MEMS-Based Acoustic Array Technology for Real-Time Monitoring

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0097636NishidaThe objective of this research effort is to develop a MEMS-based acoustic array using expertise in acoustics, MEMS design and fabrication, adaptive signal processing, and DSP hardware development for distributed sensing and control. The technology offers the potential to economically scale directional microphone array technology to hundreds of microphones while improving data handling and portability. The potential impact includes directional microphones for communication devices to industrial screening for noise abatement. This research will explore the microphone design, beamforming algorithms, and DSP hardware required to realize a MEMS-based acoustic array. The microphone design involves the modeling, fabrication, and characterization of a dual back plate force-feedback capacitive MEMS microphone as the array element to avoid the electrostatic pull-in instability of open-loop capactive microphones while yielding a wider bandwidth, dynamic range, and larger signal-to-noise ratio. Due to the presence of strong acoustic interference signals, requirements for the beamforming algorithm include adaptive approaches that can be used for simultaneous interference suppression. One of the most effective adaptive beamforming approaches is the Capon beamformer which has been widely used in many applications in radar and communications. This research includes the implementation of the real time adaptive acoustic imaging algorithms with MEMS-based acoustic arrays. These algorithms include: 1. adaptive beamforming algorithms for acoustic sources with arbitrary radiation patterns, 2. steering vector estimation algorithms in the presence of interference, 3. adaptive beamforming with gapped or missing data information, and 4. recursive implementations of the adaptive algorithms for moving sources. This creates a substantial computation problem that has traditionally been handled in a non-real time manner. I