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1
Messenger, Robert K. "Modeling and Control of Surface Micromachined Thermal Actuators." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd434.pdf.
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Fleming, Mark Richard. "An experimental investigation of the harmonic excitation of simply supported plates with multiple surface-bonded piezoceramic actuators." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-06082009-171009/.
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Dessolin, Samuel. "Membrane models for a controllable surface." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/17527.
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Spano, Joseph S. (Joseph Samuel). "Surface wave distributed actuators for plannar manipulation with application to human transport." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/88840.
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Montgomery, Matthew. "Magnetically Deflectable MEMS Actuators for Optical Sensing Applications." Master's thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6226.
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In this work, new small deflection magnetic actuators have been proposed, designed, and tested for applications in Surface Enhanced Raman Scattering optical sensors. Despite the fact that SERS sensors have been shown to increase Raman over ten orders of magnitude for molecular detection, several technological challenges have prevented the design of practical sensors, such as making SERS sensors that can efficiently detect a wide variety of molecules. Since the optimum signal-to-noise in SERS occurs at different excitation wavelengths for different molecules, individual metal nanostructures need to be designed and fabricated for each independent chemical species. One possible solution to this problem is to tune the plasmon resonance frequency of the metal nanoparticles to eliminate the need for individually optimized particles. In order to achieve a tunable local dielectric environment, and thus allow for control over the resonance frequency of metal nanoparticles, a new SERS sensor geometry is proposed and a large deflection magnetic actuator is fabricated and tested as a starting point for the design of a small deflection magnetic actuator. Using the newly developed SERS geometry and the optimized fabrication processing techniques, two small deflection magnetic actuator beam structures were designed, fabricated, and tested. These devices utilizes an off-chip electromagnet source able to produce a magnetic force of approximately 14 ?N on the on-chip nickel film generating deflections up to 139 nm for the straight beam device and 164 nm for the curved beam device. In the process of characterizing the newly developed small deflection magnetic actuator, an integrated magnetic actuator with electrostatic restoration geometry was conceived. This device was designed to meet the specifications of the small deflection magnetic actuator as well as eliminate the need of an off-chip magnetic source and fully integrate the process atop the metal nanoparticle arrays. Using adhesive iron based magnetic strips as the magnetic drive source, circular NiFe beams with 1, 2, 3, and 4 mm diameters were designed and simulated. Calculations predicted maximum achievable actuation of up to 2.5 ?m. Processing steps were laid out for a set of integrated devices as a possible predecessor to the newly designed small deflection magnetic actuator.M.S.E.E.
Masters
Electrical Engineering and Computer Science
Engineering and Computer Science
6
Tong, Daqun. "Modeling and Optimal Shape Control of a Laminated Composite Thin Plate with Piezoelectric Actuators Surface Embedded or Bonded." Ohio University / OhioLINK, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1184345824.
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Doepke, Edward Brady. "Design Demonstration and Optimization of a Morphing Aircraft Control Surface Using Flexible Matrix Composite Actuators." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82494.
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The morphing of aircraft wings for flight control started as a necessity for the Wright Brothers but quickly fell out of favor as aircraft increased speed. Currently morphing aircraft control is one of many ideas being explored as we seek to improve aircraft efficiency, reduce noise, and other alternative aircraft solutions. The conventional hinged control surface took over as the predominant method for control due to its simplicity and allowing stiffer wings to be built. With modern technologies in variable stiffness materials, actuators, and design methods, a morphing control surface, which considers deforming a significant portion of the wing's surface continuously, can be considered.
While many have considered morphing designs on the scale of small and medium size UAVs, few look at it for full-size commercial transport aircraft. One promising technology in this field is the flexible matrix composite (FMC) actuator. This muscle-like actuator can be embedded with the deformable structure and unlike many other actuators continue to actuate with the morphing of the structure. This was demonstrated in the FMC active spoiler prototype, which was a full-scale benchtop prototype, demonstrated to perform under closed-loop control for both the required deflection and load cases.
Based on this FMC active spoiler concept a morphing aileron design was examined. To do this an analysis coupling the structure, fluid, and FMC actuator models was created. This allows for optimization of the design with the objectives of minimizing the hydraulic energy required and mass of the system by varying the layout of the FMC aileron, the material properties used, and the actuator's design and placement with the morphing section.
Based on a commercial transport aircraft a design case was developed to investigate the optimal design of a morphing aileron using the developed analysis tool. The optimization looked at minimizing the mass and energy requirements of the morphing aileron and was subject to a series of constraints developed from the design case and the physical limitations of the system. A Pareto front was developed for these two objectives and the resulting designs along the Pareto front explored. From this optimization, a series of design guidelines were developed.Ph. D.
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Oliver, Danielle Simonette. "Power Requirements of Control Surface Actuators Towards Active Aeroelastic Control Using the Method of Receptances." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami159601703575348.
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Jeličić, Aleksandra, Alwin Friedrich, Katarina Jeremić, Gerd Siekmeyer, and Andreas Taubert. "Polymer hydrogel/polybutadiene/iron oxide nanoparticle hybrid actuators for the characterization of NiTi implants." Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2010/4858/.
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One of the main issues with the use of nickel titanium alloy (NiTi) implants in cardiovascular implants (stents) is that these devices must be of very high quality in order to avoid subsequent operations due to failing stents. For small stents with diameters below ca. 2 mm, however, stent characterization is not straightforward. One of the main problems is that there are virtually no methods to characterize the interior of the NiTi tubes used for fabrication of these tiny stents. The current paper reports on a robust hybrid actuator for the characterization of NiTi tubes prior to stent fabrication. The method is based on a polymer/hydrogel/magnetic nanoparticle hybrid material and allows for the determination of the inner diameter at virtually all places in the raw NiTi tubes. Knowledge of the inner structure of the raw NiTi tubes is crucial to avoid regions that are not hollow or regions that are likely to fail due to defects inside the raw tube. The actuator enables close contact of a magnetic polymer film with the inner NiTi tube surface. The magnetic signal can be detected from outside and be used for a direct mapping of the tube interior. As a result, it is possible to detect critical regions prior to expensive and slow stent fabrication processes.
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Lin, I.-Ting. "Dielectric elastomer actuators in electro-responsive surfaces based on tunable wrinkling and the robotic arm for powerful and continuous movement." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289711.
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Dielectric elastomer actuators (DEAs) have been used for artificial muscles for years. Recently the DEA-based deformable surfaces have demonstrated controllable microscale roughness, ease of operation, fast response, and possibilities for programmable control. DEA muscles used in bioinspired robotic arms for large deformation and strong force also become desirable for their efficiency, low manufacturing cost, high force-to-weight ratio, and noiseless operation. The DEA-based responsive surfaces in microscale roughness control, however, exhibit limited durability due to irreversible dielectric breakdown. Lowering device voltage to avoid this issue is hindered by an inadequate understanding of the electrically-induced wrinkling deformation as a function of the deformable dielectric film thickness. Also, the programmable control and geometric analysis of the structured surface deformation have not yet been fully explored. Current methods to generate anisotropic wrinkles rely on mechanical pre-loading such as stretching or bending, which complicates the fabrication and operation of the devices. With a fixed mechanical pre-loading, the device can only switch between the flat state and the preset wrinkling state. In this thesis, we overcome these shortcomings by demonstrating a simple method for fabricating fault-tolerant electro-responsive surfaces and for controlling surface wrinkling patterns. The DEA-based system can produce different reversible surface topographies (craters, irregular wrinkles, structured wrinkles) upon the geometrical design of electrode and application of voltage. It remains functional due to its ability to self-insulate breakdown faults even after multiple high voltage breakdowns, and the induced breakdown punctures can be used for amplification of local electric fields for wrinkle formation at lower applied voltages. We enhance fundamental understanding of the system by using different analytical models combined with numerical simulation to discuss the mechanism and critical conditions for wrinkle formation, and compare it with the experimental results from surface topography, critical field to induce wrinkles in films of different thickness, and wrinkling patterns quantitatively analysed by different disorder metrics. Based on the results, we demonstrate its wide applicability in adjustable transparency films, dynamic light-grating filter, molding for static surface patterns, and multi-stable mirror-diffusor-diffraction grating device. For DEAs used for macroscopic-scale deformation in robotic arms, the main issue that undermines the performance of DEA muscles is the trade-off between strong force and large displacement, which limits the durability and range of potential robotic and automation applications of DEA-driven devices. In this thesis, this challenge is tackled by using DEAs in loudspeaker configuration for independent scaling-up of force and displacement, developing a theoretical prediction to optimise the operation of such DEAs in bioinspired antagonistic system to maximise speed and power of the robotic arm, and designing a clutch-gear-shaft mechanical system collaborating with the muscles to decouple the displacement and output force. Therefore, the trade-off between force and displacement in traditional DEA muscles can be resolved. The mechanical system can also convert the short linear spurt to an unlimited rotary motion. Combining these advantages, continuous movement with high output force can be accomplished.
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Jaquet, Christopher Denis. "Control surfaces in confined spaces : the optimisation of trailing edge tabs to reduce control surface hinge moments." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4327.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: This thesis describes the first project relating to the Control Surfaces in Confined Spaces (CoSICS) project at Stellenbosch University. The aim of CoSICS project is to reduce the size of control surface actuators, and this thesis considers the aileron system of commercial aircraft such as the Airbus A320 and A330. Specifically the project aims to reduce the aileron hinge moment, as this will result in smaller actuators. Possible methods are discussed where aerodynamic forces are used to reduce the aileron hinge moment through the use of a wing-aileron-tab configuration. In order to examine the use of the configuration, first order aerodynamic modelling is performed using two-dimensional thin-aerofoil theory, which is also extended to a basic three-dimensional approximation. To determine the maximum reduction in hinge moment several optimisations are performed where only the tab chord length is varied, both tab and aileron chord lengths are varied, and finally the tab chord length and aileron span are varied. The optimisation methods used, namely the gradient-based sequential quadratic programming (SQP) and a real-encoded genetic algorithm (REGA) are discussed in detail and include general implementations which are then applied to the problem. The optimisations performed are dual-layered where optimal deflection angles are determined as well as the optimal geometry. The results of the optimisation are tested using a roll manoeuvre in a specially developed Simulink simulation environment for this purpose. The study produces results where new hinge moment values are an order of magnitude smaller than those of the old configuration, while maintaining suitable lift and rolling moment coefficients. The optimisation and simulation infrastructure developed in this thesis provides a platform for higher-fidelity models and components being developed in future work to provide higher fidelity results.
AFRIKAANSE OPSOMMING: Hierdie tesis beskryf die eerste projek in die Control Surfaces in Confined Spaces-projek1 (CoSICS-projek) uitgevoer by die Universiteit Stellenbosch. Die doel van die COSICs-projek is om die grootte van beheervlak aktueerders te minimeer en hierdie tesis handel oor die aileron stelsel van kommersiële vliegtuie soos die Airbus A320 en A330. Die doel van hierdie tesisis om die skarnier draaimoment van die aileron te minimeer deur aërodinamiese kragte in te span in ’n vlerk-aileron-hulpvlak konfigurasie. Eerste-orde aërodinamiese modelle is afgelei met behulp van twee-dimensionele dunvlerkteorie en is gebruik om die konfigurasie te analiseer. ’n Eerste orde drie-dimensionele benadering is ook ontwikkel. Om die maksimum vermindering in die skarnier draaimoment te bepaal, is verskeie optimerings uitgevoer waar eers die hulpvlak se koordlengte gevarieer word, daarna beide die aileron en hulp-vlak se koordlengtes en laastens die hulp-vlak se koordlengte en wydte. Die twee optimerings metodes wat gebruik is, nl. ’n sekwensiële kwadratiese programmerings (SKP) tegniek, en ’n reële getal-geënkodeerde genetiese algoritme (RGGA), word bespreek en ontwikkel voor hulle toegepas word op die probleem. Twee-vlak optimerings word uitgevoer waar beide die optimale defleksiehoeke en die optimale geometrie bepaal word. Die resultate van die optimering word daarna getoets deur middel van ’n rol maneuver wat uitgevoer word in ’n Simulink simulasie omgewing wat daarvoor geskep is. Hierdie studie lei tot goeie resultate met skarnier draaimoment waardes ’n ordegrootte kleiner as dié van die vorige stelsel, terwyl goeie waardes van rol-moment en verheffingskrag koëffisiënte behou word. Die optimering en simulasie infrastruktuur wat hier ontwikkel word verskaf ’n platform vir meer akkurate modelle en komponente wat ontwikkel word in toekomstige projekte om meer akkurate resultate te lewer.
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Hubbard, Neal B. "Dual-stage Thermally Actuated Surface-Micromachined Nanopositioners." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd743.pdf.
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Cho, Gyoungil. "Design, fabrication, and testing of a variable focusing micromirror array lens." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2186.
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A reflective type Fresnel lens using an array of micromirrors is designed and fabricated using the MUMPs?? surface micromachining process. The focal length of the lens can be rapidly changed by controlling both the rotation and translation of electrostatically actuated micromirrors. The suspension spring, pedestal and electrodes are located under the mirror to maximize the optical efficiency. The micromirror translation and rotation are plotted versus the applied voltage. Relations are provided for the fill-factor and the numerical aperture as functions of the lens diameter, the mirror size, and the tolerances specified by the MUMPs?? design rules. Linnik interferometry is used to measure the translation, rotation, and flatness of a fabricated micromirror. The reflective type Fresnel lens is controlled by independent DC voltages of 16 channels with a 0 to 50V range, and translational and torsional stiffness are calibrated with measured data. The spot diameter of the point source by the fabricated and electrostatically controlled reflective type Fresnel lens is measured to test focusing quality of the lens.
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Saal, Sheldon C. "The development of an active surface using shape memory alloys." Thesis, Cape Peninsula University of Technology, 2006. http://hdl.handle.net/20.500.11838/1292.
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This thesis work was conducted in the Department of Mechanical Engineering
at the Cape Peninsula University of Technology (CPUT) and was submitted
towards the partial fulfilment of the Masters Degree in Technology:
Mechanical Engineering.Recent years have witnessed a tremendous growth and significant advances in “smart” composites and “smart” composite structures. These smart composites integrate active elements such as sensors and actuators into a host structure to create improved or new functionalities through a clever choice of the active elements and/or a proper design of the structure. Such composites are able to sense a change in the environment and make a useful response by using an external feedback control system. Depending on their applications, smart composites usually make use of either the joint properties of the structure or the properties of the individual elements within the composites. The accumulation in the understanding of materials science and the rapid developments in computational capabilities have provided an even wider framework for the implementation of multi-functionality in composites and make “smart” composites “intelligent”.
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Anderson, Theodore E. "Simulation and Fabrication of a Formable Surface for the Digital Clay Haptic Device." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14494.
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A formable surface is part of an effort to create a haptic device that allows for a three dimensional human-computer interface called digital clay. As with real clay, digital clay allows a user to physically manipulate the surface into some form or orientation that is sensed and directly represented in a computer model. Furthermore, digital clay will allow a user to change the computer model by manipulating the inputs that are directly represented in the physical model. The digital clay device being researched involves a computer-interfaced array of vertically displacing actuators that is bound by a formable surface. The surface is composed of an array of unit cells that are constructed of
compliant spherical joints and translational joints.
As part of this thesis, a series of unit cells were developed and planar surfaces were fabricated utilizing the additive manufacturing process of stereolithography. The process of computing the resultant shape of a manipulated surface was modeled mathematically through energy minimization algorithms that utilized least squares analysis to compute the positions of the unit cells of the surface. Simulation results were computed and analyzed against the movement of a fabricated planar surface.
Once the mathematical models were validated against the manufactured surface, a
method for attaching the surface to an array of actuators was recommended.
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Kluge, Axel, Johannes Henneberg, Chokri Cherif, and Andreas Nocke. "Methods for adhesion/friction reduction of novel wire-shaped actuators, based on shape memory alloys, for use in adaptive fiber-reinforced plastic composites." Sage, 2015. https://tud.qucosa.de/id/qucosa%3A35612.
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For fiber-reinforced plastic composites, fiber-matrix adhesion is a significant aspect of composite properties. While conventional lightweight structures are always aiming for high fiber-matrix adhesion, innovative and unconventional functional constructions require different concepts. The research work treating adaptive fiber-reinforced plastic composites with shape memory alloy wires presented here uses the approach of actuators freely movable within the composite. This is supposed to prevent mechanical tensions in the interfaces of actuator and composite structure, which would otherwise cause damages of the composite. This work examines hybrid yarns based on friction spinning technology, with shape memory alloy wires as their core component as well as glass fibers, and partly polypropylene, as their sheath component. Additionally, the surface properties of the shape memory alloy wires being used are modified by sanding and coating. The results of a characterization by pull-out testing clearly show that a coating of the shape memory alloy wires with an abherent causes considerable decrease in adhesion and friction in the interface and leads to the mobility of the shape memory alloy wires in the later composite. An even greater effect is attained by sheathing the hybrid yarns in an additional layer of polypropylene, compacting the yarn cross-section. Thus, the pull-out force could be reduced to 35–40% of the reference structure.
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Pawar, Amita A. "Smart Material Actuators For Active Tactile Surfaces." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338400866.
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Hervagault, Yoann. "Conception et réalisation d'un système efficace de communication et de coordination au sein d'une flotille de drones aquatiques de surface." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT048.
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The work described herein concerns the development of a communication strategy for a fleet of USVs (Unmanned Surface Vehicles). This project's aim is to improve the performances of the SPYBOAT system, developed by the French company CT2MC to perform environmental monitoring missions in fresh waters. In order to successfully fulfill their task, autonomous surface vehicles must be able to maintain a reliable communication link. This thesis's goal is twofold and complementary:- propose the design of an antenna dedicated to the particular conditions of an USV environment and contained in the vessel's hull,- take into account the effective radio ranges and the limited onboard computing resources to develop an admissible deployment strategy.First, the system under study is identified through experiments performed in the Bourget Lake. The differential flatness property of the model is also proved for further use in the computation of reference trajectories.Subsequently, the characteristics of the USV are described from a radio-frequency point of view. The environmental conditions involved by the water proximity, the low heights of the antennas and the high density of conductive materials in unmanned systems are very challenging. The selected antenna configuration is a planar antenna array, composed of three elementary semi-circular monopoles. Low-height measurements over the ground in open space, in good agreement with simulations, have proven that the proposed antenna and the currently used wire antennas exhibit good electrical performances. Antennas simulations have shown that the radiation pattern loses its omnidirectional property when placed in the vessel's hull due to the reflexions on the embedded equipment, and multiple antennas are required to maintain a reliable communication link.Finally, an algorithm able to compute a feasible reference trajectory for a fleet of USVs is proposed. The flatness-based optimization algorithm takes into account communication constraints to ensure that none of the agents in the network becomes isolated. The optimization problem is solved offline to reduce the computation task of the embedded controller. Then, the trajectory tracking algorithm is implemented online via an LQR (Linear Quadratic Regulator) controller which has been simulated and successfully experimented under various scenarios over the real platforms of CT2MC. The experimental tests show that the pre-established communication constraints are preserved while minimizing the tracking errorLes travaux présentés dans cette thèse visent à améliorer les performances du système SPYBOAT, une gamme de drones aquatiques de surface développés par l'entreprise CT2MC et destinés à la réalisation de missions de surveillance environementale en eau douce. Afin de pouvoir mener à bien leurs missions, le maintien de la communication radio avec ces équipements est primordial à la fois pour pouvoir envoyer de nouvelles instructions aux agents, et pour évaluer l'état d'avancement de la mission. Les objectifs de cette thèse sont donc complémentaires:- concevoir une antenne dédiée à un véhicule autonome de surface et contenue dans sa coque,- développer une stratégie de déploiement qui prend en compte la portée radio et les ressources de calcul limitées.Dans un premier temps, les paramètres dynamiques d'un des modèles SPYBOAT ont été identifiés au cours d'une campagne de mesures réalisée sur le Lac du Bourget (73). Le modèle dynamique est ensuite approfondi afin de mettre en évidence sa platitude qui sera utilisée lors de la génération des trajectoires de référence.Ensuite, les conditions particulières d'un point de vue radio-fréquence sont abordées telles que la proximité de l'eau, les faibles hauteurs et le voisinage d'éléments conducteurs. La topologie choisie consiste en un réseau d'antennes constitué de 3 monopoles semi-circulaires. Les performances de cette antenne ont été évaluées par simulation et confirmées par le biais de mesures effectuées sur des prototypes. Les résultats montrent que ces antennes offrent des performances comparables aux dipoles filaires classiquement utilisés dans ce domaine.Enfin, nous proposons un algorithme de génération d'une trajectoire de référence pour une flotte de drones exploitant la platitude des systèmes à contrôler. Les contraintes de portée induites par l'utilisation de l'antenne sont prises en compte afin de garantir le contact radio avec chaque agent. Cette étape d'optimisation est réalisée en amont de la mission afin de minimiser la tâche alouée au contrôleur, qui consiste en une commande LQR (Linear Quadratic Regulator) à gain variable. Cette stratégie de commande a été simulée et testée avec succès sur un système réel
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Ehlers, Righardt Frederick. "Feedback control of a shape memory alloy actuator for control surface deflection." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/19977.
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Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The successful design, implementation and testing of a feedback control system for tab-deflection control of a shape memory alloy (SMA) based control surface actuator is presented. The research is performed as part of the Control Surfaces in Confined Spaces (CoSICS) research project conducted at Stellenbosch University. The research group investigates ways to provide control surface actuation in size-restricted spaces in commercial aircraft such as the Airbus A320 and A330. This is achieved by investigating the concept of trailing edge tabs to reduce the required torque load, resulting in reduced actuator requirements enabling the use of smaller actuators. This thesis contributes to the project by investigating the possibility of using SMA-based actuators in reduced hinge moment requirement applications. An SMA-based tab actuator demonstrator design is presented. Mathematical models are derived for the SMA material, thermodynamics and actuator geometry. The models are combined to formulate an SMA-based control surface actuator model. The model is utilised in four tracking feedback controller designs; two based on linear and two based on non-linear control techniques. The manufactured prototype is presented along with the incorporated hardware for controller implementation. System identification follows and validates the three mathematical models. Practical verification of the model and two of the controllers is conducted. The unimplemented controllers are implemented through a validated model simulation. Controller evaluation, based on the dynamic controller performance, is conducted. The results validate the concept of using an SMA actuator for tab-deflection control and indicate important limitations for the intended application.
AFRIKAANSE OPSOMMING: Die tesis behels die ontwerp, implementering en toetsing van ’n terugvoer beheerstelsel vir hulpvlak defleksie beheer van ’n vorm-geheue allooi (SMA) gebaseerde aktueerder. Die navorsing vorm deel van die Beheervlakke in Begrensde Ruimtes (CoSICS) navorsingsprojek by Stellenbosch Universiteit. Die CoSICS navorsing behels ’n ondersoek na beheervlak aktueering in beknopte spasies in kommersiële vliegtuie soos die Airbus A320 en A330. Die probleem word aangespreek deur ’n ondersoek na aerodinamiese hulpvlakke wat ’n vermindering in skarnier moment tot gevolg het en sodoende die aktueerder vereistes verminder. Hierdie tesis dra by tot die projek deur die moontlikheid van die gebruik van SMAgebaseerde aktueerders in verminderde skarnier moment vereiste toepassings te ondersoek. ‘n SMA gebaseerde hulpvlak demonstrasie aktueerder ontwerp word voorgelê. Wiskundige modelle vir die SMA materiaal, termodinamika en prototipe geometrie is geformuleer en gekombineer om ‘n SMA gebaseerde beheervlak aktueerder model te ontwikkel. Die model word in vier beheerder ontwerpe toegepas. Twee ontwerpe is op liniëre en twee op nie-liniëre beheer tegnieke gebaseer. Die prototipe en nodige hardeware vir beheerder implementasie is voorgedra. Stelsel identifikasie is toegepas en verifieer die drie wiskundige modelle. Praktiese verifikasie van die model en twee beheerders is gedoen. Die ongeïmplementeerde beheerders is deur die geverifieerde aktueerder model gesimuleer. ‘n Beheerder evaluasie gebaseer op die dinamiese beheerder gedrag word toegepas. Die evaluasie beklemtoon kritiese aspekte en beperkinge in verband met SMA aktueering. Die resultate regverdig die gebruik van ‘n SMA aktueerder vir hulpvlak defleksie beheer en beklemtoon belangrike beperkinge ten opsigte van die voorgestelde toepassing.
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Ni, Qi. "Droplet-based Mechanical Actuator Utilizing Electrowetting Effect." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6337.
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The goal of this work is to quantify the key design parameters such as the load capacity, actuation force, positioning repeatability, and reliability for droplet-based electrowetting actuators. Due to the fact that surface tension dominates gravity at both the mesoscale and microscale, droplet-based actuators can provide adequate force in manipulation tasks at those scales. Electrowetting, which uses an electric field to modulate the apparent surface tension of the liquid-ambient, provides a method to actuate droplets, which in turn transports the object carried by the droplet.
Most previous electrowetting actuation efforts have concentrated on manipulating droplets in a closed two-plate configuration. In these configurations, a voltage potential is applied between a series of electrodes. The droplets can merge, split, and mix with only a voltage input, and without any external machinery. While some mechanical actuation demonstrations have been done, limited studies have been performed to investigate the key actuation performance characteristics of droplet-based actuators carrying solid objects. Design criteria for using droplets to carry solid components are still not well defined.
The first part of this work provides fundamental understanding of the forces in electrowetting-based droplet actuation. The actuation force during electrowetting was experimentally validated according to the governing relation (Young–Lippmann equation) on a custom-designed testing apparatus. The results from the experiments show that the electrowetting actuation force is independent of surface tension below saturation, but the peak force is proportional to surface tension. Higher surface/interfacial tension would increase the actuation force in the horizontal direction, as well as the speed of the actuator.
The second part of the dissertation demonstrates two actuation configurations based on electrowetting. The first actuator uses a droplet to carry a solid object and can be actuated in discrete steps to function as a micro-stepping linear motor. By implementing a leaky dielectric coating, the droplet/substrate contact area acts as an electrical diode. By varying the duty cycle of a square waveform, a range of droplet/part equilibrium position combinations are established. The underlying actuation mechanism was investigated and the position versus duty cycle relation was shown to be symmetrical but non–linear around the center of the electrodes. In contrast to the conventional electrowetting control scheme, the proposed actuation method required no feedback control loop while achieving a repeatability of less than 0.8% of the droplet diameter. Positioning matched a theoretical model based on idealized electrical elements to within 2.5% of the droplet diameter.
The second type of electrowetting actuation uses metal-semiconductor diodes (Schottky diodes) in place of electrochemical diodes. This configuration uses only one pair of electrodes to actuate the droplet over a large distance (5X or more the droplet diameter). While the actuation concept had been previously demonstrated, the reliability of the diodes were shown to be insufficient. The new diodes actuated without degradation under repeated actuation (2000 cycles). Comparing this to electrochemical diodes, a 50% reduction in actuation voltage was also accomplished by Schottky diodes. The measured maximum speed also increased from 32 mm/s (electrochemical diodes) to 240 mm/s (Schottky), a 7.5 fold improvement.
The last part of this dissertation used numerical simulations to investigate the load bearing capability and the stiffness variation of droplet-based actuators. The vertical force and stiffness - which are the primary figure of merit in designing droplet-based actuators are quantified. Three types of loading conditions were analyzed using simulation software and a simple analytical equation is shown to provide a useful approximation of the droplet force and stiffness. The results were further used in various case studies to demonstrate the optimal design strategy when using an electrowetting driven droplet as a fluidic bearing.
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Finger, William H. (William Helmut) 1975. "Design and control of a surface wave actuator for bedridden patients." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80499.
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Mani, Saikumar. "Surface characterization of polyvinylidene fluoride (pvdf) in its application as an actuator." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1349.
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Lott, Christian D. "Electrothermomechanical Modeling of a Surface-micromachined Linear Displacement Microactuator." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/306.
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The electrothermomechanical characteristics of an electrically-heated polycrystallinesilicon microactuator are explored. Using finite-difference techniques, an electrothermal model based on the balance of heat dissipation and heat losses is developed. For accurate simulation, the relevant temperature dependent properties from the microactuator material are included in the model. The electrothermal model accurately predicts the steady-state power required to hold position, and the energy consumed during the thermal transient. Thermomechanical models use the predictions of temperature from the electrothermal solution to calculate displacement and force from pseudo-rigid-body approximations and commercial finite-element code. The models are verified by comparing experimental data to simulation results of a single leg-pair on a particular configuration of the device.
The particular microactuator studied is called a Thermomechanical In-plane Microactuator, or TIM, and was fabricated with surface micromachining technology. A TIM requires a single releasable structural layer, is extremely flexible in design, and can operate with simple drive and control circuitry. The TIM produces linear motion of a center shuttle when slender legs on either side move the shuttle as a result of constrained thermal expansion.
In a single example, when the current through a leg with dimensions 250×3×3.5 µm^3 and suspended 2 µm off the substrate is sufficient to maintain an average temperature of 615 C in air and vacuum environments, model simulated temperatures along the leg have a peak of 860 C in air and 1100 C in vacuum. The final measured and predicted displacement is 14 µm. In air, the power predicted by the model needed to maintain this average temperature profile is 95 mW while consuming 16.4 µJ in 0.22 ms to reach 90 percent of the final average temperature. In a vacuum, only 6.4 mW are required to maintain the same average temperature with 97.6 µJ consumed in 18.5 ms. Simulation results suggest that short-duration high-current pulses can improve the transient response and energy consumed in a vacuum when steady-state temperatures are not required. For a TIM leg with the dimensions above, the maximum measured force is approximately 47 µN per leg-pair when enough current is provided to move the TIM 8 µm as a result of ohmic heating and thermal expansion.
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Li, Zhisong. "Advanced Computational Modeling for Marine Tidal Turbine Farm." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1337889611.
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Okyay, Ahmet. "Sliding Mode Control Algorithm Development For Anti-lock Brake System." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613568/index.pdf.
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In this thesis, a sliding mode controller employing a new sliding surface for
antilock brake system (ABS) is proposed, its stability is proven formally and its
performance is compared with existing sliding mode controllers. The new sliding
mode controller uses the integral-derivative surface, which includes error, its
derivative and its integral, all at the same time. This and the already existing
derivative surface, which includes error and its derivative only, are named zerothorder
sliding surfaces. Their stability analysis is done using first-order auxiliary
surfaces. Auxiliary surfaces equal the sliding surfaces when derivative of the error
becomes zero. The first-order error surface, which includes only the error, and the
integral surface, which includes error and its integral, were also designed for
comparison. During design, tire brake force response is modelled as an
uncertainty. Controllers are simulated on a road with an abrupt change in road
coefficient of adhesion. Controller parameters used are optimized, which results in
comparable stopping distances while braking on a constant coefficient of adhesion
road. Effect of first order actuator dynamics with varying time constants and
actuator absolute time delay were considered. Reaching and sliding properties of
controllers were also investigated, using results on a constant coefficient of
adhesion road. It is observed that zeroth-order sliding surfaces give smoother
response for both derivative and integral-derivative cases. As the controllers
employing error and derivative surfaces get unstable in the presence of actuator
time delay, the integral-derivative surface, proposed in this study, stands as the
best controller.
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Lammers, Zachary A. "Thermal Management of Electromechanical Actuation System for Aircraft Primary Flight Control Surfaces." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1399021324.
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Rubrice, Kevin. "Matériaux composites commandables pour applications hyperfréquences dans les structures navales." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S127.
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Les matériaux composites prennent une place de plus en plus importante dans la conception et la fabrication des moyens de transport et notamment dans le domaine naval où ils sont particulièrement privilégiés. En effet, ces matériaux sont utilisés pour leur légèreté, insensibilité à la corrosion et leurs caractéristiques mécaniques. Dans le domaine militaire, où l'optimisation des moyens de communication et de protection électromagnétique est primordiale, le développement de matériaux composites dotés de propriétés de reconfigurabilité sous commande(s) externe(s), présente un atout opérationnel majeur pour les parois structurales exploitant ces matériaux. Afin d'explorer cette voie, DCNS et l'Institut d’Électronique et de Télécommunications de Rennes (IETR, UMR-6164) se sont associés. Les travaux de thèse engagés ont pour objectif d'étudier et de développer des matériaux composites présentant des fonctions de reconfigurabilité applicables aux systèmes navals tels que les radômes, les antennes et exploitables pour répondre aux problématiques de furtivité (SER). Une première étude a permis d'explorer les matériaux à base de carbone, présentant une potentielle agilité de leurs caractéristiques diélectriques sous actuateur électrique. Ces matériaux présentent également un fort pouvoir absorbant électromagnétique, tributaire des propriétés diélectriques, elles-mêmes potentiellement reconfigurables. La seconde étude engagée a étudié l'impact des matériaux ferroélectriques, c'est-à-dire des matériaux reconfigurables sous champ électrique, lorsqu'ils sont intégrés comme charge dans une résine d'imprégnation. Ce nouveau matériau composite présente alors une reconfigurabilité de ses caractéristiques diélectriques, rendant commandable en fréquence sa structure hôte. Une troisième étude, exploitant aussi le matériau ferroélectrique a permis l'obtention d'une reconfigurabilité des caractéristiques de réflectivité de panneaux composites grâce au développement de surfaces sélectives en fréquence reconfigurables. De nouvelles propriétés ont ainsi été mises en évidence en hyperfréquences. Enfin, les matériaux d'âmes et spécifiquement les nids d'abeilles diélectriques ont fait l'étude d'une fonctionnalisation pour des applications DC et hyperfréquencesComposite materials are used for their lightness, high resistance to corrosion and high mechanical properties over large application areas, such as naval, ground and aerial. Collaboration between DCNS group and the Institute of Electronics and Telecommunications of Rennes (IETR, UMR-6164) has been initiated to develop smart composite materials with tunable properties at microwaves. Three different routes have been investigated during the thesis work. The first one is based on carbon composite material, its electromagnetic absorbing ability and its potential dielectric tunability. For this, we develop composite materials loaded with various carbon particles (carbon nanotube, graphene, black carbon). Next, to elaborate smart composite materials, a ferroelectric material has been used as filler. The dielectric characteristics of such materials can be tuned under external biasing for example. Thus we develop an active composite material under various external actuators for naval application, and especially for new reconfigurable frequency selective surface (RFSS). Finally dielectric honeycomb materials have been specifically elaborated and studied to develop smart properties for DC and microwave applications. During this work, three different prototypes improving composite materials in naval area have been performed: reconfigurable radome, RCS reduction, and antenna isolation
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Guskey, Christopher R. "NEAR WALL SHEAR STRESS MODIFICATION USING AN ACTIVE PIEZOELECTRIC NANOWIRE SURFACE." UKnowledge, 2013. http://uknowledge.uky.edu/me_etds/27.
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An experimental study was conducted to explore the possible application of dynamically actuated nanowires to effectively disturb the wall layer in fully developed, turbulent channel flow. Actuated nanowires have the potential to be used for the mixing and filtering of chemicals, enhancing convective heat transfer and reducing drag. The first experimental evidence is presented suggesting it is possible to manipulate and subsequently control turbulent flow structures with active nanowires. An array of rigid, ultra-long (40 μm) TiO2 nanowires was fabricated and installed in the bounding wall of turbulent channel flow then oscillated using an attached piezoelectric actuator. Flow velocity and variance measurements were taken using a single sensor hot-wire with results indicating the nanowire array significantly influenced the flow by increasing the turbulent kinetic energy through the entire wall layer.
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Marks, Christopher R. "Surface Stress Sensors for Closed Loop Low Reynolds Number Separation Control." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1309998636.
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Sedlačík, Jan. "Progresivní zařízení pro tvorbu mikrovtisků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230803.
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The diploma thesis deals with an engineering design, a realization and a calibration of a apparatus for surface texturing of test samples. Microdents are produced by a diamond tool pressing. Electromagnetic linear actuator is used for pressing. Translation and rotation of the sample are secured by a couple of stepping motors. Thanks to this the apparatus can produce texture with well defined and easily controlled geometry. The diploma thesis contains a summary of surface texturing methods, designs of constructional variations, a electronic device of the apparatus and the calibration are also included.
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Castera, Philippe. "Energy coupling mechanisms in pulsed surface discharges for flow control." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2015. http://www.theses.fr/2015ECAP0041/document.
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Ce travail s'intéresse aux effets mécaniques créés par les décharges de surface et à leur efficacité comme actionneur. Une géométrie particulière d'électrodes permet de créer de manière pulsée un filament linéaire de plasma et de le chauffer très rapidement par effet Joule (à raison de plusieurs Joules en moins d'une microseconde). Ce chauffage rapide entraîne la formation d'ondes de choc qui peuvent interagir avec l'écoulement ambiant.Nous étudions le comportement électrique de la décharge de surface afin d'évaluer l'énergie déposée dans le filament de plasma par effet Joule. Pour ce faire, nous réalisons une étude paramétrique sur la configuration du circuit et nous déterminons les principaux paramètres qui pilotent la dynamique de la décharge. Différents modèles de résistance sont utilisés dans un code de simulation du circuit électrique, et leurs prédictions du courant et du dépôt d'énergie sont confrontées aux mesures expérimentales.Des mesures spectroscopiques dans différentes configurations de circuit donnent accès à certaines propriétés de la décharge comme la densité électronique, qui atteint des valeurs de 2x1018 cm-3. Le rayon du canal est également mesuré par imagerie rapide. Les ondes de chocs créées par la décharge de surface sont visualisées en imagerie Schlieren pour plusieurs configurations de circuit. Ces ondes de chocs créent une impulsion proportionnelle à l'énergie déposée dans la décharge. Nos développons un modèle de choc pour décrire la trajectoire du choc et pour calculer l'impulsion communiquée par la décharge de surface. Le modèle est en bon accord avec les mesures expérimentales et la décharge de surface a une efficacité mécanique de 0.12mNs/J pour notre configuration d'étude. Nous terminons cette étude en comparant cet actionneur potentiel avec d'autres actionneurs courants et proposons plusieurs pistes pour de futurs travauxIn this study, we investigate the mechanical effects generated by pulsed surface discharges and their efficiency as an actuator. Using a specific electrode configuration, it is possible to create a short-lived, pulsed, rectilinear plasma channel and to heat it up rapidly (several Joules in less than a microsecond) through Joule heating. This fast energy deposition causes the formation of shock waves that can then interact with the surrounding flow.We study the electrical behavior of the pulsed surface discharge to assess the energy deposited in the plasma channel through Joule heating. To do so, we perform a parametric study on the circuit configuration and identify the main parameters driving the discharge dynamics. Several resistance models are implemented in a numerical description of the electrical circuit and their predictions of the current and deposited energy are compared with experimental measurements.Spectroscopic measurements in different circuit configurations give access to some of the plasma properties such as the electron number density that can reach values up to 2x1018 cm-3. Fast imaging also gives insight into the plasma channel radius. The shock waves generated by the pulsed surface discharge in different circuit configurations are visualized through Schlieren imaging. These shock waves generate an impulse that increases linearly with the energy deposited in the discharge. We develop a shock model to describe the shock trajectory and to compute the impulse imparted by the pulsed surface discharge. The model is in good agreement with our measurements and the pulsed surface discharge is found to have a mechanical efficiency of 0.12 mNs/J for our setup configuration. We conclude this study by comparing the proposed pulsed surface discharge actuator with other common designs and offer some directions for future studies
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Barnett, Street. "Laboratory Test Set-up to Evaluate Electromechanical Actuation System for Aircraft Flight Control." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1429461885.
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Tsala, Moto Serge Parfait. "Compatibilité tribologique d’un revêtement de surface avec une application donnée : Cas d’un revêtement de WS2 sur une tige de piston de frein aéronautique." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI035.
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Le chrome dur, utilisé comme revêtement de tige d’actionneurs hydrauliques linéaires, a été interdit pour risque sanitaire (directive européenne REACH). A cet effet, un revêtement de WS2 a été sélectionné par Safran Landing Systems pour substituer le chrome dur comme revêtement de tige de piston de frein hydraulique. La démarche de sélection utilisée, est limitée par son incapacité à expliquer les performances observées et démontre le besoin d’une démarche de sélection d’autant plus appropriée que la notion d’étanchéité des actionneurs hydrauliques linéaires est « floue ». Comme, la tribologie n’a pas vocation à caractériser les revêtements de surface, parce que son plus petit objet d’étude est un triplet tribologique, cette étude propose l’évaluation de la compatibilité tribologique du revêtement de WS2, avec la fonction d’étanchéité. La démarche utilisée montre que l’étanchéité est régie, par un critère en pression, et par une vérification des caractéristiques tribologiques du système tige/joints requises pour la réalisation de l’étanchéité ; ce qui nécessite un piston hydraulique instrumenté. L’absence de ce piston est compensée par une « caractérisation tribologique approchée » du contact tige/joints, qui associe les expertises tribologiques de pistons hydrauliques d’essais de qualification, appuyées par un modèle éléments finis (EF) du piston hydraulique d’une part, et les résultats d’un essai de frottement piste/joints, conçus à cet effet à l’aide d’un modèle EF d’autre part. Les résultats montrent que le système tige/joints présente de bonnes caractéristiques tribologiques pour le facteur de frottement et l’usure, alors que la localisation de l’accommodation de vitesses dans le cas du contact tige/joint d’étanchéité, accélère le débit source du revêtement et limite sa durée de vie. Enfin, cette thèse comble un vide méthodologique en proposant, une démarche de sélection d’un revêtement pour une application tribologique, et une démarche de triboconception d’un actionneur hydraulique linéaire dans le cas d’un fonctionnement quasi-statiqueHard chromium used as rod coating in linear hydraulic actuators has been forbidden by the European Directive REACH. In this situation, a WS2 coating has been selected by Safran Landing Systems to replace the hard chromium coating on rod pistons actuators of landing gear braking systems. The selection method was unable to explain the observed performance, and shows the lack of an appropriate methodology for the rod coating selection, mainly because the sealing concept is rather vague. Since tribology is not intended to characterize surface coatings, because its smallest object of study is a tribological triplet, this study proposes the evaluation of the tribological compatibility of the WS2 coating with the sealing function of the hydraulic piston. The adopted approach shows that the sealing performance is governed by a rod/seal contact pressure criterion and by the verification of the tribological characteristics of the rod/seal contact required to achieve a sealing performance. This tribological characterization requires an instrumented hydraulic piston. The absence of this piston is compensated by an "approximate tribological characterization" of the rod/seal contact, which combines the tribological expert analysis of hydraulic pistons of qualification tests, supported by a finite elements model (FE) of the hydraulic piston, and the results of a plate rod/seal friction test, designed for this purpose using another FE model. The results show that the rod/seal contact exhibits good tribological characteristics for the friction factor and wear, whereas the location of the velocity accommodation in the case of the rod/anti-extrusion seal contact accelerates the 3rd body generation of the coating and limits its life expectancy. Finally, this thesis fills a methodological lack by proposing a method of selecting a coating for a tribological application and a triboconception method of a linear hydraulic actuator in the case of quasi-static operating conditions
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Treviso, Felipe. "Estudo de um atuador planar de indução para a inspeção de superfícies metálicas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/141822.
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Um atuador planar de indução é um dispositivo baseado no mesmo princípio de funcionamento de um motor linear de indução, onde a interação de um campo magnético viajante produzido pelo primário do dispositivo com uma superfície de boa condutividade elétrica induz correntes parasitas que levam à produção de uma força de propulsão. O movimento planar sobre essa superfície é produzido através da movimentação linear em dois eixos ortogonais. Uma aplicação deste movimento é na propulsão de uma plataforma equipada com câmeras e sensores para a realização da inspeção em uma superfície metálica, que se beneficiaria da força normal que o motor planar de indução produz quando acionado sobre uma superfície ferromagnética para anexar a plataforma à superfície. Um modelo analítico que fornece equações para o campo elétrico e magnético é apresentado, e simulações numéricas baseadas no método dos elementos finitos são realizadas para avaliar o comportamento do dispositivo utilizando três tipos diferentes de superfícies como secundário: um secundário com duas camadas formadas por uma chapa de alumínio com outra de aço por baixo; apenas a chapa de alumínio; e apenas a chapa de aço. As distribuições de campo magnético calculadas por estes dois modelos teóricos mostram boa concordância entre si, e são utilizadas para calcular as forças de propulsão e normal produzidas pelo atuador. Medidas experimentais são realizadas em um protótipo de atuador planar de indução, e seus resultados são comparados com os resultados obtidos nos modelos teóricos, mostrando uma boa concordância e potencial para a aplicação do atuador planar de indução na inspeção de superfícies horizontais.An induction planar actuator is a device that, based on the operating principle of a linear induction motor, in which the interaction between a travelling magnetic field produced by the primary of the device and a conducting surface generates eddy currents in the surface and leads to the generation of a thrust force. The device produces planar motion over this surface through movement on two orthogonal axis. An application of this movement is in a platform for the inspection of metallic surfaces, which is driven by the planar induction motor and equipped with cameras and sensors to inspect the surface. This application benefits from the normal force produced by the induction planar actuator operating over a ferromagnetic surface to attach the driving platform to it. An analytical model with equations for the electric and magnetic fields is presented, and numerical simulations based on the finite element method are carried out to assess the behaviour of the device using three different surfaces as secondary: a double-layered secondary formed by an aluminum plate over a steel plate; a aluminum only plate; and a single steel plate. The distributions for the magnetic field computed through these theoretical models show good agreement, and are employed to evaluate the thrust and normal forces produced by the planar induction actuator. Experimental measurements are made on a prototype of the device, and the results are compared to the results of the theoretical models, showing good agreement and potential in the application of the induction planar motor for the inspection of horizontal metallic surfaces.
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M, Venkata Raghu Chaitanya. "Model Based Aircraft Control System Design and Simulation." Thesis, Linköping University, Linköping University, Department of Management and Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-19264.
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Development of modern aircraft has become more and more expensive and time consuming. In order to minimize the development cost, an improvement of the conceptual design phase is needed. The desired goal of the project is to enhance the functionality of an in house produced framework conducted at the department of machine design, consisting of parametric models representing a large variety of aircraft concepts.
The first part of the work consists of the construction of geometric aircraft control surfaces such as flaps, aileron, rudder and elevator parametrically in CATIA V5.
The second part of the work involves designing and simulating an Inverse dynamic model in Dymola software.
An Excel interface has been developed between CATIA and Dymola. Parameters can be varied in the interface as per user specification; these values are sent to CATIA or Dymola and vice versa. The constructed concept model of control surfaces has been tested for different aircraft shapes and layout. The simulation has been done in Dymola for the control surfaces.
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Fabbiane, Nicolò. "Adaptive and model-based control in laminar boundary-layer flows." Licentiate thesis, KTH, Mekanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154052.
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In boundary-layer flows it is possible to reduce the friction drag by breaking the path from laminar to turbulent state. In low turbulence environments, the laminar-to-turbulent transition is dominated by local flow instabilities – Tollmien-Schlichting (TS) waves – that exponentially grows while being con- vected by the flow and, eventually, lead to transition. Hence, by attenuating these disturbances via localised forcing in the flow it is possible to delay farther downstream the onset of turbulence and reduce the friction drag. Reactive control techniques are widely investigated to this end. The aim of this work is to compare model-based and adaptive control techniques and show how the adaptivity is crucial to control TS-waves in real applications. The control design consists in (i) choosing sensors and actuators and (ii) designing the system responsible to process on-line the measurement signals in order to compute an appropriate forcing by the actuators. This system, called compen- sator, can be static or adaptive, depending on the possibility of self-adjusting its response to unmodelled flow dynamics. A Linear Quadratic Gaussian (LQG) regulator is chosen as representative of static controllers. Direct numerical simulations of the flow are performed to provide a model for the compensator design and test its performance. An adaptive Filtered-X Least-Mean-Squares (FXLMS) compensator is also designed for the same flow case and its per- formance is compared to the model-based compensator via simulations and experiments. Although the LQG regulator behaves better at design conditions, it lacks robustness to small flow variations. On the other hand, the FXLMS compensator proved to be able to adapt its response to overcome the varied conditions and perform an adequate control action. It is thus found that an adaptive control technique is more suitable to delay the laminar-to-turbulent transition in situations where an accurate model of the flow is not available.I det tunna gränsskikt som uppstår en yta, kan friktionen minskas genom att förhindra omslag från ett laminärt till ett turbulent flöde. När turbulensnivån är låg i omgivningen, domineras till en början omslaget av lokala instabiliteter (Tollmien-Schlichting (TS) v ågor) som växer i en exponentiell takt samtidigt som de propagerar nedströms. Därför, kan man förskjuta omslaget genom att dämpa TS vågors tillväxt i ett gränsskikt och därmed minska friktionen.Med detta mål i sikte, tillämpas och jämförs två reglertekniska metoder, nämligen en adaptiv signalbaserad metod och en statiskt modellbaserad metod. Vi visar att adaptivitet är av avgörande betydelse för att kunna dämpa TS vågor i en verklig miljö. Den reglertekniska konstruktionen består av val av givare och aktuatorer samt att bestämma det system som behandlar mätsignaler (on- line) för beräkning av en lämplig signal till aktuatorer. Detta system, som kallas för en kompensator, kan vara antingen statisk eller adaptiv, beroende på om det har möjlighet till att anpassa sig till omgivningen. En så kallad linjär regulator (LQG), som representerar den statiska kompensator, har tagits fram med hjälp av numeriska simuleringar of strömningsfältet. Denna kompensator jämförs med en adaptiv regulator som kallas för Filtered-X Least-Mean-Squares (FXLMS) både experimentellt och numeriskt. Det visar sig att LQG regulatorn har en bättre prestanda än FXLMS för de parametrar som den var framtagen för, men brister i robusthet. FXLMS å andra sidan, anpassar sig till icke- modellerade störningar och variationer, och kan därmed hålla en god och jämn prestanda.Man kan därmed dra slutsaten att adaptiva regulatorer är mer lämpliga för att förhala omslaget fr ån laminär till turbulent strömning i situationer då en exakt modell av fysiken saknas.
QC 20141020
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Marzette, Russell K. Jr. "A Feasibility Study of Thin-Shell Deformable Mirrors with Adaptive Truss Support for Spaced-Based Telescopes." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/16214.
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Space-based telescopes are limit by the payload requirements of existing launch vehicles. Thus, despite distinct advantages the resolution of terrestrial telescopes exceeds space-based telescopes due to larger size and powerful adaptive optics. To overcome payload limitations, a primary mirror technology that is lighter in weight, but no less effective, is required. As this will result in new structural conditions, new approaches to maintaining the optical shape (figure) of the mirror will also be required.
This thesis culminates work at the Georgia Institute of Technology in modelling a hexagonal thin-shell deformation mirror manipulated by an adaptive truss. This research specifically examines the feasibility of a surface parallel actuated (SPA) thin-shell CuZr deformable mirror (DM) as an alternative to a typical surface normal actuated (SNA) based mirror. It is believed that by using a thin-shell mirror (100 m or less in thickness) with a light weight substrate, such as a truss, that a significant weight-savings will occur, thus enabling larger space based telescopes.
This thesis advances the SPA DM concept by 1) creating a representative model, 2) developing design evaluation methods, 3) evaluating the FEA simulated response of the deformable mirror over Zernike error modes, 4) evaluating the FEA simulated response to select thermal loads, and 5) evaluating the ability of the DM to remove thermal error, and the forces required to do so. Finally, it is concluded that overall the SPA DM concept is feasible.
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Liu, Xingxing. "Contribution to optical wireless multi-stable micro-actuation." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2214/document.
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Cette thèse traite le sujet du micro-actionnement multistable employant des radiations optiques pour atteindre les différentes positions offertes par le micro-actionneur. Dans le cadre des travaux réalisés, un mécanisme bistable reposant sur un principe de doubles poutres préformées situées en position antagoniste est proposé, et, sur cette brique élémentaire, un micro-actionneur quadristable a été conçu. Afin de valider le principe de fonctionnement de micro-actionneur, des procédés de fabrication Laser (sur le matériau « médium - MDF») puis DRIE (sur un wafer SOI de silicium) ont été utilisés. Sur le prototype en silicium, permettant une réduction des courses du rang interne et du rang externe du micro-actionneur, celles-ci ont été fixées à 300 µm et 200 µm respectivement. L’actionnement à distance de ce micro-actionneur a été prouvé en utilisant le chauffage laser d’un élément actif en Nitinol structuré par un dépôt de SiO2, ceci générant un effet « deux sens » de l’élément actif permettant d’annuler la charge sur les poutres du micro-actionneur une fois celui-ci déclenché puis en position stable. L’utilisation d’un banc expérimental incluant une membrane MEMS de balayage laser a permis de démontrer la quadristabilité du micro-actionneur sur 90 000 cycles. Afin de réduire davantage la course de ce micro-actionneur, des concepts de dispositifs de réduction de course ont été développés pour démontrer, à partir de prototypes fabriqué en MDF par usinage laser, la capacité à atteindre une course de 1 µm. Enfin, à la suite de ces travaux de réduction de course, un concept de nano-actionneur multistable a été proposé. Ce nano-actionneur est composé de quatre modules bistables liés et disposés en parallèle pour offrir 16 positions discrètes sur une course rectiligne. Les simulations de cet actionneur montrent la possibilité d’atteindre les 15 positions espacées de 10 nm sur une course de 150 nmIn this work, a bistable mechanism based on antagonistic pre-shaped double beams was proposed. Employing the proposed bistable mechanism, a quadristable micro-actuator was designed. ln order to validate the quadristability of the device, a meso-scaled prototype was fabricated from MDF by laser cutting. After the quadristability was experimentally confirmed, a quadristable micro-actuator was realized on SOl wafer using DRIE technique. Strokes for inner row and outer row were reduced to 300 µm and 200 µm respectively. For the actuation of the quadristable micro-actuator,laser heated SMA elements with deposited Si02 layer were used to realize the optical wireless actuation. With the help of a laser beam steering micro-mirror, both inner row and outer row were successfully actuated. ln order to further reduce the stroke, a bistable actuator with stroke reducing structure was designed and a prototype eut from MDF was tested. Bistability was validated and a stroke of 1µm was experimentally achieved. Based on this bistable module, a multistable nano-actuator, which contains four parallel coupled bistable modules,was designed and simulated. The simulated result have indicated that it was capable of outputs 16 discrete stable positions available from 0 nm to 150 nm with a step of 10 nm between two stable positions
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Debien, Antoine. "Étude électromécanique et optimisation d'actionneurs plasmas à décharge à barrièrediélectrique – Application au contrôle de décollement sur un profil d'aile de type NACA0015." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2253/document.
Full textAbstract:
Cette thèse est effectuée dans le cadre du projet Européen "PlasmAero" dont le but est de développer et d'étudier des actionneurs plasmas, et de démontrer leur capacité à contrôler des écoulements aérodynamiques. L'actionneur plasma à Décharge à Barrière Diélectrique (DBD) de surface est un moyen innovant pour contrôler un écoulement en utilisant le vent électrique induit par la force électrohydrodynamique (EHD) générée au sein du gaz ionisé. Une première partie est dédiée à l'étude des actionneurs plasmas. L'influence de la géométrie de l'électrode active d'une DBD est précisée par des mesures électriques, optiques et mécaniques. Les régimes de la décharge de surface peuvent être totalement modifiés, tout commel'évolution de la force EHD en fonction du temps, calculée ici par bilan intégral. Une géométrie optimisée permet de supprimer le régime de décharge streamer et d'augmenter l'efficacité de l'actionneur de 0,65 à 0,97 mN/W. De plus, des configurations à multi-électrodes (sliding discharge et multi-DBD) sont étudiées et développées. Une multi-DBD à potentiels alternés a permis d'obtenir un vent électrique record de 10,5 m/s.L'étude du contrôle d'un écoulement décollé à mi-corde ou en bord de fuite sur l'extrados d'un profil NACA 0015 fait l'objet de la seconde partie de la thèse. Une DBD standard à deux électrodes, une multi-DBD à six électrodes et une DBD de type "nanoseconde" sont utilisées pour agir sur une séparation à des nombres de Reynolds atteignant 1,3μ106, avec une transition naturelle ou déclenchée. Les résultats démontrent que le contrôle permet de repousser efficacement la séparation, améliorant ainsi les performances aérodynamiques du profilThis work is conducted in the framework of the European PlasmAero project that aims to demonstrate how plasma actuators can be used to control aircraft aerodynamic. Surface Dielectric Barrier Discharge (DBD) is an innovative solution to control a flow with the electric wind induced by the electrohydrodynamic (EHD) force produced by a surface discharge. A first part is dedicated to plasma actuators study. The exposed electrode shape of a DBD actuator is investigated by electrical, optical and mechanical characterization. Discharges properties and EHD force evolution is fully dependent of exposed electrode shape. With an optimized active electrode shape, streamer discharge is cancelled while actuator effectiveness is increased from 0.65 to 0.97 mN/W. Flow field induced by multiple electrode design is also investigated. An innovative multi-DBD design is proposed. Inhibition of mutual interaction between successive DBD actuators and exposed electrode shape optimization conduct to an electric wind velocity of 10.5 m/s. In a second part, the control of boundary layer separation on a NACA 0015 airfoil is investigated. An ac DBD, a multi-DBD and a nanosecond DBD are used to manipulate separation at a Reynolds number Re = 1.3μ106, with tripped and natural boundary layer. Results show that actuators can effectively remove the separation existing without actuation
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Liao, Tingsin, and 廖挺欣. "Fabrication of Micro Actuators by Metal-Based Surface Micromachining." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/43984291042030181394.
Full textAbstract:
碩士國立交通大學
機械工程系
90
Here, a metal-based surface micromachining technology is developed to realize two micro actuators, long-stretch micro drives and vertical comb drives, which includes lithography, sacrificial layer, and electroplating technique. Long-stretch micro drives with compact size are fabricated and tested to provide large displacements at low input voltage. The micro drives are electro-thermally driven, and fabricated through Ni electroplating process. The fabricated LSMDs have connected cascaded structures in parallel arrangement. The typical dimension is about 2000 µm x 300 µm in area. Experimental data show that the maximum displacement can reach about 202 µm at 3 volts, and the corresponding power consumption is 300 mW. The dynamic measurement shows that the LSMD can maintain its maximum displacement until 110-120Hz, and reaches the DC mode with frequency up to 3.8-4k Hz. Finally, the LSMD is proven to operate over 2 x 107 times without damage. The vertical comb drives is electrostatically driven by means of two interdigitated-comb structures, one fixed at the surface of the substrate, the other suspended by torsion beams. It is expected to have larger displacements than that of conventional parallel-plate actuators. Metal-based surface micromachining technology can fabricate VCDs without any assembly process. The gap thickness between upper and lower fingers can be simply made identical by electroplating. Thus the misalignment can be avoided. However, in final removal of seed layer, the lower fingers are attacked by acids, thus cannot stand over the substrate.
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Jin, Congrui. "Electromechanical Behaviour of Surface-Bonded Piezoelectric Sensors/Actuators with Imperfect Adhesive Layers." Master's thesis, 2009. http://hdl.handle.net/10048/546.
Full textAbstract:
The performance of smart structures depends on the electromechanical behaviour of piezoelectric sensors/actuators and the bonding condition along the interface, which connects the sensor/actuator
and the host structures. This thesis documents a theoretical study
of the influence of material parameters of the imperfect bonding
layer on the coupled electromechanical characteristics of piezoelectric sensors/actuators. A one dimensional sensor/actuator model
with an imperfect bonding layer, which undergoes a shear deformation, is proposed. The emphasis of the current study is on the local
stress and strain fields near imperfectly bonded sensors/actuators
and the load transfer. Analytical solutions based on the integral
equation method are provided. Detailed numerical simulation is
conducted to evaluate the influence of the geometry and the material mismatch of the adhesive layer upon the sensing/actuating process. The interfacial debonding and its effect upon the strain/stress
distribution and the overall performance of the integrated structure
are evaluated in detail.
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Yeh, Tien-Hsiao, and 葉天嘯. "The Stress and Deflection Analysis of The Beam and Plate Induced by The Surface Bonded or Embedded Piezoelectric Actuators." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/13177467605346907515.
Full textAbstract:
碩士元智大學
機械工程學系
96
In this investigation, the normal force and bending moment induced by the surface bonded or embedded piezoelectric actuators on the beam and plate are derived basing on the Euler beam theory. The effects of material property and thickness on the stress distribution are examined through a parametric study. The flexural deflection of a simply supported plate subjected to the bending moment is derived basing on the plate theory. The deflection is validated with the 3-D finite element results. Several examples are presented to demonstrate the capability of using the piezoelectric actuators to control the deformed shape of the plate.
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Lin, Shiao Hong, and 林曉宏. "Surface Micromachined Vertically Driven Actuator." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/33465937842417550353.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
85
A vertically driven microactuator by using thermal forces is described. The device is suspended about 2um above the substrate. It consists of a rectangular thin plate（300um×300um ×2um ）and two Z shape beams. The microactuator has been built by using a surface mcromachining technology.d The process include four masks. Those are V groove, anchor, structure and resistors. Several thin film depositions and need including LPCVD silicon nitride, undoped polysilicon and APCVD silicon dioxide. Other micromachining processes such lithography, dry and wet etching have all been utilized to fabricate these microactuators. The microactuator has achieved vertical movement of 50um under an input current of 50mA at 15 Volts. It has been demonstrated to lift up a copper with diameter of 330um and length of 760um under an input voltage of 9 Volts. The equivalent vertical force is 5.7uN. Compared with the traditional actuator actuated by the electrostatic force, the actuator presented in this report has larger vertical displacement (50um ) and requires smaller driving voltage (15V ) while the whole structure is made of a single layer.
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Chen, Ting Hsuan, and 陳定璿. "Micro Droplet Actuator Driven by Dynamic Surface Roughness Effect." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/31811472471982533444.
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Wang, Yang-Jr, and 翁揚智. "A feasibility study of miniaturized surface acoustic wave actuator to drive optical lens." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/v5s8va.
Full textAbstract:
碩士國立中興大學
機械工程學系所
99
The cell phone market request the new cell phone become smaller, so the cell phone designer restrict every component’s volume which inside the cell phone. The main stream of auto-focus actuator of cell phone is voice coil motor (VCM). But the output force of VCM will decrease proportionally when it was miniaturized. The paper introduces the surface acoustic wave (SAW) motor to satisfy the auto-focus function of smaller cell phone. The output force of SAW motor can be expected by simulation model. But the important parameter called normal displacement amplitude of surface particle can be found only by laser Doppler vibrometer. The paper can be separate into two parts. The first, use coupling of model (COM) and finite element method (FEM) to obtain the parameter which is 25.5nm and 40.3nm. The second, taking the result into the simulation model to discuss the relationship between inter digital transducer type, applied voltage, stator size, slider size, projection geometry and the SAW motor output force. The paper contributes a consultation to SAW motor designer.
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ZHAO, SHI-HONG, and 趙世宏. "On the actuator dynamics and structural vibration of flight-vehicle control surfaces." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/21253021306230964814.
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Yang, Tsung Hsun, and 楊宗勳. "Distributed Adaptive Dynamic Surface Formation Controller Design for Multi-Robots System under Partial Loss of Actuator Effectiveness." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/41933256154407176101.
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Lin, Jun-hong, and 林俊宏. "Fabrication of Surfaced Micromachined Driven Actuator and Improvement of Fabrication Process of Hemispherical Polysilicon Shells." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/42322575951909521762.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
87
Abstract This thesis includes two parts : one is the fabrication of micro-actuators and the other is the improvement of the fabrication process of hemispherical polysilicon shells. In the aspect of micro-actuators , we design the fabrication process of only one mask by the rules simple and economically. The micro-actuator is consisted of the beams of 175μm long with an angle of 156 degrees. The micro-actuator has achieved vertical movement of 5μm and horizontal movement of 3μm under an input current 33.6 mA at 8.9 Volts. Its ability to lift up a copper with 0.76 μN weight has been demonstrated. Compared with the traditional actuators actuated by the electrostatic force , the actuator presented in this report has larger driving force and requires smaller driving voltage . In the second part , regarding to the fabrication process of the hemispherical polysilicon shells , we solve the problem of the over etching of alignment key in the isotropic etching process and find out two prescriptions of isotropic etching with nice isotropy and improve the phenomenon of rough surface of the hemispherical hole .
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Karpenko, Mark. "Fault tolerant control design for an electrohydraulic actuator with application to positioning of aircraft flight control surfaces." 2002. http://hdl.handle.net/1993/19645.
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