Robust internal model-based LQG design for active noise control of a one-dimensional acoustic duct system

A control design method is proposed to design controllers to achieve global sound pressure attenuation for noise of narrow-band frequencies in a one-d imensional acoustic duct system. This method combines a linear-quadratic-ga ussian (LQG) theory with an internal model principle to design internal mod el-based active noise controllers so that noise of a specific (target) freq uency in a duct can be reduced. The designed controller is, nevertheless, h yper sensitive to the perturbation of the target noise frequency. A reduced parameter sensitivity technique is further incorporated to improve robustn ess such that noise of narrow-band frequencies can be attenuated. Computer simulation shows the effectiveness of robustness improvement for the propos ed design method. In addition, global sound pressure attenuation along the duct is achieved. Experimental results also demonstrate frequency robustnes s improvement and global sound pressure attenuation despite the fact that t he dynamic effects of the actuator are not considered in the control design . Both simulation and experimental results support the feasibility of the p roposed design method. Copyright (C) 1999 John Wiley & Sons, Ltd.