Missiles

Along with the advances in the area of missiles, a current trend is getting more and more obvious that the values of thrust-to-weight and length-to-diameter ratios are bigger. Corresponding to this trend, the flexibility of missiles increases, for which, dynamic response and vibration characteristics are of vital importance. Traditional modeling and control theory based on rigid dynamics couldn't meet the practical demand of high-speed and high-precision operation. It's necessary to model such plants to be flexible systems, so as to account for the effects of flexible vibration on system dynamics. Consequently modeling and controller design is a challenging problem. The research in this field has intensive background in practice and prominent importance in theory.In view of recent advances in the field of flexible missile dynamics, this dissertation investigates modeling and active vibration control of flexible missile. Flexible missile is idealized as a uniform free beam. The vibration model is obtained using finite element method, and then elastic vibration is simulated and analyses. On the base of rigid body equations and disturbance equations of motion of missiles, utilizing the coupling relationship between rigid-body movement and flexible vibration of missile, the model of flexible missile movement can be obtained.Throughout the dissertation, the state-space model of flexible missile is obtained with the introduction of active additional force. The H∞controller is designed as rigid missile controller for decoupling rigid subsystem, and LQR controller for decoupling elastic subsystem. Then, the controller for coupling elastic subsystem is designed. control scheme is proposed for active vibration control. Simulations show the controller can not only accomplish the attitude control, but also suppress the transverse vibration effectively.