Semi-active Control Using Adaptive Helmholtz Resonators

Abstract

Active control systems want external power to operate the actuators and controller. Large power sources may be required in some applications, and it may make the control systems very bulky. In addition, the usual concerns associated with all active systems, i.e., stability robustness and actuator saturation, hold true for active sound and vibration control systems too. Semi-active devices require less energy than active devices. The main advantages of semi-active control are that it requires less power, costs less, and has reduced complexity in comparison to active system. Furthermore, the semi-active control is nearly as effective as active system. Semi-active systems are inherently passive and always stable. They are also less vulnerable to power failure. In this chapter, adaptive (semi-active) Helmholtz resonators for noise control are presented. In Sects. 7.1 and 7.2, the basic theory of the Helmholtz resonator (HR) is presented, and then an experimental setup is designed to measure the frequency response of the HR to verify the numerical results. In Sect. 7.3, the theoretical and experimental studies are presented for the sound control in rigid duct structures by using HRs. In Sects. 7.4 and 7.5, control sound transmission through double-plate structures using optimally tuned HRs is discussed, an analytical model of fully coupled structural–acoustic-HRs inside a double-plate structure is established, and then some experimental results are presented. In Sect. 7.6, the design of adaptive HRs is presented and experimentally verified.