Feedforward Control of a Light-Weight Device Casing for Active Noise Reduction

Abstract

It is possible to enhance acoustic isolation of the device from the environment by appropriately controlling vibration of a device casing. Sound insulation efficiency of this technique for a rigid casing was confirmed by the authors in previous publications. In this paper, a light-weight casing is investigated, where vibrational couplings between walls are much greater due to lack of a rigid frame. A laboratory setup is described in details. The influence of the cross-paths on successful global noise reduction is considered. Multiple vibration actuators are installed on each of the casing walls. An adaptive control strategy based on the Least Mean Square (LMS) algorithm is used to update control filter parameters. Obtained results are reported, discussed, and conclusions for future research are drawn.

Active Structural Acoustic Control of an Active Casing Placed in a Corner

“…The loudspeaker as a noise source provides a more reproducible environment for control system evaluation as compared to a real device (which is also examined in other studies performed by the authors). The employed active casing itself is described in more detail in [12,14,15]. It is important to emphasise that such a construction of the casing is very challenging from the control point of view.…”

“…Active control is employed to reduce noise in this research, hence knowledge of the dynamic properties of primary and secondary paths in the frequency range of interest for active control will facilitate the control system development and implementation [12]. Their analysis is provided in this section.…”

“…However, this paper is focused more on the investigation of the control system performance for specific configurations, rather than on introducing the control algorithm itself. Hence, the reader is referred to previous publications, where a more detailed description of the control system with a switched-error modification employed for the active casing is given [12,24].…”

“…In Figures 14 and 15, frequency characteristics for the active control experiments are presented. Time plots of signals obtained by individual sensors are not shown in this paper, as such insight into the control system behavior has been previously presented, e.g., in [12]. In the previous experiments, the active casing was placed distant from the enclosure walls and several control approaches were examined and described, e.g., in [12,14].…”

“…This is a very desirable property of any active noise-reducing system. Efficiency of this method was previously investigated by the authors and the results have been reported in multiple publications [12][13][14]. However, in the previous research, the active casing was placed distant from the walls of the room the casing was enclosed by.…”