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-dimensional acoustic duct system. This method combines a linear-quadratic-gaussian (LQG) theory with an internal model principle to design internal model-based active noise controllers so that noise of a specific (target) frequency in a duct can be reduced. The designed controller is, nevertheless, hyper sensitive to the perturbation of the target noise frequency. A reduced parameter sensitivity technique is further incorporated to improve robustness such that noise of narrow-band frequencies can be attenuated. Computer simulation shows the effectiveness of robustness improvement for the proposed design method. In addition, global sound pressure attenuation along the duct is achieved. Experimental results also demonstrate frequency robustness improvement and global sound pressure attenuation despite the fact that the dynamic effects of the actuator are not considered in the control design. Both simulation and experimental results support the feasibility of the proposed design method. Copyright (C) 1999 John Wiley & Sons, Ltd