Active control of sounds, vibrations and fluid-structure interactions

我的研究领域将是主动声控制（ASC），主动振动控制（AVC）和流体-结构相互作用（FSI）控制的设备和控制器的设计。术语控制意味着声音和振动的衰减，但它也可以用于增强振荡。 这些设备的重点将是开发一种新的高水平子带声学气动源（例如，使用压缩空气工作的气动扬声器），该源能够在给定的载波频率下产生完全受控的时变振幅和相位。挑战将是驱动气动源的瞬时相量，以产生窄带随机信号。这种气动扬声器的主要实际利益将是在恶劣环境中衰减高水平窄带声音（例如涡轮风扇）。这种新的源也可以用于消声器中的流体-结构相互作用的研究，衬垫的表征，口部噪声产生的观察，或用于流体的主动控制。 控制器上的轴将集中在多个致动器的命令上，以便衰减远场中的压力声音，但是在致动器的近距离处进行麦克风测量。通常，控制目标将是最小化辐射声功率，这不等同于最小化输出的范数。目标是开发一种通用的实验方法来学习（或识别）内部模型，该内部模型将允许使用输出（y）来控制输入（u），以便最小化z的范数。该研究将定义该方法的局限性，以提供有关致动器和传感器的数量和位置以及不确定性的影响的指导方针。该方法将首先限于谐波信号。在实际应用中，本文的研究将为多执行器和多传感器的ASC/AVC系统的设计提供参考。因为它将是一种通用的方法，它可以被翻译成活性超材料的设计。 流固耦合的轴将涉及充满液体的柔性管的振荡（或不稳定）响应的增强或衰减。操作变量为非平稳流速，观察变量为顶叶压力。将开发一个实验装置，以产生不同的动力学。一个灰箱非线性建模方法将被开发来识别非线性模型，并设计观测器。最后，将设计极值搜索控制器来增强或减弱不稳定性。FSI的这种主动控制的实际主要动机是研究在完全液体通气（当肺用可呼吸液体通气时）中呼气期间气管的塌陷。然而，开发的知识和实验装置将用于与类似生理问题相关的其他研究。

The domain of my research program will be in the design of devices and controllers for active sound control (ASC), active vibration control (AVC) and control of fluid-structure interaction (FSI). The term control means attenuation of sound and vibration, but it also can be used for the enhancement of the oscillation. The axis on the devices will be on the development of a new high level subband acoustic pneumatic source (e.g. a pneumatic loudspeaker working with compressed air) able to generate a perfectly controlled time-varying amplitude and phase at a given carrier frequency. The challenge will be to drive the instantaneous phasor of the pneumatic source in order to generate a narrowband stochastic signal. The main practical interest of such pneumatic loudspeaker will be to attenuate high level narrow-band sounds in harsh environment (e.g. turbofan). Such new source can also be used for the study of the fluid-structure interaction in mufflers, the characterization of liners, the observation of the mouth noise generation, or for active control of fluid. The axis on the controller will focus on the command of multiple actuators in order to attenuate a pressure sound in far field, but with microphone measurements at a close distance of the actuators. Typically, the control objective will be to minimize the radiated acoustic power which is not equivalent to minimize a norm of outpu. The objective is to develop a generic experimental method to learn (or identify) the internal model that will allow to use the outputs (y) to control the inputs (u) in order to minimize a norm of z. The research will define the limitations of the method in order to provide guidelines about the number and the location of actuators and sensors, and the impact of uncertainties. The method will be first limited to harmonic signal. In practical applications, this research will give knowledge for the design of ASC/AVC with multiples actuators and sensors. Because it will be a generic method, it could be translated in the design of active meta-materials. The axis of FSI will concern the enhancement, or the attenuation, of the oscillatory (or unstable) response of a flexible tube filled with a liquid. The manipulated variable is the unstationnary flow rate, and the observed variable is the parietal pressure. An experimental set-up will be developed to generate different dynamics. A grey-box non-linear modeling approach will be developed to identify the nonlinear model, and to design observers. Finally, an extremum seeking controller will be designed to enhance or to attenuate the instability. The practical main motivation for such active control of FSI is the study of the collapse of the trachea during expiration in total liquid ventilation (when the lungs is ventilated with a breathable liquid). However, the developed knowledge and the experimental set-up will be used in other studies related to similar physiological problems.