Robust Design of a Decoupled Vibratory Microgyroscope Considering Over-Etching as a Fabrication Tolerance Factor

Ha, Sung Kyu; Jeong, Hee-Moon; Kim, JunO

doi:10.1299/jsmea.49.273

Cited by 5 publications

(4 citation statements)

References 15 publications

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“…Furthermore, slight asymmetries in the structure due to fabrication imperfections cause both anisoelasticity in the gyroscopes structure and dynamic cross-coupling between the drive and sense directions. All these factors play a major role in limiting the performance of resonant gyroscopes [ 13 – 15 ].…”

Section: Design Concept and Its Implementationmentioning

confidence: 99%

Thermal Actuation Based 3-DoF Non-Resonant Microgyroscope Using MetalMUMPs

Shakoor

Bazaz

Kraft

et al. 2009

Sensors

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High force, large displacement and low voltage consumption are a primary concern for microgyroscopes. The chevron-shaped thermal actuators are unique in terms of high force generation combined with the large displacements at a low operating voltage in comparison with traditional electrostatic actuators. A Nickel based 3-DoF micromachined gyroscope comprising 2-DoF drive mode and 1-DoF sense mode oscillator utilizing the chevron-shaped thermal actuators is presented here. Analytical derivations and finite element simulations are carried out to predict the performance of the proposed device using the thermo-physical properties of electroplated nickel. The device sensitivity is improved by utilizing the dynamical amplification of the oscillation in 2-DoF drive mode using an active-passive mass configuration. A comprehensive theoretical description, dynamics and mechanical design considerations of the proposed gyroscopes model are discussed in detail. Parametric optimization of gyroscope, its prototype modeling and fabrication using MetalMUMPs has also been investigated. Dynamic transient simulation results predicted that the sense mass of the proposed device achieved a drive displacement of 4.1μm when a sinusoidal voltage of 0.5V is applied at 1.77 kHz exhibiting a mechanical sensitivity of 1.7μm /°/s in vacuum. The wide bandwidth frequency response of the 2-DoF drive mode oscillator consists of two resonant peaks and a flat region of 2.11 kHz between the peaks defining the operational frequency region. The sense mode resonant frequency can lie anywhere within this region and therefore the amplitude of the response is insensitive to structural parameter variations, enhancing device robustness against such variations. The proposed device has a size of 2.2 × 2.6 mm2, almost one third in comparison with existing M-DoF vibratory gyroscope with an estimated power consumption of 0.26 Watts. These predicted results illustrate that the chevron-shaped thermal actuator has a large voltage-stroke ratio shifting the paradigm in MEMS gyroscope design from the traditional interdigitated comb drive electrostatic actuator. These actuators have low damping compared to electrostatic comb drive actuators which may result in high quality factor microgyroscopes operating at atmospheric pressure.

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Section: Design Concept and Its Implementationmentioning

confidence: 99%

Thermal Actuation Based 3-DoF Non-Resonant Microgyroscope Using MetalMUMPs

Shakoor

Bazaz

Kraft

et al. 2009

Sensors

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“…Previously, effect of fabrication imperfections in MEMS gyroscopes is investigated through developing the theoretical models from the lumped-mass-spring systems (Gyimesi and Ketal 2004;Zhang et al 2006) but these have limitations in analyzing the asymmetric defects and imperfections along with the many approximations made in developing the theoretical models. Nodal analysis and finite element method (FEM) based simulations (Ha et al 2006;Iyer and Mukherjee 2002;Xiao et al 2004;Bo et al 2008;Han and Kwak 2001) have been used to address the fabrication induced asymmetric defects. But difficulty in building 3D models with the nodal analysis method and the time consuming FEM simulations make these approaches generally impractical for complex structured MEMS gyroscopes.…”

Section: Introductionmentioning

confidence: 99%

Design and robustness analysis of structurally decoupled 3-DoF MEMS gyroscope in the presence of worst-case process tolerances

Saleem

Bazaz

2011

Microsyst Technol

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This paper presents design of a structurally decoupled 3-DoF non-resonant MEMS gyroscope with increased robustness and gain. The proposed design utilizes dynamic amplification in 2-DoF drive mode oscillator to achieve large gain. The device performance is verified through behavioral model simulations considering the fabrication limitations of standard electroplated nickel micromachining process, MetalMUMPs, of 20 lm structural layer thickness. A wide operational bandwidth of 1.74 kHz with dynamically amplified again of 0.2 lm is achieved at low actuation voltages. A design sensitivity and Monte Carlo analysis is carried out to show the robustness of the design, without any feedback control, within the fabrication process tolerances. Moreover to verify the device performance under the application of angular velocity, a rate table characterization is carried out which resulted in sense mass displacement of 30 nm corresponding to the rotation induced Coriolis force at actuation voltage of 20 V ac and 30 V dc with angular rotation of 50 rad/s. Behavioral model simulations proved to be an cost-effective and time-saving alternative to the traditional iterative fabrications and physical level simulations.

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“…Understanding the behavior of gyroscopes in the presence of fabrication imperfections is essential for improving their performance (Shkel et al 1999). Although theoretical model and Monte-Carlo simulation can be used to analyze such non-ideal performances (Ha et al 2006;Han and Kwak 2001;Iyer and Mukherjee 2002;Shkel et al 1999), the deducing process makes many approximations, so errors brought by the theoretical deduction itself are difficult to be distinguished from the errors caused by the fabrication imperfections. Moreover, most analyses above used models built from lumped mass-damp-spring systems, which could not simulate the asymmetric performances caused by asymmetric defects and imperfections within a design.…”

Section: Introductionmentioning

confidence: 99%

Simulation of a novel lateral axis micromachined gyroscope in the presence of fabrication imperfections

et al. 2008

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This paper proposes a method to simulate a lateral axis micromachined gyroscope in the presence of two kinds of fabrication imperfections using finite element simulation. Non-ideal performances caused by lateral overetching are simulated by modal analysis. Beam width variations are simulated by harmonic analysis. Simulation and discussion of the asymmetric motion caused by beam width variations show the advantage of our design with doubly decoupled structure and special arrangement of sensing capacitors.

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Robust Design of a Decoupled Vibratory Microgyroscope Considering Over-Etching as a Fabrication Tolerance Factor

Cited by 5 publications

References 15 publications

Thermal Actuation Based 3-DoF Non-Resonant Microgyroscope Using MetalMUMPs

Thermal Actuation Based 3-DoF Non-Resonant Microgyroscope Using MetalMUMPs

Design and robustness analysis of structurally decoupled 3-DoF MEMS gyroscope in the presence of worst-case process tolerances

Simulation of a novel lateral axis micromachined gyroscope in the presence of fabrication imperfections

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