Mechanically Amplified 3-DoF Nonresonant Microelectromechanical Systems Gyroscope Fabricated in Low Cost MetalMUMPs Process

Author(s): Rana I. Shakoor, Shafaat A. Bazaz, M. Mubasher Saleem,
Volume: 133(11) - November, 2011

This paper introduces the design implementation of 3-DoF Microelectromechanical Systems (MEMS) based gyroscope concept, which allows shaping up the dynamic response without using advance control system strategies, with less compromise in performance. The proposed architecture utilizes an active–passive mass configuration in order to achieve the dynamic amplification of the oscillation in 2-DoF drive-mode. A comprehensive theoretical description, dynamics, and mechanical design configuration of the proposed gyroscope design are discussed in detail. A complete test methodology has also been devised for the proposed nonresonant 3-DoF gyroscope. A cost effective commercially available metal-multi user MEMS process is used to fabricate a 20 µm thick nickel based micromachined vibratory gyroscope with an overall chip size of 2.2 mm × 2.6 mm. A good agreement is found between the tested and the simulated results. The experimental characterization demonstrated that the wide bandwidth frequency response of the 2-DoF drive-mode oscillator consists of two resonant peaks at 754 Hz and 2.170 kHz, respectively, with a flat region of 1.4 kHz between the peaks, defining the operational frequency region. The sense-mode resonant frequency lies within this region at 1.868 kHz allowing the amplitude of the response to be insensitive to structural parameter and damping variations, with improved robustness against such variations. The passive mass achieved a dynamic amplification of three times at first resonant peak of 754 Hz and five times at the second resonant peak of 2.170 kHz in comparison with the active mass, resulting in improved sensitivity in response to the Coriolis torque induced due to rotation.

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