Model building and verification for active control of microvibrations with probabilistic assessment of the effects of uncertainties

Abstract

M icrovibrations, generally de ned as low-amplitude vibrations at frequencies up to 1 kH z, are of critical importance in a number of areas. It is now well known that, in general, the suppression of such microvibrations to acceptable levels requires the use of active control techniques which, in turn, require suf ciently accurate and tractable models of the underlying dynamics on which to base controller design and initial performance evaluation. Previous work has developed a systematic procedure for obtaining a nite-dimensional state-space model approximation of the underlying dynamics from the de ning equations of motion, which has then been shown to be a suitable basis for robust controller design. In this paper, the experimental validation of this model prior to experimental studies is described in order to determine the effectiveness of the designed controllers. This includes details of the experimental rig and also the use of methods for assessing the safety of the resulting structure against uncertain parameters.

Microvibrations Induced by a Cantilevered Wheel Assembly with a Soft-Suspension System

“…Introduction M INIMIZING microvibrations onboard spacecraft is a key issue for current and future space systems that require high pointing accuracy and stringent stability performance [1][2][3], for example. In this context, the term microvibration refers to low-level mechanical disturbances in the region of microgravity, typically occurring at frequencies from less than 1 Hz up to 1 kHz [4]. Microvibrations are mainly generated by mechanical systems located on the spacecraft, including cryocoolers, solar array drive mechanisms, drives for pointing mechanisms, and rotating devices such as reaction wheel assemblies (RWAs) and momentum wheel assemblies (MWAs), collectively referred to here as wheel assemblies (WAs).…”

Dynamic Mass of a Reaction Wheel Including Gyroscopic Effects: An Experimental Approach

“…[7,1419]. Moreover, their mitigation and control using passive or active damping systems have been thoroughly investigated, for example [16,17,2022], with the nal objective to estimate and minimise payload pointing errors [23,24].…”

Vibration isolation using a hybrid lever-type isolation system with an X-shape supporting structure

“…A typical example can be seen in microvibration control of on-orbit spacecraft. Micro-vibration can be produced by various mechanical parts in on-orbit spacecraft such as cryocoolers, mobile mirrors, and reaction/momentum wheel assemblies, mainly appearing in the frequency range from less than 1 Hz up to 1 kHz [1,2]. Because of the tiny environmental damping in aerospace, micro-vibration may exist for a long time, which can thus degrade working environment of sensitive instruments in onboard spacecraft.…”