Microvibrations, generally defined as low-amplitude vibrations at frequencies up to 1 kHz, are now of critical importance in a number of areas. One such area is onboard spacecraft carrying sensitive payloads, such as accurately targeted optical instruments or microgravity experiments, where the microvibrations are caused by the operation of other equipment, e.g. reaction wheels, necessary for its correct functioning. It is now well known that the suppression of such microvibrations to acceptable levels requires the use of active control techniques which, in turn, require sufficiently accurate and tractable models of the underlying dynamics on which to base controller design and initial performance evaluation. This chapter describes the development of a modelling technique for either mass or equipment loaded panels and the subsequent use of such models in controller design and basic performance prediction of the resulting feedback control schemes.

11.1 Introduction

Microvibrations is the term used to describe low-amplitude vibrations which occur at frequencies up to 1 kHz and which have often been neglected in the past owing to the low levels of disturbances they induce. In recent years, however, the need to suppress the effects of microvibrations has become much greater. This is especially true for spacecraft structures where, due to the ever increasing requirements to protect sensitive payloads, such as optical instruments or microgravity experiments, there is a pressing need to obtain a very high level...