Archives of Acoustics, 42, 1, pp. 93–104, 2017
10.1515/aoa-2017-0010

Optimized Driver Placement for Array-Driven Flat-Panel Loudspeakers

David A. ANDERSON
University of Rochester
United States

Michael C. HEILEMANN
University of Rochester
United States

Mark F. BOCKO
University of Rochester
United States

The recently demonstrated ‘modal crossover network’ method for flat panel loudspeaker tuning employs an array of force drivers to selectively excite one or more panel bending modes from a spectrum of panel bending modes. A regularly spaced grid of drivers is a logical configuration for a two-dimensional driver array, and although this can be effective for exciting multiple panel modes it will not necessarily exhibit strong coupling to all of the modes within a given band of frequencies. In this paper a method is described to find optimal force driver array layouts to enable control of all the panel bending modes within a given frequency band. The optimization is carried out both for dynamic force actuators, treated as point forces, and for piezoelectric patch actuators. The optimized array layouts achieve similar maximum mode coupling efficiencies in comparison with regularly spaced driver arrays; however, in the optimized arrays all of the modes within a specified frequency band may be independently addressed, which is important for achieving a desired loudspeaker frequency response. Experiments on flat panel loudspeakers with optimized force actuator array layouts show that each of the panel modes within a selected frequency band may be addressed independently and that the inter-modal crosstalk is typically −30 dB or less with non-ideal drivers.
Keywords: loudspeaker; array; crossover network; spatial sampling
Full Text: PDF

References

Anderson D., Bocko M.F. (2015), A model for the impulse response of distributed-mode loudspeakers and multi-actuator panels, 139th Convention of the AES.

Anderson D., Bocko M.F. (2016a), Modal crossover networks for flat-panel loudspeakers, J. Audio Eng. Soc., 90, 1, 346–357.

Anderson D., Bocko M.F. (2016b), Measures of vibrational localization on point-driven flat-panel loudspeakers, 171st Meeting of the Acoustical Society of America.

Bank G., Harris N. (1998), The distributed mode loudspeaker-theory and practice, AES 13th UK Conference: Microphones & Loudspeakers.

Clark R.L., Fuller C.R.,Wicks A. (1991), Characterization of multiple piezoelectric actuators for structural excitation, J. Acoust. Soc. Am., 90, 1, 346–357.

Clark R.L., Flemming M.R., Fuller C.R. (1993), Piezoelectric actuators for distributed vibration excitation of thin plates: a comparison between theory experiment, ASME J. Vib. Acoust., 115, 3, 332–339.

Demetriou M.A. (2000), A numerical algorithm for the optimal placement of actuators and sensors for flexible structures, Proceedings of the American Control Conference.

Devasia D., Meressi T., Paden B., Bayo E. (1993), Piezoelectric actuator design for vibrations suppression: placement and sizing, J. Guid. Control Dynam., 16, 5, 859–864.

Dimitriadis E.K., Fuller C.R., Rogers C.A. (1991), Piezoelectric actuators for distributed vibration excitation of thin plates, ASME J. Vib. Acoust., 113, 1, 100–107.

Fahroo F., Wang Y. (1997), Optimal location of piezoceramic actuators for vibration suppression of a flexible structure, Proceedings of the 36th Conference on Decision and Control.

Fuller C., Elliott S., Nelson P. (1996), Active Control of Vibration, Associated Press.

Hwang J.K., Choi C.-H., Song C.K., Lee J.M. (1997), Robust LQG control of an all-clamped thin plate with piezoelectric actuators/sensors, IEEE/ASME Transactions on Mechatronics, 2, 3, 205–212.

Jia J. (1990), Optimization of Piezoelectric Actuator Systems for Vibration Control of Flexible Structures, PhD thesis, Virginia Polytechnic Institute and State University.

Li L.X., Shen Y.P., Gao F. (2001), The optimal design of piezoelectric actuators for acoustic control, Smart Materials and Structures, 10, 2, 421–426.

Mitchell A.K., Hazell C.R. (1987), A simple frequency formula for clamped rectangular plates, J. Sound and Vib., 118, 2, 271–281.

Porter B., Crossley R. (1972), Modal Control: Theory and Applications, Taylor and Francis.

Rabbiolo G., Bernhard R., Milner F. (2004), Definition of a high-frequency threshold for plates and acoustical spaces, J. Sound and Vib., 277, 4–5, 647– 667.

Wang B.T., Burdisso R.A., Fuller C.R. (1994), Optimal placement of piezoelectric actuators for active structural acoustic control, Journal of Intelligent Material Systems and Structures, 5, 1, 67–77.




DOI: 10.1515/aoa-2017-0010

Copyright © Polish Academy of Sciences & Institute of Fundamental Technological Research (IPPT PAN)