Decentralized Control of Structural Acoustic Radiation

Although the application of active control to vibrations has been investigated from many years, the extension of this technology to large-scale systems has been thwarted, in part, by an overwhelming need for computational effort, data transmission and electrical power. This need has been overwhelming in the sense that the potential applications are unable to bear the power, weight and complex communications requirement of large-scale centralized control systems. Recent developments in MEMS devices and networked embedded devices have changed the focus of such applications from centralized control architectures to decentralized ones. A decentralized control system is one that consists of many autonomous, or semi-autonomous, localized controllers called nodes, acting on a single plant, in order to achieve a global control objective. Each of these nodes has the following capabilities and assets: 1) a relatively limited computational capability including limited memory, 2) oversight of a suite of sensors and actuators and 3) a communications link (either wired or wireless) with neighboring or regional nodes. The objective of a decentralized controller is the same as for a centralized control system: to maintain some desirable global system behavior in the presences of disturbances. However, decentralized controllers do so with each node possessing only a limited amount of information on the global systems response. Exactly what information each node has access to, and how that information is used, is the topic of this investigation. INTRODUCTION Although the application of active control structural acoustic control has been investigated from many years, the extension of this technology to large-scale systems has been thwarted, in part, by an overwhelming need for computational effort, data transmission and electrical power. This need has been overwhelming in the sense that the potential applications are unable to bear the power, weight and complex communications requirement of large-scale centralized control systems. Recent developments in MEMS devices and networked embedded technologies have changed the focus of such applications from centralized control architectures to decentralized ones. A decentralized control system is one that consists many autonomous, or semi-autonomous, localized controllers called nodes, acting on a single plant, in order to achieve a global control objective. Each of these nodes has the following capabilities and assets: 1) a relatively limited computational capability including limited memory, 2) oversight of a suite of sensors and actuators and 3) a communications link (either wired or wireless) with neighboring or regional nodes. The objective of a decentralized controller is the same as for a centralized control system: to maintain some desirable global system behavior in the presences of disturbances. However, decentralized controllers do so with each node possessing only a limited amount of information on the global systems response. Exactly what information each node has access to, and how that information is used, is the topic of this investigation. The field of decentralized control has been the topic of numerous investigations for over 30 years. Most of these studies have considered “weakly connected” systems or architectures wherein each node only experiences a few of the degrees of freedom of the entire system while being weakly connected to other parts of the system. Robotic swarms are a good example of weakly connected systems and have been the topic of many research projects in recent years. Decentralized control has been considered in a few vibration control projects for application in space structures although no investigations have considered its application to structural acoustic control.