Self-Scheduled Control of a Gyroscope

IFAC Proceedings Volumes, Volume 47, Issue 3, 2014, Pages 6129-6134

Abstract: A classical mixed sensitivity minimization approach and a model matching formulation are compared with the goal to design a linear parameter-varying augmented state feedback control law for a laboratory-scale control moment gyroscope. Dynamic weighting filters are used to impose integral action and roll-off on the controller. Consequently, measurement noise is effectively suppressed and steady state accuracy is guaranteed even in the presence of input disturbances. Both designs are validated in real-time experiments and compared to a previous design that uses static weights. With the new designs, control effort is reduced while transient performance is maintained and tracking accuracy, as well as disturbance attenuation, is improved.

Study of the Fabrication Process for a Dual Mass Tuning Fork Gyro

Procedia Engineering, Volume 87, 2014, Pages 991-994

F. Santoni, E. Giovine, G. Torrioli, F. Chiarello, M.G. Castellano

Abstract:The fabrication process of a dual mass tuning for gyroscope presents many different challenges: the aspect ratio of the sidewalls, the Aspect Ratio Dependent Etch (ARDE) which causes different gaps to be etched in different etching time [1], the stiction during the release of the free structures, the notching effect that occurs with a dielectric etch stop layer [2], the thermal contact during the etch process. In this paper are presented different processes and studies of the etching characteristics in order to avoid or minimize these problems.

A Novel Design of Fiber Optic Gyroscope Based INS System for UAS Applications

Procedia Computer Science, Volume 57, 2015, Pages 1317-1323

Bhupendra Singh, Haneet Rana, Sunil Kumar, Paurush Bhulania, Gagan Minocha

Abstract:This paper describes an inertial navigation system (INS) for autonomous quad copter application, based on Fiber Optic Gyroscopes (FOG). As the FOG lack the mechanical components of the age old traditional Gyroscopes, they show good performance in terms of weight, size, sensitivity, robustness and resistance to physical forces. These characteristics make a FOG very efficient and extremely useful in strap down altitude navigational systems using heading reference. In this paper, an effort has been made to design and test run an INS based on FOG, which tries to satisfy the generic positioning requirements for typical UAS applications. The paper also cover lab-evaluations of testing the response of the system based on several test cases which also include errors owing from alignment and those induced by the sensor itself. Simulation results suggest good performance of the test system developed. Detailed results of system simulation are also reproduced.

Gyroscope sensing and self-calibration architecture based on signal phase shift

Sensors and Actuators A: Physical, Volume 241, 15 April 2016, Pages 1-11

Giorgio Casinovi, Arashk Norouzpour-Shirazi, Milap Dalal, Farrokh Ayazi

Abstract:MEMS vibratory gyroscopes measure rotation rates by sensing in various ways the effects of the Coriolis force on the gyroscope dynamics. This paper presents a rotation rate sensing method that is based on the phase shift induced by the Coriolis force in the gyroscope outputs. In principle, this method is applicable to any gyroscope that can be modeled at the functional level as a 2-DOF mass-spring system. Devices of this type include those based on various kinds of vibrating structures, as well as bulk acoustic wave (BAW) gyroscopes. Furthermore, it is shown that the sensing method presented in this paper can be used also for gyroscope calibration with only minor modifications to the control electronics, and without the need for additional moving parts or calibration stage. This is a significant benefit in applications that require in-situ gyroscope calibration.

Fixed-order Linear Parameter Varying Controller Design for a 2DOF Gyroscope

IFAC-PapersOnLine, Volume 48, Issue 26, 2015, Pages 230-235

Zlatko Emedi, Alireza Karimi

Abstract:This paper presents an approach for fixed-order Linear Parameter Varying (LPV) controller design with application to a 2 Degree-of-Freedom (2DOF) gyroscope experimental setup. Inner convex approximation of the non-convex set of all stabilizing fixed-order LPV controllers is characterized through a set of Linear Matrix Inequalities (LMIs). This is achieved through the use of two slack matrices which enable decoupling of the controller and Lyapunov matrix parameters in the derivative of Lyapunov function. The LPV model obtained by the approximation of the nonlinear model of the 2DOF gyroscope is used for the design of a second-order LPV controller. Experimental results show good tracking performance in the presence of scheduling parameter variations.

Rotation rate estimation in parametrically excited micro gyroscopes

Mechatronics, Volume 31, October 2015, Pages 264-275

Mahyar Fazlyab, Hassan Salarieh, Aria Alasty

Abstract:This paper reports the estimation of angular velocity in micro gyroscopes with parametric excitation. The identification procedure is done into two consecutive steps: In the first step, the physical parameters of the gyroscope (stiffness, damping, and actuator parameters) are estimated via continuous time Extended and Unscented Kalman filter. In the second step, a separate Kalman filter is dedicated to estimate the time varying rotation rate, using the output of the first step. Using numerical simulations, it is found that by introducing an artificial noise in the observer equations and tuning its variance, arbitrary temporal variation of angular velocity can be well tracked by the proposed observer.

Design and Development of a 3-axis Micro Gyroscope with Vibratory Ring Springs

Procedia Engineering, Volume 87, 2014, Pages 975-978

Yeonhwa Jeon, Heejun Kwon, Hyeon Cheol Kim, Sung Wook Kim

Abstract: This work presents the design, simulation and experiment of a miniaturized 3-axis gyroscope with vibratory ring springs. Its total size is 2mmx2 mm. The designed gyroscope has the vibrating ring spring to accomplish all sensing schemes necessary for 3-axis angular rate. The gyroscope is composed of the inner and outer ring springs, the x- direction and y-direction driving parts, the rolling sensing, and the pitch sensing and the yaw sensing parts. FEA analysis was performed to get the driving mode and the sensing mode using ANSYS program. The gyroscope was fabricated by using SOI process. The resonance frequencies of the fabricated gyroscope are respectively 16.9 kHz for the driving mode, 17.04 kHz for the yaw sensing mode, and 16.47 kHz for the pitch and rolling sensing modes. The frequency difference for the mode matching sensing is within 0.1% and it is in the controllable range. The resonance Q factors are 720 for the driving mode, 4370 for the pitch and roll sensing mode and 3922 for the yaw sensing mode, respectively.

Parameter Estimation of MEMS Gyroscope Using Local State Estimation Methods

IFAC-PapersOnLine, Volume 48, Issue 28, 2015, Pages 279-284

Ladislav Král, Miroslav šimandl

Abstract:The topic of unknown parameters estimation of a MEMS gyroscope system in real-time is proposed and discussed. The problem is tackled using state estimation methodology. It is formulated as joint state and parameter estimation where three local estimators are utilized. The estimates are used to control the proof mass trajectory adaptively where the system is enforced to operate at the resonant frequency of the system without damping coefficients. The estimate quality of the considered estimators is compared. Numerical simulation results indicate that the proposed approach provides a better estimate quality in comparison with the extended Kalman filter both in terms of convergence speed and quality of estimates.

Model Predictive Control of MEMS Vibratory Gyroscope

IFAC Proceedings Volumes, Volume 47, Issue 3, 2014, Pages 7278-7283

M. Hoseini Pishrobat, J. Keighobadi

Abstract:This paper presents a MPC (Model Predictive Control) algorithm for MEMS vibratory gyroscopes based on force-balancing control strategy. In the proposed MPC method, using a set of orthonormal basis functions named Laguerre functions, a new prediction and optimization technique is designed. To enhance the capability of proposed MPC method for tracking time-varying reference trajectories, first a repetitive control technique is developed. Second, following representing the governing dynamical equations of the vibratory gyroscope, discrete-time Laguerre network based MPC has been developed. The effective tracking performance of the proposed control methods has been shown through computer simulations.

Analog-CMDA based interfaces for MEMS gyroscopes

Microelectronics Journal, Volume 45, Issue 1, January 2014, Pages 78-88

E. Giomi, L. Fanucci, A. Rocchi

Abstract:This work moves toward the state-of-the-art for the interfaces usually employed for three-axes micromachined gyroscopes. Several architectures based on multiplexing schemes in order to extremely simplify the analog front-end which can be based on a single charge amplifier are analyzed and compared. This paper presents a novel solution that experiments an innovative readout technique based on a special analog-CDMA (Code Division Multiplexing Access); this architecture can reach a considerable reduction of the analog front-end with reference to other multiplexing schemes. Many family codes have been considered in order to find the best trade-off between performance and complexity. System-level simulations prove the effectiveness of this technique in processing all the required signals. Finally, a case study is analyzed: a comparison with the SD740 micro-machined integrated inertial module with a tri-axial gyroscope by SensorDynamics AG is provided.

Vibration-induced errors in MEMS tuning fork gyroscopes

Sensors and Actuators A: Physical, Volume 180, June 2012, Pages 32-44

Sang Won Yoon, Sangwoo Lee, Khalil Najafi

Abstract:This paper analyzes potential causes of vibration-induced error in ideal MEMS tuning fork gyroscopes. Even though MEMS gyros are known to be highly susceptible to mechanical vibration, the mechanisms responsible for generating vibration-induced errors are not well understood. We focus on the tuning fork gyroscope (TFG) design that is known to be relatively immune to vibration because of its differential operation and common-mode rejection. Our analysis, however, demonstrates that even an ideal TFG cannot completely eliminate vibrations in special situations because of vibration-induced asymmetry and nonlinearity. We identify three major causes of error that arise from (1) capacitive nonlinearity at the sense electrode, (2) asymmetric electrostatic forces along sense direction at the drive electrodes, and (3) asymmetric electrostatic forces (i.e., drive-electrode capacitance) along drive direction at the drive electrodes. The occurrence conditions and characteristics of each cause are analyzed. The effects of the causes on three classes of TFG gyro designs are analyzed and compared both qualitatively and quantitatively using dynamic analysis and simulation. Interestingly, in our simulation conditions, one TFG design (denoted as Type-DD) is less sensitive to vibration (>99% reduction) than the other two TFG designs (denoted as Type-CP and Type-DS). The reason for this difference is that Type-DD gyroscopes are immune to the dominant cause of error afflicting Type-CP and Type-DS designs. Our analysis also demonstrates that the most critical error-generation condition is vibration along with the sense direction of gyroscopes (denoted as sense-direction vibration) because of its contribution to all causes of error.

Analysis of acceleration sensitivity in frequency decoupled MEMS tuning fork gyroscope

Procedia Engineering, Volume 25, 2011, Pages 51-54

Thakur Praveen Singh, Koji Sugano, Toshiyuki Tsuchiya, Osamu Tabata

Abstract:This paper presents an analysis of the acceleration output (sensitivity) in frequency decoupled MEMS tuning fork gyroscopes (TFG). We found that in-phase acceleration input is transduced into excitation of anti-phase mode, which results into acceleration output. Therefore, frequency decoupling (decoupling ratio, DR) of in- and anti-phase modes of sense resonators is key factor to suppress acceleration output in TFG, which was verified in a fully operating tuning fork gyroscope. The FEA simulation results showed that as DR increases, the acceleration output decreased from 73.56deg/s/g to 23.42deg/s/g.

GaAs-based tuning fork microresonators: A first step towards a GaAs-based coriolis 3-axis Micro-Vibrating Rate Gyro (GaAs 3-axis μCVG)

Sensors and Actuators A: Physical, Volume 172, Issue 1, December 2011, Pages 204-211

I. Roland, S. Masson, O. Ducloux, O. Le Traon, A. Bosseboeuf

Abstract:This paper presents the design of a piezoelectric MEMS Coriolis Vibrating Gyroscope (CVG) based on a single gallium arsenide vibrating structure allowing the measurement of rotation rate along 3 orthogonal sensitive axes. Based on a theoretical and FEM study, we demonstrate that the achieved sensitivities reached for each axis is about 1.6 × 10−16 C/(°/s). We then demonstrate the feasibility of the realization of simple MEMS structures from C-doped Gallium Arsenide (GaAs) using standard micromachining processes. Finally, we show the fabrication and characterization of GaAs-based tuning fork microresonators as a first step towards a complete 3-axis GaAs MEMS CVG. These resonators show a resonance frequency of 42 350 Hz, a quality factor of 122 000 and a frequency temperature coefficient of 24 ppm/°K, validating the high potential of GaAs as a structural material for 3-axis MEMS CVGs.

Closed-loop compensation of the cross-coupling error in a quartz Coriolis Vibrating Gyro

Sensors and Actuators A: Physical, Volume 181, July 2012, Pages 25-32

Mélanie Descharles, Jean Guérard, Hamid Kokabi, Olivier Le Traon

Abstract:In this paper, the issue related to the quadrature error in a piezoelectric angular rate gyro is studied. Fabrication process and anisoelasticity of the material are known to reduce the performance of the bias stability of micromachined gyros. However, solutions exist to compensate for the quadrature error in silicon-based gyros: DC voltage, parallel capacitance. The principle of operation presented in this paper is based on charge injection in opposite phase to balance the charges induced by the quadrature error in quartz Coriolis Vibrating Gyros. The concept is experimentally tested first with an open-loop circuit. The result of this experiment showed a bias stability of 96°/h RMS over the temperature range. An additional closed-loop feedback circuit is designed and experimented. The active compensation of the quadrature error then improves the bias stability by 5 times, leading to a performance of 20°/h RMS over temperature.

Analysis of the electro-elastic properties of custom quartz tuning forks for optoacoustic gas sensing

Sensors and Actuators B: Chemical, Volume 227, May 2016, Pages 539-546

P. Patimisco, A. Sampaolo, L. Dong, M. Giglio, G. Scamarcio, F.K. Tittel, V. Spagnolo

Abstract:We report a detailed experimental and theoretical analysis of the influence of quartz tuning fork (QTF) dimensions on the main physical parameters controlling the QTF performance, namely, the quality factor Q, the resonance frequency, the fork stiffness, the spring constant, and the electrical resistance. Two different gold contact patterns were also compared. As a general trend, the QTF performance in terms of Q and electrical conductance values improves at increasing both the crystal thickness T and prong thickness w, while decreasing the prongs length Lp. However, since the QTF resonance frequency f0 is proportional to T/Lp2, a trade-off should be found in order to keep f0 < 40 kHz, i.e., well below the typical values of non-radiative relaxation rate of a targeted gas absorption lines.

A very-low cross-axis sensitivity piezoresistive accelerometer with an electroplated gold layer atop a thickness reduced proof mass

Sensors and Actuators A: Physical, Volume 189, 15 January 2013, Pages 125-133

A. Ravi Sankar, S. Das

Abstract:This paper presents fabrication and testing of a high performance quad beam silicon piezoresistive Z-axis accelerometer with a very-low cross-axis sensitivity. Cross-axis sensitivity in piezoresistive accelerometers, mainly caused by the asymmetric structural design is an important issue primarily for high performance applications. In the present study, symmetry of the structure is achieved by shifting the center of mass of the proof mass toward the beam plane by selectively electroplating a 20 μm thick gold layer atop the proof mass and simultaneously reducing the silicon thickness from backside of the proof mass surface. Silicon shadow mask technique was used to deposit a Cr/Au seed layer on the selected regions of the proof mass followed by an electroplating process to achieve the 20 μm thick gold layer. Theoretical analysis shows that for an in-plane acceleration, the rotation of the thickness reduced proof mass with the electroplated gold layer is reduced by 69% compared to the accelerometer device with normal all-silicon proof mass keeping the resonant frequency of both the structures nearly equal. The accelerometer device was realized by a bulk micromachining technique using a 5% dual doped tetra methyl ammonium hydroxide (TMAH) solution. A new figure of merit called the performance factor (PF) defined as the ratio of the product of the prime-axis sensitivity and the square of the resonant frequency to the maximum cross-axis sensitivity is used as a quantitative index to evaluate the fabricated sensors with already reported devices. Test results of a fabricated device with 30 μm flexure thickness show a very-low cross-axis sensitivity of 0.316 μV/Vg for an in-plane acceleration and a PF of around 2900 MHz2.

2.05 - Accelerometers

Reference Module in Materials Science and Materials Engineering, from Comprehensive Microsystems, 2008, Pages 135-180, Current as of 28 October 2015

Huikai Xie, Gary K. Fedder, Robert E. Sulouff

Abstract:Micromachined accelerometer developments have been ever increasing due to the demand for smaller size and lower cost with greater performance. The automotive industry used to be the dominating market, but now use of microaccelerometers is booming in portable electronics, video games, health care, and structural vibration monitoring. This chapter provides a comprehensive review of the operational principles of various acceleration sensing mechanisms, and is accompanied with a review of different fabrication technologies and topological designs. The process flows of some commercial products are described in detail. Design trade-offs such as monolithic integration versus hybrid and single-axis versus three-axis are discussed. Packaging issues and future trends are also addressed.

Application of vibrating beam technology to digital acceleration measurement

Sensors and Actuators A: Physical, Volume 21, Issues 1–3, February 1990, Pages 377-380

M.A. Meldrum

Abstract:Vibrating beam technology is currently being used for many types of static and dynamic transducer applications for the measurement of temperature, pressure, load and acceleration. This paper describes the application of a piezoelectric quartz vibrating beam in a digital accelerometer. The dynamic environment, in which this instrument must operate, poses some significant design challenges that are not encountered in transducer design for static applications. This paper will describe the design, performance and test results of an accelerometer used for vehicle control and navigation applications.

13 - MEMS integrating motion and displacement sensors

Smart Sensors and Mems, 2014, Pages 366-401

G. Langfelder, A. Tocchio

Abstract:The purpose of this chapter is to describe the working principle of the micro electro mechanical systems (MEMS) devices used in motion sensors, and to consider their level of sophistication and future evolution. The integration of a multi-parameter sensor in a single unit can increase the smartness of the device and enables the implementation of new functionalities in existing electronic systems. MEMS accelerometers, gyroscopes and magnetometers are discussed in detail, as they represent the core devices for the development of a high-precision inertial measurement unit (IMU). At the end of the chapter, consideration is given to the evolution of these units integrating new MEMS devices for added functionalities, such as proximity measurements.

Chapter 2.2 - Wearable Inertial Sensors and Their Applications

Wearable Sensors, 2014, Pages 85-104

Toshiyo Tamura

Abstract:Wearable inertial sensors have been developed extensively over the past several years. Inertial sensors, including accelerometers, gyroscopic sensors, and magnetic sensors, can be embedded in the body, such as the trunk, leg, arm, etc., for monitoring the motion associated with human activities. In this chapter, we examine the technological principles of several types of inertial sensors, and provide an assessment and evaluation of these sensors for patient rehabilitation in clinical practice.