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1	Degree-per-hour mode-matched micromachined silicon vibratory gyroscopes Zaman, Mohammad Faisal 31 March 2008 (has links) The objective of this research dissertation is to design and implement two novel micromachined silicon vibratory gyroscopes, which attempt to incorporate all the necessary attributes of sub-deg/hr noise performance requirements in a single framework: large resonant mass, high drive-mode oscillation amplitudes, large device capacitance (coupled with optimized electronics), and high-Q resonant mode-matched operation. Mode-matching leverages the high-Q (mechanical gain) of the operating modes of the gyroscope and offers significant improvements in mechanical and electronic noise floor, sensitivity, and bias stability. The first micromachined silicon vibratory gyroscope presented in this work is the resonating star gyroscope (RSG): a novel Class-II shell-type structure which utilizes degenerate flexural modes. After an iterative cycle of design optimization, an RSG prototype was implemented using a multiple-shell approach on (111) SOI substrate. Experimental data indicates sub-5 deg/hr Allan deviation bias instability operating under a mode-matched operating Q of 30,000 at 23ºC (in vacuum). The second micromachined silicon vibratory gyroscope presented in this work is the mode-matched tuning fork gyroscope (M2-TFG): a novel Class-I tuning fork structure which utilizes in-plane non-degenerate resonant flexural modes. Operated under vacuum, the M2-TFG represents the first reported high-Q perfectly mode-matched operation in Class-I vibratory microgyroscope. Experimental results of device implemented on (100) SOI substrate demonstrates sub-deg/hr Allan deviation bias instability operating under a mode-matched operating Q of 50,000 at 23ºC. In an effort to increase capacitive aspect ratio, a new fabrication technology was developed that involved the selective deposition of doped-polysilicon inside the capacitive sensing gaps (SPD Process). By preserving the structural composition integrity of the flexural springs, it is possible to accurately predict the operating-mode frequencies while maintaining high-Q operation. Preliminary characterization of vacuum-packaged prototypes was performed. Initial results demonstrated high-Q mode-matched operation, excellent thermal stability, and sub-deg/hr Allan variance bias instability. SOI Silicon micromachining Vibratory gyroscopes Mode-matching High-Q Gyroscopes Damping (Mechanics) Vibration Silicon Micromachining
2	Modelling of MEMS vibratory gyroscopes utilizing phase detection Dreyer, Antonie Christoffel 03 1900 (has links) Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2008. / This thesis aims to contribute to the modelling and analysis of MEMS gyroscope technologies. Various gyroscope types are studied, and the phase-based vibratory gyroscope is then selected for further investigation. In the literature, vibratory MEMS gyroscopes are mostly used in a single excitation and amplitude detection mode. However, a dual excitation and phase detection mode has recently been proposed, since phase-based detection, as opposed to amplitude-based detection modes, may be expected to increase measurement accuracy (in turn since improved signal-to-noise ratios may be expected). However, the presented analytical model was relatively crude, and the assumptions made appear unrealistic. Accordingly, in this thesis, an improved analyticalmodel is developed. To describe the dual excitation and phase detection problem more comprehensively, principles of classical dynamics are used herein to investigate the dual excitation of a two degree of freedom spring-mass-damper system subjected to an applied rotation rate. In doing so, an analytical formulation including mechanical coupling effects is extended into a generalized form, after which the amplitude and phase responses of the mechanically uncoupled system are interpreted. The differences between the amplitude and phase measurement techniques are illustrated. Finally, the system is modelled numerically, and the scale factor of a hypothetical device based on the phase-based detection method is optimized, subject to constraints on the nonlinearity of the device, using constrained mathematical optimization techniques. MEMS Vibratory gyroscopes Phase-based Mathematical modelling Dissertations -- Mechanical engineering Theses -- Mechanical engineering Gyroscopes Mechanical and Mechatronic Engineering
3	Interface circuits for readout and control of a micro-hemispherical resonating gyroscope Mayberry, Curtis Lee 12 January 2015 (has links) Gyroscopes are inertial sensors that measure the rate or angle of rotation. One of the most promising technologies for reaching a high-performance MEMS gyroscope has been development of the micro-hemispherical shell resonator. (μHSR) This thesis presents the electronic control and read-out interface that has been developed to turn the μHSR into a fully functional micro-hemispherical resonating gyroscope (μHRG) capable of measuring the rate of rotation. First, the μHSR was characterized, which both enabled the design of the interface and led to new insights into the linearity and feed-through characteristics of the μHSR. Then a detailed analysis of the rate mode interface including calculations and simulations was performed. This interface was then implemented on custom printed circuit boards for both the analog front-end and analog back-end, along with a custom on-board vacuum chamber and chassis to house the μHSR and interface electronics. Finally the performance of the rate mode gyroscope interface was characterized, showing a linear scale factor of 8.57 mv/deg/s, an angle random walk (ARW) of 34 deg/sqrt(hr) and a bias instability of 330 deg/hr. uHRG µHRG MEMS CVG Coriolis TIA AM FM Micro-hemispherical resonating gyroscope 3D-HARPSS High-Q Gyroscopes Gyroscopic instruments Gyroscope Vibratory Coriolis vibratory gyroscope Interface Circuits Transimpedance amplifier Rate integrating Inertial sensor Sensor Oscillator Analog Control Electrostatic Capacitive Noise Characterization Mode-matching Wine-glass Duffing Non-linearity Feed-through cancellation Vibratory gyroscopes Polysilicon

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