Design and Evaluation of a Scalable and Reconfigurable Multi-Platform System for Acoustic Imaging

Abstract

This paper proposes a scalable and multi-platform framework for signal acquisition and processing, which allows for the generation of acoustic images using planar arrays of MEMS (Micro-Electro-Mechanical Systems) microphones with low development and deployment costs. Acoustic characterization of MEMS sensors was performed, and the beam pattern of a module, based on an 8 × 8 planar array and of several clusters of modules, was obtained. A flexible framework, formed by an FPGA, an embedded processor, a computer desktop, and a graphic processing unit, was defined. The processing times of the algorithms used to obtain the acoustic images, including signal processing and wideband beamforming via FFT, were evaluated in each subsystem of the framework. Based on this analysis, three frameworks are proposed, defined by the specific subsystems used and the algorithms shared. Finally, a set of acoustic images obtained from sound reflected from a person are presented as a case study in the field of biometric identification. These results reveal the feasibility of the proposed system.

Using a Planar Array of MEMS Microphones to Obtain Acoustic Images of a Fan Matrix

“…The tests which have been developed in order to obtain acoustic images of a fan matrix by means of the use of the system based on a planar array of MEMS microphones [11] have been carried out inside an anechoic chamber, as can be observed in Figure 6. Figure 6 shows the assembly of the tests: the array of the system is located opposite the fan matrix to capture the noise that it generates.…”

“…This section shows the acquisition and processing system used in this study, based on a 2D array of MEMS microphones [11]. This system is based on a set of processing routines focused on obtaining acoustic images.…”

“…The algorithms implemented in the system [11], shown in Figure 3, can be divided into three blocks: MEMS acquisition, signal processing, and image generation.…”

“…In order to obtain spatial information in two dimensions, it is necessary to work with planar arrays with sensors distributed on a surface. This is the reason why the authors have developed a new system based on a planar array [11].…”

“…Due to the high diversity of the applications of these arrays, the authors try to widen these uses to other fields, such as the industrial one. The system used in this paper [11] has two main characteristics/novelties: (i) it is scalable using several subarrays or modules, increasing the number of sensors used, and it is reconfigurable in the position and orientation of the modules and (ii) its multiplatform framework is reconfigurable. These characteristics make the system flexible and suitable for many different applications, such as localization and characterization of noise or vibration sources, spatial filtering and elimination of acoustic interference, acoustic biometry, ambient assisted living, and acoustic holography.…”