Design Of Robust Controller In ASAC Based On The Radiation Modes

Active Structural Acoustic Control(ASAC) based on the radiation modes of vibration structure,which is developed in recent years,is an effective method to analyze and control the behavior of the sound field caused by the vibration body.One of the important aspects of the radiation modes is that at low frequencies,when the modes order increases their radiation efficiencies will fall off rapidly.Therefore,the control strategy of the ASAC system based on the radiation modes is to minimize the adjoint coefficients of the firstκradiation modes.Depend on the control strategy, a modal of ASAC based on radiation modes is established.The choice of algorithm and the design of controller,which have direct relationship to the control effect,is a key step in implementing an ASAC system.This paper approaches the control algorithm and controller for ASAC system based on radiation modes with the robust H_∞control theory.Firstly,the H_∞state feedback controller and the H_∞output feedback controller are respectively designed using the LMI method for ASAC system based on velocity adjoint coefficient and acceleration adjoint coefficient.The simulation shows that the control strategy based on radiation modes is rather effective.And from the simulation we can also know that the choice of the locations of control forces has huge effect on the control effect,especially when the control forces were placed according to the symmetry and anti-symmetry of radiation modes shape,there will be only one order adjiont coefficient was controlled,but the others remain unchanged.For the above two feedback systems,the robust H_∞state feedback controller and robust H_∞output controller are designed in consideration of the system parameters uncertainties.The simulation indicates the presented controller has great robust and effective.In the real control systems,uncertainties not only exist in the system parameters,but also in controller parameters.Therefore,considering the addition uncertainties and the multiplication uncertainties of controller parameters,this paper finally designed the non-fragile H_∞robust state feedback controller for uncertain system based on acceleration adjiont coefficient.Through the comparison of the normal standard controller and the robust controller,the results demonstrate the presented non-fragile robust controller is effective.