MEMS Disk Resonator Research Articles

An In-Run Automatic Mode-Matching Method With Amplitude Correction and Phase Compensation for MEMS Disk Resonator Gyroscope

An In-Run Automatic Mode-Matching Method With Amplitude Correction and Phase Compensation for MEMS Disk Resonator Gyroscope

A MEMS Rate-Integrating Gyroscope (RIG) With In-Run Automatic Mode-Matching

Toward the objective of eliminating the angle error and rate threshold of the rate integrating gyroscope (RIG) caused by stiffness asymmetry, a novel in-run automatic mode-matching method is presented in this paper. Although other manual mode-matching methods can reduce the stiffness asymmetry temporarily, the environmental factors will interfere the manual calibration. Combined with virtual rotation, the processing circuits obtain the resonant frequencies of RIG operation modes and a controller is used to reduce the frequency difference. Meanwhile, an innovative method is proposed for RIG angle error analysis, avoiding the drawbacks of the traditional analysis methods. An FPGA based platform using a MEMS disk resonator is tested and the angle error is reduced to 1 degree compared with the manual calibration result 6.1 degrees.

A Wafer-Level Vacuum Packaged MEMS Disk Resonator Gyroscope With 0.42°/h Bias Instability Within ±300°/s Full Scale

This article reports a MEMS disk resonator gyroscope (DRG) with superior overall performance in terms of bias instability, measurement range, and size. Specifically, a fully filled electrodes MEMS DRG is proposed to improve sensing capacitance to 23.66 pF and drive capacitance to 6.14 pF. The DRG is fabricated using a wafer-level vacuum-package process and is controlled and sensed by a configurable ASIC, enabling a small footprint. The DRG achieves an angle random walk of 0.05°/√h and bias instability of 0.42°/h within a full scale of ±300°/s, making it a very promising solution for angular measurement in high-end industrial applications.

Multi-objective Design Optimization of Microdisk Resonator

Objective: This paper presents a multi-objective design optimization of MEMS disk resonator using two techniques. Methods: Determining the optimized dimensions of disk resonator for a particular resonance frequency so as to achieve higher quality factor and lower motional resistance is attempted. One technique used is constraint-based multi-objective optimization using the interior-point algorithm. The second technique is based on multi-objective genetic algorithm. Results: The algorithms are implemented using MATLAB. The two techniques of optimization are compared. Conclusion: The developed optimization methods can provide faster design optimization compared to full-wave simulators resulting in significant reduction of design time.

Quality Factor Trimming Method Using Thermoelastic Dissipation for Ring-Shape MEMS Resonator

We report a new method to control the quality factor (Q-factor) mismatch in a MEMS disk resonator using the effect of thermoelastic dissipation (TED). The heat conduction path was trimmed to control the thermal time constant, eventually Qfactor determined by TED. The heat conduction beams with small mechanical stiffness were placed in between large temperature difference areas. The Q-factors of two orthogonal modes could be independently controlled with little effect on the resonance frequency. By the proposed method, Q-factor could be trimmed as high as 38%, while the frequency change was only 0.5%.

Inclination Effects on Voltage-controlled Tuning of MEMS Disk Resonator Array Composite Fabricated by Deep Reactive Ion Etching Process

Inclination Effects on Voltage-controlled Tuning of MEMS Disk Resonator Array Composite Fabricated by Deep Reactive Ion Etching Process

0.04 degree-per-hour MEMS disk resonator gyroscope with high-quality factor (510\u2009k) and long decaying time constant (74.9\u2009s)

The disk resonator gyroscope is an attractive candidate for high-performance MEMS gyroscopes. This gyroscope consists of a sensor and readout electronics, and the characteristics of the sensor directly determine the performance. For the sensor, a high-quality factor and long decaying time constant are the most important characteristics required to achieve high performance. We report a disk resonator gyroscope with a measured quality factor of 510 k and decaying time constant of 74.9 s, which is a record for MEMS silicon disk resonator gyroscopes, to the best of our knowledge. To improve the quality factor of the DRG, the quality factor improvement mechanism is first analyzed, and based on this mechanism two stiffness-mass decoupled methods, i.e., spoke length distribution optimization and lumped mass configuration design, are proposed and demonstrated. A disk resonator gyroscope prototype is fabricated based on these design strategies, and the sensor itself shows an angle random walk as low as 0.001°/√h, demonstrating true potential to achieve navigation-grade performance. The gyroscope with readout electronics shows an angle random walk of 0.01°/√h and a bias instability of 0.04°/h at room temperature without compensation, revealing that the performance of the gyroscope is severely limited by the readout electronics, which should be further improved. We expect that the quality factor improvement methods can be used in the design of other MEMS gyroscopes and that the newly designed DRG can be further improved to achieve navigation-grade performances for high-end industrial, transportation, aerospace, and automotive applications.

Decaying Time Constant Enhanced MEMS Disk Resonator for High Precision Gyroscopic Application

This paper reports a new design strategy of adding lumped masses to the frame structure of a disk resonator gyroscope (DRG) to mitigate its figure of merit (FOM). A greatly enhanced decaying time constant τ can lead to very small FOM, which could then greatly mitigate the DRG's bias and bias drift. Additionally, this technique could also reduce the Brownian noise floor. A comprehensive investigation of the possible ways to add the lumped masses is presented, and a detailed design guideline is provided. A DRG prototype based on this design strategy is then presented and shows a τ of 38.5 s, a quality factor Q of 358 k, and a FOM of 1.9°/s. The prototype is operated in the force-to-rebalance mode, and an angle random walk of 0.012°/√h and a bias stability of 0.08°/h are demonstrated experimentally. This design strategy is suitable for use in batch fabrication of very high precision microelectromechanical systems devices such as gyroscopes.

Modeling and analysis of MEMS disk resonators

In this work a very accurate process for modeling a microdisk resonator is presented and the dynamic behavior of the resonator is investigated. Using the minimization of the Hamiltonian, the governing equation of the motion is derived. The periodic solutions in the vicinity of primary resonance are determined by means of shooting method and their stability is investigated by determining the so-called Floquet exponents of the perturbed motions. To obtain a very accurate model, the influences of intermolecular forces such as van der Waals and Casimir is included in the modeling process. The effect of the design parameters on the dynamic responses is discussed. The results indicate that, high quality factor in the ultra-high frequency (UHF), weak nonlinearity, low actuation voltage and very high pull-in voltage, make these polydiamond disk resonators the most likely leaders in the next-generation micromechanical RF filters and channelizers.

Reliable operation conditions of MEMS capacitive disk resonator fabricated by deep RIE process under step and shock signals

ABSTRACTThe deep reactive ion etching (DRIE) process is commonly used for fabricating the MEMS resonators, which sometimes causes the profile of the resonator capacitor inclined. This nonideal feature significantly affects the motion stability of the resonator. In present work, for different inclination angles, the reliable operation conditions of the MEMS disk resonator for step inertial signal and pulse inertial signal are analyzed using the energy method. The dependence of the critical inertial acceleration on inclination angle and testing signal level is given both in expressions and curves. The results show that for a step inertial signal, the reliable operation range of the resonator with an inclination angle of 0.1° is larger than that of 0.25° by a factor of 2.32 for the same testing signal level, and for a pulse inertial signal, the factor is 2.29. With the increase of the inclination angle, the motion stability of the resonators becomes more and more enhanced. This results can provide a theoretical basis for the design of MEMS disk resonator working in the dynamic inertial environment.

The slope effect of a capacitive resonator profile fabricated by a DRIE process on the performance of an MEMS disk resonator

The thickness of a capacitive disk resonator can be increased by selecting a deep reactive ion etching (DRIE) process for reducing motional resistance. However, the DRIE process sometimes causes MEMS capacitive resonators to have a non-ideal profile. In this paper, the slope effect of a resonator profile fabricated by a DRIE process on the capacitance, electrostatic force, electrical stiffness, motional resistance and output current of the capacitive resonator is analyzed. The relation curves between these parameters and the sloped angle are obtained theoretically. The results show that the capacitance, electrostatic force, electrical stiffness and output current decrease as the sloped angle increases, but the motional resistance obviously increases. By capturing the electric field distribution of a capacitive resonator with different ratios of the gap to thickness by using FEM software ANSYS, the effects of slope angle and thickness on the natural frequency of the resonator are investigated. The analyzed results can provide the theoretical basis for designing high-performance MEMS disk resonators fabricated by the DRIE process.

Analysis of reliability factors of MEMS disk resonator under the strong inertial impact

Increasing the bias voltage is a method of reducing the motional resistance of the capacitive disk resonator to match the impedance of the RF circuit. But there are few reports on the study of reliable working range of bias voltage under the shock and vibration environment. Therefore, the reliability of disk resonator under the step and pulse acceleration impact respectively is systematically analyzed in this paper. By the expression of the biggest inertial acceleration the disk can bear under the reliable condition, the maximal reliable range curves of the disk resonator under the dynamic impact environment are obtained. According to the actual sizes of disk in the literature, it can be seen that when a step shock of 13000g is supplied, the reliability range is reduced to 75% compared with the original state. For the pulse shock, the reliability range is related to the pulse amplitude and time width. Research of this paper can provide the basis for the selection of bias voltage of disk resonator under the inertial shock.

The Effects of Air Damping on MEMS Wine-Glass Resonator

In this paper, the Reynolds equation of air damping of MEMS wine-glass resonator is solved by numerical calculation method considering the air slip boundary conditions. The corresponding pressure distribution between internal gaps is obtained by MATLAB software. And then size effects of resonator on air damping and quality factor are analyzed. It is found that MEMS disk radius and thickness have slight effects on the change of the pressure distribution. But the effects of spacing between disk body and electrodes are very significant. The designed ratio value of disk amplitude and spacing should not be over 70%, otherwise the changes of air pressure between gaps will be very remarkable and increased exponentially, the air damping will begin to increase doubly, and the quality factor will be reduced greatly. The analyzed results are very meaningful for optimizing design size of MEMS disk resonator.