Browsing by Author "Zeung, PS"

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Design of a broadband active silencer using mu-synthesis
(2004-01-06)
Bai, MR
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Zeung, PS
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機械工程學系
;
Department of Mechanical Engineering
A robust spatially feedforward controller is developed for broadband attenuation of noise in ducts. To meet the requirements of robust performance and robust stability in the presence of plant uncertainties, a mu-synthesis procedure via D-K iteration is exploited to obtain the optimal controller. This approach considers uncertainties as modelling errors of the nominal plant in high frequency and is implemented using a floating point digital signal processor (DSP). Experimental investigation was undertaken on a finite-length duct to justify the proposed controller. The mu- controller is compared to other control algorithms such as the H-2 method, the H-infinity method and the filtered-U least mean square (FULMS) algorithm. Experimental results indicate that the proposed system has attained 25.8 dB maximal attenuation in the band 250-650 Hz. (C) 2003 Elsevier Science Ltd. All rights reserved.
Synthesis of a robust broadband duct ANC system using convex programming approach
(2002-04-01)
Bai, MSR
;
Zeung, PS
;
機械工程學系
;
Department of Mechanical Engineering
A robust active controller using spatially feedforward structure is proposed for broadband attenuation of noise in ducts. To meet the requirements of performance and robust stability in the presence of plant uncertainties, an H-2 cost function and an H. constrain are employed in the synthesis of the controller. The design is then converted into a convex programming problem using Q-parametrization and frequency discretization. An optimal controller that satisfies the quadratic cost functions and linear inequality constraints can be found by sequential quadratic programming. The optimal controller was implemented via a digital signal processor (DSP) and verified by experiments. Experiment results showed that the system attained 16.5 dB maximal attenuation and 5.9 dB total attenuation in the frequency band 200-600 Hz. (C) 2002 Acoustical Society of America.