Nonlinear control of boundary impedance in an acoustic waveguide
Nonlinear control of boundary impedance in an acoustic waveguide
Wavetubes are employed for measurements of acoustic properties in various fluids. The ability to manipulate and control the frequency-dependent boundary impedance of the tube improves the estimation accuracy. Passive solutions, which use composite materials to change the boundary impedance, enable one to realize a finite combination of boundary impedances. In this paper, the tube boundary impedance is tuned at will by using two loudspeakers. The suggested method operates in the presence of dispersion by estimating, in real-time, a parametric reduced-order model using a multichannel least mean square algorithm. The identified model is fed to a nonlinear, adaptive control algorithm to realize modal traveling wave ratio (TWR) control. It has been noted that the TWR is smooth and parabolic across closed regions in the parameter space, thus assuring the convergence of the nonlinear control. Several methods to estimate the TWR gradient are considered and compared based on an analytical model of a rigid impedance tube. An experimental case study utilizing an air-filled impedance tube with two loudspeakers is presented. The results demonstrate the ability to control the dynamics of the principal acoustic mode at will, thus enabling one to set the desired tube's boundary impedance.
3889-3903
Vered, Yoav
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Bucher, Izhak
53f51e1b-46cb-45f6-b812-14cc3a0be938
Vered, Yoav
c13938de-457b-4e25-b57b-7471c7bc832a
Bucher, Izhak
53f51e1b-46cb-45f6-b812-14cc3a0be938
Vered, Yoav and Bucher, Izhak
(2021)
Nonlinear control of boundary impedance in an acoustic waveguide.
Journal of the Acoustical Society of America, 150 (5), .
(doi:10.1121/10.0007228).
Abstract
Wavetubes are employed for measurements of acoustic properties in various fluids. The ability to manipulate and control the frequency-dependent boundary impedance of the tube improves the estimation accuracy. Passive solutions, which use composite materials to change the boundary impedance, enable one to realize a finite combination of boundary impedances. In this paper, the tube boundary impedance is tuned at will by using two loudspeakers. The suggested method operates in the presence of dispersion by estimating, in real-time, a parametric reduced-order model using a multichannel least mean square algorithm. The identified model is fed to a nonlinear, adaptive control algorithm to realize modal traveling wave ratio (TWR) control. It has been noted that the TWR is smooth and parabolic across closed regions in the parameter space, thus assuring the convergence of the nonlinear control. Several methods to estimate the TWR gradient are considered and compared based on an analytical model of a rigid impedance tube. An experimental case study utilizing an air-filled impedance tube with two loudspeakers is presented. The results demonstrate the ability to control the dynamics of the principal acoustic mode at will, thus enabling one to set the desired tube's boundary impedance.
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Nonlinear control of boundary impedance in an acoustic
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Preprint Nonlinear control of boundary impedance in an acoustic waveguide
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e-pub ahead of print date: 22 November 2021
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Local EPrints ID: 457171
URI: http://eprints.soton.ac.uk/id/eprint/457171
ISSN: 0001-4966
PURE UUID: 49fe8b55-b3e0-44c4-957b-3a19a2390d76
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Date deposited: 25 May 2022 16:55
Last modified: 16 Mar 2024 17:19
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Author:
Yoav Vered
Author:
Izhak Bucher
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