Micromachined gyroscopes with 2-DOF sense modes allowing interchangeable robust and precision operation
First Claim
1. A micromachined z-axis vibratory rate gyroscope formed on a substrate comprising:
- an outer anchor;
an inner anchor;
an outer decoupling drive frame coupled to the outer anchor restrained to oscillate substantially only in a drive direction;
an inner decoupling drive frame coupled to the inner anchor restrained to oscillate substantially only in a drive direction, the inner and outer decoupling drive frames being decoupled from each other and both resiliently coupled to the substrate;
a first sense mass ma resiliently coupled to the outer decoupling drive frame and restrained to oscillate substantially only in the sense direction;
a second sense mass mb resiliently coupled to the inner decoupling drive frame and restrained to oscillate substantially only in the sense direction, the first and second sense masses ma and mb being independently resiliently coupled to each other to allow relative oscillation in the sense direction;
a drive electrostatic comb coupled to either the inner decoupling drive frame or the outer decoupling frame or both; and
a sense electrostatic comb coupled to either the first sense mass or the second sense mass or both.
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Abstract
A z-axis gyroscope design is presented with a 2-degree of freedom (DOF) sense mode allowing interchangeable operation in either precision (mode-matched) or robust (wide-bandwidth) modes. This is accomplished using a complete 2-DOF coupled system which allows for the specification of the sense mode resonant frequencies and coupling independent of frequency. By decoupling the frame connecting the sense system to a central anchor, x-y symmetry is preserved while enabling a fully coupled 2-DOF sense mode providing control over both the bandwidth and the amount of coupling independent of operational frequency. The robust mode corresponds to operation between the 2-DOF sense mode resonant frequencies providing a response gain and bandwidth controlled by frequency spacing. Precision mode of operation, however, relies on mode-matching the drive to the second, anti-phase sense mode resonant frequency which can be designed to provide a gain advantage over a similar 1-DOF system.
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Citations
1 Claim
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1. A micromachined z-axis vibratory rate gyroscope formed on a substrate comprising:
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an outer anchor; an inner anchor; an outer decoupling drive frame coupled to the outer anchor restrained to oscillate substantially only in a drive direction; an inner decoupling drive frame coupled to the inner anchor restrained to oscillate substantially only in a drive direction, the inner and outer decoupling drive frames being decoupled from each other and both resiliently coupled to the substrate; a first sense mass ma resiliently coupled to the outer decoupling drive frame and restrained to oscillate substantially only in the sense direction; a second sense mass mb resiliently coupled to the inner decoupling drive frame and restrained to oscillate substantially only in the sense direction, the first and second sense masses ma and mb being independently resiliently coupled to each other to allow relative oscillation in the sense direction; a drive electrostatic comb coupled to either the inner decoupling drive frame or the outer decoupling frame or both; and a sense electrostatic comb coupled to either the first sense mass or the second sense mass or both.
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Specification