Dissertations / Theses on the topic 'Actuating'
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Bernier, Jobe Paul. "Entropy and Architecture entropic phenomena actuating dynamic space /." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/bernier/BernierJ0508.pdf.
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Kwok, Christopher (Christopher L. ). "Exploring and evaluating methods of actuating an active lens." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105694.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (page 24).
Active lenses today have a variety of uses from photographic capabilities in small mobile devices to applications in engineering. They provide faster response times and higher portability and efficiency when compared to their traditional lens assemblies. For this project, I have evaluated two different methods of active lens actuation: using an electromagnetic actuator and using an electroactive polymer. From testing each method's abilities, it was found that the electromagnetic actuator, though robust in design poses issues over long-time use. The electromagnetic actuator was able to generate a focal power range of 11.9 to 19.2 diopters (52 to 84mm focal length range), but a high power consumption led to problems with heating the internal components of the active lens assembly. In the EAP method, a lower power consumption proved to be a viable option for actuation, and through testing and calculation, it was determined to be useful in application. However, a proposed efficient design must be further explored.
by Christopher Kwok.
S.B.
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Johnson, Roger Warren. "Design and development of a three link in-parallel actuating prototype manipulator." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/15961.
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McMahon, Michael. "A novel accelerated life cycle methodology for actuating MEMS membranes via mechanical contact : innovation report." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/45946/.
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In the emerging technology of Micro Electronic Mechanical Systems (MEMS) there are challenges such as adoption, economies of scale, packaging and reliability incurred by many nascent technologies. The advantages of MEMS devices such as small micron scale, low power consumption and lab on a chip style data processing clearly outline the practical potential for the technology. Packaging and reliability driven by cost, however; are the factors that hinder progress of the technology and further entry into market. In the case of MEMS however, existing methods must be reassessed as fundamentally the concepts and scales have changed. MEMS is a market that despite challenges of the economy is still committed to heavy global investment from figures of $7bn in 2009 with 13% growth in 2010 with a projected growth rate of 14-15% over the years 2011 – 2015. (Dempsey, 2010) Reliability in essence holds the key to driving down the unit cost of production and technology adoption; if units are more reliable there is a potential for increased sales, further refinement and development as the case with mobile phones and the automotive industry. Thus the aim of this project is to create and apply a methodology of assessing the reliability of MEMS components. This research project focused on using a scientific based research methodology, conventional metrology and engineering techniques to produce a method of predicting lifetime information for a particular device component. A broad selection of experimental techniques were assessed and deemed unsuitable, primarily due to inflicting unnecessary damage of the fragile structures, range restrictions on forces that could be loaded and availability of equipment. Following laboratory work and iterative refinement, a successful methodology was created and refined; allowing to mechanically actuate a MEMS membrane to high cycle fatigue failure without damage due to contact force. This used with the bulge test can provide information on new MEMS composites and how they behave as realistically as possible in their future application space. Working closely with QinetiQ and an international collaboration funded by the European Defence Agency (EDA), on a broader MEMS reliability project called POLYNOE; it is now possible to achieve lifetime information for MEMS membranes and use the created experimental technique to cater for any micron sized membrane for any duration at a cycle rate not known or explored in this domain before. Characterisation data, of the membrane and thin film with substrate structure was obtained and using traditional Finite Element Analysis (FEA) and Accelerated Life Cycle Prediction techniques the stresses incurred and Mean Times to Failures (MTTF) for the membranes was calculated as 32million cycles at a comparative operating force of 0.14mN. Suggestions have been made at the possibilities of implementing the methodology and techniques at QinetiQ; to complement their traditional low cycle method of stressing the membranes and therefore iterate the useful information back into the development cycle to refine designs increase reliability and therefore reduce unit cost.
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Marett, Josh Michael. "The Isolation of Cellulose Nanocrystals from Pistachio Shells and Their Use in Water Actuating Smart Composites." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78902.
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Composites are a category of materials where two or more materials are used
together to enhance each of their strengths. Such materials are often used in airplanes,
spacecraft, sporting equipment, and many high-end products. Cellulose nanocrystals
(CNCs) have been research with the goal of improving the environmental sustainability
and performance of composite materials. This newly utilized material is found in plants
and some animals to provide them with their strength. Researches have already shown
that CNCs can improve the performance of many materials while reducing their lifetime
environmental impact. In order to increase the market for CNCs, we are looking at costreducing
methods of producing them as well as finding exciting new uses for them once
they are made.
Right now, most CNCs are isolated from wood or cotton, which already have
existing markets. This thesis presents a method of using pistachio shells, which are a
waste product in many parts of the world including the United States. By finding new
sources of CNCs, we hope to add to the body of knowledge and reduce the price of CNC
production.
This thesis also lays the groundwork for a material that changes shape when
exposed to water. By integrating CNCs into only part of a polymer, when water is added,
the part with the CNCs will increase in size, causing it to push on the polymer. Our hope
is to create a new use for CNC composites to help to increase the market for them. We
discuss potential methods and proofs of concept on how to create a 3D-printed part using CNCs and polyurethane.Master of Science
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Meisel, Nicholas Alexander. "Design for Additive Manufacturing Considerations for Self-Actuating Compliant Mechanisms Created via Multi-Material PolyJet 3D Printing." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/54033.
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The work herein is, in part, motivated by the idea of creating optimized, actuating structures using additive manufacturing processes (AM). By developing a consistent, repeatable method for designing and manufacturing multi-material compliant mechanisms, significant performance improvements can be seen in application, such as increased mechanism deflection. There are three distinct categories of research that contribute to this overall motivating idea: 1) investigation of an appropriate multi-material topology optimization process for multi-material jetting, 2) understanding the role that manufacturing constraints play in the fabrication of complex, optimized structures, and 3) investigation of an appropriate process for embedding actuating elements within material jetted parts. PolyJet material jetting is the focus of this dissertation research as it is one of the only AM processes capable of utilizing multiple material phases (e.g., stiff and flexible) within a single build, making it uniquely qualified for manufacturing complex, multi-material compliant mechanisms. However, there are two limitations with the PolyJet process within this context: 1) there is currently a dearth of understanding regarding both single and multi-material manufacturing constraints in the PolyJet process and 2) there is no robust embedding methodology for the in-situ embedding of foreign actuating elements within the PolyJet process. These two gaps (and how they relate to the field of compliant mechanism design) will be discussed in detail in this dissertation. Specific manufacturing constraints investigated include 1) "design for embedding" considerations, 2) removal of support material from printed parts, 3) self-supporting angle of surfaces, 4) post-process survivability of fine features, 5) minimum manufacturable feature size, and 6) material properties of digital materials with relation to feature size. The key manufacturing process and geometric design factors that influence each of these constraints are experimentally determined, as well as the quantitative limitations that each constraint imposes on design.Ph. D.
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Gorges, Stephan [Verfasser], René [Akademischer Betreuer] Theska, Christoph [Gutachter] Schäffel, and Bernd Hans [Gutachter] Schmidt. "A lifting and actuating unit for a planar nanoprecision drive system / Stephan Gorges ; Gutachter: Christoph Schäffel, Bernd Hans Schmidt ; Betreuer: René Theska." Ilmenau : TU Ilmenau, 2020. http://d-nb.info/1224416589/34.
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Úšela, Tomáš. "Revolverová hlava pro dlouhotočný automat s elektricky ovládaným indexováním." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-227980.
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Imposition of my diploma thesis is replace current fluid motor that the derive benefit from to indexing turret head behind electrically driven motor in the sliding headstock machine with indication KMX 326 C. Suggested system must be the most toughest and have to correspond with all the dated up parameters for cutting. Integral part of structural design is also becomingly select accurate blocking a turret head. Fluid motor substitutes behind electrical drive from next reasons: - high transmission loss on energy - sensitivity to cleanness liquid - characteristics mechanism depend upon features liquid ( thermal expansivity, fadeaway)
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Guiducci, Lorenzo. "Passive biomimetic actuators : the role of material architecture." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2014/7044/.
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Passive plant actuators have fascinated many researchers in the field of botany and structural biology since at least one century. Up to date, the most investigated tissue types in plant and artificial passive actuators are fibre-reinforced composites (and multilayered assemblies thereof) where stiff, almost inextensible cellulose microfibrils direct the otherwise isotropic swelling of a matrix. In addition, Nature provides examples of actuating systems based on lignified, low-swelling, cellular solids enclosing a high-swelling cellulosic phase. This is the case of the Delosperma nakurense seed capsule, in which a specialized tissue promotes the reversible opening of the capsule upon wetting. This tissue has a diamond-shaped honeycomb microstructure characterized by high geometrical anisotropy: when the cellulosic phase swells inside this constraining structure, the tissue deforms up to four times in one principal direction while maintaining its original dimension in the other.
Inspired by the example of the Delosoperma nakurense, in this thesis we analyze the role of architecture of 2D cellular solids as models for natural hygromorphs. To start off, we consider a simple fluid pressure acting in the cells and try to assess the influence of several architectural parameters onto their mechanical actuation. Since internal pressurization is a configurational type of load (that is the load direction is not fixed but it “follows” the structure as it deforms) it will result in the cellular structure acquiring a “spontaneous” shape. This shape is independent of the load but just depends on the architectural characteristics of the cells making up the structure itself. Whereas regular convex tiled cellular solids (such as hexagonal, triangular or square lattices) deform isotropically upon pressurization, we show through finite element simulations that by introducing anisotropic and non-convex, reentrant tiling large expansions can be achieved in each individual cell.
The influence of geometrical anisotropy onto the expansion behaviour of a diamond shaped honeycomb is assessed by FEM calculations and a Born lattice approximation. We found that anisotropic expansions (eigenstrains) comparable to those observed in the keels tissue of the Delosoperma nakurense are possible. In particular these depend on the relative contributions of bending and stretching of the beams building up the honeycomb.
Moreover, by varying the walls’ Young modulus E and internal pressure p we found that both the eigenstrains and 2D elastic moduli scale with the ratio p/E. Therefore the potential of these pressurized structures as soft actuators is outlined.
This approach was extended by considering several 2D cellular solids based on two types of non-convex cells. Each honeycomb is build as a lattice made of only one non-convex cell. Compared to usual honeycombs, these lattices have kinked walls between neighbouring cells which offers a hidden length scale allowing large directed deformations. By comparing the area expansion in all lattices, we were able to show that less convex cells are prone to achieve larger area expansions, but the direction in which the material expands is variable and depends on the local cell’s connectivity. This has repercussions both at the macroscopic (lattice level) and microscopic (cells level) scales. At the macroscopic scale, these non-convex lattices can experience large anisotropic (similarly to the diamond shaped honeycomb) or perfectly isotropic principal expansions, large shearing deformations or a mixed behaviour. Moreover, lattices that at the macroscopic scale expand similarly can show quite different microscopic deformation patterns that include zig-zag motions and radical changes of the initial cell shape. Depending on the lattice architecture, the microscopic deformations of the individual cells can be equal or not, so that they can build up or mutually compensate and hence give rise to the aforementioned variety of macroscopic behaviours. Interestingly, simple geometrical arguments involving the undeformed cell shape and its local connectivity enable to predict the results of the FE simulations.
Motivated by the results of the simulations, we also created experimental 3D printed models of such actuating structures. When swollen, the models undergo substantial deformation with deformation patterns qualitatively following those predicted by the simulations.
This work highlights how the internal architecture of a swellable cellular solid can lead to complex shape changes which may be useful in the fields of soft robotics or morphing structures.Passive pflanzliche Aktuatoren sind bewegliche Strukturen, die eine komplexe Bewegung ohne jegliche metabolische Energiequelle erzeugen können. Diese Fähigkeit entstammt dabei der Materialverteilung mit unterschiedlicher Quellbarkeit innerhalb der Gewebsstruktur.Die bis heute am besten untersuchten Gewebearten pflanzlicher und künstlicher Passivaktuatoren sind Faserverbundwerkstoffe, in denen steife, fast undehnbare Zellulosemikrofibrillen die ansonsten isotrope Schwellung einer Matrix leiten. Darüber hinaus gibt es in der Natur Beispiele für Aktuationssysteme, wie z.B. die Delosoperma nakurense Samenkapsel, in der das Aktuatorgewebe eine Wabenstruktur aufweist, deren Zellen mit einem hochquellenden Material gefüllt sind. Dabei hat die Wabenstruktur des Gewebes eine hohe geometrische Anisotropie, so dass sich das Gewebe bei Wasseraufnahme bis zur vierfachen Länge entlang einer Hauptrichtung ausdehnt und somit die reversible Öffnung der Kapsel angetrieben wird. Inspiriert durch das Vorbild der Delosoperma nakurense, wird in der vorliegenden Arbeit die Rolle der Architektur von 2D-Zellulärmaterialien als Modell für natürliche passive Aktuatoren analysiert. Zunächst wird anhand eines einfachen Flüssigkeitsdrucks in den Zellen der Einfluss verschiedener architektonischer Parameter auf deren mechanische Betätigung untersucht. Wohingegen regelmäßige konvexe Wabenstrukturen (wie z. B. sechseckige, dreieckige oder quadratische Gitter) sich unter Druck isotropisch verformen, wird durch Finite-Elemente-Simulationen gezeigt, dass es bei anisotropen und nicht-konvexen Zellen zu großen Ausdehnungen jeder einzelnen Zelle kommt. Auch wenn nur eine einzelne Zellgeometrie betrachtet wird, können hierbei viele verschiedene Gitter entstehen. Die Ausdehnungsrichtung des Gitters ist variabel und hängt von der lokalen Konnektivität der Zellen ab. Dies hat Auswirkungen sowohl auf makroskopischer (Gitter-) als auch auf mikroskopischer (Zell-) Ebene. Auf makroskopischer Ebene erfahren diese nicht-konvexen Gitter entweder große anisotrope (ähnlich der Delosperma nakurense Samenkapsel) oder vollkommen isotrope Eigendehnungen, große Scherverformungen oder jeweilige Mischformen. Überdies können Gitter mit ähnlichem makroskopischem Verhalten gänzlich unterschiedliche mikroskopische Verformungsmuster zeigen, wie z.B. Zick-Zack-Bewegungen oder radikale Änderungen der ursprünglichen Zellform. Dies verursacht auch eine entsprechende Änderung der elastischen Eigenschaften. In Abhängigkeit der Gitterarchitektur kann es zu gleichen oder unterschiedlichen mikroskopischen Zelldeformationen kommen, die sich in Summe entweder verstärken oder ausgleichen, und somit die Vielzahl an makroskopischen Verhalten erklären. Interessanterweise lassen sich mit Hilfe einfacher geometrischer Argumente aus der nichtdeformierten Zellform und Zellkonnektivität die Ergebnisse der FE-Simulationen vorhersagen. Die Ergebnisse der Finite-Elemente-Simulationen wurden durch Laborversuche bestätigt, in denen (mit 3D-Drucktechnik gefertigte) Modellgitter ähnliches Ausdehnungsverhalten beim Quellen zeigen. Diese Arbeit zeigt auf, wie die Innenarchitektur eines quellfähigen zellulären Feststoffs zu komplexen Formänderungen führen kann, die in den Bereichen der Soft-Robotik oder bei Morphing-Strukturen angewandt werden können.
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Wenzel, Ute Verfasser], Ivo W. [Akademischer Betreuer] [Rangelow, D. Frank [Akademischer Betreuer] Ogletree, and Teodor P. [Akademischer Betreuer] Gotszalk. "Fabrication and characterization of self-sensing and self-actuating piezoresistive microscale silicon cantilevers for an integrated scanning probe microscopy and scanning electron microscopy system / Ute Wenzel. Gutachter: D. Frank Ogletree ; Teodor P. Gotszalk. Betreuer: Ivo W. Rangelow." Ilmenau : Universitätsbibliothek Ilmenau, 2013. http://d-nb.info/1034527770/34.
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Iamratanakul, Dhanakorn. "Pre-actuation and post-actuation in control applications /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/9968.
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Rocco, Pete Angelo. "Actuation training and its effects on actuation fatigue of Nitinol Shape Memory Wires." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1564737605232559.
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McEwan, William Thomas. "Periodic actuation of vortex generators." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485005.
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The basis of this research is the augmentation of turbulent boundary layer stability. Here stability is referred to as ,the boundary layer's ability to withstand adverse pressure gradient and therefore separation. A practical example of an' issue involving a requirement for greater stability, where separation is a typical and detrimental feature, would be a deployed flap during a critical regime of the flight envelope such as landing. A sub-boundary layer vortex generator (SBVG) is a static flow control device which does not carry the drag penalty of its traditional larger counterparts. It is however less effective. An excited SBVG may be more effective than a static model, in terms of enhancement of stability, with the added benefit of not requiring sophisticated feedback systems to prevent the device from generating detrimental effects during periods other than the flight regime for which it is intended to operate, since the SBVG is embedded within the boundary layer. Here an SBVG was oscillated (or swept) between three inclination ranges at a number of frequencies. The swept inclination ranges were 16° to 24°, 20° to 28° and 24° to 32°. These motions were executed at reduced frequencies of 0.1,0.6, 1.6,3.1,4.7, and 6.3. The data show that dynamic actuation of a sub-boundary layer vortex generator results in a weaker vortex with accelerated decay than is generated by a static vortex generator at equivalent incidence. The strength and persistence of the dynamically generated vortex is closely linked with the reduced frequency, in that increase in frequency results in an increasingly weak vortex with an increasing rate of decay.
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Gomez, Teresa M. "Binary actuation of solar mirrors." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68528.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 42).
This thesis explores the use of binary actuators to adjust the shape of an array of mirrors. To explore this concept, an experimental system was refurbished and recalibrated. This experimental system was used to explore the range of possible configurations that could be reached by a simple binary actuated system. System models are required for accurate control of these binary actuated structures. This thesis develops and tests the accuracy of two different modeling approaches, linear and iterative. The linear model assumes that each actuator contributes a constant value to the angle of the center mirror, and that this value is not dependent on the other actuator positions. The actuator contributions are summed to find the angle of the center mirror. These contributions are found two ways: by taking a relevant single data point for each actuator, and by using a least squares fitting of a large subset of data. The iterative model assumes that each actuator adds some constant value, similar to the previous model, and that it also adds some portion of the current angle. A multiplication and shift are therefore found for each actuator, and these multiplications and shifts successively applied, starting with the initial angles, to find the final angular position. While the linear model with measured values for the actuator contributions predicted the data poorly, the linear model with the least squares fitted values performed much better. The iterative model initially produced large errors, but these errors were found to be readily correctable and once removed, the iterative model predicted the data better than the linear model.
by Teresa M. Gomez.
S.B.
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Ahir, Samit Vallabhbhai. "Nanotube-polymer actuation & relaxation." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612763.
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Lauback, Stephanie Diane. "Magnetic Actuation of Biological Systems." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1494262695434601.
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Gustavsson, Sofie, and Anders Carlsson. "Electric Actuation of Controllable Pitch Propellers." Thesis, Karlstad University, Faculty of Technology and Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-3771.
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This bachelor’s degree project has been conducted at the Innovation and Design Engineering programme at Karlstad University and responds to 22.5 ETCS credits. The project has been carried out in co-operation with Rolls-Royce AB in Kristinehamn.
Based upon a virtual order concerning a super yacht the objective has been to develop a controllable pitch propeller that is adjusted using electro mechanics, to eliminate the use of hydraulic oils and thus the risk of leakage to the seawater.
The pre-study consisted of the two first phases of QFD-analysis (Quality Function Deployment). The first phase consists of gathering customer requirements. Representatives from different functions within Rolls-Royce AB were interviewed, as representatives for the customer. The demands they presented were used to find product features and functionalities.
The results were put together in two Houses of Quality. The first house shows the relations between requirements and features/functionalities and their respective relevance in correlation to each other. House of Quality two describes the relations between features/functionalities and design solutions in a similar way.
Based upon the QFD-analysis, a specification was generated to be used as guidance to generate ideas of how to solve the problem. A number of brainstorming methods were used and students from Karlstad University and Rolls-Royce AB participated in those sessions. Overall, some twenty ideas were gathered and five of those were considered feasible concepts.
For further development, two of those concepts were chosen, using relative and weighted decision matrixes. This development consisted of solid modelling, based on current propeller arrangement designs, and stress calculations of the new parts of the system.
Both concepts consist of an electrical engine, powering a trapezoid screw, which moves the crosshead. In Concept 1, the screw is mounted directly into the crosshead while in Concept 2; a push rod is used to transmit the motion. Both concepts appeared to meet up to the objectives, though Concept 1 fulfilled more demands and to a greater extent.
For further development of this product, customer inquiries with closer customer contacts need to be conducted. It will also be necessary to contact the concerned classing societies, since current classification rules not can be applied to electromechanically controlled propellers.
Detta examensarbete har utförts för examen på Innovations- och designingenjörsprogrammet vid Karlstads universitet och motsvarar 22,5 hp. Projektet har genomförts tillsammans med Rolls-Royce AB i Kristinehamn.
Baserad på en virtuell order på en superyacht har målet varit att utveckla en justerbar propeller som regleras helt med elektromekanik. Detta för att eliminera användandet av hydraulolja och därmed risken för läckage till havsvattnet.
Förstudien har bestått av de två första faserna av QFD-studie (Quality Function Deployment). Den första fasen består av insamlande av kundernas önskemål. Olika representanter inom företaget, som fått representera slutkunden, intervjuades och de önskemål som kom fram användes för att hitta produktegenskaper och funktioner.
Resultaten sammanställdes i två kvalitetshus (House of Quality). Det första visar förhållandet mellan önskemål och egenskaper/funktioner samt deras respektive relevans i förhållande till varandra. Hus två beskriver på samma sätt förhållandet mellan egenskaper/funktioner och konstruktionslösningar.
Utifrån QFD-studien sammanställdes en specifikation som användes som mall för att generera idéer kring lösningen av problemet. Ett antal olika kreativitetsmetoder användes och studenter från Karlstads universitet samt anställda från Rolls-Royce AB deltog i sessionerna. Totalt togs ett tjugotal idéer fram och fem av dessa bedömdes vara genomförbara koncept.
Två av koncepten valdes ut, med hjälp av en relativ viktad kriterievalsmatris, för att utvecklas vidare. Utvecklingen bestod i att göra solidmodeller, baserat på de befintliga delarna i propellerarrangemanget, samt hållfasthetsberäkningar av de nya delar som kom att ingå i systemet.
Båda koncepten bygger på att en trapetsgängad skruv, driven av en elmotor, förflyttar kolvstångshuvudet. I koncept 1 är skruven monterad direkt i detta och i koncept 2 överförs rörelsen via en tryckstång. Båda koncepten föreföll sig lösa det uppsatta problemet även om koncept 1 visade sig uppfylla fler önskemål och i högre utsträckning.
För att komma vidare med produkten bör kundundersökningar med närmare kontakter till kunden genomföras. Det är också nödvändigt att kontakta berörda klassningssällskap, då dagens klassningsregler ej kan appliceras på elektromekaniska propellrar.
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Miller, Adam Cole. "Flow control via synthetic jet actuation." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1409.
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An experimental investigation was undertaken to determine the ability of Synthetic Jet
Actuators to control the aerodynamic properties of a wing. The Synthetic Jet Actuator
(SJA) was placed at two separate positions on a wing comprised of a NACA0015 airfoil.
The first of the jet positions is located at 12% of the chord, hereby referred to as the
leading edge Synthetic Jet Actuator. The second exit position is located at 99% chord of
an airfoil and hereby is referred to as the trailing edge Synthetic Jet Actuator. The two
locations produced different benefits as the angle of attack of the wing was increased.
The leading edge Synthetic Jet Actuator delayed the onset of stall of an airfoil,
suppressing stall up to 25 degrees angle of attack. The control of the aerodynamic
characteristics was achieved by influencing the amount of the separated flowfield region.
The effects of the dynamic stall vortex were investigated with wind tunnel testing during
the pitching motion of an airfoil to determine how the flow reacts dynamically.
The trailing edge synthetic jet actuator was investigated as a form of low angle hingeless
control. The study investigated the effect of the jet momentum coefficient on the
ability of the synthetic jet to modify the lifting and pitching moment produced from the
wind tunnel model. The data indicates that, with the present implementation, the SJA-jet
flap generates moderate lift and moment coefficient increments that should be suitable
for hinge- less control. It was also shown that, for the current experimental setup and a
given jet momentum coefficient, continuous blowing is more effective than oscillatory
blowing/sucking. The data shows that combining the SJA with a Gurney flap does not
result in performance enhancement.
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Gilson, Gareth M. "Cooling of advanced aircraft actuation systems." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12568/.
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Electrical machines for aerospace applications often operate close to the allowable thermal limits due to high power density requirements. The power density of electrical machines is generally dependent on the machine and thermal management design. At flight level, a reduced pressure exists which in turn results in more challenging thermal management. Aerospace electric machine manufacturers are often limited with respect to the implemented cooling mechanisms. That is, natural convection systems are the norm, as fan cooled and fluid cooled machines may suffer from reliability issues. The original contribution of this work, is the design, testing, and implementation of an alternative forced cooling convective system (FCCS) based on piezoelectric fans. This thesis commences by an investigation of the capabilities of MotorCAD (a sophisticated analytical lumped thermal package) and how it can be utilised in a fully integrated way to optimise (for a maximum power density and an overall minimum motor mass) both the electromagnetic and thermal aspects of a typical traditional horizontally-mounted permanent magnet synchronous machine (PMSM) operating at flight level. The resultant analytical temperature values were then compared to actual experimental temperature data. Piezoelectric fans are then investigated as a potential, fault tolerant FCCS that may enhance the overall cooling of a motor. These fans could be implemented in the aerospace industry as they do not suffer from the same reliability issues as traditional FFCS’s. Detailed thermal results indicating the effective piezoelectric fan cooling range together with the overall cooling effectiveness over a traditional vertical straight-finned heat sink (unit – cell) , operating under different operating conditions are also presented. Furthermore, the fin/fan geometry that minimises the thermal resistance whilst minimising the overall cooling mass is presented. Particle Image Velocimetry (PIV) techniques were implemented to further understand the flow fields generated by an oscillating piezoelectric fan. Common parameters governing the fluid flow (vibration amplitude, separation distance, fin spacing and fan orientation) were investigated and the results are herewith presented. Designs of a supporting structure for the proposed FCCS implementation are drawn up and analysed through FEA. A prototype structure was built and its durability tested. Furthermore, the reliability (fault tolerance) of the suggested FCCS was evaluated. The feasibility of implementing this innovative cooling technique was further investigated by performing a study on the weight saving potential of the FCCS over traditional natural convective fins, and the FCCS geometry that minimises the thermal resistance whilst minimising the overall mass is selected. Furthermore, a prototype FCCS was built and tested.
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Lazarus, Kenneth B. "Induced strain actuation of composite plates." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/41235.
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Bent, Aaron Alton. "Piezoelectric fiber composites for structural actuation." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12322.
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Bent, Aaron Alton. "Active fiber composites for structural actuation." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10254.
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Leung, Anthony Chi Hin. "Actuation properties of kagome lattice structures." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613328.
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Li, Wei. "More Electric Landing Gear Actuation Study." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/9589.
Full textAbstract:
This report addresses the problem of landing gear actuation system design on
more-electric aircraft (MEA).
Firstly, information about more-electric aircraft and more-electric actuators was
gathered and sorted. Current more-electric landing actuation system applications and
researches were also summarized. Then several possible more-electric landing gear
actuation concepts were identified. To evaluate these concepts, the case study method
has been used. A concept aircraft “MRT7-T”, which has similar maximum takeoff
weight to that of Boeing 787, has been chosen as the design case. Systems of different
configurations and architectures were designed for this aircraft. In the end of this
study, a comparison between different more-electric landing gear actuation systems,
and also with traditional central hydraulic system was made. The best concept was
proposed.
More-electric actuation technology has made considerable progress in the last two
decades. However, most of the applications and researches have focused on flight
control actuation and brakes. Using more-electric drives for landing gear actuation has
been well known to be difficult, for the reason of massive power needs and difficulties
in achieving redundancy levels. Famous more-electric research projects like POA and
Power-By-Wire only gave recommendation of using electro-hydrostatic actuators
(EHA) in landing gear actuation. And no further information is available to the public.
In this study, DHS (distributed hydraulic system), EHA (electro-hydrostatic actuator)
and EMA (electro-mechanical actuator) were identified as candidate solutions. Design
requirements such as retraction time, load and redundancy levels were derived
through analysis. As a unique feature, landing gear kinematics concepts were also
subject to optimization. Various kinematics concepts were proposed and analyzed in
detail, to provide favorable loading and geometrical conditions for the systems.
Kinematics design guidelines were built through discussion. Different motors such as
AC induction motor, BDCM (brushless DC motor) and PMSM (permanent magnetic
synchronous motor) were evaluated for use. Different system architectures were also
explored.
The multi-discipline optimization method has been extensively used in the design
process of the systems. Firstly, each node of the actuation systems was optimized.
Then optimizations were made to the systems. Performances of each system were
analyzed in several aspects such as weight, power, reliability and maintenance.
Comparison of different systems was made through scoring method. The results
suggested that DHS, EHA and EMA are all applicable for landing gear actuation. And
isolated EHA is the best.
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O'Brien, Sean D. "Electro-osmotic actuation for micropump applications /." Online version of thesis, 2009. http://hdl.handle.net/1850/11634.
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Richardson, Robert C. "Actuation and control for robotic physiotherapy." Thesis, University of Leeds, 2001. http://etheses.whiterose.ac.uk/1534/.
Full textAbstract:
Over the last few years researchers have developed prototype robots that are capable of administering physiotherapy, however, these devices tend to be complex and expensive. The use of modem pneumatic servo systems as actuators would make such devices simpler and cheaper. This thesis assesses the feasibility of a pneumatically actuated robotic physiotherapy device through the implementation of force and position control strategies. Traditional pneumatic servo systems consist of a pneumatic cylinder prone to stiction effects and a single spool valve. Here the performance of modem pneumatic servo system, consisting of a low friction pneumatic cylinder and two electropneumatic proportional valves has been evaluated. The increased linearity of the modem pneumatic system enabled a self-tuning pole-placement controller to be implemented that would be unsuitable for conventional pneumatic systems. The selftuning pole-placement controller enabled consistent and accurate position control. Other researchers have achieved force control of pneumatic systems, however their force models are not applicable on this modem configuration. Accurate control of the servo system force output, while the position of the cylinder piston is fixed, has been achieved through an open-loop force controller, however applications for fixed position force control are limited. The servo system force output, during motion, has been found to be a function of the piston velocity and input control signal. A pneumatic robot has been designed and fabricated with a position workspace that enables the average male to perform upper limb reach and retrieve exercises when attached to the robot. The pneumatically actuated robot, combined with a simple three degree-of-freedom force sensor, form a device capable of administering upper-limb robotic physiotherapy. Impedance control has been identified as the most suitable force and position control strategy for implementing physiotherapy. Applying the impedance control strategy, to a single link of the robot, resulted in accurate implementation of the desired force and position relationship. Extending the controller to two and three degrees of freedom has resulted in degradation of the controller performance due to limitations of the three degree-offreedom force sensor. The controller performance is also found to be dependent upon selection of the impedance characteristics. Low stiffness and high damping, along with high stiffness and high damping have been identified as particular low points in controller performance due to the requirement for the system to provide large forces with little resulting motion. It was concluded that the pneumatic robot and impedance control strategy have the potential to administer physiotherapy. However, further work incorporating a force sensor with greater accuracy that is robust to torque inputs and a rigorous stability analysis would be required before the device could be clinically evaluated.
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Maldonado, Luis A. "A methodology for evaluating mine actuation data." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA311410.
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Meng, Fanliang. "Actuation system design with electrically powered actuators." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/6282.
Full textAbstract:
This project addresses the actuation system architecture of future All-electric
aircraft (AEA) with electrically powered actuators (EPA).
Firstly, the information of EPAs is reviewed, and then an electro-hydrostatic
actuator (EHA) and electro-mechanical actuator (EMA) are selected for further
system research. The actuation system architecture of Boeing and Airbus is
then presented as a conventional design where the new design concepts are
also researched and the distributed architecture was proposed as another
design trend. To find out which one is better, both of them are selected for
further research.
The easily available data makes the Flying Crane a better choice for the case
study. Stall load, maximum rate and power are the main elements for electric
actuator requirements and power consumption, weight, cost and safety are the
most important aspects for civil aircraft actuation systems.
The conventional and distributed flight actuation system design considered the
redundancy of systems and actuators, and also the relationship of the power,
control channel and actuator work mode. But only primary flight actuation
control system specifications are calculated since this data has better precision
and also the limited time has to be taken into consideration. Brief comparisons
of the two system specifications demonstrate that the higher power actuator
have has higher efficiency and distributed actuators could reduce the system
weight through reduce the system redundancy with a power efficiency decline.
The electrically powered actuation system for future aircraft design is a balance
between actuator number, system weight and power consumption.
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McKenzie, James Stuart. "Optical actuation and control-by-light systems." Thesis, Brunel University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286728.
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Syvertsen, James Michael. "Force override rate controller for remote actuation." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23905.
Full textAbstract:
Approved for public release; distribution is unlimitedMany remotely operated robotic manipulator systems are operated in rate control mode to achieve a commanded position and orientation of the end-effector. Performance of certain tasks, such as applying a torque to a screw, would be more efficient if performed in unilateral force control mode. A six axis force-torque model was developed to determine the required number and positioning of sensors and using force sensing resistors, a prototype force-torque transducer was built for testing. Using a force error signal, individual manipulator joint angles may be computed in an algorithm to achieve force replication in the end-effector.
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Yu, Tian. "Actuation and control of lower limb prostheses." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760933.
Full textAbstract:
Millions of people are suffering from lower limb loss all around the world. Passive ankle prostheses in the market cannot fully restore ankle function and will cause asymmetrical walking gaits. Several powered ankle prostheses, which provide net power in the stance phase to assist walking, have been developed by the researchers, but their walking range is significantly limited by the power requirement. In this thesis, an electrohydrostatic actuator (EHA) powered ankle prosthesis is proposed. This is intended to actively assist walking at certain points in the gait cycle, namely the plantarflexion (PF) before toe-off and dorsiflexion (DF) in the early swing phase for toe-lifting. In the rest of the gait, the ankle prosthesis actuation system can operate passively with controllable damping. This approach can increase the working time range compared to a continually powered ankle and ensure safe passive prosthetic function after the battery discharged. A prototype of the EHA powered ankle prosthesis has been developed. A 100 W brushless DC motor is used driving a 0.45 cc/rev bi-directional gear pump. The damping ratios of the ankle PF and DF are controlled by bypass restriction valves. The EHA system and the foot springs at the ankle joint weigh 2.2 kg. The controller and a 2 Ah battery are held in a backpack. Walking characteristics with a passive ankle were studied in an amputee trial to gather ankle sensor signals for the controller design. A timing control method is proposed which uses the foot spring strain gauge signals to detect heel strike. A middle stance time delay is added between the end of the heel strike and the start of the powered PF phase. This delay time length can be adjusted to fit different walking speeds. Heel strike detection using hydraulic pressure signals is also studied. The EHA powered ankle prosthesis and its controller has been tested by a 70 kg transtibial amputee. According to the amputee trial results, the EHA can provide sufficient power to assist walking in the terminal stance and the energy consumption in the passive phases are proximately zero. The on-board battery is able to power over 5500 level walking steps. In the amputee trial, the ankle prosthesis controller correctly recognises the heel strike and triggers the powered PF phase. According to feedback from the amputee, the EHA powered ankle prosthesis provided beneficial level walking assistance and a very natural walking gait. The characteristics of the powered ankle prosthesis are analysed by comparing with the healthy ankle and by testing at different walking speeds. A simulation model was developed to help analyse the performance characteristics of the EHA. This includes a brushless DC motor model and a symmetric hydraulic actuation model. The laboratory-based experiment results and amputee trial results are used to analyse and validate the simulation model. The model can be used for future development and refinement of EHA powered ankle prostheses.
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Lai, Guanyu. "Distributed actuation and control for morphing structures." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760934.
Full textAbstract:
It is believed that structures and actuation systems should be tightly integrated together in the future to create fast moving, efficient, lightweight dynamic machines. Such actuated structures could be used for morphing aircraft wings, lightweight actuated space structures, or in robotics. This requires actuators to be distributed through the structure. A tensegrity structure is a very promising candidate for this future integration due to its potentially excellent stiffness and strength-to-weight ratio, and the inherent advantage of being a multi-element structure into which actuators can be embedded. Development of these machines will utilise expertise in several fields, involving kinematics, dynamics, actuation and multi-axis motion control. The research presented in this thesis concerns the study of multi-axis actuated tensegrity structures. A form-finding method has been developed to find stable geometries and determine stiffness properties of the type of tensegrity structure proposed. It has been shown that a tensegrity structure, with practical nodes of finite size, can be designed with actuated members to give shape-changing properties while potentially allowing a good stiffness to mass ratio. An antagonistic multi-axis control scheme has been developed for the tensegrity structure. The describing function technique has been used to analyse the dead band controller in the control scheme, giving a stability criterion. An experimental actuated tensegrity system has been designed and built incorporating pneumatic muscles controlled by switching valves. Mathematical models for the experimental actuated tensegrity system have been developed in detail, including the pneumatic actuation system and the structure geometry. The dynamic behaviour of the tensegrity system has been investigated via several simulation studies, using the developed models and the proposed control scheme. Experimental validation has been successfully conducted. The multi-axis control scheme can accurately control the tensegrity structure to achieve shape changes while maintaining a desired level of internal pre-load. The mathematical models can be used as a basis for further development.
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Henderson, Jean-Paul. "Vibration isolation for rotorcraft using electrical actuation." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558879.
Full textAbstract:
The Active Control of Structural Response (ACSR) vibration suppression system, where hydraulic actuators located between the gearbox and the fuselage are used to cancel vibration in large helicopters, has been used successfully for many years. However the power consumed by the actuators can be high, and using hydraulic actuation for smaller rotorcraft has not been seen as practical. In contrast to active vibration reduction systems, passive vibration isolation systems require no external power. Passive vibration isolation systems however have the disadvantage of being limited to working at one specific frequency which will not be acceptable as slowed rotor flight becomes more common for fuel efficiency and noise legislation reasons. In this thesis two electrically powered actuation concepts, one piezoelectric, and one electromagnetic were initially evaluated. An electrically powered actively augmented passive, or hybrid, vibration reduction system based on an electro hydrostatic actuator (EHA) concept was proposed to be developed further. This hybrid actuator will have a wider range of operating frequencies than a purely passive system, and have lower power consumption than a purely active system. The design is termed a “Resonant EHA”; in that the resonant frequency of the coupled fluid, pump and electric motor rotor inertia matches the fundamental vibration frequency. The hydraulic cylinder, fluid and pump act as a single stage gear ratio, and the. brushless electric motor’s inertia is the main resonating mass as in a Dynamic Antiresonant Vibration Isolator (DAVI) passive vibration reduction system. The electrical power is used to compensate for friction in the actuator and other losses, and if needed can shift the operating point away from the resonant frequency. Simulation results indicated that a hydraulic circuit in which the pump leakage is fed back into the low pressure line would introduce unacceptable disturbances in the flows to and from the cylinder. To eliminate the source of the disturbances, a fully integrated electric motor and pump circuit design was chosen in which the electric motor is immersed in hydraulic fluid. An EHA demonstrator was built sized for a 1.5 tonne rotorcraft. For sizing comparison purposes the frameless brushless D.C motor for each strut of 1.5 tonne rotorcraft has a rotor and stator mass of approximately 1 kg, and can produce a continuous stall torque of 2 Nm. The bidirectional pump has a displacement of 1.5 cm3/rev, the mean system pressure was taken as 90 bar, and the double ended hydraulic cylinder has a 32 mm diameter bore, and 18 mm rod. Initial test results for the proof of concept EHA showed highly significant free play with a reversal of torque direction, resulting in unacceptable loss in transmission stiffness. The free play was traced to the gear pump and a hypothesis for the origin of the free play was put forward. To avoid torque reversals the EHA was further tested with a constant offset torque bias which proved successful in restoring a sufficient stiffness to the transmission. The sizing of the electric motor and power consumed with a non-zero offset torque is greater than a torque reversing motor, which limits the immediate application of the device in the present form. Future research investigating the use of other transmission elements, such as a piston pump, to obtain a more linear stiffness is recommended. As a hybrid vibration isolation system a Root Mean Square (RMS) reduction by a factor of four and near elimination of the fundamental frequency vibrations was achieved for the frequency range of 10 to 20 hertz.
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Eslinger, Gregory John. "Dynamic programming applied to electromagnetic satellite actuation." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82480.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.
"June 2013." Cataloged from department-submitted PDF version of thesis
Includes bibliographical references (p. 135-140).
Electromagnetic formation flight (EMFF) is an enabling technology for a number of space mission architectures. While much work has been done for EMFF control for large separation distances, little work has been done for close-proximity EMFF control, where the system dynamics are quite complex. Dynamic programming has been heavily used in the optimization world, but not on embedded systems. In this thesis, dynamic programming is applied to satellite control, using close-proximity EMFF control as a case study. The concepts of dynamic programming and approximate dynamic programming are discussed. Several versions of the close-proximity EMFF control problem are formulated as a dynamic programming problems. One of the formulations is used as a case study for developing and examining the cost-to-go. Methods for implementing an approximate dynamic programming controller on a satellite are discussed. Methods for resolving physical states and dynamic programming states are presented. Because the success of dynamic programming depends on the system model, a novel method for finding the mass properties of a satellite, which would likely be used in the dynamic programming model, is introduced. This method is used to characterize the mass properties of three satellite systems: SPHERES, VERTIGO, and RINGS. Finally, a method for position and attitude estimation for systems that use line-of-sight measurements that does not require the use of a model is developed. This method is useful for model validation of the models used in the dynamic programming formulation.
by Gregory John Eslinger.
S.M.
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Steyn, J. Lodewyk (Jasper Lodewyk) 1976. "Hydraulic amplification for actuation in microelectromechanical systems." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16834.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002.Includes bibliographical references (p. [121]-123).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
In this work the concept of hydraulic amplification as a means of stroke amplification is explored for applications in MicroElectroMechanical Systems (MEMS). Building on the batch fabrication technologies of the semiconductor industry, MEMS technology could enable the simultaneous fabrication of multiple microhydraulic systems of which hydraulic amplifiers would form part. Precision lithography would furthermore make dense arrays of microhydraulic systems possible, with the eventual goal being to create high power density microscale actuation and power generation systems. This document provides an overview of the design considerations required for a successful microfabricated hydraulic amplifier, and proceeds to discuss the techniques developed to successfully fabricate, assemble and test such a device. Deep Reactive Ion Etching (DRIE) techniques were developed for creating strong tethered membrane structures using Silicon On Insulator (SOI) technology. Bonding techniques included silicon-silicon fusion bonding of fragile wafers and silicon-glass anodic bonding and alignment on the wafer and die level to produce multi-layered structures. Liquid filling of micromachined dead volumes through micron-size channels was performed. Static sealing techniques for leak-free sealing of micromachined, filled dead volumes with minimal seal compression and dynamic sealing techniques when quasi-static actuation is not a prerequisite were successfully developed. Using these techniques, several hydraulic amplification devices have been produced. Testing of these devices revealed good correlation with theoretical predictions. Stroke amplification ratios as high as 48 : 1 have been observed. In addition, natural frequencies of up to 10kHz were measured. In conclusion, this work verifies the viability of hydraulic amplification for applications in microscale actuation systems.
by J. Lodewyk Steyn.
S.M.
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Hartwell, Ashley (Ashley Jessica). "Shape Memory Alloys for small scale actuation." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118714.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 51-52).
Shape Memory Alloys (SMAs), materials that can undergo a fully recoverable strain change due to a thermal cycle, and which can be produced in a form that is superelastic are only utilized limitedly. In this thesis, I investigated the relationship between the material properties of shape memory alloy micro-wires and their mechanical performance. This study was conducted with two main types of SMAs, the first a commercially available NiTi wire, and the second an emerging Cu-based alternative. This comparison allows an understanding of the current state of the art for small scale actuation with SMA wires, and to evaluate the Cu-based alternative SMA, which has a reduced cost and improved thermal properties. This thesis evaluates Cu-based SMAs as substitutes for NiTi in terms of activation strain of wire during a shape memory cycle, power consumption during actuation, heating and cooling times during actuation, and cost. Furthermore this thesis includes studies on the processing of Cu-based alternatives to enhance shape memory properties of interests, such as transformation temperature and fatigue, and suggests future work to improve Cu-based SMA wires..
by Ashley Hartwell.
S.M.
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Munro, Logan. "Investigation of deployable structures and their actuation." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40447.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 27).
Deployable Structures had not been designed for use in the oil field industry, and additionally have not been designed as devices to perform mechanical work. By analyzing deployable structures a detailed understanding of the mechanism kinematics has been developed. Further, we have analyzed new design concepts of deployable structures that include void filling alterations and snap fit strengthening. The actuation and mechanical loading of the structures and the input to output force ratio were investigated. This understanding was applied to several actuation methods.
by Logan Munro.
S.B.
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Ghandi, Kamyar. "Shape memory ceramic actuation of adaptive structures." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/49938.
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Fox, Matthew Edward. "Blade mounted actuation for helicopter rotor control." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/49586.
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Dunn, Christopher Thomas 1971. "Thermoplastic active fiber composites for structural actuation." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16851.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002.Includes bibliographical references (v. 2, leaves 267-276).
The integration of piezoelectric actuators into a structure can lead to an active structural surface that can adapt by bending or straining to different operational conditions. This can be used to tune desired properties of the active system to their optimal levels. Due to their fast response time, high bandwidth, and the level of force that the actuator can apply, it has been proposed that monolithic piezoelectric materials be used for active structural control. Monolithic piezoelectric materials for planar actuation have several drawbacks including: (a) use of the lower 3-1 actuation for planar actuation, (b) low strain before failure, (c) inability to conform to curved surfaces. Active Fiber Composites (AFCs) have been developed to address some of these shortcomings of monolithic piezoceramic materials. AFCs are thin composite plies comprised of unidirectional piezoelectric fibers imbedded in a thermoset matrix. An electric field is supplied to the fibers by use of an interdigitated electrode pattern adhered to either side of the AFC. The benefits of AFCs include: the interdigital electrode design uses 3-3 actuation offering increased levels of actuation, AFCs allows for anisotropic planar actuation, the AFCs matrix provides load transfer and load distribution, AFCs allows for coverage of curved shapes. A major drawback of the AFCs with PZT-5A fibers is that the level of actuation is 60% lower than that of the 3-3 actuation of monolithic PZT-5A. This is due primarily to a small layer of low dielectric matrix material that is trapped between the electrodes and the high dielectric fibers during manufacturing.
(cont.) This dielectric mismatch causes a large voltage drop in the matrix thereby reducing actuation. A method that has been developed to reduce this matrix gap, and thus increasing actuation, is to transfer the electrode pattern onto plastic sheets, and heat and press the sheets around the fibers to make Thermoplastic Active Fiber Composites (tmAFCs). tmAFCs also have simpler processing when compared to AFCs and are reshapeable. The focus of this research is to analyze, manufacture, and test tmAFCs to be used in structural control applications with the goal of producing high quality and high performance actuators.
by Christopher T. Dunn.
Ph.D.
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Shu, Wenmiao. "Biomolecular sensing and actuation using microcantilever systems." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612828.
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Tsai, Tsung-Ying, and 蔡宗穎. "Design , Fabrication and Actuation of Thermal Actuating XY-stage for Image Stabilization." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/77068698764761899459.
Full textAbstract:
碩士國立交通大學
電控工程研究所
99
This research presents a MEMS micro electro - thermal actuating XY-stage fabricated by SOI process, and an image-sensor or a micro-lens can be mounted on this stage. A suitable fabrication process is designed to fabricate the stage in this research. The design-flow, fabrication process and measurements are all shown in the paper. The first step is to survey and set up the specification of the XY-stage. The main goals of this research are smaller device size, lower driving voltage and larger actuating displacement, besides, establishing decoupling function and increasing linearity and controllability are our goals, too. The stiffness, Young’s module, coefficient of thermal expansion and distribution of heat are the important factors which will affect the driving efficiency of the stabilizer, so we will pay most attention on design them. To increase yield, the promotion of fabrication process and design skills are presented in this research.
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Yang, Ichieh, and 楊毅杰. "Magnetic Actuating MEMS Display Device." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/37290132554234254197.
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Liao, Chien-An, and 廖健安. "iExoskeleton: Air Muscle Actuating System." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/49535369604131446697.
Full textAbstract:
碩士國立雲林科技大學
機械工程系碩士班
101
It is an inevitable trend that we are going to become an aging population society in Taiwan. Owing to walking inconvenience in elders, there is an idea starting in our mind of developing iExoskeleton. This essay mainly focuses on development of air muscle actuating system, belonging to the energy source of walking assistant engineering. Air muscle is a newly equipment, working by traction exercise. Our research target is to make it automatic developed ability. 20mm silicone rubber tube is applied in our air muscle, surrounded by PET texture nets outside. The final product also goes through the performance tests, comparing with commercial air muscle as well, and we find the result is satisfying in a positive direction.
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Liang, Chia-Lun, and 梁家倫. "Residual Stress Measurement of Actuating Plane in Micromirror." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/11922249086731964944.
Full textAbstract:
碩士國立中央大學
機械工程研究所
92
Abstract In this study, in order to make the material reaching qualities of strength and toughness, so select aluminum nitride to do the hinge of micromirror actuator. In fabrication produce, to deposition and manufacture the contact holes and hinges by reactive sputtering deposition. By this way can improve the problem of membranes etched by hydrofluoric acid after selectivity tungsten deposition. To adjust deposition power and nitrogen flow rate also can confer the change in characters of aluminum nitride membranes for different nitrogen flow rate, including the thermal stresses, sheet resistances, and hardness that cased by membrane. Furthermore, in order to understand the compose components, and lattice space in aluminum nitride membranes, used the X-ray powder diffractometer to analyze the phase structure in membranes. Employing the lattice space that measured in front and behind of sacrifical layer released, could calculate the residual stress value that cased from membrane, investigating the influences to fabrication process. And we could get that a twenty percent nitrogen flow and 1500 watts plasma power would cause a tensile force in actuating plane material.
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Sung, Meng-Ying, and 宋孟瑛. "Application of Piezoelectric-actuating Table in Optical Alignment." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/02830502649226862464.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
91
The positioning technique is widely applied in manufacturing, measurement, and machines operating. Currently, the micro-positioner has become an important developing target for achieving the requirement of precision machinery. The piezoelectric actuator has the advantages of ultrahigh precision, high resolution, tiny size and fast response. The main objective of this thesis is to design a controller for piezoelectric actuating x-y table, and then use to establish laser optical alignment system for evaluating the motion control performance and system stability. Since the piezoelectric actuating system has obvious dead-zone offset control voltage and hysteresis nonlinear behaviors, it is difficult to establish a dynamic model for model-based control design. Here, the model free fuzzy control algorithm is employed, and the look ahead control target is chosen for trajectory planning to reduce the chance of trapping into the bang-bang dead zone area. Finally, the implementation technology of optical axis alignment in laser packaging is planned to verify the system performance and stability of this micro positioner. Piezoelectric actuating table brings the photo diode to search the optical axis of a specified laser diode by using a serried of algorithm with precise x-y plane motion control.
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Wiggins, Ian David. "Evaluation of an actuating mechanism for the electrical industry." Thesis, 2012. http://hdl.handle.net/10539/11747.
Full textAbstract:
A class of electrical devices reacts to fault conditions by disengaging from the circuit.
A particular sub-system of the device, the actuating mechanism, was identified as having potential for improvement in the first pass yield achieved for its manufacturing and assembly process. The critical characteristic of the actuating mechanism, its sensitivity or “lock load”, was found to be within functional limits in 94% of mechanisms tested at the end of the production line. An increase in this value to a tentative target of 99% was proposed. Such an increase in first pass yield has typically been shown to translate into a financial advantage, offsetting any investment required for its implementation. It was conjectured that a modification to the actuating mechanism design might be indicated to enable the target to be achieved.
In order to examine the feasibility of improving the process, models were developed to represent two variations of the current actuating mechanism design. The models were implemented by means of vector loop analysis, and were used to predict the lock load distribution of the mechanisms. The accuracy of the models was first validated by comparison with parametric CAD models of the mechanisms, and then with actual lock load distribution data derived from measurement of production samples. An interactive computer application was developed to facilitate the manipulation of individual model variables within their tolerance bands, and to evaluate the effect of such manipulation on the calculated value of the lock load. A Pareto analysis was conducted to identify the independent component variables that were the most critical for control of the correct functioning of the mechanism, and thus where the priorities lay for further optimisation.
The results were analysed, and a comparison of the strengths and weaknesses of the two existing designs suggested that a third variation of the mechanism had the potential of achieving the process yield target.
The mathematical model was adapted to predict the behaviour of the third actuating mechanism variation. The first pass yield predicted by the new model was 99.36%. The implementation costs of the new design were estimated, and offset against the potential savings resulting from the improved first pass yield. A payback period of 2.7 years was projected.
It was recommended that the accuracy of the critical data used in the analysis be refined by means of larger scale testing, and that ancillary recommendations stemming from the Pareto analysis be implemented. Finally it was concluded that based on the currently available data, the design modifications proposed for the actuating mechanism were both financially and practically feasible, and should be implemented.
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Li, I.-Han, and 李易翰. "Performance of Thin Valveless One-side Actuating Diaphragm Micropump." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/12967402816098918965.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
98
A novel designed of valveless diaphragm micropump is consisted of chamber, the middle passage, import and export of pipe. By using one-side piezoelectric (PZT) as actuating device, the diaphragm by middle passage will be divided into the active area by direct force from PZT and the passive area affected by the fluid flow. Experimental direction is the gradual enhancement of micropump performance. First, in the light of characteristics of one-side actuating design entrance location and find the reason of flow rate generation. We know that the vibration of diaphragm in passive area is an important role in order to improve the performance of micropump. Take this feature to enlarge the passive area of diaphragm. Later, middle passage width is reduced for micropump flow resistance. Then change the location of PZT fixed end, to confirm the passive area of diaphragm as flow control and flow amplification components. In simulation to see the vibration phenomenon of each node in passive area of diaphragm obtain two key points to achieve high performance in micropump. One is to reduce the distance from diaphragm to the exit, the other is to reduce the number of more large displacement position of the whole diaphragm. Therefore, using high of 0.3 mm, 10 x 10 mm2 size shim placed in the chamber of passive area of diaphragm for verify the simulation. We would get under the 70 Hz the maximum average flow rate 101.5 ml/min, pressure head height 21.3 cm of performance and a wide range of flow rate on the frequency distribution.
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Chu, Ren-De, and 褚仁德. "Design and Performance Analysis of Twisted String Actuating System." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/ugzb4j.
Full textAbstract:
碩士健行科技大學
機械工程系碩士班
105
The advantages of twisted string actuator (TSA) owns light weight, low inertia, high efficiency, low cost and simple mechanism. Due to multiple advantages on TSA, the design of using such actuators are mostly on robotic manipulators, but these features is also suitable for material handling. Thus, the main goal of this thesis is concentrated on deign of the one dimension moving platform based on TSA to meet low cost and simple structure demand request. The driving unit is adapting servo motor with Arduino control board. Moreover, the film potentiometer is using as the position sensor to measure moving platform displacement owing to TSA actuation. The software package LabView2014 is introduced to build the control environment. However, the performance for TSA is influence by the string material properties, hence, this research select six different string to verify their functioning. Consequently, the new measurement model is proposed while modify the positioning equation. Experimental results confirm that such design is reliable and possesses low implementation cost.
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Wu, Yuh-Chian, and 吳育騫. "ActiveErgo: Automatic and Personalized Ergonomics using Self-actuating Furniture." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/y6x6y4.
Full textAbstract:
碩士國立臺灣大學
資訊工程學研究所
106
Proper ergonomics improves productivity and reduces risks for injuries such as tendinosis, tension neck syndrome, and back injuries. Despite having ergonomics standards and guidelines for computer usage since the 1980s, injuries due to poor ergonomics remain widespread. We present ActiveErgo, the first active approach to improving ergonomics by combining sensing and actuation of motorized furniture. It provides automatic and personalized er- gonomics of computer workspaces in accordance to the recommended ergonomics guidelines. Our prototype system uses a Microsoft Kinect sensor for skeletal sensing and monitoring to determine the ideal furniture positions for each user, then uses a combination of automatic adjustment and real-time feedback to adjust the computer monitor, desk, and chair positions. Results from our 12-person user study demonstrated that ActiveErgo significantly improves ergonomics compared to manual configuration in both speed and accuracy, and helps significantly more users to fully meet ergonomics guide- lines.