Collet M, David P, Berthillier M
FEMTO-ST, DMA, CNRS UMR 6604, University of Franche-Comte, Besancon, France.
J Acoust Soc Am. 2009 Feb;125(2):882-94. doi: 10.1121/1.3026329.
New miniaturization and integration capabilities available from emerging microelectromechanical system (MEMS) technology will allow silicon-based artificial skins involving thousands of elementary actuators to be developed in the near future. SMART structures combining large arrays of elementary motion pixels coated with macroscopic components are thus being studied so that fundamental properties such as shape, stiffness, and even reflectivity of light and sound could be dynamically adjusted. This paper investigates the acoustic impedance capabilities of a set of distributed transducers connected with a suitable controlling strategy. Research in this domain aims at designing integrated active interfaces with a desired acoustical impedance for reaching an appropriate global acoustical behavior. This generic problem is intrinsically connected with the control of multiphysical systems based on partial differential equations (PDEs) and with the notion of multiscaled physics when a dense array of electromechanical systems (or MEMS) is considered. By using specific techniques based on PDE control theory, a simple boundary control equation capable of annihilating the wave reflections has been built. The obtained strategy is also discretized as a low order time-space operator for experimental implementation by using a dense network of interlaced microphones and loudspeakers. The resulting quasicollocated architecture guarantees robustness and stability margins. This paper aims at showing how a well controlled semidistributed active skin can substantially modify the sound transmissibility or reflectivity of the corresponding homogeneous passive interface. In Sec. IV, numerical and experimental results demonstrate the capabilities of such a method for controlling sound propagation in ducts. Finally, in Sec. V, an energy-based comparison with a classical open-loop strategy underlines the system's efficiency.
新兴的微机电系统（MEMS）技术所具备的新型小型化和集成能力，将使在不久的将来开发出包含数千个基本致动器的硅基人造皮肤成为可能。因此，正在研究将涂覆有宏观组件的大量基本运动像素阵列相结合的智能结构，以便能够动态调整诸如形状、刚度，甚至光和声音的反射率等基本特性。本文研究了一组采用适当控制策略连接的分布式换能器的声阻抗能力。该领域的研究旨在设计具有所需声阻抗的集成有源接口，以实现适当的整体声学行为。当考虑密集排列的机电系统（或MEMS）时，这个一般性问题与基于偏微分方程（PDE）的多物理系统控制以及多尺度物理概念有着内在联系。通过使用基于PDE控制理论的特定技术，构建了一个能够消除波反射的简单边界控制方程。所获得的策略还被离散化为一个低阶时空算子，以便通过使用交错排列的密集麦克风和扬声器网络进行实验实现。由此产生的准并置架构保证了鲁棒性和稳定性裕度。本文旨在展示一个控制良好的半分布式有源皮肤如何能够显著改变相应均匀无源界面的声音传播能力或反射率。在第四节中，数值和实验结果证明了这种控制管道中声音传播方法的能力。最后，在第五节中，与经典开环策略进行的基于能量的比较突出了该系统的效率。
