Inertial Measurement Units, the main component of a navigation system, are used in several systems today. IMU&rsquo / s main components, gyroscopes and accelerometers, can be produced at a lower cost and higher quantity. Together with the decrease in the production cost of sensors it is observed that the performances of these sensors are getting worse. In order to improve the performance of an IMU, the error compensation algorithms came into question and several algorithms have been designed. Inertial sensors contain two main types of errors which are deterministic errors like scale factor, bias, misalignment and stochastic errors such as bias instability and scale factor instability. Deterministic errors are the main part of error compensation algorithms. This thesis study explains the methodology of how the deterministic errors are defined by 27 state static and 60 state dynamic rate table calibration test data and how those errors are used in the error compensation model. In addition, the stochastic error parameters, gyroscope and bias instability, are also modeled with Gauss Markov Model and instant sensor bias instability values are estimated by Kalman Filter algorithm. Therefore, accelerometer and gyroscope bias instability can be compensated in real time. In conclusion, this thesis study explores how the IMU performance is improved by compensating the deterministic end stochastic errors. The simulation results are supported by a real IMU test data.

Design and analysis of polysilicon and single crystal silicon gyroscopes have been carried out. Variations in suspension design have been explored. Designs that utilize in-plane and out-of-plane sensing are studied. Damping plays an important role in determining the sense response. Reduction in damping directly affects sensor performance. The various damping mechanisms that are prevalent in gyroscopes are studied. Perforations on the proof mass are observed to significantly reduce the damping in the device when operated in air. The effects of perforation geometry and density have been analyzed. The analysis results show that there is a two orders of magnitude reduction in damping of thick gyroscope structures with optimized perforation design. Equivalent circuit lumped parameter models have been developed to analyze gyroscope performance. The simulation results of these models have been compared with results obtained from SABER, a MEMS specific system level design tool from Coventorware. The lumped parameter models are observed to produce faster simulation results with an accuracy comparable to that of Coventorware Three gyroscopes specific to the PolyMUMPS fabrication process have been designed and their performance analyzed. Two of the designs sense motion out-of-plane and the other senses motion in-plane. Results of the simulation show that for a given damping, the gyro design with in-plane modes gives a resolution of 4º/s. The out-of-plane gyroscopes have two variations in suspension. The hammock suspension resolves a rate of 25º/s in a 200 Hz bandwidth while the design with folded beam suspension resolves a rate of 2º/s in a 12 Hz bandwidth. A single crystal silicon in-plane gyroscope has been designed with vertical electrodes to sense Coriolis motion. This design gives an order of magnitude higher Capacitance change for a given rotation in comparison to conventional comb-finger design. The effects of process induced residual stress on the characteristic frequencies of the polysilicon gyroscopes are also studied. The in-plane gyroscope is found to be robust to stress variations. Analysis results indicate that the tuning fork gyroscope with the hammock suspension is the most susceptible to compressive residual stress, with a significant drop in sensitivity at high stress values.

This thesis project considers the potential use of inertial navigation on a consumer grade tablet mounted in a vehicle in an underground mine. The goal is to identify which sensors and techniques are useful and to design a navigation algorithm based on those results. The navigation algorithm is intended to work alongside the current received signal strength indication (RSSI) positioning system. Testing of the gyroscope, accelerometer and magnetometer sensors suggest that, while dead reckoning is likely not precise enough, an orientation filter can be designed that can be used for navigation. A complementary orientation filter using the gyroscope and accelerometer is then designed that shows better results than the default sensor fusion solutions available in Android. The filter is expandable and can come to include magnetometer data in the future. Based on the outputs of this filter, a navigation algorithm based onangle matching with map information is proposed. Precise positioning in an underground mine can be crucial to employee safety, and may also bring production benefits.

This thesis reports the development of high-performance symmetric and decoupled micromachined gyroscopes for tactical-grade inertial measurement applications. The symmetric structure allows easy matching of the resonance frequencies of the drive and sense modes of the gyroscopes for achieving high angular rate sensitivity / while the decoupled drive and sense modes minimizes mechanical cross-coupling for low-noise and stable operation. Three different and new symmetric and decoupled gyroscope structures with unique features are presented. These structures are fabricated in four different micromachining processes: nickel electroforming (NE), dissolved-wafer silicon micromachining (DWSM), silicon-on-insulator (SOI) micromachining, and silicon-on-glass (SOG) micromachining. The fabricated gyroscopes have capacitive gaps from 1.5&micro / m to 5.5&micro / m and structural layer thicknesses from 12&micro / m to 100&micro / m, yielding aspect ratios up to 20 depending on the fabrication process. The size of fabricated gyroscope chips varies from 1x1mm2 up to 4.2x4.6mm2. Fabricated gyroscopes are hybrid-connected to a designed capacitive interface circuit, fabricated in a standard 0.6&micro / m CMOS process. They have resonance frequencies as small as 2kHz and as large as 40kHz / sense-mode resonance frequencies can be electrostatically tuned to the drive-mode frequency by DC voltages less than 16V. The quality factors reach to 500 at atmospheric pressure and exceed 10,000 for the silicon gyroscopes at vacuum. The parasitic capacitance of the gyroscopes on glass substrates is measured to be as small as 120fF. The gyroscope and interface assemblies are then combined with electronic control and feedback circuits constructed with off-the-shelf IC components to perform angular rate measurements. Measured angular rate sensitivities are in the range from 12&micro / V/(deg/sec) to 180&micro / V/(deg/sec), at atmospheric pressure. The SOI gyroscope demonstrates the best performance at atmospheric pressure, with noise equivalent rate (NER) of 0.025(deg/sec)/Hz1/2, whereas the remaining gyroscopes has an NER better than 0.1(deg/sec)/Hz1/2, limited by either the small sensor size or by small quality factors. Gyroscopes have scale-factor nonlinearities better than 1.1% with the best value of 0.06%, and their bias drifts are dominated by the phase errors in the demodulation electronics and are over 1deg/sec. The characterization of the SOI and SOG gyroscopes at below 50mTorr vacuum ambient yield angular rate sensitivities as high as 1.6mV/(deg/sec) and 0.9mV/(deg/sec), respectively. The NER values of these gyroscopes at vacuum are smaller than 50(deg/hr)/Hz1/2 and 36(deg/hr)/Hz1/2, respectively, being close to the tactical-grade application limits. Gyroscope structures are expected to provide a performance better than 10 deg/hr in a practical measurement bandwidth such as 50Hz, provided that capacitive gaps are minimized while preserving the aspect ratio, and the demodulation electronics are improved.

Orientador: Jose Manoel Balthazar / Dissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-27T20:47:10Z (GMT). No. of bitstreams: 1 Rodrigues_KellyCristinePonte_M.pdf: 4972667 bytes, checksum: d58345ad745e5f34e613d6e211e516f0 (MD5) Previous issue date: 2001 / Resumo: Neste trabalho apresenta-se o estudo de um rotor com efeito giroscópico não linear e dois graus de liberdade que exibe ressonâncias internas do tipo w2= 2 w1 e do tipo w2= w1 solução geral obtida para a primeira aproximação da solução do sistema perturbado é utilizada para a obtenção das condições de estabilidade dessas ressonâncias de acordo com o critério de Routh-Hurwitz. Como pré-requisito para a compreensão do comportamento de um rotor com efeito giroscópico não linear, objetivo principal de estudo deste trabalho, estuda-se a estabilidade de um sistema giroscópico não linear, apresentando-se uma forma de se obter a solução desse sistema. O sistema fracamente não linear é estudado nas vizinhanças de uma solução conhecida. Analisa-se o efeito do rotor de eixo flexível na freqüência de oscilação de um giroscópio sem influências de forças externas / Abstract: In this work one presents the study of a rotor with gyroscopic nonlinear effects and two degrees of freedom that exibits internal resonances of the kind w2= 2 w1 and of the kind w2= w1. The general solution obtained for the solution first approximation of the perturbed system is used for obtaining the stability conditions for these resonances according to the Routh-Hurwitz criteria. As an important result to be considered in the comprehension of the behavior of a rotor with nonlinear gyroscopic effects, the main objective of the study developed here, one studies the stability of a nonlinear giroscopic system, presenting a way of obtaining the solution for this system. The weak1y nonlinear system is studied in the neighborhood of a known solution. One analyses the effects of the rotor with flexible axis over the oscilation frequency of a gyroscope without the influences of external forces / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Elnatan Chagas Ferreira / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-15T01:31:53Z (GMT). No. of bitstreams: 1 Melo_FernandoFerreirade_D.pdf: 5797933 bytes, checksum: a063234832f57c466d1189c44c7fffaa (MD5) Previous issue date: 2009 / Resumo: Esta tese apresenta o estudo e o projeto de um processador eletrônico do sinal de um interferômetro de Sagnac a fibra óptica que procura atender especificações para aplicação em navegação inercial. Estudou-se o comportamento de Girômetros a fibra óptica com modulação de fase senoidal através de modelos e simulações de algumas técnicas de processamento do sinal fotodetectado. Procurou-se responder questões como o sinal mínimo detectável para processadores de sinal específicos, como a técnica Lock-in e da técnica Mean Value. A técnica Mean Value foi modificada visando facilitar a implementação eletrônica e melhorar o desempenho em relação à proposta original. Compromissos entre estabilidade e pontos de operação com melhor resolução, na medida da diferença de fase de Sagnac, foram estabelecidos para o processador projetado. Este processador foi aplicado a um giroscópio óptico projetado por pesquisadores do IEAv/CTA, em São José dos Campos/SP. / Abstract: This thesis presents the study and design of an electronic signal processor for an optical-fiber Sagnac interferometer aimed at inertial navigation applications. The fiberoptic gyroscope behavior under sinusoidal phase modulations was studied through models and simulation of some signal processing techniques. It was attempted to answer questions like lowest detectable signal for some particular processors, such as synchronous (lock-in) detection and mean value. Modifications to the mean value technique aimed at improving its performance and easing its electronics implementation are presented. Tradeoffs between stability and resolution in Sagnac phase difference measurement were determined for the processor designed and for specific points of operation. This processor was used to extract rotation information from a fiber-optic gyroscope designed and assembled by IEAV/CTA investigators based at São José dos Campos/SP. / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica

Orientador: José Maria Campos dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-23T14:00:55Z (GMT). No. of bitstreams: 1 Ferreira_AndersonHenriqueRodrigues_M.pdf: 13469668 bytes, checksum: 25f9c2a03e6a62e5d1a871b78053c4b1 (MD5) Previous issue date: 2013 / Resumo: Este trabalho apresenta uma análise dos problemas físicos associados ao projeto de um sensor inercial giroscópio baseado na tecnologia MEMS (micro-electro-mechanical-system). O dispositivo oferece uma resposta elétrica na forma de uma variação da capacitância devido à força de Coriolis e como consequência obtém-se uma medida da velocidade angular de um sistema. Uma formulação analítica da dinâmica eletromecânica de um giroscópio com dois graus de liberdade é revista e implementada em um programa MATLAB/Simulink (R2011a) ®, onde são obtidas as respostas em deslocamento nos domínios do tempo e da frequência. Para melhorar a capacidade do projeto de sensores inerciais, uma abordagem da análise eletromecânica do giroscópio usando o Método dos Elementos Finitos (MEF) do programa comercial ANSYS 12.0® é apresentada. Neste contexto, dois projetos de giroscópios MEMS encontrados na literatura (giroscópio de ACAR e de NGUYEN) são analisados. Análises estática, modal e harmônica são realizadas e os resultados comparados com aqueles obtidos com os modelos analíticos. A resposta harmônica para o modelo eletromecânico completo de MEF não foi realizada devido à dificuldade de simular análises harmônicas incluindo os elementos de Atuação e Detecção simultaneamente. Para superar este problema o elemento Detector foi substituído por um elemento de mola. Os resultados obtidos no giroscópio de NGUYEN apresentaram boa concordância entre os modelos. Contudo, os resultados com o giroscópio de ACAR apresentaram erros significativos entre os modelos, os quais são oriundos da geometria usada no modelo de MEF que se mostrou flexível em regiões que deveriam ser rígidas. Uma análise estática de diferentes tipos de suspensão elástica para giroscópios MEMS é apresentada no Apêndice B / Abstract: This paper presents an analysis of the physical problems associated with the design of a gyroscope inertial sensor based on MEMS technology (MicroEletroMechanical System). The device gives a response in the form of an electrical capacitance change due to the Coriolis force and as a result obtains a measure of the angular velocity of a system. Analytical formulation of the electromechanical dynamics of a gyroscope with two degrees of freedom is reviewed and implemented in a MATLAB/Simulink (R2011a) ® code, where the displacement responses are obtained in time and frequency domains. To improve the capacity of the inertial sensors design, another electromechanical gyroscope analysis approach using the Finite Element Method (FEM) of commercial software ANSYS ® 12.0 is presented. In this context, two designs of MEMS gyroscopes from the literature (NGUYEN's and ACAR's gyroscopes) are analyzed. Static, modal and harmonic analysis are performed and the results compared with those obtained with the analytical models. The harmonic response for the complete electromechanical model of MEF was not performed due to the inability to run harmonic analysis including Actuator and Detector elements simultaneously. To overcome this difficulty, the Detector element was replaced by a spring element. The results obtained with NGUYEN's gyroscope showed good agreement between the models. However, the results with the ACAR's gyroscope showed significant errors between the models, which are derived from the geometry used in the FEM model, that was flexible to regions that should be rigid. A static analysis of different types of elastic suspension for MEMS gyroscopes are shown in Appendix B / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Every smartphone today includes an accelerometer. An accelerometer works by detecting acceleration affecting the device, meaning it can be used to identify incidents such as collisions at a relatively high speed where large spikes of acceleration often occur.A gyroscope on the other hand is not as common as the accelerometer but it does exists in most newer phones. Gyroscopes can detect rotations around an arbitrary axis and as such can be used to detect critical rotations.This thesis work will present an algorithm for utilising the accelerometer and gyroscope in a smartphone to detect incidents occurring on a test track for cars. / Alla smarta telefoner innehåller idag en accelerometer. En accelerometer analyserar acceleration som påverkar enheten, vilket innebär att den kan användas för att detektera incidenter så som kollisioner vid relativt höga hastigheter där stora spikar avacceleration vanligtvis påträffas. Ett gyroskop däremot är inte lika vanlig som en accelerometer men finns i de flesta nyare telefoner. Ett gyroskop kan detektera rotationer runt en godtycklig axel och kan på så vis användas för att detektera kritiska rotationer. Detta examensarbete kommer att presentera en algoritm för att utnyttja accelerometern och gyroskopet i en telefon för att detektera incidenter som inträffar på en testbana för bilar.

Many surveying engineering applications require the knowledge of the orientation parameters of instruments. One can use inertial measurement units (IMUs) to determine that. IMUs are combinations of several inertial sensors and comprise at least an accelerometer and a gyroscope. Therefore, they can detect accelerations and angular rates in a three-dimensional space. As micro-electro-mechanical systems, the sensors are increasingly getting smaller and lighter, but without being reduced in their accuracy. The smaller size facilitates diverse placing of the sensors, which allows a variety of uses. Moreover, several low-cost IMUs have been devised since the development of single-board computers. The main objectives of this work are to determine tilts using a low-cost IMU, and the accuracy of the sensor. Furthermore, it studies general IMU applications in surveying engineering, and examines whether low-cost versions are applicable. To fulfil the objectives, the study was based on a selected low-cost IMU. Two programs were developed as part of this work. One was to control the sensor and the other, to calculate the tilts and analyse the data. The IMU was mounted in front of the objective of the total station and aligned in different reference orientations. All measurements were performed under controlled thermal conditions. Thereby, it was ensured that no falsifications could appear due to ambient temperature influences. As a first step, the sensor calibration process was completed. It helped determine the signal offset parameter and their time-dependent change. The calibration was done using two present methods, the six-position and the multi-position methods. The calibrated IMU helped determine the tilts. This was done in the case of the accelerometer via trigonometric functions, which allowed an absolute orientation statement. In contrast, the gyroscope provided relative orientation with the multiplication of the detected angular variance and the time that passed. After that, a target-actual comparison with the reference information of the total station helped determine the external accuracy of the tilt from the IMU. Moreover, multiple measurements could give a statement of the internal accuracy. Finally, the Kalman Filter was added to smooth out the sensor data and combine it in real-time. The calibration methods showed similar results, and it was striking that the sensors did not show the expected drifts. The reason could be related to a pre-calibration by the manufacturer. On the one hand, the used IMU showed differences in the total station alignments in the order of 0.798° for the accelerometer and up to 4.3° for the gyroscope with the calibrated data. On the other, the differences in repeated measurements were at 0.024° for the accelerometer and 0.5° for the gyroscope. It was figured out different possible applications of IMUs in surveying engineering. Among other things, these included orientation monitoring of sensor platforms or the determination of the external orientation of unmanned aerial systems. For these applications, the usability depends on the achievable accuracy. In the case of the IMU chosen in this study, the proven accuracy is too inaccurate for these applications. There is a need for further investigation because the use of another sensor type may rectify the insufficient accuracy problem. Moreover, to achieve better accuracies and to make it possible to use the IMU in different ambient temperatures, the temperature influence must be determined.

An IMU is a sensor with many differing use cases, it makes use of an accelerometer, gyroscope and sometimes a magnetometer. One of the biggest problems with IMU sensors is the effect vibrations can have on their data. The reason for this study is to find a solution to this problem by filtering the data. The tests for this study were conducted in cooperation with Husqvarna using two of their automowers. The tests were made by running the automowers across different surfaces and recording the IMU data. To find filters for the IMU data a comprehensive literature survey was conducted to find suitable methods to filter out vibrations. The two filters selected for further testing were the complementary filter and the LMS filter. When the tests had been run all the data was added to data sheets where it could be analyzed and have the filters added to the data. From the gathered data the data spikes were clearly visible and were more than enough to trigger the mower's emergency stop and need to be manually reset. The vibrations were too irregular to filter using the LMS filter since it requires a known signal to filter against. Hence only the complementary filter was implemented fully. With the complementary filter these vibrations can be minimized and brought well below the level required to trigger an emergency stop. With a high filter weight constant such as 0.98, the margin of error from vibrations can be brought down to +- 1 degrees as the lowest and +- 4,6 degrees as highest depending on the surface and automower under testing. The main advantage with using the complementary filter is that it only requires one weight constant to adjust the filter intensity making it easy to use. The one disadvantage is that the higher the weight constant is the more delay there is on the data.