Active control of sounds, vibrations and fluid-structure interactions

我的研究领域将是主动声音控制（ASC）、主动振动控制（AVC）和流固耦合控制（FSI）的设备和控制器的设计。控制一词意味着声音和振动的衰减，但它也可以用于增强振荡。设备的轴将是开发一种新的高电平子波段声学气动源（例如，气动扬声器与压缩空气一起工作），能够在给定的载波频率下产生完全可控的时变幅度和相位。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用途是在恶劣环境下（如涡轮风扇）衰减高电平窄带声音。这种新声源还可用于消声器内流固耦合的研究、衬里特性的表征、口噪声产生的观察，或用于流体的主动控制。控制器上的轴将聚焦于多个致动器的命令，以便在远场衰减压力声音，但在致动器的近距离处进行麦克风测量。通常，控制目标将是使辐射声功率最小化，这并不等同于使输出功率的范数最小化。目标是开发一种通用的实验方法来学习（或识别）内部模型，该模型将允许使用输出(y)来控制输入(u)，以最小化z的范数。该研究将定义该方法的局限性，以便提供有关执行器和传感器的数量和位置以及不确定性影响的指导方针。该方法将首先局限于谐波信号。在实际应用中，本研究将为具有多个执行器和传感器的ASC/AVC的设计提供知识。由于这将是一种通用的方法，因此可以将其转化为活性超材料的设计。FSI的轴将关注充满液体的柔性管的振荡（或不稳定）响应的增强或衰减。操纵变量为非平稳流量，观测变量为顶压。将开发一个实验装置来产生不同的动力学。灰盒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，设计一个极值寻求控制器来增强或减弱系统的不稳定性。这种主动控制FSI的实际主要动机是研究全液体通气（当肺部用可呼吸的液体通气时）呼气时气管塌陷。然而，发展的知识和实验设置将用于其他研究相关的类似的生理问题。

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.