Wideband Active Vibration Control Synthesis and Implementation on Uncertain Resonant Structures

Abstract

Large, ``rigid'' structures made of interconnecting beams and tendons represent a type of construction that has many engineering benefits. Lightweight, strong, and generally constructed of standard-shaped metal framework, they also incur significant challenges to control vibration. The construction that makes them strong, light, and ``rigid'' also makes them have very small inherent structural damping, and highly-complex modal structure. A myriad of control techniques have been developed to work on this problem with success usually in very small bandwidths related to a specific frequency ``hot-spot'' around a few specific modes.

This work describes the design, analysis, and implementation of a novel controller configuration applicable to broadband vibration suppression on a large, uncertain resonant structure. The measurement, identification, characterization, and modeling of a large, flexible, lightly-damped test structure with in excess of 1000 modes in 50-5000Hz range was used as the basis for choosing a control configuration. This choice leverages the relative benefits of different control types to obtain one with a combination of the best features of all of them. High-order and low-order feedback, and feed-forward controller configurations were all used in different frequency ranges. Real design tradeoffs such as computation complexity, model accuracy, and available actuator technologies were fundamental to the design choices.

Measured individual modal reduction was as much as 15dB for feedback control, 20dB for feed-forward control, and 4dB broadband over the range of 50-5000Hz.