• 전기학회논문지
• /
• 제63권8호
• /
• pp.1075-1079
• /
• 2014

In this paper, we describe the analysis and the compensation method of the g-sensitivity error for MEMS vibratory gyroscopes. Usually, the g-sensitivity error has been ignored in the commercial MEMS gyroscope, but it deserves our attention to apply for the missile application as a tactical grade performance. Thus, it is necessary to compensate for the g-sensitivity error to reach a tactical grade performance. Generally, the g-sensitivity error seems intuitively to be a gyroscope bias error proportional to the linear acceleration. However, we assert that the g-sensitivity error mainly causes not a bias error but a scale-factor error. And we verify that the g-sensitivity scale-factor error occurs due to the non-linearity of parallel plate electrodes. Therefore, we propose the compensation method to remove the g-sensitivity scale-factor error. The experimental result showed that a proposed compensation method improved successfully the performance of the MEMS vibratory gyroscope.

• 한국정밀공학회지
• /
• 제22권11호
• /
• pp.165-172
• /
• 2005

In MEMS (Micro-Electro-Mechanical System), packaging induced stress or stress induced structure deformation becomes increasing concerns since it directly affects the performance of the device. In the decoupled vibratory MEMS gyroscope, the main factor that determines the yield rate is the frequency difference between the sensing and driving modes. The gyroscope, packaged using the anodic bonding at the wafer level and EMC (epoxy molding compound) molding, has a deformation of MEMS structure caused by thermal expansion mismatch. This effect results in large distribution in the frequency difference, and thereby a lower yield rate. To improve the yield rate we propose a packaged SiOG (Silicon On Glass) process technology. It uses a silicon wafer and two glass wafers to minimize the wafer warpage. Thus the warpage of the wafer is greatly reduced and the frequency difference is more uniformly distributed. In addition. in order to increase robustness of the structure against deformation caused by EMC molding, a 'crab-leg' type spring is replaced with a semi-folded spring. The results show that the frequency shift is greatly reduced after applying the semi-folded spring. Therefore we can achieve a more robust vibratory MEMS gyroscope with a higher yield rate.

• 마이크로전자및패키징학회지
• /
• 제12권3호
• /
• pp.187-196
• /
• 2005

MEMS에서 제조 공정 오차 및 외부 응력은 진동형 자이로스코프와 같은 MEMS 소자의 제조 수율에 많은 영향을 미친다. 특히 비연성 진동형 자이로스코프의 경우 감지모드와 구동모드의 주파수 차의 특성은 수율에 직접적인 영향을 미친다. SOI (Silicon-On-Insulator) 공정 및 양극접합 공정으로 패키징된 자이로스코프의 경우, 노칭현상으로 인하여 구조물이 불균일하게 가공되며, 동시에 열팽창계수 차로 인하여 접합된 기판에 큰 휨이 발생한다. 그 결과주파수 차의 분포가 커지고, 동시에 수율은 저하되었다. 이를 개선하기 위하여 SiOG (Silicon On Glass) 기술을 적용하였다. SiOG 공정에서는 접합 후에 기판의 휨을 최소화 하기 위하여 1장의 실리콘 기관과 2장의 유리 기판을 사용하였으며, 노칭을 방지하기 위하여 금속 박막을 사용하였다. 그 결과 노칭 현상이 방지되었으며, 기판의 휨도 감소하였다. 또한 주파수 차의 분포도 매우 균일하게 되었으며, 주파수 차의 편차 또한 개선이 되었다. 그 결과 높은 수율 및 보다 강건한 MEMS 자이로스코프를 개발할 수 있었다.

• Smart Structures and Systems
• /
• 제6권7호
• /
• pp.793-810
• /
• 2010

This paper addresses the control issue of vibratory MEMS-based gyroscopes. This study considers a gyroscope that can be modeled by an inner mass attached to an outer mass by four springs and four dampers. The outer mass itself is attached to the rotating frame by an equal number of springs and dampers. In order to measure the angular rate of the rotating frame, a driving force is applied to the inner mass and the Coriolis force is sensed along the y-direction associated with the outer mass. Due to micro-fabrication imperfections, including anisoelasticity and damping effects, both gyroscopes do not allow accurate measurements, and therefore, it becomes necessary to devise feedback controllers to reduce the effects of such imperfections. Given an ideal gyroscope that meets certain performance specifications, a feedback control strategy is synthesized to reduce the error dynamics between the actual and ideal gyroscopes. For a dual-mass gyroscope, it is demonstrated that the error dynamics are remarkably decreased with the application of four actuators applied to both masses in the x and y directions. It is also shown that it is possible to reduce the error dynamics with only two actuators applied to the outer mass only. Simulation results are presented to prove the efficiency of the proposed control design.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.1537-1541
• /
• 2003

In this paper, presented is a feedback control performance of vibratory gyroscope at various vacuum levels. Micro gyroscope, whose operation is based on the vibrating motion at the vacuum conditions, is highly influenced by the vacuum level of the operating circumstances. In general, we apply the feedback control scheme to the gyroscope in order to improve the performances of the sensor. And control performances of the gyroscope are related to those vacuum levels. So we need investigate the performances of the closed loop control at various vacuum conditions comparing with those of the open loop. The experimental results show that the sensitivity of the closed loop is less than that of the open loop especially in low vacuum conditions. Therefore, there should be trade-off between sensitivity and other sensor performances such as linearity, bandwidth when we apply feedback control to the gyroscope.

• 한국항공우주학회지
• /
• 제47권6호
• /
• pp.438-445
• /
• 2019

본 논문에서는 MEMS 자이로스코프에서 발생하는 G-민감도 오차를 관성센서 오차 모델에 정의하고, 이를 분석하여 오차 성분을 추출하는 기법을 제안한다. 일반적으로 MEMS기반 자이로스코프는 스프링과 관성질량체를 갖는 진동형 방식으로 개발된다. 따라서 구조적으로 고기동 환경에서 인가되는 가속도에 비례하는 G-민감도 오차 특성을 갖게 된다. 이러한 G-민감도 오차는 외부에서 높은 가속도가 인가되지 않는 민수분야에서는 무시할 정도로 작다. 하지만 전술급 성능의 MEMS 관성측정기가 고가속 환경에서 외란과 가속도에 의해 G-민감도 오차가 발생하게 되면 항체의 유도조종을 위한 항법장치 성능에 큰 영향을 미치게 되므로 오차 분석과 보상은 필수적이다. 따라서 본 논문에서는 MEMS 자이로스코프에 발생하는 G-민감도 오차를 분석하고 정의하여 관성센서 오차모델에 적용한다. 새로 정의된 관성센서 오차모델을 분석하여, 오차 성분을 고가속도 시험환경이 아닌 FMS 시험만으로 정확히 추출하는 방법을 제안한다. 그리고 제안한 방법으로 얻은 오차를 보상하여 고가속도 시험을 수행하고 그 결과를 분석하여 성능과 신뢰성을 검증한다.

• 대한기계학회논문집A
• /
• 제28권8호
• /
• pp.1065-1074
• /
• 2004

A robust optimal design considering fabrication influence has been performed for the decoupled vibratory microgyroscope fabricated by the bulk micromachining. For the analysis of the gyroscope, a design tool has been developed, by which user can perform the system level design considering electric signal process and the fabrication influence as well as mechanical characteristics. An initial design of the gyroscope is performed satisfying the performances of scale factor (or sensitivity) and phase delay, which depend on the frequency difference between driving and sensing resonant frequencies. The objective functions are formulated in order to reduce the variances of the frequency difference and the frequency in itself by fabrication error. To certify the results, the standard deviations are calculated through the Monte Caries Simulation (MCS) and compared initial deviation that is measured fabricated gyroscope chip.

• 센서학회지
• /
• 제19권3호
• /
• pp.191-196
• /
• 2010

In this paper, modeling of the non-ideal frequency response, especially "notch-and-spike" magnitude phenomenon and phase lag distortion, are discussed. To characterize the non-ideal frequency response, a new electro-mechanical simulation model based on SPICE is proposed using the driving loop of the capacitive vibratory gyroscope. The parasitic components of the driving loop are found to be the major factors of non-ideal frequency response, and it is verified with the measurement results.

• 전기학회논문지
• /
• 제60권9호
• /
• pp.1733-1740
• /
• 2011

In this research, a MEMS vibratory gyroscope with dual-mass system in the sensing mode has been proposed to increase the stability of the device using wide bandwidth. A wide flat region between the two resonance peaks of the dual-mass system removes the need for a frequency matching typically required for single mass vibratory gyroscopes. Bandwidth, mass ratio, spring constant, and frequency response of the dual-mass system have been analyzed with MATLAB and ANSYS simulation. Designed first and second peaks of sensing mode are 5,917 and 8,210Hz, respectively. Driving mode resonance frequency of 7,180Hz was located in the flat region between the two resonance peaks of the sensing mode. The device is fabricated with anodically bonded silicon-on-glass substrate. The chip size is 6mm x 6mm and the thickness of the silicon device layer is $50{\mu}m$. Despite the driving mode resonance frequency decrease of 2.8kHz and frequency shift of 176Hz from the sensing mode due to fabrication imperfections, measured driving frequency was located within the bandwidth of sensing part, which validates the utilized dual-mass concept. Measured bandwidth was 768Hz. Sensitivity calculated with measured displacement of driving and sensing parts was 22.4aF/deg/sec. Measured slope of the sensing point was 0.008dB/Hz.

• 센서학회지
• /
• 제26권4호
• /
• pp.235-238
• /
• 2017

In this study, the design of a tri-axis micromachined gyroscope is proposed and the vibration characteristic of the structure is analyzed. Tri-axis vibratory gyroscopes that utilize Coriolis effect are the most commonly used micromachined inertial sensors because of their advantages, such as low cost, small packaging size, and low power consumption. The proposed design is a single structure with four proof masses, which are coupled to their adjacent ones. The coupling springs of the proof masses orthogonally transfer the driving vibrational motion. The resonant frequencies of the gyroscope are analyzed by finite element method (FEM) simulation. The suspension beam spring design of proof masses limits the resonance frequencies of four modes, viz., drive mode, pitch, roll and yaw sensing mode in the range of 110 Hz near 21 kHz, 21173 Hz, 21239 Hz, 21244 Hz, and 21280 Hz, respectively. The unwanted modes are separated from the drive and sense modes by more than 700 Hz. Thereafter the drive and the sense mode vibrations are calculated and simulated to confirm the driving feasibility and estimate the sensitivity of the gyroscope. The cross-axis sensitivities caused by driving motion are 1.5 deg/s for both x- and y-axis, and 0.2 deg/s for z-axis.