PERFORMANCE ENHANCEMENTS OF MICRO CORIOLIS VIBRATORY GYROSCOPES THROUGH LINEARIZED TRANSDUCTION AND TUNING MECHANISMS

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dc.contributor.advisorDeVoe, Don Len_US
dc.contributor.authorKnight, Ryanen_US
dc.contributor.departmentMechanical Engineeringen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2024-02-10T06:37:02Z
dc.date.available2024-02-10T06:37:02Z
dc.date.issued2023en_US
dc.description.abstractA quadruple mass Microelectromechanical System (MEMS) Coriolis vibratory gyroscope has been re-engineered with the singular focus of minimizing nonlinear transduction mechanisms, thereby allowing for angle random walk (ARW) noise reduction when operating at amplitudes higher than 2 μm. The redesign involved six primary steps: (i) the creation of an aspect-ratio independent deep reactive ion etch with minimal notching on 100 μm thick silicon-on-insulator device layer, (ii) the creation of micro-torr vacuum packaging capability, enabling operation at the thermoelastic dissipation limit of silicon, (iii) the redesign of Coriolis mass folded flexures and shuttle springs, (iv) the linearization of the antiphase coupler spring rate while maintaining parasitic modal separation, (v) the substitution of parallel plate transducers with linear combs, and (vi) the implementation of dedicated force-balanced electrostatic frequency tuners. Cross-axis stiffness is also reduced through folded-flexure moment balancing to further reduce ARW. By balancing positive and negative Duffing frequency contributions, net fractional frequency nonlinearity was reduced to -20 ppm. The gyroscope presented in this research has achieved, a first reported of its kind, an ARW of 0.0005 °/√hr, with an uncompensated bias instability of 0.08 °/hr. These advancements hold promise for enhancing navigation and North-finding applications. In tandem with gyroscope performance enhancements, vacuum packaging of ceramic chip carrier physics packages has achieved pressure levels below 1 micro-torr, a first in the field and remains state-of-the-art. Besides high-performance MEMS inertial sensors, ultrahigh vacuum packaging proves beneficial for chip scale atomic clocks, which require micro-torr vacuum levels to maintain fractional frequencies less than 10^-12. Finally, an approach to tuning the quality factor mismatch between degenerate modes in as-fabricated gyroscopes has demonstrated a reduction in gyroscope bias instability. This tuning can be achieved by incorporating lead zirconate titanate into regions where the trade-off between mechanical Q, tuning Q, and bias instability reduction is balanced. Both modeling and empirical frequency data justify this approach, suggesting, for typical MEMS foundry Q mismatch of 7%, a 70× reduction in bias instability.en_US
dc.identifierhttps://doi.org/10.13016/dspace/1ayp-fs6u
dc.identifier.urihttp://hdl.handle.net/1903/31680
dc.language.isoenen_US
dc.subject.pqcontrolledMechanical engineeringen_US
dc.subject.pqcontrolledPackagingen_US
dc.subject.pqcontrolledNanotechnologyen_US
dc.subject.pquncontrolledgyroscopeen_US
dc.subject.pquncontrolledmicroelectromechanicalen_US
dc.subject.pquncontrollednavigationen_US
dc.subject.pquncontrolledpackagingen_US
dc.subject.pquncontrolledquality factoren_US
dc.subject.pquncontrolledvacuumen_US
dc.titlePERFORMANCE ENHANCEMENTS OF MICRO CORIOLIS VIBRATORY GYROSCOPES THROUGH LINEARIZED TRANSDUCTION AND TUNING MECHANISMSen_US
dc.typeDissertationen_US

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