Active vibroacoustic control with multiple local feedback loops

TLDR

Vibration and sound control of panels typically uses centrally connected actuators and sensors that target specific modes. The study examines the effects of using a regular array of actuator–sensor pairs linked solely by local feedback loops. Simulations of a 4×4 array of force actuators with velocity sensors, and later a piezoelectric actuator–velocity sensor pair, demonstrate that decentralized controllers are unconditionally stable across a wide range of feedback gains. Optimal feedback gain yields significant reductions in panel kinetic energy and radiated sound power, though higher gains introduce resonances that degrade performance; with piezoelectric transducers the reductions are smaller but still beneficial, indicating that modular local-loop systems can robustly control broadband sound transmission.

Abstract

When multiple actuators and sensors are used to control the vibration of a panel, or its sound radiation, they are usually positioned so that they couple into specific modes and are all connected together with a centralized control system. This paper investigates the physical effects of having a regular array of actuator and sensor pairs that are connected only by local feedback loops. An array of 4 x 4 force actuators and velocity sensors is first simulated, for which such a decentralized controller can be shown to be unconditionally stable. Significant reductions in both the kinetic energy of the panel and in its radiated sound power can be obtained for an optimal value of feedback gain, although higher values of feedback gain can induce extra resonances in the system and degrade the performance. A more practical transducer pair, consisting of a piezoelectric actuator and velocity sensor, is also investigated and the simulations suggest that a decentralized controller with this arrangement is also stable over a wide range of feedback gains. The resulting reductions in kinetic energy and sound power are not as great as with the force actuators, due to the extra resonances being more prominent and at lower frequencies, but are still worthwhile. This suggests that an array of independent modular systems, each of which included an actuator, a sensor, and a local feedback control loop, could be a simple and robust method of controlling broadband sound transmission when integrated into a panel.