Numerical Modeling, Testing and Bias Drift Analysis of MEMS Based Three-Axis Gyroscope for Accurate Angular Rate Estimation for Attitude Determination of Nano-Satellites

Mohammed Irfan Rashed,Seunghan Lim,Hyochoong Bang 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

This paper deals with the mathematical analysis, testing and necessary assessment on the source of drift was done both statistically as well as experimentally for accurate attitude determination of specifically Nano-satellites using Micro-Electro Mechanical Systems based three-axis gyroscopes. In the recent times, the gyroscope application has been a major concern during the important missions due to their inability to transfer data efficiently and effectively during the mission period due to which there had been immense data loss and in some cases even failure. Especially, the MEMS based low cost gyroscopes are of an important concern due to their high bias drift rate in the space environment. Hence, in order to study, simulate, test, analyze and evaluate the performance of the three-axis MEMS based gyroscope, intensive research was carried out. A potential quaternion based mathematical model was simulated to scrutinize the bias drift variation in the 3-axis gyroscope and then a testing of a unique MEMS based 3-axis gyroscopes was done to practically learn and understand the variation and actual source of drift at different situations under operation. After the testing, the data was compiled and the necessary basic bias drift analysis was done. Noting the results of simulations and testing, some significant conclusions were made.

자기-자이로 유도 장치를 위한 MEMS형 자이로의 민감도 최적화

이인성,김재용,정은국,정경훈,김정민,김성신 한국로봇학회 2013 로봇학회 논문지 Vol.8 No.1

This paper presents a sensitivity optimization of a MEMS (microelectromechanical systems) gyroscope for a magnet-gyro system. The magnet-gyro system, which is a guidance system for a AGV (automatic or automated guided vehicle), uses a magnet positioning system and a yaw gyroscope. The magnet positioning system measures magnetism of a cylindrical magnet embedded on the floor, and AGV is guided by the motion direction angle calculated with the measured magnetism. If the magnet positioning system does not measure the magnetism, the AGV is guided by using angular velocity measured with the gyroscope. The gyroscope used for the magnet-gyro system is usually MEMS type. Because the MEMS gyroscope is made from the process technology in semiconductor device fabrication, it has small size, low-power and low price. However, the MEMS gyroscope has drift phenomenon caused by noise and calculation error. Precision ADC (analog to digital converter) and accurate sensitivity are needed to minimize the drift phenomenon. Therefore, this paper proposes the method of the sensitivity optimization of the MEMS gyroscope using DEAS (dynamic encoding algorithm for searches). For experiment, we used the AGV mounted with a laser navigation system which is able to measure accurate position of the AGV and compared result by the sensitivity value calculated by the proposed method with result by the sensitivity in specification of the MEMS gyroscope. In experimental results, we verified that the sensitivity value through the proposed method can calculate more accurate motion direction angle of the AGV.

Performance comparison between 87Rb‑natural Xe–N2 and 87 Rb–129Xe–131Xe–N2 atom spin gyroscopes

Lee Sangkyung,Lee Deok Young,Shim Kyu Min,Yim Sin Hyuk 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.3

We have developed an atom spin gyroscope that uses a Rb–Xe vapor cell. The signal-to-noise ratio (SNR) and the angular random walk (ARW) of a Rb-natural Xe–N 2 vapor cell and a Rb–129Xe–131Xe–N 2 vapor cell were compared in terms of the Allan deviation. The low SNR of the 131 Xe signal was the main limitation of the ARW in the 87Rb-natural Xe–N 2 atom spin gyroscope. The 87Rb–129Xe–131Xe–N 2 atom spin gyroscope with a partial pressure ratio of 129 Xe to 131 Xe of 1:5 provided a SNR of 879 and a transverse relaxation time of 19.6 s, respectively, for an 131 Xe signal. Compared to the 87Rb-natural Xe–N 2 atom spin gyroscope, the 87Rb–129Xe–131Xe–N 2 atom spin gyroscope with an improved SNR showed that the magnetic-fieldinduced noise limited the ARW of our system. To stabilize the bias magnetic field, we applied a magnetic field feedback of 300-fT resolution with a 4-Hz bandwidth. As a result, the correlation between the magnetic field and the rotation rate from the atom spin gyroscope output was removed. The 87Rb–129Xe–131Xe–N 2 atom spin gyroscope achieved an ARW of 0.11◦∕ h1∕2 and a bias instability of 0.5◦∕h.

Gyroscope Free 관성 항법 장치의 데이터 보정을 위한 퍼지 추론 시스템

김재용(Jaeyong Kim),김정민(Jungmin Kim),우승범(Seungbeom Woo),김성신(Sungshin Kim) 한국지능시스템학회 2011 한국지능시스템학회논문지 Vol.21 No.4

본 논문은 퍼지 추론 시스템(FIS: fuzzy inference system)을 이용하여 자이로스코프를 사용하지 않는 관성 항법 장치(GFINS: gyroscope free inertial navigation system)의 가속도계 데이터를 보정하는 방법에 관한 연구이다. 일반적인 관성항법 장치(INS: inertial navigation system)는 주로 가속도계와 같은 병진운동을 감지하는 관성 센서와 자이로스코프와 같은 회전 운동을 감지하는 관성 센서를 이용하여 위치와 yaw각을 측정하는 장치이다. 하지만 INS는 자이로스코프를 사용하기 때문에 소형화 및 저전력 설계가 어렵다. 이러한 문제를 해결하기 위하여 자이로스코프를 사용하지 않는 GFINS에 대한 연구가 활발히 진행되고 있다. GFINS에 사용되는 가속도계는 적분과 외란에 의한 오차가 시간이 지남에 따라 누적되는 문제가 있다. 따라서 본 논문에서는 가속도계의 누적 오차 문제를 해결하기 위해, 레이저 내비게이션과 가속도계의 선속도 비율과 엔코더와 가속도계의 선속도 비율을 통해 GFINS의 데이터를 보정하는 FIS를 제안한다. 제안된 Fuzzy-GFINS를 평가하기 위해, 직접 제작한 메카넘 휠 AGV(autonomous ground vehicle)에 제안된 GFINS를 적용하였다. 실험 결과, 제안된 방법이 GFINS의 출력 데이터를 효과적으로 보정하는 것을 확인 할 수 있었다. This paper presents a study on the calibration of accelerometer data in the gyroscope free inertial navigation system(GFINS) using fuzzy inference system(FIS). The conventional INS(inertial navigation system) which can measure yaw rate and linear velocity using inertial sensors as the gyroscope and accelerometer. However, the INS is difficult to design as small size and low power because it uses the gyroscope. To solve the problem, the GFINS which does not have the gyroscope have been studied actively. However, the GFINS has cumulative error problem still. Hence, this paper proposes Fuzzy-GFINS which can calibrate the data of an accelerometer using FIS consists of two inputs that are ratio between linear velocity of the autonomous ground vehicle(AGV) and the accelerometer and ratio between linear velocity of the encoders and the accelerometer. To evaluate the proposed Fuzzy-GFINS, we made the AGV with Mecanum wheels and applied the proposed Fuzzy-GFINS. In experimental result, we verified that the proposed method can calibrate effectively data of the accelerometer in the GFINS.

부양형 고속회전 자이로의 질량불균형 모멘트 제어를 위한 비선형 제어기 설계

송형민,이영재,성상경,이상우 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11

부양형 고속회전 자이로는 정전기력을 이용하여 관성 질량체를 물리적 접촉 없이 부양시키고 이후 고속회전 운동을 하는 구조로 되어있다. 이때 관성 질량체의 질량 불균형으로 인해, 고속회전 운동 시와블링 효과가 발생할 수 있다. 이로 인해 부양형 자이로스코프의 수직축 변위신호의 안정성이 떨어질 수 있다. 이를 제어하기 위해 본 논문에서는 부양형 자이로스코프의 수직축 변위 모델과 x, y 축별 모멘트 모델에 대한 운동방정식을 세우고, 비선형 제어기를 구성하여 시뮬레이션을 수행하였다. 제시된 비선형 제어기를 이용해 부양형 자이로스코프의 수직축 변위량이 감소하는 결과를 얻을 수 있었다. A Levitated gyroscope is operated by nonphysical connection and excited by electrostatic force. If proof mass has a unbalancing mass distribution, then the gyroscope rotated with wobbling effect. This wobbling effect cause unstable vertical displacement output. In this paper, I design a motion of equation about gyroscope’s vertical displacement and axial moment. To control gyroscope’s vertical displacement and axial moment, I use a nonlinear controller based on Lyapunov stability theorem.

MEMS Gyroscope를 위한 feed-through 노이즈 제거 기법

박경진(Kyung-Jin Park),강성묵(Seong-Mook Kang),백창욱(Chang-Wook Baek),김호성(Ho-Seong Kim) 대한전기학회 2009 전기학회논문지 Vol.58 No.11

Since the dimensions of MEMS gyroscope are very small compared to those of conventional gyroscope, MEMS gyroscope should be able to measure charge of pico-coulomb caused by very small change of electrodes gap. However, feed-through signal from driving electrodes to the sensing electrodes due to the electromagnetic coupling is much greater than the sensing signal, which degrades the sensitivity of MEMS gyroscope. This paper introduces the feed-through noise canceling technique using dummy port and confirms the feasibility of feed-through noise canceling experimentally. Experimental results shows that, when driving signal is 6 Vpp, 30 ㎑, feed-through signal of vacuum packaged Si Gyroscope decreases from -53.2 ㏈m to -77.1 ㏈m by using feed-through reduction technique. Q-factor that could not be measured without noise reduction is measured to be about 2500 and resonance frequency to be 7.018 ㎑.

On the control of vibratory MEMS gyroscopes

S. Choura,N. Aouni,S. El-Borgi 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.7

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.

On the control of vibratory MEMS gyroscopes

Choura, S.,Aouni, N.,El-Borgi, S. Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.7

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.

고체형 정밀 공진 자이로스코프를 위한 이차 PLL 루프필터 기반 위상제어루프 설계

박상준(Sang-Jun Park),용기력(Ki Ryeok Yong),이영재(Young Jae Lee),성상경(Sangkyung Sung) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.6

This paper suggests a design method of an improved phase control loop for tracking resonant frequency of solid type precision resonant gyroscope. In general, a low cost MEMS gyroscope adapts the automatic gain control loops by taking a velocity feedback configuration. This control technique for controlling the resonance amplitude shows a stable performance. But in terms of resonant frequency tracking, this technique shows an unreliable performance due to phase errors because the AGC method cannot provide an active phase control capability. For the resonance control loop design of a solid type precision resonant gyroscope, this paper presents a phase domain control loop based on linear PLL (Phase Locked Loop). In particular, phase control loop is exploited using a higher order PLL loop filter by extending the first order active PI (Proportion-Integral) filter. For the verification of the proposed loop design, a hemispherical resonant gyroscope is considered. Numerical simulation result demonstrates that the control loop shows a robust performance against initial resonant frequency gap between resonator and voltage control oscillator. Also it is verified that the designed loop achieves a stable oscillation even under the initial frequency gap condition of about 25 Hz, which amounts to about 1% of the natural frequency of a conventional resonant gyroscope.

편심형 MEMS 자이로스코프의 동적 모델링 및 해석

하동진(Dong Jin Ha),신상하(Sang Ha Shin),유홍희(Hong Hee Yoo) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

Dynamic modeling of an eccentric MEMS gyroscope is presented and the dynamic characteristics of the gyroscope are investigated with the modeling method. It is found that the eccentricity of the MEMS gyroscope affects the dynamic characteristics significantly. Different from conventional MEMS gyroscopes, the zero-rate output is significantly reduced in this gyroscope. To obtain general guidelines of the gyroscope design, dimensionless parameters are first identified and the effects of the parameters on the gyroscope performance measures are investigated.