An Active Microvibration Isolation System for Hi-tech Manufacturing Facilities

Abstract

This paper presents an active microvibration isolation system using voice-coil linear motors, and pneumatic and piezoelectric actuators. This system is designed to reduce microvibration of the six degrees-of-freedom associated with the rigid body modes of the vibration isolation table by feeding back the pseudo absolute displacement and velocity of the table. To improve vibration isolation performance, a feed-forward control link is added to the sway components in each dimension. This system can also control bending modes of the table in the frequency range up to 200 Hz by employing a proposed Virtual Tuned-Mass Damper control strategy, which is a type of the pole assignment method. In this approach, the pole locations are chosen by a genetic algorithm. For ambient microvibration of the floor around 0.5 cm/s2 and for small earthquakes of around 8 cm/s2 a reduction by a factor of 100 was achieved in the acceleration of the vibration isolation table. Moreover, the vibration of the isolation table was decreased over the entire frequency range. This system also showed good vibration control performance when an impact excitation was applied directly to the table; vibration was damped out within about 0.1 sec. Additionally, the resonance amplitudes around the bending modes of the table were reduced from 1/5 to 1/15 by the Virtual Tuned-Mass Damper method.

A Suspended Floor for High-Performance Electron Microscopy and Nanoscience

“…Prior approaches for specification of microscope installation sites and nanoscale facilities utilized primarily frequency-based [2,4,[6][7][8][9],or time-based [3] criteria, or emphasized displacement vs. velocity vs. acceleration limits. As a result, it is more common to find a variety of measurements in the literature, including power spectral density, 1/3 octave spectrally filtered measurements and r.m.s.…”

Hybrid platform for vibration control of high‐tech equipment in buildings subject to ground motion. Part 1: experiment

“…The passive mount of very low frequency may also lead to static instability of high-tech equipment. To overcome these problems, a hybrid control by coupling active actuators with passive mounts to prevent individual high-tech equipment being a ected by building oor vibration has been recently investigated [4][5][6]. The hybrid control has the advantage of adaptability over passive mounts as any structural change of either building or isolation system can be taken into account in real time through feedback control.…”

Experimental study of a hybrid platform for high‐tech equipment protection against earthquake and microvibration

“…These vibration isolation systems include small passive mounts, hybrid tables and active tables, which are mainly used for isolating individual or a small quantity of high-tech equipment [3][4][5]. The corresponding analytical model often takes building floor vibration as a direct base excitation to the vibration isolation system: dynamic interaction between the building and the high-tech equipment/vibration isolation system, however, is not considered.…”