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Research Papers

Active Vibration Control and Isolation for Micromachined Devices

[+] Author and Article Information
Seong Jin Kim

Auburn University, Auburn, AL 36849kimseon@auburn.edu

Robert Dean

Auburn University, Auburn, AL 36849deanron@auburn.edu

George Flowers

Auburn University, Auburn, AL 36849flowegt@auburn.edu

Chen Chen

Auburn University, Auburn, AL 36849chenche@auburn.edu

J. Mech. Des 131(9), 091002 (Aug 17, 2009) (6 pages) doi:10.1115/1.3159042 History: Received November 19, 2008; Revised May 27, 2009; Published August 17, 2009

Abstract

Some harsh environments contain high frequency, high amplitude mechanical vibrations. Unfortunately some very useful components, such as micro-electro-mechanical systems (MEMS) gyroscopes, can be very sensitive to these high frequency mechanical vibrations. Passive micromachined silicon low-pass filter structures (spring-mass-damper) have been demonstrated in recent years. However, the performance of these filter structures is typically limited by low damping. This is especially true if operated in low pressure environments, which is often the optimal operating environment for the attached device that requires vibration isolation. An active micromachined vibration isolator can be realized by combining a state sensor, and electrostatic actuator and feedback electronics with the passive isolator. Using this approach, a prototype active micromachined vibration isolator is realized and used to decrease the filter $Q$ from approximately 135 to approximately 60, when evaluated in a low pressure environment. The physical size of these active isolators is suitable for use in or as packaging for sensitive electronic and MEMS devices, such as MEMS vibratory gyros.

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Figures

Figure 1

An illustration of a parallel plate capacitor structure with one movable electrode

Figure 2

(a) A photograph of a passive MEMS vibration isolation filter chip and (b) a typical measured frequency response (14)

Figure 3

A drawing of the active filter with an integrated parallel plate electrostatic actuator

Figure 4

A schematic diagram of the resulting second order mechanical system

Figure 5

A block diagram of the closed loop active filter

Figure 6

An illustration of the implementation of the prototype micromachined active vibration isolator

Figure 7

(a) A photograph of the front side of the feedback controller electronics circuit board and (b) a photograph of the back side of the feedback controller electronics circuit board

Figure 8

A photograph of an assembled prototype mounted on top of an electromechanical shaker

Figure 9

A plot of the measured relative electrode displacement and the relative velocity sensor output (17)

Figure 10

A plot of the transmissibility of the prototype device with and without the feedback controller activated

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