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Cormier, Roger. "Isolation of concurrent faults in sensors and actuators in control systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/NQ46290.pdf.
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Do, Trong Hieu. "Analyse structurelle de réseaux de capteurs pour la commande et l'observation." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENT061/document.
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Dans ce travail, on s'intéresse aux problèmes de localisation et de classification des capteurs pour des propriétés de commande et d'observation de systèmes dynamiques. Lorsqu'une propriété considérée du système n'est pas vérifiée avec l'ensemble des capteurs initiaux, on cherche à implanter de nouveaux capteurs pour rendre cette propriété vraie. Lorsqu'une propriété du système est vérifiée avec l'ensemble des capteurs existants, on classe ces capteurs en différentes catégories en fonction de leur importance pour la préservation de cette propriété. On détermine les capteurs essentiels dont la défaillance fait perdre la propriété considérée et les capteurs inutiles qui peuvent tomber en panne sans aucun impact sur la propriété. Pour étudier ces deux problèmes, on utilise l'approche des systèmes linéaires structurés avec les graphes orientés associés. Les systèmes linéaires structurés sont une classe particulière de systèmes linéaires où les éléments des matrices d'état sont soit fixés à zéro soit des paramètres libres. Avec cette approche structurée, on étudie les problèmes de localisation et de classification des capteurs pour le rejet de perturbation par retour de mesure et la détection et localisation de défauts. Les résultats sont représentés en termes graphiques. Mots-Clés:Systèmes linéaires structurés ; Analyse structurelle ; Localisation de capteurs ; Classification de capteurs ; Rejet de perturbation; Détection et localisation de défaut<br>In this work, we are interested in sensor location and classification problems for control and observation of dynamical systems. When a considered property of the system is not satisfied with the initial set of sensors, we seek to implement additional sensors to make this property true. When a property is satisfied with the existing sensors, these sensors are classified into different categories according to their importance for the preservation of this property. We determine the critical sensors whose failure implies the property loss and the useless sensors which can fail without impact on the property. To study these two problems, we use the structured system approach with the associated directed graphs. Structured linear systems are a particular class of linear systems where the elements of state matrices are either zero or free parameters. With this approach, we study the problems of location and classification of sensors for disturbance rejection by measurement feedback and fault detection and isolation. The results are given in graphic terms. Keywords: Structured linear systems ; Structural analysis ; Sensor location ; Sensor classification; Disturbance rejection ; Fault detection and isolation
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Mitwalli, Ahmed Hamdi. "Polymer gel actuators and sensors." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9969.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.<br>Includes bibliographical references (p. [351]-361).<br>by Ahmed Hamdi Mitwalli.<br>Sc.D.
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Scheidl, Rudolf. "Actuators and Sensors for Smart Systems." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200616.
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Smartness of technical systems relies also on appropriate actuators and sensors. Different to the prevalent definition of smartness to be embedded machine intelligence, in this paper elegance and simplicity of solutions is postulated be a more uniform and useful characterization. This is discussed in view of the current trends towards cyber physical systems and the role of components and subsystems, as well as of models for their effective realization. Current research on actuators and sensing in the fluid power area has some emphasis on simplicity and elegance of solution concepts and sophisticated modeling. This is demonstrated by examples from sensorless positioning, valve actuation, and compact hydraulic power supply.
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MOHAMED, MOHAMED ELSAID ELKHAYAT MOATAZBELLAH. "Interface Circuits for Sensors and Actuators." Doctoral thesis, Università degli studi di Pavia, 2018. http://hdl.handle.net/11571/1214860.
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The research activity described in this Thesis is the result of three different projects, all dealing with interface circuits for sensors and actuators.
1) Capacitive Humidity sensor with temperature controller and heater integrated in CMOS technology
The first project deals with the design of the integrated interface circuit for accurately controlling the temperature of a CMOS capacitive humidity sensor, with the final goal of allowing self-dignostics and self-calibration of the sensor. The humidity sensor used is equipped with an integrated resistor and a temperature sensor which allow changing and measuring the actual sensor temperature.
This activity concentrated initially on the characterization of the humidity sensor provided by Texas Instruments, with the goal of determining the features and the behavior of the device and identifying the specifications of the integrated interface circuit. A measurement setup based on LabView has been developed to allow controlling the temperature of the sensor with an accuracy of 0.005˚C and measuring both the relative humidity and the temperature.
Based on the sensor measurement results we developed a model of the humidity sensor with built-in heater and thermometer in the Cadence framework, to allow the simulation of the complete system. In this sensor model, all the dynamic effects of the heater and relative humidity variation have been considered, to guarantee proper design of the temperature controller integrated circuit. The temperature controller is designed in CMOS technology; it allows a precise adjustment of the temperature with an accuracy better than 0.1˚C. The circuit is based on an analog control loop with PWM modulator.
The circuit has been fabricated using a 0.35µm CMOS technology.
2) Scaltech28 (test structures in CMOS 28nm)
The second project deals with the design of test structures in CMOS 28nm technology, to evaluate it potential for the implementation of sensor interface circuits in future high-energy physics experiments. This work has been carried out in the frame of project, SCALTECH28, which continues the tradition of other similar studies carried out in previous technology generations for achieving optimal results in IC design for various detectors.
This investigation within the selected 28nm technology had to address basic analysis on the single MOS devices (n-MOS and p-MOS), on passive elements like resistors and capacitors, and finally on basic circuits and system building blocks, among the most critical in the sensor interface circuits for different physics experiments.
The main purpose of the work is to investigate the performance of the 28nm technology in terms of signal processing quality, power consumption, and radiation hardness with respect to previous technological generations. An additional target is to experimentally evaluate radiation damage effects on single devices and on full circuits to develop rad-models for simulations. A test chip including elementary device arrays and dedicated read-out circuits has been developed and fully characterized. In particular, a capacitance to frequency converter has been integrated to measure the matching between different capacitors of a programmable array.<br>Experimental measurements showed that the worst-case measurement for the capacitor pair matching is around 0.98% error at 500fF. This value is compliant to the feasibility of A/D converters for sensor readout with resolution better than 10 bits. It is clear from the results that matching performance is comparable to previous technologies, making the 28nm technology eligible for analog signal processing in front-end circuits for physical experiments and related data converters. Samples have been sent to irradiation facility to be exposed to different radiation doses in order to be re-measured and compared in terms of matching and absolute capacitance values with respect to the measurements done before.
Based on the results obtained on the basic devices in 28nm technology, we designed a 14-bit 1MS/s extended range incremental A/D converter composed by the cascade of two resettable second-order sigma-delta modulators. The system is designed for reading out detector arrays in particle physics experiments. The two stages, ideally targeting 9 and 6 bits, respectively, are both based on a cascade of integrators with feed-forward (CIFF) architecture to maximize linearity. If necessary, they can work in pipeline to minimize conversion time. When the conversion of each sample by the two stages is completed, a digital recombination filter produces the overall ADC output word with the required resolution (ENOB) of at least 13 bits and a throughput of 1MS/s at the very low over sampling ratio (OSR) of 16. Each stage, implemented with the switched capacitor technique, consists of two integrators followed by a multi-bit quantizer and a capacitive DAC for the feedback. At the start of each conversion cycle, both analog integrators and the digital filter memory elements are reset. The ADC has been sent for fabrication in 28nm technology.
Driving circuit for the piezoelectric actuators in ultrasonic washing machines
The third project deals with the design of the driving circuit for the piezoelectric actuators in ultrasonic washing machines.
The object of this project concerns the study and design of a driving and control system for an ultrasonic cleaning machine, or more commonly called ultrasonic washing machine. These devices are used in several industrial applications. Ultrasonic washing machines consist of a tank filled with a detergent solvent, an electronic interface circuit and one or more piezoelectric transducers, which are mechanically connected to the tank and electrically to the driving circuit.
The driving system is connected from the AC mains and consists of three cascaded stages: a rectifier followed by a boost converter, to regulate the power factor and produce an intermediate DC voltage; a buck converter, to adjust the amplitude of the supply voltage for the piezoelectric transducers; an inverter, to drive the actuators with a square wave at their resonance frequency between 30kHz and 40kHz. A flyback converter has also been designed for generating the auxiliary power supply voltage for all the integrated components in the system. A control system based on an Arduino microcontroller has been developed to adjust the frequency of the square wave to the resonance frequency of the transducer, control the output voltage of the buck converter and read data from a current sensor. The system is designed and implemented on a PCB board of 10cm×15cm. The system has been tested on machined with two different tank sizes.
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McCasland, William Neil. "Sensor and actuator selection for fault-tolerant control of flexible structures." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14459.
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Johnson, David Gary. "Integrating sensors and actuators for robotic assembly." Thesis, University of Hull, 1986. http://hydra.hull.ac.uk/resources/hull:11276.
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This thesis addresses the problem of integrating sensors and actuators for closed-loop control of a robotic assembly cell. In addition to the problems of interfacing the physical components of the work-cell, the difficulties of representing sensory feedback at a high level within the robot control program are investigated. A new level of robot programming, called sensor-level programming, is introduced. In this, the movements of the actuators are not given explicitly, but rather are inferred by the programming system to achieve new sensor conditions given by the programmer. Control of each sensor and actuator is distributed through a master-slave hierarchy, with each sensor and actuator having its own slave controller. A protocol for information interchange between each controller and the master is defined. If possible, the control of the kinematics of a robot arm is achieved through the manufacturer's existing control system. Under these circumstances, the actuator slave would be acting as an interface between the generic command codes issued from the central controller, and the syntax of the corresponding control instructions required by the commercial system. Sensor information is preprocessed in the sensor slaves and a set of high-level descriptors, called attributes, are sent to the central controller. Closed-loop control is achieved on the basis of these attributes. The processing of sensor information which is corrupted by noise is investigated. Sources of sensor noise are identified and new algorithms are developed to quantify the noise based on information obtained from the closed-loop servoing. Once the relative magnitudes of the system and measurement noise have been estimated, a Kalman filter is used to weight the sensor information and hence reduce the credibility given to noisy sensors; in the limit ignoring the information completely. The improvements in system performance by processing the sensor information in this way are demonstrated. The sensor-level representation and automatic error processing are embedded in a software control system, which can be used to interface commercial systems as well as purpose-built devices. An'industrial research project associated with the lay-up of carbon-fibre provides an example of its operation. A list of publications resulting from the work in this thesis is given in Appendix E.
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Dogramadzi, Sanja. "Sensors and actuators in computer controlled colonoscopy." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369813.
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Ehresman, Jonathan David. "Integration of actuators and sensors into composite structures." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/ehresman/EhresmanJ0809.pdf.
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The need for more efficient wind turbine blades is growing in our society. One step in accomplishing this task would be to make wind turbines blades into smart structures. A smart structure is one that incorporates sensors, complete control systems, and active control devices, in order to shed, or redistribute the load placed on the structure. For wind turbine blades this means changing the shape of the blade profile as it encounters different wind conditions. In order to have active control surfaces functioning on wind turbine blades, the existing blades would have to be retrofitted, and the new blades being manufactured would have to be redesigned. There are different control surfaces to consider: gurney flaps and false wall flaps are two that can perturb the boundary layer across the low pressure side of the wing. A flat plate and blade section test bed will be manufactured in order to gather empirical data from wind tunnel testing. For actuation of the control surface there are many choices: electrical, hydraulic, pneumatic, and electro-hydrostatic. These actuator types will be investigated under a set of criterion to determine the best one for turbine blade application. Sensors will be investigated with respect to their use in sensing strain, temperature, acceleration, humidity, and delamination. Sensors are also used for health monitoring. This helps engineers design under a damage tolerant philosophy as opposed to a safe life structure philosophy. These sensors will be placed into laminates and different surface treatments will be reviewed to find the best configuration for each sensor. The sensor will be cleaned with isopropyl alcohol, dipped in a 20% by mass solution of nitric acid, and submerged in a 20% by mass solution of nitric acid for 10 seconds. Detailed surface images will be taken of sensors with different surface treatments in order to better understand the bonding between the sensor and laminate. These images indicate that submerging the sensors into 20% by mass solution of nitric acid is the best surface treatment.
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Song, Changsik. "Design and synthesis of molecular actuators and sensors." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41554.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Includes bibliographical references.<br>To date, the most successful conducting polymer actuators are based on polypyrrole, which operates through incorporating and expelling counterions and solvent molecules to balance the charges generated by electrochemical stimuli (swelling mechanism). Although significant progress has been made, there still exists a need for developing new materials that would overcome the intrinsic limitations in the swelling mechanism, such as slow diffusion rate, limited expansion volume, etc. Our group has contributed this area with a different approach -- lecular mechanisms, which utilize a dimensional change of a single polymer chain. We propose two types of molecular mechanisms: contracting and expanding. We proposed earlier a calix[4]arenebased molecular actuator for the contracting mechanism, in which p-dimer formation was proposed as a driving force. In this dissertation, we first confirm by model studies that p-dimer formation can indeed be a driving force for the calix[4]arene-based system. We propose another molecular hinge, binaphthol moiety, for the contracting model. The syntheses of polymers with binaphthols and their characterization, including signatures of oligothiophene interactions, are described. Due to its chirality, we examined the possibilities of the binaphthol polymer as a chiral amine sensor. To create actuators that make use of the expanding model, we propose new conjugated seven-membered ring systems with heteroatoms (thiepin with sulfur and azepine with nitrogen) and their syntheses and characterization will be described. Inspired by the fact that sulfoxide has very low extrusion barrier in the related system, we applied the thiepin molecules to create a peroxide sensor.<br>(cont.) In addition, during the investigation of phenol functional groups in conducting polymers, we found interesting properties that strategic positioning of phenol groups can render a conjugation-broken meta-linked system just as conductive as a fully conjugated para-linked isomeric system.<br>by Changsik Song.<br>Ph.D.
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Yun, Yeoheung. "Nanotube Sensors and Actuators in Mechanics and Medicine." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1150836513.
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Aphanuphong, Sutha. "Embedded heaters and sensors for micro SMA actuators." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1458441.
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Rostain, William. "Engineering of RNA sensors and actuators in living cells." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/95177/.
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The aim of synthetic biology is to create a new discipline of engineering based on biological parts, devices and systems. The availability of predictable, programmable tools to sense and to control gene expression is central to our ability to engineer such systems. Ribonucleic acid (RNA) is an attractive building material to create such programmable tools, as RNA-RNA interactions are predictable and RNA secondary structure prediction software has been developed. Design rules for creating such parts using RNA can be established, based on a standardised approach or on structural design rules into which function is implicitly encoded. In this latter case, RNA folding software can be used to create RNA sequence which satisfy generalisable structural characteristics, but are tailored to a specific application. In this work, new design rules for the creation of RNA-based sensors and actuators are developed. The actuator parts are based on riboregulators, but with a circular topology generated through splicing of a ribozyme. The ability of these circular riboregulators to activate transcription of gene expression in E. coli cells is demonstrated. A method for improving these actuators by directed evolution is then tested. Finally, design rules for creating sensors of RNAs based Clustered Regularly Interspaced Short Palindromic Repeat guide RNAs (CRISPR gRNAs) are developed. These gRNA-based sensors can switch states and repress gene expression through a CRISPR-Cas9 based platform, but only in the presence of an arbitrary "trigger" RNA. The rules developed for creating sensors and actuators are characterised in E. coli, but are based on general principles that could be used in other organisms including eukaryotic cells.
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Sareen, Harpreet. "Cyborg botany : augmented plants as sensors, displays and actuators." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/114063.
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Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2017.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 94-98).<br>Plants are photosynthetic eukaryotes with a billion years of evolutionary history. While primarily sessile, they have developed distinctive abilities to adapt to the environment. They are self-powered, self-fabricating, self-regenerating and active signal networks. They carry highly advanced systems to sense and respond to the environment. We strive for such sensing and responses in our electronics; self growing or self repairing abilities in our architecture; and being sustainable at scale in general. The industrial and technological thought process has mostly been devising artificial means or replicating natural systems synthetically. However, I propose a convergent view of technological evolution with our ecology where techno-plant hybrids are created. The approach is to formulate symbiotic associations and to place the technology in conjunction with the plant function(s). In this thesis, I go from the outside to inside the plants in conceiving such synergetic processes and present case studies of their implementation and analysis. I begin with a robot-plant hybrid where the robotic device adds mobility and is triggered with the plant's own signals. Next, lead (II) detection nanosensors are presented which reside inside the leaf of a plant and continuously sample through plant hydraulics. This is followed with a design study for plants with new conductive channels grown inside them and their subsequent use as inconspicuous motion sensors. I conclude with a symbiotic robot that lives on a sunflower plant and automatically trains or directs its growth with onboard lighting. The end result is an augmented-plant society where technology adds non-native functions or redirects the natural processes..<br>by Harpreet Sareen.<br>S.M.
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Kabeya, Kazuhisa III. "Structural Health Monitoring Using Multiple Piezoelectric Sensors and Actuators." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36709.
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A piezoelectric impedance-based structural health monitoring technique was developed at the Center for Intelligent Material Systems and Structures. It has been successfully implemented on several complex structures to detect incipient-type damage such as small cracks or loose connections. However, there are still some problems to be solved before full scale development and commercialization can take place. These include: i) the damage assessment is influenced by ambient temperature change; ii) the sensing area is small; and iii) the ability to identify the damage location is poor. The objective of this research is to solve these problems in order to apply the impedance-based structural health monitoring technique to real structures.
First, an empirical compensation technique to minimize the temperature effect on the damage assessment has been developed. The compensation technique utilizes the fact that the temperature change causes vertical and horizontal shifts of the signature pattern in the impedance versus frequency plot, while damage causes somewhat irregular changes.
Second, a new impedance-based technique that uses multiple piezoelectric sensor-actuators has been developed which extends the sensing area. The new technique relies on the measurement of electrical transfer admittance, which gives us mutual information between multiple piezoelectric sensor-actuators. We found that this technique increases the sensing region by at least an order of magnitude.
Third, a time domain technique to identify the damage location has been proposed. This technique also uses multiple piezoelectric sensors and actuators. The basic idea utilizes the pulse-echo method often used in ultrasonic testing, together with wavelet decomposition to extract traveling pulses from a noisy signal. The results for a one-dimensional structure show that we can determine the damage location to within a spatial resolution determined by the temporal resolution of the data acquisition.
The validity of all these techniques has been verified by proof-of-concept experiments. These techniques help bring conventional impedance-based structural health monitoring closer to full scale development and commercialization.<br>Master of Science
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Lloyd, Justin Michael. "Electrical Properties of Macro-Fiber Composite Actuators and Sensors." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/10013.
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Piezoceramic fiber composite (PFC) actuators and sensors offer many advantages over conventional monolithic piezoceramic devices. Conformable, durable and, when equipped with interdigitated electrodes (IDEs), more responsive than regular monolithic devices, PFCs promise to revolutionize the application of piezoelectric materials. Developed by the NASA-Langley Research Center, the Macro-Fiber Composite (MFC) actuator and sensor is the most sophisticated PFC device yet invented. With superior qualities among PFCs in performance, behavior repeatability and manufacturability, the MFC has spawned great interest in the commercial and academic community as a tool in multitudinous engineering applications.
While the MFC's characteristics render it a singularly useful device, limited characterization and modeling research on the MFC exists. Empirically designed and assembled, the MFC is poorly understood, especially in terms of its underlying operating principles, its dependence on design parameters and its electrical properties. The majority of published MFC studies focus on experimental quantification of MFC mechanical and actuation properties, and the research that attempts to model the MFC relies totally on finite element analysis. Published works widely assume that analytical models of the MFC are totally impossible.
Rectifying gaps in the current body of MFC research, this study presents the first accurate analytical model of the static electrical field properties of the MFC. Implementing the techniques of conformal mapping, a branch of complex analysis, the following chapters derive a closed-form, exact analytical solution describing the electrical potential field and electrical field of the MFC's dual-IDE structure. Based on the conformal mapping solution for the MFC's electrical field, the electrical field of the commercially available MFC is examined and analyzed, introducing an intuitive knowledge of the MFC's operation. Demonstrating the utility of this solution in modeling the MFC, this work also predicts the capacitance and induced strain properties of a continuum of potential MFC designs and offers final suggestions on improving the current commercial MFC design. After establishing the theoretical underpinnings of the analytical MFC model, this report derives the conformal mapping solutions for the MFC, discusses the computational application of the resulting equations and then presents the results of numerical analyses executed using the new analytical model.<br>Master of Science
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Kostner, Stefan [Verfasser]. "Sensors and Actuators for Single Particles and Cells / Stefan Kostner." Aachen : Shaker, 2010. http://d-nb.info/1124365214/34.
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Savran, Cagri Abdullah 1976. "Broadband active structural control using collocated piezoelectric sensors and actuators." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/89278.
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McCain, Amy Jean. "Shaped actuators and sensors for local control of intelligent structures." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/46445.
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Yung, Jeremy Hoyt 1971. "Compensation methodologies for local control using strain actuators and sensors." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10627.
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Kar, S. B. "Studies on electromechanical sensors and actuators based on conducting polymers." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2005. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2488.
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Tamirisa, Prabhakar A. "Plasma polymerized hydrogel thin films for applications in sensors and actuators." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/19827.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2007.<br>Committee Chair: Hess, Dennis W.; Committee Member: Henderson, Cliff L.; Committee Member: Hunt, William D.; Committee Member: Meredith, J. Carson; Committee Member: Prausnitz, Mark R.
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Sivakumar, Kousik. "Nanowire sensor and actuator." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 5.53 Mb., 108 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435931.
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Hamadi, Hussein. "Fault-tolerant control of a multirotor unmanned aerial vehicle under hardware and software failures." Thesis, Compiègne, 2020. http://www.theses.fr/2020COMP2555.
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Le but de ce travail est de proposer des mécanismes pour les drones multirotors qui permettent d'une part de tolérer des fautes sur le drone, et d'autre part de prendre en compte les effets du vent en extérieur. Les fautes visées comportent des fautes d'actionneurs, de capteurs, mais également des fautes logicielles sur les algorithmes de fusion de données. Dans nos travaux, nous avons développé un contrôleur robuste et un observateur des perturbations extérieures capables de coopérer avec la méthode de reconfiguration des commandes, pour tolérer de façon simultanée les défaillances de moteurs et les perturbations extérieures du vent par des techniques de tolérance aux fautes active. Egalement, nous avons proposé une nouvelle technique de tolérance aux fautes des actionneurs pour un drone octorotor coaxial. Cette technique est basée sur une loi de commande robuste avec des gains reconfigurables "self tuning sliding mode control (STSMC)", où les gains de contrôle sont réajustés en fonction de l'erreur détectée afin de maintenir la stabilité du système. Des expériences à l'intérieur ont été menées pour montrer et comparer notre solution avec deux autres techniques de tolérances aux fautes. L'efficacité et le comportement de chaque méthode ont été étudiés après des injections de fautes successives dans les actionneurs. Les principaux avantages et inconvénients de chaque méthode sont déduits en analysant les résultats obtenus. En outre, nous proposons une approche pour la tolérance aux fautes des capteurs et mécanismes logiciels de fusion de données du drone. Cette approche est basée sur la redondance des capteurs et la diversification des composants logiciels<br>The aim of this work is to propose mechanisms for multirotor drones that allow, on the one hand, to tolerate faults on the drone, and on the other hand to take into account the effects of the wind outdoors. The faults targeted include fault in actuators, sensors, but also software faults on the data fusion algorithms. ln our work, we have developed a robust controller and an exterior disturbance observer capable of cooperating with th, contrai reconfiguration method, to simultaneously tolerate motor failures and exterior wind disturbances through active fault tolerance techniques… We have also proposed a new technique for tolerating actuator faults for a coaxial octorotor drone. This technique is based on a robust command law with reconfigurable "self tuning sliding mode control (STSMC)" gains, where the control gains are readjusted according to the detected error in order to maintain the stability of the system. lndoor experiments are conducted to show and compare our solution with two other fault tolerance techniques. The efficiency and behavior of each method are studied after successive fault injections into the actuators. The main advantages and disadvantages of each method are deduced by analyzing the results obtained. Additionally, we provide an approach for fault tolerance of drone data fusion sensors and software mechanisms. This approach is based on the redundancy of sensors and the diversification of software components
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Isaac, Leslie Thomas. "Puffer circuit breaker diagnostics using novel optical fibre sensors." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263762.
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Ferrell, Cynthia. "Robust Agent Control of an Autonomous Robot with Many Sensors and Actuators." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/6791.
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This thesis presents methods for implementing robust hexpod locomotion on an autonomous robot with many sensors and actuators. The controller is based on the Subsumption Architecture and is fully distributed over approximately 1500 simple, concurrent processes. The robot, Hannibal, weighs approximately 6 pounds and is equipped with over 100 physical sensors, 19 degrees of freedom, and 8 on board computers. We investigate the following topics in depth: distributed control of a complex robot, insect-inspired locomotion control for gait generation and rough terrain mobility, and fault tolerance. The controller was implemented, debugged, and tested on Hannibal. Through a series of experiments, we examined Hannibal's gait generation, rough terrain locomotion, and fault tolerance performance. These results demonstrate that Hannibal exhibits robust, flexible, real-time locomotion over a variety of terrain and tolerates a multitude of hardware failures.
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Obal, Michael Walter. "Vibration control of flexible structures using piezoelectric devices as sensors and actuators." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/12025.
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Szczepanski, Robert Walter. "Optimal placement of actuators and sensors for vibration control using genetic algorithms." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341754.
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Daraji, Ali Hossain Alewai. "Active vibration control of flexible structures by optimally placed sensors and actuators." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/2484.
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The active vibration reduction of plane and stiffened plates was investigated using a genetic algorithm based on finite element modelling to optimise the location of sensors and actuators. The main aspects of this work were: Development of a finite element model for a plate stiffened by beams with discrete sensors and actuators bonded to its surface. Development of a finite element program for steel plates with various symmetrical and asymmetrical stiffening and edge conditions. Development of a genetic algorithm program based on the finite element modelling for the optimisation of the location and number of sensor/actuator pairs and feedback gain. Determination of optimum locations and feedback gain for collocated piezoelectric sensors and actuators on steel plates with various symmetrical and asymmetrical stiffening and edge conditions. Development of fitness and objective functions to locate sensors and actuators. Development of fitness and objective functions to determine the optimal number of sensors and actuators. Development of a reduced search space technique for symmetrical problems. Optimisation of vibration reduction control scheme parameters using the genetic algorithm. Optimisation of the number and location of sensor/actuator pairs and feedback gain to reduce material costs and structural weight and to achieve effective vibration reduction. The modelling was validated by comparison with conventional finite element analysis using ANSYS, and by experiment. The modelling was developed using a quadrilateral isoparametric finite element, based on first order shear deformation theory and Hamilton’s principle, which may be arbitrarily stiffened by beams on its edges. The model can be applied to flat plates with or without stiffening, with discrete piezoelectric sensors and actuators bonded to its surfaces. The finite element modelling was tested for flat and stiffened plates with different boundary conditions and geometries, and the results of the first six natural frequencies were validated with the ANSYS package and experimentally. A genetic algorithm placement strategy is proposed to find the global optimal distribution of two, four, six and ten sensor/actuator pairs and feedback gain based on the minimisation of optimal linear quadratic index as an objective function, and applied to a cantilever plate to attenuate the first six modes of vibration. The configuration of this global optimum was found to be symmetrically distributed about the dynamic axes of symmetry and gave higher vibration attenuation than previously published results with an asymmetrical distribution which was claimed to be optimal. Another genetic algorithm placement strategy is proposed to optimise sensor/actuator locations using new fitness and objective functions based on . This is applied to the same cantilever plate, and was also found to give a symmetrical optimal sensor/actuator configuration. As before, it was found that the optimal transducer locations are distributed with the same axes of symmetry and in agreement with the ANSYS results. A program to simulate the active vibration reduction of stiffened plates with piezoelectric sensors and actuators was written in the ANSYS Parametric Design Language (APDL). This makes use of the finite element capability of ANSYS and incorporates an estimator based on optimal linear quadratic and proportional differential control schemes to investigate the open and closed loop time responses. The complexity of the genetic algorithm problem is represented by the number of finite elements, sensor/actuator pairs and modes required to be suppressed giving a very large search space. In this study, this problem was reduced by the development of a new half and quarter chromosomes technique exploiting the symmetries of the structure. This greatly reduces the number of generations, and hence the computing time, required for the genetic algorithm to converge on the global optimal solution. This could be significant when the technique is applied to large and complex structures. Finally, new fitness and objective functions were proposed to optimise the number of sensor/actuator pairs required for effective active vibration reduction in order to reduce the added cost and weight. The number, location and feedback gain were optimised for the same cantilever plate and it was found that two sensor/actuator pairs in optimal locations could be made to give almost as much vibration reduction as ten pairs.
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Huang, Wei-Ping. "Quasilinear Control of Systems with Time-Delays and Nonlinear Actuators and Sensors." ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/967.
Full textAbstract:
This thesis investigates Quasilinear Control (QLC) of time-delay systems with nonlinear actuators and sensors and analyzes the accuracy of stochastic linearization for these systems. QLC leverages the method of stochastic linearization to replace each nonlinearity with an equivalent gain, which is obtained by solving a transcendental equation. The idea of QLC is to stochastically linearize the system in order to analyze and design controllers using classical linear control theory. In this thesis, the existence of the equivalent gain for a closed-loop time-delay system is discussed. To compute the equivalent gain, two methods are explored. The first method uses an explicit but complex algorithm based on delay Lyapunov equation to study the time-delay, while the second method uses Pade approximant. It is shown that, under a suitable criterion, Pade approximant can be effectively applied for QLC of time-delay systems. Furthermore, the method of Saturated-Root Locus (S-RL) is extended to nonlinear time-delay systems. It turns out that, in a time-delay system, S-RL always terminates prematurely as opposed to a delay-free system, which may or may not terminate prematurely. Statistical experiments are performed to investigate the accuracy of stochastic linearization compared to a system without time-delay. The impact of increasing the time-delay in the approach of stochastic linearization is also investigated. Results show that stochastic linearization effectively linearizes a nonlinear time-delay system, even though delays generally degrade accuracy. Overall, the accuracy remains relatively high over the selected parameters. Finally, this approach is applied to pitch control in a wind turbine system as a practical example of a nonlinear time-delay system, and its performance is analyzed to demonstrate the efficacy of the approach.
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Wei, Yu Zhang. "Design and development of new micro-force sensors." Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691170.
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BELMONTE, DARIO. "MODEL BASED CORRELATION METHODS FOR FAULTS DETECTION AND IDENTIFICATION ALGORITHMS ON ELECTROMECHANICAL ACTUATORS USED IN PRIMARY FLIGHT CONTROL SYSTEMSMODEL BASED CORRELATION METHODS FOR FAULTS DETECTION AND IDENTIFICATION ALGORITHMS ON ELECTROMECHANICAL ACTUATORS USED IN PRIMARY FLIGHT CONTROL SYSTEMS." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2746072.
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Chandroth, Gopinath Odayammadath. "Diagnostic classifier ensembles : enforcing diversity for reliability in the combination." Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322873.
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Antrobus, Charles Edward Lindsay. "Non-invasive imaging of sub-surface faults in materials using electric potential sensors." Thesis, University of Sussex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439173.
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An, Younghwan. "A design of fault tolerant flight control systems for sensor and actuator failures using on-line learning neural networks." Morgantown, W. Va. : [West Virginia University Libraries], 1998.
Find full textAbstract:
Thesis (Ph. D.)--West Virginia University, 1998.<br>Title from document title page. Document formatted into pages; contains xix, 179 p. : ill. Includes abstract. Includes bibliographical references (p. 173-178).
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Mewer, Richard C. "Analysis and Structural Health Monitoring of Composite Plates with Piezoelectric Sensors and Actuators." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/MewerRC2003.pdf.
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Newman, Scott M. "Active damping control of a flexible space structure using piezoelectric sensors and actuators." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23517.
Full textAbstract:
Approved for public release; distribution is unlimited<br>This thesis details the experimental analysis of an active damping control technique applied to the Naval Postgraduate School's Flexible Spacecraft Simulator using piezoceramic sensors and actuators. The mass property of the flexible arm is varied to study the frequency effects on the Positive Position Feedback (PPF) algorithm. Multi-modal dynamics response is analytically studied using a finite-element model of a cantilevered beam while under the influence of three different control laws: a basic law derived rom the Lyapunov Stability Theorem, PPF and Strain Rate Feedback (SRF). The advantages and disadvantages of using PPF and SRF for active damping control are discussed.
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Raykar, Vikas Chandrakant. "Position calibration of acoustic sensors and actuators on distributed general purpose computing platforms." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/39.
Full textAbstract:
Thesis (M.S.) -- University of Maryland, College Park, 2003.<br>Thesis research directed by: Dept. of Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Ryerson, Cody. "A fault detection scheme for modeled and unmodeled faults in a simple hydraulic actuator system using an extended Kalman filter." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4535.
Full textAbstract:
Thesis (M.S.) University of Missouri-Columbia, 2006.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (June 26, 2007) Includes bibliographical references.
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Hixenbaugh, Franklin D. "A study on piezoelectric actuators and sensors for vibration control of flexible space structures." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA274925.
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Thesis (M.S. in Systems Technology (Space Systems Operations)) Naval Postgraduate School, September 1993.<br>Thesis advisor(s): Brij N. Agrawal. "September 1993." Includes bibliographical references. Also available online.
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Miller, Duncan Lee. "Development of resource-constrained sensors and actuators for in-space satellite docking and servicing." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98697.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 171-177).<br>Most satellites on-orbit today are not intended to physically approach or interact with other spacecraft. However, the robotic servicing of orbiting assets will be an economically desirable (and often scientifically necessary) capability in future space enterprises. With the right set of tools and technologies, satellites will be able to autonomously refuel, repair, or replace each other. This has the potential to extend mission lifetimes, reduce orbital debris and make space more sustainable. Spacecraft may also assemble on-orbit into larger aggregate spaceflight systems, with applications to sparse aperture telescopes, solar power stations, fuel depots and space habitats. The purpose of this thesis is to address the highest risk elements associated with the docking and servicing of satellites: the sensors, actuators, and associated algorithms. First, a peripheral agnostic robotics platform is introduced, upon which a suite of technology payloads may be developed. Next, a flight qualified docking port for small satellites is presented, and the results detailing its operation in a relevant environment are discussed. In addition, we review a high precision relative sensor designed to enable boresight visual docking. The measurements from this optical camera are applied to a nonlinear estimator to provide the highly accurate sensing necessary for docking. Finally, a free-flying robotic arm is examined and modeled as an experimental payload for the SPHERES Facility on the International Space Station.<br>by Duncan Lee Miller.<br>S.M.
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SADLER, DANIEL J. "DEVELOPMENT OF A NEW MAGNETIC INERCONNECTION TECHNOLOGY FOR MAGNETIC MEMS DEVICE APPLICATIONS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin983800458.
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Nowak, Brent Michael. "A conceptual high-resolution MR encoder and torque transducer for precision actuators /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Jha, Akhilesh K. "Vibration Analysis and Control of an Inflatable Toroidal Satellite Component Using Piezoelectric Actuators and Sensors." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/28243.
Full textAbstract:
Inflatable structures have been a subject of renewed interest in recent years for space applications such as communication antennas, solar thermal propulsion, and entry/landing systems. This is because inflatable structures are very lightweight and on-orbit deployable. In addition, they have high strength-to-mass ratio and require minimal stowage volume, which makes them especially suitable for cost-effective large space structures. An inflated toroidal structure (torus) is often used there in order to provide structural support. For these structures to be effective, their vibration must be controlled while keeping the weight low. Piezoelectric materials have become strong candidates for actuator and sensor applications in the active vibration control of such structures due to their lightweight, conformability to the host structure, and distributed nature. In this study, our main focus is to understand the dynamic characteristics of an inflatable torus and to control its vibration using piezoelectric actuators and sensors.
The first part of this study is concerned with theoretical formulations. We use Sanders' shell theory to derive the governing equations of motion for a shell subjected to pressure. To take into account the prestress effects of internal pressure, we use geometric nonlinearity, and to model the follower action of pressure force, we consider the work done by internal pressure during the vibration of the shell. These equations are then specialized to obtain approximate equations presented by previous researchers. We extend this analytical formulation to derive the equivalent forces due to piezoelectric actuators in unimorph and bimorph configurations and include their mass and stiffness effects in the governing equations. A sensor equation is also developed for the shell. The actuator and sensor equations are then written in terms of modal displacements and velocities so as to evaluate their interactions with different vibratory modes.
In the second part, we focus on numerical studies related to an inflated torus. At first, we perform a free vibration analysis of the inflated torus using Galerkin's method. We study how different parameters (aspect ratio, internal pressure, and wall-thickness) of the inflated torus affect the natural frequencies and mode shapes of the inflated torus. We compare the results obtained from the theory used in this research with the results from different approximate theories and commercial finite element codes. The results suggest that the use of an accurate shell theory and pressure effect is very important for the vibration analysis of an inflated torus. Next, the modal behaviors of piezoelectric actuator and sensor are analyzed. A detailed study is done in order to understand how the size and location of actuator and sensor affect the modal forces, the modal sensing constants, and the overall performance for all the considered modes. In order to determine the optimal locations and sizes of actuators and sensors, we use a genetic algorithm. Natural frequencies and mode shapes are calculated considering the passive effects of actuators and sensors. Finally, we attempt the vibration control of the inflated torus using the optimally designed actuators and sensors and sliding mode controller/observer. The numerical simulations show that piezoelectric actuators and sensors can be used in the vibration control of an inflatable torus. The robustness properties of the controller and observer against the parameter uncertainty and disturbances are verified.<br>Ph. D.
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Wu, Weiliang. "The detection of incipient faults in small multi-cylinder diesel engines using multiple acoustic emission sensors." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/65649/1/Weiliang_Wu_Thesis.pdf.
Full textAbstract:
This thesis investigates condition monitoring (CM) of diesel engines using acoustic emission (AE) techniques. The AE signals recorded from a small size diesel engine are mixtures of multiple sources from multiple cylinders. Thus, it is difficult to interpret the information conveyed in the signals for CM purposes. This thesis develops a series of practical signal processing techniques to overcome this problem. Various experimental studies conducted to assess the CM capabilities of AE analysis for diesel engines. A series of modified signal processing techniques were proposed. These techniques showed promising results of capability for CM of multiple cylinders diesel engine using multiple AE sensors.
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Cortés, Francisco Meritxell. "Electrodeposició de capes metàl·liques per a la seva incorporació en sensors i actuadors / Metallic films deposition for their incorporation in sensors and actuators." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/96476.
Full textAbstract:
Electrodeposition involves chemical phenomena associated with charge separation and transfer that can occur homogeneously in solution, or heterogeneously over electrode surfaces. In order to assure electroneutrality at least two charge transfer half-reactions should take place. In the case of heterogeneous redox reactions, these half-reactions occur over two different electrodes immersed in a solution.
It presents several advantatges over other methods commonly used to prepare films and structures which require vacuum conditions, physical or chemical vapor deposition (PVD or CVD), plasma enhanced deposition (PLD), sputtering. One of these advantages is its low cost and high simplicity of the experimental setup. The equipment used is cheap and maintenance is hardly required. On the other hand, room temperature is commonly used to grow the material or, at least, temperatures lower than 100°C.
Nowadays electrodeposition is used in a wide range of applications as metal processing and finishing. Electroplating is a process widely used in industry for coating metal objects with a thin layer of a different metal. It is one of the most important in terms of volume of production, and it also has one of the greatest economic impacts. The purpose of these coatings is to provide the metal object with some desired property that the metal object does not have. Electrodeposition has come a long way since its inception; developing new techniques that have increased the range of applications of the same.
This thesis mainly focuses on the new applications and uses of electrodeposition as a tool of fabricating some materials that can be integrated in different kind of devices such as sensors and actuators. Electrodeposition has a high materials and structures versatility that can be obtained which permits its integration in lots of processes.
In this tesis different applications for electrodeposition have been studied:
First of all, the design, preparation and characterisation of planar coils to be implemented in inductive biosensors has been performed. It was necessary to perform the study of the optimum bath, electrodeposition conditions and fabrication processes to prepare robust, low resistant and adherent planar copper coils of different aspect ratios, which allow detecting magnetic particles. In order to do that, simulations of the main parameters based in previous designs to improve the sensitivity of the coils have been executed. The final objectives were the fabrication of the new designed coils and to perform the first tests of their sensing ability.
Then, the deposition of a hard magnetic alloy for MEMS application has been tested. A basic study of the electrodeposition process of the CoPt alloy to find the optimum bath has been performed. Structures with different shapes and geometries (films, thin films, photolitographied microstructures, nanoparticles, nanowires...) over different substrates have been obtained applying the conditions based on the previous electrochemical results. The influence of the electrodeposition and preparation conditions on the properties of the CoPt alloy (morphology, composition, crystalline structure, magnetic properties,) and analysis of the relationship among those properties has been studied.
Finally, the organic monolayer formation on top of several electrodeposited magnetic substrates (magnetic/non-magnetic assembly) as the first step to fabricate a molecular spintronic device has been performed. The preparation of smooth thin films of magnetite and CoP by means of electrodeposition and the formation and study of octanethiol and acid oleic monolayers on top have been achieved as the first step to obtain a molecular spintronic device.
Electrodeposition has been demonstrated to be a useful technique for the design and fabrication of micro/nanomaterials with specific properties that allow them to be implemented in biosensors, MEMS and molecular spintronic devices.<br>Aquesta tesi es centra principalment en les noves aplicacions i usos de l'electrodeposició com a eina de fabricació de nous materials que poden ser integrats en diferents tipus de dispositius com ara sensors i actuadors. L'electrodeposició presenta diversos avantatges respecte a altres tècniques, sobre tot respecte aquelles que utilitzen el buit.
Els objectius específics plantejats en aquesta tesi han estat en primer lloc el disseny, preparació i caracterització de bobines planes per fabricar biosensors inductius. Per això ha calgut escollir el bany i les condicions de treball òptims, així com els processos de fabricació més adequats a seguir per tal de preparar bobines planes de coure resistents, robustes, ben definides i adherents amb diferents relacions d'aspecte, que siguin capaces de detectar partícules magnètiques. També s'han realitzat càlculs simulant els principals paràmetres de les bobines per millorar-ne la sensibilitat. En una etapa posterior, s'han fabricat les noves bobines dissenyades i s'han dut a terme les primeres proves de la capacitat de detecció.
En segon lloc, es va proposar la deposició d'un aliatge magnètic dur per a la seva aplicació en MEMS. L'aliatge escollit va ser el CoPt. Per tal de trobar un bany òptim per a la seva deposició s'ha dut a terme l'estudi bàsic del procés d'electrodeposició de l'aliatge. S'han preparat estructures amb diferents formes i geometries (dipòsits, pel•lícules primes, microestructures, nanopartícules, nanofils, ...) sobre diferents substrats i s'ha estudiat la influència de les condicions d'electrodeposició sobre les propietats de l'aliatge de CoPt (morfologia, composició, estructura cristal•lina, propietats magnètiques, ...) i s'ha realitzat l'anàlisi de la relació entre aquestes propietats.
Per últim, s'ha dut a terme un estudi inicial de la formació de monocapes orgàniques sobre diferents substrats magnètics, com al primer pas per fabricar un dispositiu d'espintrònica molecular. Per aquest motiu s'han preparat pel•lícules primes de magnetita i d'aliatge CoP per mitjà de l'electrodeposició i s'ha dut a terme l'estudi de la formació de les monocapes d'octanotiol i d'àcid oleic sobre els substrats
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Cortés, Francisco Meritxell. "Electrodeposició de capes metàl.liques per a la seva incorporació en sensors i actuadors / Metallic films deposition for their incorporation in sensors and actuators." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/96476.
Full textAbstract:
Electrodeposition involves chemical phenomena associated with charge separation and transfer that can occur homogeneously in solution, or heterogeneously over electrode surfaces. In order to assure electroneutrality at least two charge transfer half-reactions should take place. In the case of heterogeneous redox reactions, these half-reactions occur over two different electrodes immersed in a solution.
It presents several advantatges over other methods commonly used to prepare films and structures which require vacuum conditions, physical or chemical vapor deposition (PVD or CVD), plasma enhanced deposition (PLD), sputtering. One of these advantages is its low cost and high simplicity of the experimental setup. The equipment used is cheap and maintenance is hardly required. On the other hand, room temperature is commonly used to grow the material or, at least, temperatures lower than 100°C.
Nowadays electrodeposition is used in a wide range of applications as metal processing and finishing. Electroplating is a process widely used in industry for coating metal objects with a thin layer of a different metal. It is one of the most important in terms of volume of production, and it also has one of the greatest economic impacts. The purpose of these coatings is to provide the metal object with some desired property that the metal object does not have. Electrodeposition has come a long way since its inception; developing new techniques that have increased the range of applications of the same.
This thesis mainly focuses on the new applications and uses of electrodeposition as a tool of fabricating some materials that can be integrated in different kind of devices such as sensors and actuators. Electrodeposition has a high materials and structures versatility that can be obtained which permits its integration in lots of processes.
In this tesis different applications for electrodeposition have been studied:
First of all, the design, preparation and characterisation of planar coils to be implemented in inductive biosensors has been performed. It was necessary to perform the study of the optimum bath, electrodeposition conditions and fabrication processes to prepare robust, low resistant and adherent planar copper coils of different aspect ratios, which allow detecting magnetic particles. In order to do that, simulations of the main parameters based in previous designs to improve the sensitivity of the coils have been executed. The final objectives were the fabrication of the new designed coils and to perform the first tests of their sensing ability.
Then, the deposition of a hard magnetic alloy for MEMS application has been tested. A basic study of the electrodeposition process of the CoPt alloy to find the optimum bath has been performed. Structures with different shapes and geometries (films, thin films, photolitographied microstructures, nanoparticles, nanowires...) over different substrates have been obtained applying the conditions based on the previous electrochemical results. The influence of the electrodeposition and preparation conditions on the properties of the CoPt alloy (morphology, composition, crystalline structure, magnetic properties,) and analysis of the relationship among those properties has been studied.
Finally, the organic monolayer formation on top of several electrodeposited magnetic substrates (magnetic/non-magnetic assembly) as the first step to fabricate a molecular spintronic device has been performed. The preparation of smooth thin films of magnetite and CoP by means of electrodeposition and the formation and study of octanethiol and acid oleic monolayers on top have been achieved as the first step to obtain a molecular spintronic device.
Electrodeposition has been demonstrated to be a useful technique for the design and fabrication of micro/nanomaterials with specific properties that allow them to be implemented in biosensors, MEMS and molecular spintronic devices.<br>Aquesta tesi es centra principalment en les noves aplicacions i usos de l'electrodeposició com a eina de fabricació de nous materials que poden ser integrats en diferents tipus de dispositius com ara sensors i actuadors. L'electrodeposició presenta diversos avantatges respecte a altres tècniques, sobre tot respecte aquelles que utilitzen el buit.
Els objectius específics plantejats en aquesta tesi han estat en primer lloc el disseny, preparació i caracterització de bobines planes per fabricar biosensors inductius. Per això ha calgut escollir el bany i les condicions de treball òptims, així com els processos de fabricació més adequats a seguir per tal de preparar bobines planes de coure resistents, robustes, ben definides i adherents amb diferents relacions d'aspecte, que siguin capaces de detectar partícules magnètiques. També s'han realitzat càlculs simulant els principals paràmetres de les bobines per millorar-ne la sensibilitat. En una etapa posterior, s'han fabricat les noves bobines dissenyades i s'han dut a terme les primeres proves de la capacitat de detecció.
En segon lloc, es va proposar la deposició d'un aliatge magnètic dur per a la seva aplicació en MEMS. L'aliatge escollit va ser el CoPt. Per tal de trobar un bany òptim per a la seva deposició s'ha dut a terme l'estudi bàsic del procés d'electrodeposició de l'aliatge. S'han preparat estructures amb diferents formes i geometries (dipòsits, pel•lícules primes, microestructures, nanopartícules, nanofils, ...) sobre diferents substrats i s'ha estudiat la influència de les condicions d'electrodeposició sobre les propietats de l'aliatge de CoPt (morfologia, composició, estructura cristal•lina, propietats magnètiques, ...) i s'ha realitzat l'anàlisi de la relació entre aquestes propietats.
Per últim, s'ha dut a terme un estudi inicial de la formació de monocapes orgàniques sobre diferents substrats magnètics, com al primer pas per fabricar un dispositiu d'espintrònica molecular. Per aquest motiu s'han preparat pel•lícules primes de magnetita i d'aliatge CoP per mitjà de l'electrodeposició i s'ha dut a terme l'estudi de la formació de les monocapes d'octanotiol i d'àcid oleic sobre els substrats
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Polyzos, Dimitrios. ""Measuring System Properties & Structured Diagnostics for the Selection of Sensors, Actuators Placement & Eigenstructure Assignment"." Thesis, City University London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.524712.
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Wu, Yongxian. "Experimental characterization and modeling of ionic polymer-metal composites as biomimetic actuators, sensors, and artificial muscles /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3167842.
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Dunbabin, Matthew D. "The influence of temperature on PZT sensors & actuators for active vibration control of flexible structures." Thesis, Queensland University of Technology, 2002. https://eprints.qut.edu.au/36162/7/36162_Digitised%20Thesis-4_Redacted.pdf.
Full textAbstract:
In real operating environments, flexible structures exhibiting dynamic oscillations such as aircraft and spacecraft can experience large changes in temperature during their normal operating cycle, typically in the range -70 to 80 degrees Celsius. The use of piezoelectric actuators and sensors to control these dynamic oscillations have been widely explored at constant temperature, although only limited studies have been conducted on the effect that varying temperature has on the active control of flexible structures.
The objective of this research is to study the influence of PZT sensors and actuators for vibration control of flexible structures where nonlinearities in piezoelectric and structural material properties change as the system temperatures vary significantly with time. This involved the development of a set of data based parameters that enabled the accurate modelling of a nonlinear flexible system in which its dynamics are actively controlled via the use of piezoelectric sensors and actuators. These parameters determined the design of a control scheme to actively control the system over a large range of operating temperatures, and give an optimised control performance throughout its operating regime.
The work reported in this thesis describes selected methods for rapidly examining a number of the more common nonlinear properties of PZT associated with vibration control. An extensive numerical and experimental investigation is performed which shows that when used in active vibration control applications, the variations in PZT properties with temperature can ultimately affect the ability of the piezoelectric actuator and sensors to suppress vibration in flexible structures.
Accurate simulation models of the lightweight piezo-actuated cantilevered structures were developed to evaluate the performance of a number of common vibration control schemes subject to significant temperature variations. This research was then extended to an innovative scaled wing-type structure subjected to temperature variations. A suitable adaptive self-tuning control scheme was developed and investigated numerically and experimentally, illustrating the benefit of adaptive control in this instance. The adaptive control technique was shown numerically and experimentally to provide improved settling times and damping ratios over equivalent fixed gain controllers for the class of structures investigated where limited control authority exists.
The experimental investigation of PZT sensors and actuators has provided further understanding of the nonlinear behaviour of various light, flexible structures where temperature effects on the system dynamics and control are significant. This research has unveiled previously unreported nonlinearities and has expanded on traditional nonlinearities. These results can assist with the detailed design of applications involving PZT sensors and actuators in for example the aerospace and automotive industries.