161 research outputs found
Hardware Implementation of Active Disturbance Rejection Control for Vibrating Beam Gyroscope
Obtaining the approximation of rotation rate form a Z-Axis MEMS gyroscope is a challenging problem. Currently, most commercially available MEMS gyroscopes are operating in an open-loop for purposes of simplicity and cost reduction. However, MEMS gyroscopes are still fairly expensive and are not robust during operation. The purpose of this research was to develop a high-performance and low-cost MEMS gyroscope using analog Active Disturbance Rejection Control (ADRC) system. By designing and implementing analog ADRC both above requirements were satisfied. Analog ADRC provides the fastest response time possible (because the circuit is analog), eliminates both internal and external disturbances, and increases the bandwidth of the gyroscope beyond its natural frequency. On the other hand, the overall design is extremely economical, given that the system is built using pure active and passive analog components. This work, besides achieving high-performance and providing low-cost solution, furnishes two novel designs concepts. First, Active Disturbance Rejection Controller can now be build using pure analog circuit, which has never been done before. Second, it is the first time that the advanced controller has been successfully implemented in hardware to control an inertial rate sensor like gyroscope. This work provides a novel solution to applications that require high-performance and low-cost inertial sensor
Hardware Implementation of Active Disturbance Rejection Control for Vibrating Beam Gyroscope
Obtaining the approximation of rotation rate form a Z-Axis MEMS gyroscope is a challenging problem. Currently, most commercially available MEMS gyroscopes are operating in an open-loop for purposes of simplicity and cost reduction. However, MEMS gyroscopes are still fairly expensive and are not robust during operation. The purpose of this research was to develop a high-performance and low-cost MEMS gyroscope using analog Active Disturbance Rejection Control (ADRC) system. By designing and implementing analog ADRC both above requirements were satisfied. Analog ADRC provides the fastest response time possible (because the circuit is analog), eliminates both internal and external disturbances, and increases the bandwidth of the gyroscope beyond its natural frequency. On the other hand, the overall design is extremely economical, given that the system is built using pure active and passive analog components. This work, besides achieving high-performance and providing low-cost solution, furnishes two novel designs concepts. First, Active Disturbance Rejection Controller can now be build using pure analog circuit, which has never been done before. Second, it is the first time that the advanced controller has been successfully implemented in hardware to control an inertial rate sensor like gyroscope. This work provides a novel solution to applications that require high-performance and low-cost inertial sensor
Hardware Implementation of Active Disturbance Rejection Control for Vibrating Beam Gyroscope
Obtaining the approximation of rotation rate form a Z-Axis MEMS gyroscope is a challenging problem. Currently, most commercially available MEMS gyroscopes are operating in an open-loop for purposes of simplicity and cost reduction. However, MEMS gyroscopes are still fairly expensive and are not robust during operation. The purpose of this research was to develop a high-performance and low-cost MEMS gyroscope using analog Active Disturbance Rejection Control (ADRC) system. By designing and implementing analog ADRC both above requirements were satisfied. Analog ADRC provides the fastest response time possible (because the circuit is analog), eliminates both internal and external disturbances, and increases the bandwidth of the gyroscope beyond its natural frequency. On the other hand, the overall design is extremely economical, given that the system is built using pure active and passive analog components. This work, besides achieving high-performance and providing low-cost solution, furnishes two novel designs concepts. First, Active Disturbance Rejection Controller can now be build using pure analog circuit, which has never been done before. Second, it is the first time that the advanced controller has been successfully implemented in hardware to control an inertial rate sensor like gyroscope. This work provides a novel solution to applications that require high-performance and low-cost inertial sensor
Characterization of MEMS Coriolis Vibratory Gyroscopes
A MEMS Gyroscope is a micromachined inertial sensor that can measure the angle of
orientation or the angular rate of rotation. These devices have the potential to be used in
high precision navigation, safety and consumer electronics applications.
Due to their complexity, MEMS Gyroscopes are prone to have imperfections that
inhibit their full potential. By deeply characterizing these sensors, it is possible to validate
fabrication methodologies, apply control circuit mechanisms, and design alternative
mechanical structures that improve the performance.
In this project, a streamlined methodology for testing and characterizing these devices
is presented and executed. Analysis to the obtained results is given. Aditionally, a
prototype circuit was designed to operate the sensors in a closed-loop mode.
Two families of gyroscopes with different thickness were characterized - 40 m and
100 m. The devices presented low sensitivity thresholds due to the presence of a large
quadrature error. A phase sensitive demodulation solution was provided to eliminate
this noise source. The 40 m presented an overall better performance. A Python Script to
extract key noise performance parameters was also displayed.Giroscópios MEMS são micro sensores inerciais que conseguem medir o ângulo de orientação
ou a variação ângular de uma rotação. Estes dispositivos têm o potencial de ser usados
em aplicações de alta precisão para sistemas de navegação, segurança e para eletrónica
comercial.
Devido à sua complexidade, os Giroscópios MEMS são propensos a imperfeições que
inibem o seu potencial máximo. Através da caracterização extensa destes sensores, é
possível validar as metodologias de fabricação, aplicar circuitos de controlo e projetar
estruturas mecânicas alternativas que melhorem a sua performance.
Neste projeto é apresentada uma metodologia substanciada para testar e caracterizar
estes dispositivos. Os resultados obtidos foram analisados. Adicionalmente, foi desenhado
um protótipo de um circuito que opera os sensores em circuito fechado.
Duas famílias de giroscópios com diferentes espessuras foram caracterizadas - 40 m
e 100 m. Os dispositivos apresentaram baixos graus de sensibilidade devido a uma forte
influência do erro de quadratura. Foi aplicada uma demodulação sensível à fase para
melhoramento da performance. Um programa em Python para extrair parâmetros de
ruído na resposta é apresentado
On Control System Design for the Conventional Mode of Operation of Vibrational Gyroscopes
This paper presents a novel control circuitry design for both vibrating axes (drive and sense) of vibrational gyroscopes, and a new sensing method for time-varying rotation rates. The control design is motivated to address the challenges posed by manufacturing imperfection and environment vibrations that are particularly pronounced in microelectromechanical systems (MEMS) gyroscopes. The method of choice is active disturbance rejection control that, unlike most existing control design methods, does not depend on an accurate model of the plant. The task of control design is simplified when the internal dynamics, such as mechanical cross coupling between the drive and sense axes, and external vibrating forces are estimated and cancelled in real time. In both simulation and hardware tests on a vibrational piezoelectric beam gyroscope, the proposed controller proves to be robust against structural uncertainties; it also facilitates accurate sensing of time-varying rotation rates. The results demonstrate a simple, economic, control solution for compensating the manufacturing imperfections and improving sensing performance of the MEMS gyroscopes
On Control System Design for the Conventional Mode of Operation of Vibrational Gyroscopes
This paper presents a novel control circuitry design for both vibrating axes (drive and sense) of vibrational gyroscopes, and a new sensing method for time-varying rotation rates. The control design is motivated to address the challenges posed by manufacturing imperfection and environment vibrations that are particularly pronounced in microelectromechanical systems (MEMS) gyroscopes. The method of choice is active disturbance rejection control that, unlike most existing control design methods, does not depend on an accurate model of the plant. The task of control design is simplified when the internal dynamics, such as mechanical cross coupling between the drive and sense axes, and external vibrating forces are estimated and cancelled in real time. In both simulation and hardware tests on a vibrational piezoelectric beam gyroscope, the proposed controller proves to be robust against structural uncertainties; it also facilitates accurate sensing of time-varying rotation rates. The results demonstrate a simple, economic, control solution for compensating the manufacturing imperfections and improving sensing performance of the MEMS gyroscopes
CMOS systems and circuits for sub-degree per hour MEMS gyroscopes
The objective of our research is to develop system architectures and CMOS circuits that interface with high-Q silicon microgyroscopes to implement navigation-grade angular rate sensors. The MEMS sensor used in this work is an in-plane bulk-micromachined mode-matched tuning fork gyroscope (M² – TFG
), fabricated on silicon-on-insulator substrate. The use of CMOS transimpedance amplifiers (TIA) as front-ends in high-Q MEMS resonant sensors is explored. A T-network TIA is proposed as the front-end for resonant capacitive detection. The T-TIA provides on-chip transimpedance gains of 25MΩ, has a measured capacitive resolution of 0.02aF /√Hz at 15kHz, a dynamic range of 104dB in a bandwidth of 10Hz and consumes 400μW of power. A second contribution is the development of an automated scheme to adaptively bias the mechanical structure, such that the sensor is operated in the mode-matched condition. Mode-matching leverages the inherently high quality factors of the microgyroscope, resulting in significant improvement in the Brownian noise floor, electronic noise, sensitivity and bias drift of the microsensor. We developed a novel architecture that utilizes the often ignored residual quadrature error in a gyroscope to achieve and maintain perfect mode-matching (i.e.0Hz split between the drive and sense mode frequencies), as well as electronically control the sensor bandwidth. A CMOS implementation is developed that allows mode-matching of the drive and sense frequencies of a gyroscope at a fraction of the time taken by current state of-the-art techniques. Further, this mode-matching technique allows for maintaining a controlled separation between the drive and sense resonant frequencies, providing a means of increasing sensor bandwidth and dynamic range. The mode-matching CMOS IC, implemented in a 0.5μm 2P3M process, and control algorithm have been interfaced with a 60μm thick M2−TFG to implement an angular rate sensor with bias drift as low as 0.1°/hr ℃ the lowest recorded to date for a silicon MEMS gyro.Ph.D.Committee Chair: Farrokh Ayazi; Committee Member: Jennifer Michaels; Committee Member: Levent Degertekin; Committee Member: Paul Hasler; Committee Member: W. Marshall Leac
Novel concept of a single-mass adaptively controlled triaxial angular rate sensor
This paper presents a novel concept for an adaptively controlled triaxial angular rate (AR) sensor device that is able to detect rotation in three orthogonal axes, using a single vibrating mass. Pedestrian navigation is presented as an example demonstrating the suitability of the proposed device to the requirements of emerging applications. The adaptive controller performs various functions. It updates estimates of all stiffness error, damping and input rotation parameters in real time, removing the need for any offline calibration stages. The parameter estimates are used in feedforward control to cancel out their otherwise erroneous effects, including zero-rate output: The controller also drives the mass along a controlled oscillation trajectory, removing the need for additional drive control. Finally, the output of the device is simply an estimate of input rotation, removing the need for additional demodulation normally used for vibratory AR sensors. To enable all unknown parameter estimates to converge to their true values, the necessary. model trajectory is shown to be a three-dimensional Lissajous pattern. A modified trajectory algorithm is presented that aims to reduce errors due to discretization of the continuous time system. Simulation results are presented to verify the operation of the adaptive controller. A finite-element modal analysis of a preliminary structural design is presented. It shows a micro electro mechanical systems realizable design having modal shapes and frequencies suitable for implementing the presented adaptive controller
Inertial MEMS: readout, test and application
This thesis moves towards the investigation of Micro Electro-Mechanical Systems
(MEMS) intertial sensors from different perspectives and points of view: readout,
test and application.
Chapter 1 deals with the state-of-the-art for the interfaces usually employed for 3-
axes micromachined gyroscopes. Several architecture based on multiplexing schemes
in order to extremely simplify the analog front-end which can be based on a single
charge amplifier are analysed and compared. A novel solution that experiments an
innovative readout technique based on a special analog-Code Division Multiplexing
Access (CDMA) is presented; this architecture can reach a considerable reduction of
the Analog Front-End (AFE) 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. A case study is also analysed: a
comparison with the SD740 micro-machined integrated inertial module with tri-axial
gyroscope by SensorDynamics AG is provided.
MEMS accelerometers are widely used in the automotive and aeronautics fields
and are becoming extremely popular in a wide range of consumer electronics
products. The cost of testing is a major one within the manufacturing process,
because MEMS accelerometer characterization requires a series of tests that include
physical stimuli. The calibration and the functional testing are the most challenging
and a wide selection of Automatic Test Equipments (ATEs) is available on the
market for this purpose; those equipments provide a full characterization of the
Device Under Test (DUT), from low-g to high-g levels, even over temperature.
Chapter 2 presents a novel solution that experiments an innovative procedure to
perform a characterization at medium-g levels. The presented approach can be
applied to low-cost ATEs obtaining challenging results. The procedure is deeply investigated and an experimental setup is described. A case study is also analysed:
some already trimmed Three Degrees of Freedom (3DoF)-Inertial Measurement
Unit (IMU) modules (three-axes accelerometer integrated with a mixed signal ASIC),
from SensorDynamics AG are tested with the experimental setup and analysed, for
the first time, at medium-g levels.
Standard preprocessing techniques for removing the ground response from vehicle-
mounted Ground Penetrating Radar (GPR) data may fail when used on rough
terrain. In Chapter 3, a Laser Imaging Detection and Ranging (LIDAR) system
and a Global Positioning System (GPS)/IMU is integrated into a prototype system
with the GPR and provided high-resolution measurements of the ground surface.
Two modifications to preprocessing were proposed for mitigating the ground bounce
based on the available LIDAR data. An experiment is carried out on a set of
GPR/LIDAR data collected with the integrated prototype vehicle over lanes with
artificially rough terrain, consisting of targets buried under or near mounds, ruts
and potholes. A stabilization technique for multi-element vehicle-mounted GPR is
also presented
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