Pole Assignment Method For Active Sound Insulation Structure

Active sound insulation is a practical approach for sound transmission control in low frequencies. Active sound insulation of a simply supported rectangle plate in reverberant field is investigated in this paper. The response of the first few modes resonance is suppressed by a distributed control system and the sound insulation effect is improved by adding the modal damping of these modes.The stability and the control effect of a control system are deeply influenced by the distribution of sensors and actuators. To enhance the control effect, optimization of such distribution is considered and by comparing the results of optimization and the experiential distribution the optimal suggestion is obtained by overflow analysis and pole distribution judgment.In this article, the vibration modes in the insulation structure are considered as states of the control system, control law is designed in the state space to control the vibration modes. Coupling control and independent control, two kinds of mainstream mode control methods, have different state equations, solving methods of feedback gain and distributions of control force in the modal space. These two means are separately adopted in this paper. Controlled modes and state equations of reduced order systems are determined by analyzing the incident wave frequency. The feedback control is realized by means of poles assignment to increase the damping of controlled modes. Thus the resonant radiation of structure under the action of sound field is reduced. At the same time, modal filter is designed to get the state information requiring by the controller. The overflow and control effect of the two different control methods are compared, and the influences of different pole assignment plans are analyzed.