Dissertations / Theses on the topic 'Mechanically Actuated System'
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Sul, Onejae Washburn Michael Sean. "Thermally actuated mechanical systems." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,392.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Physics and Astronomy." Discipline: Physics and Astronomy; Department/School: Physics and Astronomy.
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Farahat, Waleed A. (Waleed Ahmed) 1975. "Optimal workloop energetics of muscle-actuated systems." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39898.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 117-122).
Skeletal muscles are the primary actuators that power, stabilize and control locomotive and functional motor tasks in biological systems. It is well known that coordinated action and co-activation of multiple muscles give rise to desirable effects such as enhanced postural and dynamic stability. In this thesis, we study the role of muscle co-activation from an energetics perspective: Are there situations in which antagonist co-activation leads to enhanced power generation, and if so, what is the underlying mechanism? The mechanical energetics of muscles are traditionally characterized in terms of workloop measures where muscles are activated against oscillating, zero-admittance motion sources. We extend these measures to more natural, "mid-range" admittance loads, actuated by multiple muscles. Specifically, we set up the problem of a second-order mechanical system driven by a pair of antagonist muscles. This is the simplest problem where the influences of load dynamics and muscle co-activation on the output energetics may be investigated. To enable experimentation, a muscle testing apparatus capable of real-time servo emulation of the load is developed and utilized for identification and workloop measurements.
(cont.) Using this apparatus, an experimentally identified model predicting muscle contractile force is proposed. Experimental data shows that with a simple Weiner structure, the model accounts for 74% (sigma = 5.6%) of the variance in muscle force, that force dependence on contraction velocity is minimal, and that a bilinear approximation of the output nonlinearity is warranted. Based on this model we investigate what electrical stimulation input gives rise to maximal power transfer for a particular load. This question is cast in an optimal control framework. Necessary conditions for optimality are derived and methods for computing solutions are presented. Solutions demonstrate that the optimal stimulation frequencies must include the effects of muscle impedances, and that optimal co-activation levels are indeed modulated to enable a pair of muscles to produce more work synergistically rather than individually. Pilot experimental data supporting these notions is presented. Finally, we interpret these results in the context of the familiar engineering notion of impedance matching. These results shed new light on the role of antagonist co-activation from an energetics perspective.
by Walled A. Farahat.
Ph.D.
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Nahon, Meyer. "Optimization of force distribution in redundantly-actuated robotic systems." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74596.
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This thesis presents an analysis of redundantly-actuated robotic systems with emphasis on systems which have a time-varying kinematic structure such as mechanical hands, walking machines and multiple manipulators grasping a common object.Firstly, graph theory is used to characterize the kinematic structure of these systems and show that they can be decomposed into two subsystems, each with different properties. The contacts which occur between the constituent bodies in the system are then analyzed in order to determine the system's mobility (or number of degrees of freedom). It is found that this mobility varies during the task and that, at any given time, there will be more actuators active than are necessary.
The kinematic and dynamic equations governing the motion of these systems are then studied and compared to those of more conventional robotic systems. Although the inverse dynamics equations can be formulated in a number of ways, they always constitute an underdetermined system of linear equations. This allows their treatment as equality constraints in an optimization problem. In order to account for the limitations of passive contacts and actuator capabilities, inequality constraints are also considered.
The formulation of the optimization problem is then studied with emphasis on problems which are solvable in real-time and which produce time-continuous solutions. Quadratic programming is found to be a good choice of problem formulation. A quadratic-programming algorithm which efficiently includes both equality and inequality constraints is presented. A number of linear and quadratic objective functions which could be optimized are reviewed and the limitations of linear programming are made apparent through the use of numerical examples. Quadratic objective functions which minimize internal force, power consumption and solution discontinuities are examined. Finally, other applications of redundant actuation are briefly touched upon--the full dynamic balancing of linkages and the reduction of impact shocks in robotic systems.
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Mohammadshahi, Donya. "Dynamics and control of cables in cable-actuated systems." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119654.
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This thesis deals with the dynamic modeling and control of a cable-actuated system consisting of a payload attached to several actuated cables. The objective of this thesis is to design a stabilizing controller that positions the payload and suppresses the cables vibrations. The dynamics of the system is modeled using the lumped-mass method. First, PID and LQG control algorithms are used to design a controller. Later, motivated by the robust nature of the passivity-based control, its application to cable-actuated systems is investigated. Cable-actuated systems are usually non-square with non-collocated actuators and sensors, which generally limits the use of passivity-based control. In order to overcome these limitations, first a dynamic embedding is considered where an observer is used to construct a new output that realizes a passive input-output map. Next, an alternative input-output map is considered where the output is a scaled version of the true payload velocity and the input is a modified winch torque.Cette thèse présente une étude de la modélisation dynamique et commande d'un système actionné par câbles, celui-ci composé d'un effecteur attaché à une série de câbles actionnés. L'objectif de cette thèse est de développer un contrôleur qui positionne l'effecteur et diminue les vibrations des câbles. La dynamique du système est modélisée en utilisant la méthode de masses localisées. D'abord, deux algorithmes de commande, PID et LQG sont utilisés pour développer la command. Puis, nous étudions l'application de la commande passive sur le système actionné pas câbles. Les systèmes actionnés par câbles sont généralement non carré avec des actionneurs et des senseurs non colocalisés, ce qui limite généralement l'utilisation de la commande passive. Pour trouver une solution pour ces contraintes, premièrement, nous considérons une intégration dynamique, où un observateur est utilisé pour construire une nouvelle sortie qui donne un système passif. Deuxièmement, nous considérons une entrée-sortie alternative, où la sortie est une version réduit de la vitesse réelle de l'effectuer et l'entrée est une modification du couple de treuil.
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Wongviriyawong, Chanikarn Mint. "Stable hopping of a muscle-actuated leg system using positive force feedback." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39725.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaves 89-92).
In control of movement, two key components, which are pure mechanical response of the system and response due to sensory feedback, must be thoroughly understood. Recent studies suggest not only the existence of positive force feedback in vivo, but also the emergent property of positive force feedback in having a stabilizing effect on a dynamical system in the presence of disturbances. In this thesis, simulated environment of simple one-dimensional point mass hopping model with positive force feedback as well as experimental results of the same dynamical system are compared and studied in detail. Three important hypotheses are investigated. The first hypothesis involves positive force feedback and its stabilization property despite disturbances in the system. A system with positive force feedback control attains cyclic motion while system energy is being added or removed without changing its steady state system energy. Secondly, overall mechanical behavior of the leg becomes elastic in the existence of positive force feedback. In locomotion, elastic leg behavior is desired for a pertinent adaptation to physical properties of the environment and utilization of the locomotory performances.
(cont.) The last hypothesis investigated is the effect of feedback control parameters on closed loop system behavior, i.e. frequency of hopping, steady state hopping height, etc. Simulation and pilot experimental data are compared both qualitatively and quantitatively concerning all three hypotheses.
by Chanikarn Wongviriyawong.
S.M.
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Abhijit, Upadhye. "Electrostatically actuated and bi-stable MEMS structures." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/6041.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 16, 2008) Includes bibliographical references.
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Lichter, Matthew D. (Matthew Daniel) 1977. "Concept development for lightweight binary-actuated robotic devices, with application to space systems." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8546.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001."June 2001."
Includes bibliographical references (leaves 66-71).
Exploratory space missions of the future will require robotic systems to lead the way by negotiating and mapping very rough terrain, collecting samples, performing science tasks, and constructing facilities. These robots will need to be adaptable and reconfigurable in order to achieve a wide variety of objectives. Conventional designs using gears, motors, bearings, encoders, and many discrete components will be too complex, heavy, and failure-prone to allow highly-reconfigurable systems to be feasible. This thesis develops new concepts that may potentially enable the design of self-transforming space explorers. The vision of this research is to integrate compliant bistable mechanisms with large numbers of binary-actuated embedded smart materials. Compliant mechanisms are lightweight and robust. Binary actuation is the idea of using an actuator in a discrete on/off manner rather than in a continuous manner. A binary actuator is easy to control and robust, and by using tens or hundreds of binary actuators, one can approximate a continuous system, much like a digital computer can approximate an analog system. The first part of this thesis examines the fundamental planning issues involved with systems having large numbers of binary actuators. The notion of a workspace is described and applied to the optimization of a manipulator design. Methods for solving the forward and inverse kinematics are discussed in the context of this application. These methods are extended to the trajectory and locomotion planning problems. Methods for planning systems of substantial complexity are developed in the context of exploratory space robotics. The second part of this thesis presents experimental demonstrations that examine elements of the concept. The results of several design prototypes are discussed.
by Matthew D. Lichter.
S.M.
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Selden, Brian A. 1980. "Segmented binary control of shape memory actuator systems." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30307.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 51).
A new approach to the design and control of shape memory alloy (SMA) actuators is presented. SMA wires are divided into many segments and their thermal states are controlled individually as a group of finite state machines. Instead of driving a current to the entire SMA wire and controlling the wire length based on the analogue strain-temperature characteristics, the new method controls the binary state (hot or cold) of individual segments and thereby the total displacement is proportional to the length of the heated segments, i.e. austenite phase. Although the thermo-mechanical properties of SMA are highly nonlinear and uncertain with a prominent hysteresis, Segmented Binary Control is robust and stable, providing characteristics similar to a stepping motor. However, the heating and cooling of each segment to its bi-stable states entail longer time and larger energy for transition. An efficient method for improving speed of response and power consumption is developed by exploiting the inherent hysteresis of SMA. Instead of keeping the extreme temperatures continuously, the temperatures return to intermediate "hold" temperatures closer to room temperature but sufficient to keep constant phase. Coordination of the multitude of segments having independent thermal states allows for faster response with little latency time even for thick SMA wires. Based on stress dependent thermo-mechanical characteristics, the hold temperature satisfying a given Stress Margin is obtained. The new control method is implemented using the Peltier effect thermoelectric devices for selective segment-by-segment heating and cooling. Experiments demonstrate effectiveness of the proposed method.
by Brian A. Selden.
S.M.
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Rupinsky, Michael J. "Smart material electrohydrostatic actuator for intelligent transportation systems." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1391701972.
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Wester, Brock Andrew. "Development and characterization of mechanically actuated microtweezers for use in a single-cell neural injury model." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39645.
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Traumatic brain injury (TBI) affects 1.4 million people a year in the United States alone and despite the fact that 96% of people survive a TBI, the health and socioeconomic consequences can be grave, partially due to the fact that very few clinical treatments are available to reduce the damage and subsequent dysfunction following TBI. To better understand the various mechanical, electrical, and chemical events during neural injury, and to elucidate specific cellular events and mechanisms that result in cell dysfunction and death, new high-throughput models are needed to recreate the environmental conditions during injury.
This thesis project focuses on the creation of a novel and clinically relevant single-cell injury model of traumatic brain injury (TBI). The implementation of the model requires the development of a novel injury device that allows specialized micro-interfacing functionality with neural micro environments, which includes the induction of prescribed strains and strain rates onto neural tissue, such as groups of cells, individual cells, and cell processes.
The device consists of a high-resolution micro-electro-mechanical-system (MEMS) microtweezer microactuator tool that is introducible into both biological and aqueous environments and can be proximally positioned to specific targets in neural tissue and neural culture systems. This microtweezer, which is constructed using traditional photolithography and micromachining processes, is controllable by a custom developed software-automated controller that incorporates a high precision linear actuator and utilizes a luer-based microtool docking interface.
The injury studies will include examination of intracellular calcium concentration over the injury time course to evaluate neuronal plasma membrane permeability, which is a significant contributor to secondary injury cascades following initial mechanical insult. Mechanical strain and strain rate input tolerance criteria will also be used to determined thresholds for cellular dysfunction and death.
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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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De, Lillo Liliana. "A matrix converter drive system for an aircraft rudder electro-mechanical actuator." Thesis, University of Nottingham, 2006. http://eprints.nottingham.ac.uk/14034/.
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The matrix converter is an attractive topology of power converter for the Aerospace Industry where factors such as the absence of electrolytic capacitors, the potentiality of increasing power density, reducing size and weight and good input power quality are fundamental. The matrix converter potential advantages offers the possibility to achieve the aim of the More Electric Aircraft research which intends to gradually re- place, from the aircraft architecture, the hydraulic power source and its infrastructure with electric power generation and a more flexible power distribution system. The purpose of this work is to investigate the design and implementation of a 40kVA matrix converter for an Electro Mechanical Actuator (EMA) drive system. A SABER simulation analysis of the candidate matrix converter drive systems, for this application, is provided. The design and implementation of the matrix converter is described, with particular attention to the strict requirements of the given aerospace application. Finally, the matrix converter PMSM drive system and the EMA drive system are respectively assembled, tested and commissioned.
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Torabzadeh-Tari, Mohsen. "Analysis of Electro-mechanical actuator systems in more electric aircraft applications /." Stockholm : Department of electrical engineering, Royal Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-255.
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KRUTZ, JILL E. "DESIGN OF A HYDRAULIC ACTUATOR TEST STAND FOR NON-LINEAR ANALYSIS OF HYDRAULIC ACTUATOR SYSTEM." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin990813095.
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Gonthier, Yves. "Force task planning of robotic systems with limited actuator capabilities." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27222.
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In this thesis, we study the problem of large wrench application using robotic systems with limited force or torque actuators. It is shown that such systems may be able to apply a wrench in some configurations only; therefore their useful Force Workspace is limited, and may be smaller than their reachable workspace.To improve the force capabilities of a system, base mobility or redundancy can be employed. A planning algorithm is proposed which results in proper base positioning relative to large-force quasi-static tasks. Similarly, the Force Workspace can be used to position such tasks relative to a robotic system. An efficient numerical algorithm is proposed to generate the Force Workspace, based on the 2$ sp{n}$-tree decomposition of the Cartesian space. Its efficiency stems from the variable resolution nature of the Cartesian space representation, and also from the use of four test levels that restrict the search to valid regions of the Cartesian space only. Examples of Force Workspaces are given for redundant and non-redundant planar manipulators, and spatial manipulators.
Next, the case of tasks requiring the application of a wrench along a given path is considered. The Task Workspace, the set of Cartesian space locations that are valid starting positions for such tasks, is shown to be a subset of the Force Workspace.
To plan redundant manipulator postures during large force-tasks, a new method based on a mini-max optimization scheme is developed. (Abstract shortened by UMI.)
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Anderson, Catherine J. (Catherine Jane). "The design of a compact actuator system for a robotic wrist/hand." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/29546.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1992.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 103-105).
by Catherine J. Anderson.
M.S.
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Zhou, Junqiang. "CONTROL OF OVER-ACTUATED SYSTEMS WITH APPLICATION TO ADVANCED TURBOCHARGED DIESEL ENGINES." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420810533.
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Roan, Earl Taylor. "Design of an STM and EPL control system and linear actuator preload diaphragm." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40310.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 53-54).
Increasing demand for nano-scale machining processes in the semiconductor industry necessitates new mechanisms for nano-machining. A system capable of nano-scale machining of conductive material via Electronic Pen Lithography (EPL) may fit this niche. The purpose of this research is to develop a system capable of EPL based on a HexFlex six axis nano-manipulator. The system will also be capable of Scanning Tunneling Microscopy (STM), which is will locate the surface with the precision necessary for EPL and also allow the user to confirm the machined features immediately after machining. The import of this work is the development of a low-cost and compact system for nano-machining and nano-scale imaging. The impact of this work may improve the process for manufacturing semiconductors including circuitry, MEMS, and NEMS. The continued development of full six axis machining techniques may allow for the construction of features hitherto impossible to fabricate. This segment of the project focuses on the integration of the HexFlex, a micron stepper motor, precision mounts, a preload diaphragm, and an advanced control system capable of automated EPL and STM verification. Steady electron tunneling is first demonstrated, followed by STM imaging functionality. However, high-speed, high-accuracy EPL machining techniques are reserved for future work.
by Earl Taylor Roan.
S.B.
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Taylor, David Donald James. "Reducing booster-pump-induced contaminant intrusion in Indian water systems with a self-actuated, back-pressure regulating valve." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92062.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 151-155).
Intermittently-operated water systems struggle to equitably and effectively distribute clean water to customers. One common customer response to intermittency is to supplement the water system's pressure by using a household, or residential, booster pump. When such booster pumps are directly connected to the water utility's supply pipe, without an underground isolation tank (sump), they often induce negative pressure in the supply pipe which increases the flow rate. Unfortunately, where leakage rates are high, this negative pressure also increases the risk of contaminant intrusion. This thesis presents the iterative design and field testing of a patent-pending, full-bore, back-pressure regulating valve. The valve's simple mechanism relies on a stabilized collapsing tube, or 'Starling Resistor,'which when installed at a customer's connection, controls the flow rate and prevents booster pumps from creating negative pressure in the supply pipe. In collaboration with the Delhi Jal Board and several private partners, the valve's performance was verified in two rounds of field trials in neighborhoods of New Delhi, India including Pitampura, Azad Market, Vivek Vihar, Malvia Nagar, and Vasant Vihar. Using a crossover study, the valve was found to reduce the total contamination risk across all 19 tested houses during supply times by a median of 80%. The valve prevented 96% of pressure below -1 meter and an average of 53 minutes per day, per connection of total negative pressure. In an estimated worst-case scenario for contaminant intrusion, the presence of the valve reduced the contamination risk by two orders of magnitude at six customer connections - enough to correspond to significant reductions in health risks.
by David Donald James Taylor.
S.M.
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Huang, Xiaoyu. "Real-Time Parameter Estimations and Control System Designs for Lightweight Electric Ground Vehicles." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1403261078.
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Zhou, Su-Wei. "Coupled electro-mechanical system modeling and experimental investigation of piezoelectric actuator-driven adaptive structures." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-165825/.
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Chen, Yan. "Energy-Efficient Control Allocation for Over-Actuated Systems with Applications to Electric Ground Vehicles." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366305314.
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Barragán, Patrick R. "An efficient drive, sensing, and actuation system using PZT stack actuator cells." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70462.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 81-82).
The PZT cellular actuator developed in the MIT d'Arbeloff Laboratory utilizes small-strain, high-force PZT stack actuators in a mechanical flexure system to produce a larger-strain, lower-force actuator useful in robotic systems. Many functionalities for these cellular actuators are developed which can have great impact on robotic systems and actuation itself. After initial exploration into other possible circuitry, a circuit is designed to recovery unused energy for the PZT cells. The circuit design is formed around a proposed method of distributed actuation using PZT cells which imposes that different PZT cells will be activated during different periods such that the charge from some cells can be transferred to others. If the application allows actuation which can conform to this criteria, the developed circuit can be used which, without optimization, can save ~41% of the energy used to drive the actuators with a theoretical upper limit on energy efficiency of 100%. A dynamic system consisting of multiple PZT actuators driving a linear gear is analyzed and simulated which can achieve a no load speed 2.4 m/s with minimal actuators. Then, the two-way transforming properties of PZT stack actuators are utilized to allow dual sensing and actuation. This method uses an inactive PZT cell as a sensor. With no additional sensors, a pendulum system driven by antagonistic groups of PZT cells is shown to find its own resonance with no system model. These functionalities of charge recovery, distributed actuation, and dual sensing and actuation set the PZT cellular actuator as an important contribution to robotic actuation and begin to illuminate the possible impacts of the concept. The design and analysis described reveals many possibilities for future applications and developments using the PZT cellular actuator in the fields of actuation and robotics.
by Patrick R. Barragán
S.M.
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Secord, Thomas W. (Thomas William). "Design and application of a cellular, piezoelectric, artificial muscle actuator for biorobotic systems." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61612.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 219-227).
One of the foremost challenges in robotics is the development of muscle-like actuators that have the capability to reproduce the smooth motions observed in animals. Biological muscles have a unique cellular structure that departs from traditional electromechanical actuators in several ways. A muscle consists of a vast number of muscle fibers and, more fundamentally, sarcomeres that act as cellular units or building blocks. A muscle's output force and displacement are the aggregate effect of the individual building blocks. Thus, without using gearing or transmissions, muscles can be tailored to a range of loads, satisfying specific force and displacement requirements. These natural actuators are desirable for biorobotic applications, but many of their characteristics have been difficult to reproduce artificially. This thesis develops and applies a new artificial muscle actuator based on piezoelectric technology. The essential approach is to use a subdivided, cellular architecture inspired by natural muscle. The primary contributions of this work stem from three sequential aims. The first aim is to develop the operating principles and design of the actuator cellular units. The basic operating principle of the actuator involves nested flexural amplifiers applied to piezoelectric stacks thereby creating an output length strain commensurate with natural muscle. The second aim is to further improve performance of the actuator design by imparting tunable stiffness and resonance capabilities. This work demonstrates a previously unavailable level of tunability in both stiffness and resonance. The final aim is to showcase the capabilities of the actuator design by developing an underwater biorobotic fish system that utilizes the actuators for resonance-based locomotion. Each aspect of this thesis is supported by rigorous analysis and functional prototypes that augment broadly applicable design concepts.
by Thomas William Secord.
Ph.D.
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Wang, Rongrong. "Fault-Tolerant Control and Fault-Diagnosis Design for Over-Actuated Systems with Applications to Electric Ground Vehicles." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365522537.
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Sasaki, H., M. Shikida, and K. Sato. "A Novel Type of Mechanical Power Transmission Array for Switching Densely-Arrayed Actuator Systems." IEEE, 2006. http://hdl.handle.net/2237/9536.
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Baxter, Michael Scott. "An Open Architecture for Versatile Machine and Actuator Control." BYU ScholarsArchive, 2004. https://scholarsarchive.byu.edu/etd/793.
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Automatic control technology increases usability, reliability and productivity in manufacturing, transportation, and climate control. There are many additional areas of modern life that could benefit through automatic control; however, current automation components are too expensive or aren't sufficiently flexible. For example, the cost of current commercial motion control components precludes their use in an average home. This thesis describes an automatic control methodology that is low cost and is flexible enough for a wide variety of control applications. Typical applications could include:
- Home lighting, security and appliances
- Commercial building heating, ventilation and air conditioning
- Industrial machine tool and process control
This automation methodology eliminates several expensive and inflexible aspects of present-day industrial automation. This is accomplished by implementing application-specific control algorithms in software run on a generic computer rather than on purpose-built hardware. This computer calculates control values for each control application connected to it via real-time communication network. This technique is similar to that of a desktop PC. When using a peripheral device, such as a printer or scanner, the PC executes device driver software to calculate control values for the devices. These values are communicated to the device over a shared bus. The automation methodology described here seeks to emulate this software-based control paradigm. This methodology reduces cost and increases flexibility in two ways. First, it eliminates application-specific control hardware and replaces it with software. This reduces the cost by eliminating the need for unique, proprietary control hardware for each product or system. Second, the software approach increases flexibility. For example, one could download a new clothes washing machine cycle via the Internet. Software control provides considerable freedom in designing and implementing control systems by allowing the designer to change system functionality without having to replace or modify hardware or even be present at the location where the control system is used. This thesis describes the development of this new control methodology. To validate its performance a home automation system is implemented. This implementation included control of laundry appliances, lighting, TV and other common household devices.
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Lake, Melinda Ann. "Electrostatic curved electrode actuator for particle sorting at a microfluidic bifurcation." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1560441199033201.
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Artho-Bentz, Samuel S. "Telescope Parallel Actuator Mount: Control and Testing." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2242.
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This thesis approaches the task of designing a control system for the Parallel Actuator Mount developed by Dr. John Ridgely and Mr. Garrett Gudgel. It aims to create a base framework that directly controls the telescope and can be expanded to accept external command. It incorporates lower priced components and develops more easily approachable software with great functionality. An open-loop method for velocity control is established. Developing repeatable tests is a major focus. Testing finds the control methods developed result in velocity error of less than 5% and position error of less than 1.5% despite several mechanical issues and inaccuracies. Design guidelines are established that allow for the easy implementation of a Parallel Actuator Mount on other systems.
This paper proves that the Parallel Actuator Mount is a potentially viable system for aiming a telescope when an astronomer does not require full sky coverage. The tests showed too much error to fully recommend the system as built and tested, but there are paths to increase accuracy of the system without greatly increasing the complexity or cost. The inclusion of a method of feedback, including a plate solver and an inertial measurement unit, would greatly improve the system. It may also be of use to modify the software to include a variable time step for the velocity control.
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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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Long, Fei. "Three-Dimensional Motion Control and Dynamic Force Sensing of a Magnetically Propelled Micro Particle Using a Hexapole Magnetic Actuator." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1452093964.
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Wroble, Daniel G. "Force Fight Study in a Dual Electromechanical Actuator Configuration." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1512641850024148.
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Mason, Taylor William. "Design and Testing of an Electrostatic Actuator with Dual-Electrodes for Large Touch Display Applications." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1627087821308489.
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Liu, Taoming. "Design and Prototyping of a Three Degrees of Freedom Robotic Wrist Mechanism for a Robotic Surgery System." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1283538593.
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Larson, John P. "Design of a Magnetostrictive-Hydraulic Actuator Considering Nonlinear System Dynamics and Fluid-Structure Coupling." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1402566309.
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Clause, Matthew. "SPARSE APERTURE SPECKLE INTERFEROMETRY TELESCOPE ACTIVE OPTICS CONTROL SYSTEM." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1508.
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A conventional large aperture telescope required for binary star research is typically cost prohibitive. A prototype active optics system was created and fitted to a telescope frame using relatively low cost components. The active optics system was capable of tipping, tilting, and elevating the mirrors to align reflected star light. The low cost mirror position actuators have a resolution of 31 nm, repeatable to within 16 nm. This is accurate enough to perform speckle analysis for the visible light spectrum. The mirrors used in testing were not supported with a whiffletree and produced trefoil-like aberrations which made phasing two mirrors difficult.
The active optics system was able to successfully focus and align the mirrors through manual adjustment. Interference patterns could not be found due to having no method of measuring the mirror surfaces, preventing proper mirror alignment and phasing. Interference from air turbulence and trefoil-like aberrations further complicated this task. With some future project additions, this system has the potential to be completely automated. The success of the active optics actuators makes for a significant step towards a fully automated sparse aperture telescope.
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Torabzadeh-Tari, Mohsen. "Dimensioning Tools of MEA Actuator Systems, Including Modeling, Analysis and Technology Comparison." Doctoral thesis, Stockholm : Elektrotekniska system, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9727.
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Gruenwald, Benjamin Charles. "Toward Verifiable Adaptive Control Systems: High-Performance and Robust Architectures." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7676.
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In this dissertation, new model reference adaptive control architectures are presented with stability, performance, and robustness considerations, to address challenges related to the verification of adaptive control systems.
The challenges associated with the transient performance of adaptive control systems is first addressed using two new approaches that improve the transient performance. Specifically, the first approach is predicated on a novel controller architecture, which involves added terms in the update law entitled artificial basis functions. These terms are constructed through a gradient optimization procedure to minimize the system error between an uncertain dynamical system and a given reference model during the learning phase of an adaptive controller. The second approach is an extension of the first one and minimizes the effect of the system uncertainties more directly in the transient phase. In addition, this approach uses a varying gain to enforce performance bounds on the system error and is further generalized to adaptive control laws with nonlinear reference models.
Another challenge in adaptive control systems is to achieve system stability and a prescribed level performance in the presence of actuator dynamics. It is well-known that if the actuator dynamics do not have sufficiently high bandwidth, their presence cannot be practically neglected in the design since they limit the achievable stability of adaptive control laws. Another major contribution of this dissertation is to address this challenge. In particular, first a linear matrix inequalities-based hedging approach is proposed, where this approach modifies the ideal reference model dynamics to allow for correct adaptation that is not affected by the presence of actuator dynamics. The stability limits of this approach are computed using linear matrix inequalities revealing the fundamental stability interplay between the parameters of the actuator dynamics and the allowable system uncertainties. In addition, these computations are used to provide a depiction of the feasible region of the actuator parameters such that the robustness to variation in the parameters is addressed. Furthermore, the convergence properties of the modified reference model to the ideal reference model are analyzed. Generalizations and applications of the proposed approach are then provided. Finally, to improve upon this linear matrix inequalities-based hedging approach a new adaptive control architecture using expanded reference models is proposed. It is shown that the expanded reference model trajectories more closely follow the trajectories of the ideal reference model as compared to the hedging approach and through the augmentation of a command governor architecture, asymptotic convergence to the ideal reference model can be guaranteed. To provide additional robustness against possible uncertainties in the actuator bandwidths an estimation of the actuator bandwidths is incorporated.
Lastly, the challenge presented by the unknown physical interconnection of large-scale modular systems is addressed. First a decentralized adaptive architecture is proposed in an active-passive modular framework. Specifically, this architecture is based on a set-theoretic model reference adaptive control approach that allows for command following of the active module in the presence of module-level system uncertainties and unknown physical interconnections between both active and passive modules. The key feature of this framework allows the system error trajectories of the active modules to be contained within apriori, user-defined compact sets, thereby enforcing strict performance guarantees. This architecture is then extended such that performance guarantees are enforced on not only the actuated portion (active module) of the interconnected dynamics but also the unactuated portion (passive module).
For each proposed adaptive control architecture, a system theoretic approach is included to analyze the closed-loop stability properties using tools from Lyapunov stability, linear matrix inequalities, and matrix mathematics. Finally, illustrative numerical examples are included to elucidate the proposed approaches.
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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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Cragun, Rebecca. "Thermal Microactuators for Microelectromechanical Systems (MEMS)." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/54.
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Microactuators are needed to convert energy into mechanical work at the microscale. Thermal microactuators can be used to produce this needed mechanical work. The purpose of this research was to design, fabricate, and test thermal microactuators for use at the microscale in microelectromechanical systems (MEMS). The microactuators developed were tested to determine the magnitude of their deflection and estimate their force. Five groups of thermal microactuators were designed and tested. All of the groups used the geometrically constrained expansion of various segments to produce their deflection. The first group, Thermal Expansion Devices (TEDs), produced a rotational displacement and had deflections up to 20 µm. The second group, Bi-directional Thermal Expansion Devices (Bi-TEDs) were similar to the TEDs. The difference, as the name implies, was that the Bi-TEDs deflected up to 6 µm in two directions. Thermomechanical In-plane Micromechanisms (TIMs) were the third group tested. They produced a linear motion up to 20 µm. The fourth group was the Rapid Expansion Bi-directional Actuators (REBAs). These microactuators were bi-directional and produced up to 12 µm deflection in each direction. The final group of thermal microactuators was the Joint Actuating Micro-mechanical Expansion Systems (JAMESs). These thermal microactuators rotated pin joints up to 8 degrees. The thermal microactuators studied can be used in a wide variety of applications. They can move ratchets, position valves, move switches, change devices, or make connections. The thermal microactuator groups have their own unique advantages. The TIMS can be tailored for the amount of deflection and output force they produce. This will allow them to replace some microactuator arrays and decrease the space used for actuation. The Bi-TEDs and REBAs are bi-directional and can possibly replace two single direction micro-actuators. The JAMESs can be attached directly to a pin joint of an existing mechanism. These advantages allow these thermal microactuator groups to be used for a wide variety of applications.
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KIESI, MIKKO, and SJÖBLOM ROBERT AXELSSON. "Model based design of an expiratory valve and voice-coil actuator and evaluation of complete expiratory system performance with a PI controller." Thesis, KTH, Maskinkonstruktion (Inst.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193143.
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Mechanical ventilators are devices in critical care to assist breathing in case of expiratory dysfunction. The expiratory valve is a critical component to the ventilator as it controls the pressure in the patient’s lungs. The design process of a new expiratory valve assembly is a time consuming one due to the wide range of possible design solutions both the voice-coil actuators and membrane valves typically used in ventilators. This thesis evaluates the possibility of creating and using analytical models for model based development to speed up the early design phases of a expiratory valve assembly. The main components, voice-coil actuator and membrane valve are modelled separately and experimentally verified. A complete expiratory system model and hardware-in-the-loop test setup are constructed in order to explore how well can the dynamic properties and control performance of valve assembly be predicted. Finally various questions in the valve assembly design are explored and a new design is proposed to demonstrate the capabilities of the model based approach. The resulting voice-coil and membrane valve models can be considered accurate enough for fast exploration of the design space, as an error rate below 10% is reached without manual tuning for each design.Mekaniska ventilatorer är en utrustning inom intensivvården för assisterad andning för patienter med nedsatt andningsförmåga. Utandningsventilen är en kritisk komponent till ventilatorn då den kontrollerar lungtrycket hos patienten. Design processen för en ny utandningsventil är en tidskrävande process mycket på grund av den mängd olika design möjligheter som kan utforskas för både talspole aktuatorn samt membran ventilen som oftast används i ventilatorerna. I detta examensarbete utforskades möjligheterna till att skapa och använda analytiska modeller för modellbaserad utveckling för att accelerera de tidiga design stadierna för en utandningsventil. Huvudkomponenterna, talspole aktuatorn och membran ventilen är modellerade separat och experimentellt verifierade. En fullständig modell för hela utandningssystemet samt en hardware-in-the-loop test plattform är konstruerad för att utforska hur väl de dynamiska egenskaperna samt kontroll prestandan för en utandningsventil kan prediceras. Slutligen utforskas diverse frågor angående ventil designen och en ny design föreslås för att demonstrera möjligheterna med en modellbaserad metod. Den slutliga modellen för både talspole aktuatorn och membran ventilen kan betraktas som tillräcklig precisa för snabb utforskning inom de olika design möjligheterna, då en felprocent under 10% är uppnådd utan manuell finjustering för varje design.
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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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Wroblewski, Adam Christopher. "Health Monitoring of Cracked Rotor Systems using External Excitation Techniques." Cleveland State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1228312469.
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Chakrabarti, Suryarghya. "Modeling of 3D Magnetostrictive Systems with Application to Galfenol and Terfenol-D Transducers." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1322635954.
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Seung, Taehun. "Holistic-Lightweight Approach for actuation systems of the next generation aircraft." Universitätsverlag Chemnitz, 2017. https://monarch.qucosa.de/id/qucosa%3A34400.
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Currently the system development of aircraft engineering concentrates its focus on the reduction of energy consumption more than ever before. As a consequence, the efficiency of subsystems inside the aircraft is highlighted. According to previous investigations the simplification/unification of conventional multifaceted board energy systems by means of electric power management is the most promising way concerning aircraft global efficiency improvement.
The main aim of the present work was to optimize a multi-device, heavy duty EHA-System by introducing of a comprehensive perspective. In order to achieve the final, non-plus-ultra improvement level, the attributes of architecture, hardware and operation method were combined in an interactive manner, whereas particular attention has been paid to the mutual enhancing influences.
The maximum reduction of losses, the minimizing of consumption and weight optimization can be achieved concurrently when the physical coherences between the involved subsystems are understood and their hidden potentials are exploited.
This can only be achieved in one way and the detail follows: The most effective way to reduce both manufacturing effort and weight is to introduce a multiple-allocation philosophy. The highest reliability possible can be achieved by novel cascade-nested system architecture and strict restraining of the control logic. By employing an ultra-low-loss hardware concept, the energy efficiency can be maximized at a necessary minimum own weight. Last but not least, possibly the most important cognition is that an intelligent operation method will improve the actual system and influence the entire system positively and with a lower effort.
The final conclusion is that the only and reasonable way to achieve an ultimate optimized solution of an actuation system is an all-encompassing consideration. Eventually it was to recognize that the final result is nothing but ultimate lightweight architecture, i.e. a non-plus-ultra solution.Gegenwärtig konzentriert sich die Technologieentwicklung für Flugzeuge auf die Reduktion des Energieverbrauchs mehr denn je zuvor. Hierfür ist die Effizienz der an Bord befindlichen, nicht propulsiven Subsysteme neben der Wirkungsgradverbesserung der Triebwerke von zentraler Bedeutung. Laut vorangegangenen Untersuchungen und Studien ist die Vereinfachung bzw. Vereinheitlichung der Vielfalt der konventionellen Bordenergiesysteme durch ein adäquates Energiemanagement unter Verwendung von Elektrizität der aussichtsreichte Weg zur Effizienzverbesserung auf der Gesamtflugzeugebene. Durch die Elektrifizierung wurden die einzelnen Geräte zwar zuverlässiger und energieeffizienter als je zuvor aber gleichzeitig erheblich schwerer, sodaß ein signifikanter Verlust an Nutzlasten auf Gesamtflugzeugebene hervorgerufen wird. Das Hauptziel der vorliegenden Arbeit war es, ein Schwerlast-EHA-System mit mehrfachen Betätigungseinheiten durch Einführung von umfassenden Perspektiven zu optimieren. Durch Einführung der sog. ganzheitlichen Leichtbauweise demonstriert die Arbeit, wie das Subsystem mit mehreren Endgeräten ultimativ optimiert werden kann, ohne Abstriche an Gewichtsbilanz u/o Kompromiß mit der Energieeffizienz zu machen. Um eine wahrhaftige Optimierung, d.h. die Erreichung des ultimativen, Nonplusultra-Verbesserungslevels zu erreichen, wurden die Systemarchitektur, die Hardware und die Operationsmethode interaktiv kombiniert, wobei die besondere Aufmerksamkeit auf die interaktiven, zur Verbesserung führenden Einflüsse gelegt wurde. Die Minimierung des Energieverbrauchs und die ultimative Gewichtsoptimierung gleichzeitig können erreicht werden, wenn die physikalischen Zusammenhänge zwischen den involvierten Subsystemen verstanden und ihre verborgenen Potentiale ausgenutzt werden. Der einzige und vernünftige Weg zur Erreichung der ultimativen Optimierung eines Betätigungssystems ist eine allumfassende Betrachtung, also eine ganzheitliche Betrachtungs- bzw. Vorgehensweise.
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Abid, Fatma. "Contribution à la robustesse et à l'optimisation fiabiliste des structures Uncertainty of shape memory alloy micro-actuator using generalized polynomial chaos methodUncertainty of shape memory alloy micro-actuator using generalized polynomial chaos method Numerical modeling of shape memory alloy problem in presence of perturbation : application to Cu-Al-Zn-Mn specimen An approach for the reliability-based design optimization of shape memory alloy structure Surrogate models for uncertainty analysis of micro-actuator." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR24.
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La conception des ouvrages économiques a suscité de nombreux progrès dans les domaines de la modélisation et de l’optimisation, permettant l’analyse de structures de plus en plus complexes. Cependant, les conceptions optimisées sans considérer les incertitudes des paramètres, peuvent ne pas respecter certains critères de fiabilité. Pour assurer le bon fonctionnement de la structure, il est important de prendre en considération l’incertitude dès la phase de conception. Il existe plusieurs théories dans la littérature pour traiter les incertitudes. La théorie de la fiabilité des structures consiste à définir la probabilité de défaillance d’une structure par la probabilité que les conditions de bon fonctionnement ne soient pas respectées. On appelle cette étude l’analyse de la fiabilité. L’intégration de l’analyse de fiabilité dans les problèmes d’optimisation constitue une nouvelle discipline introduisant des critères de fiabilité dans la recherche de la configuration optimale des structures, c’est le domaine de l’optimisation fiabiliste (RBDO). Cette méthodologie de RBDO vise donc à considérer la propagation des incertitudes dans les performances mécaniques en s’appuyant sur une modélisation probabiliste des fluctuations des paramètres d’entrée. Dans ce cadre, ce travail de thèse porte sur l’analyse robuste et l’optimisation fiabiliste des problèmes mécaniques complexes. Il est important de tenir compte des paramètres incertains du système pour assurer une conception robuste. L’objectif de la méthode RBDO est de concevoir une structure afin d’établir un bon compromis entre le coût et l’assurance de fiabilité. Par conséquent, plusieurs méthodes, telles que la méthode hybride et la méthode optimum safety factor, ont été développées pour atteindre cet objectif. Pour remédier à la complexité des problèmes mécaniques complexes comportant des paramètres incertains, des méthodologies spécifiques à cette problématique, tel que les méthodes de méta-modélisation, ont été développées afin de bâtir un modèle de substitution mécanique, qui satisfait en même temps l’efficacité et la précision du modèleThe design of economic system leads to many advances in the fields of modeling and optimization, allowing the analysis of structures more and more complex. However, optimized designs can suffer from uncertain parameters that may not meet certain reliability criteria. To ensure the proper functioning of the structure, it is important to consider uncertainty study is called the reliability analysis. The integration of reliability analysis in optimization problems is a new discipline introducing reliability criteria in the search for the optimal configuration of structures, this is the domain of reliability optimization (RBDO). This RBDO methodology aims to consider the propagation of uncertainties in the mechanical performance by relying on a probabilistic modeling of input parameter fluctuations. In this context, this thesis focuses on a robust analysis and a reliability optimization of complex mechanical problems. It is important to consider the uncertain parameters of the system to ensure a robust design. The objective of the RBDO method is to design a structure in order to establish a good compromise between the cost and the reliability assurance. As a result, several methods, such as the hybrid method and the optimum safety factor method, have been developed to achieve this goal. To address the complexity of complex mechanical problems with uncertain parameters, methodologies specific to this issue, such as meta-modeling methods, have been developed to build a mechanical substitution model, which at the same time satisfies the efficiency and the precision of the model
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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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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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Roussel, Michael. "Intégration sur silicium et caractérisation de films minces de polyuréthane nanocomposite pour le développement de micro-actionneurs MEMS électrostrictifs." Thesis, Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0135/document.
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Ce travail de thèse s'inscrit dans le cadre général du développement de micro-actionneurs MEMS, à bas coût et de technologie simple, pour de futures applications dans le domaine de la microfluidique, notamment. La motivation de ce travail est d'évaluer la faisabilité d'un micro-actionneur électrostricitf à base de film mince polymère électroactif nanocomposite. Le polyuréthane, chargé en nanoparticules de carbone ou carbure de fer, encore peu étudié mais aux propriétés électrostrictives prometteuses, est choisi comme matériau à intégrer dans une filière MEMS silicium classique. Le premier chapitre dresse un état de l'art sur les actionneurs MEMS, présente les différentes familles de polymères électroactifs et définit ce qu'est l'électrostriction. Le second chapitre est consacré à l'intégration sur silicium de films minces de polyuréthane et au développement de différentes structures de tests. L'accent est mis sur la levée de plusieurs verrous technologiques. Le chapitre trois présente les méthodes de caractérisations mécaniques et électriques et les résultats obtenus sur films purs et nanocomposites. Le quatrième et dernier chapitre concerne la réalisation et la caractérisation de premiers démonstrateurs MEMS. Ces micro-actionneurs sont caractérisés de manière statique et dynamiqueThis thesis is part of the general development of MEMS microactuators, low cost and simple technology for future applications in the domain of microfluidics. The motivation of this work is to evaluate the feasibility of an electrostrictive microactuator based on electroactive nanocomposite polymer thin films. Polyurethane, loaded with carbon or iron carbide nanoparticles is chosen to be integrated in a conventional silicon MEMS process. The first chapter provides a state of the art of MEMS actuators, presents the different families of electroactive polymers and defines what is electrostriction. The second chapter is devoted to the integration of polyurethane thin films on silicon and to the development of different mechanical and electrical test structures. The emphasis is on identifying and overcoming technological barriers. Chapter three presents the mechanical and electrical characterization methods and the obtained results for pure and nanocomposites films. The fourth and final chapter concerns the realization and the static and dynamic characterizations of first MEMS demonstrators
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Rydén, Gustav, and Fredrik Anarp. "Beräkningsmodell för slagtider av pneumatiska manöverdon : En experimentell och teoretisk studie av beteendet för pneumatiska cylindrar samt manöverdon." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166356.
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Denna rapport redogör framtagningen av en beräkningsmodell för slagtider av pneumatiska cylindrar och manöverdon. Slagtiderna för ett manöverdon kan bestämmas genom experimentella tester. För att underlätta och minska tiden som krävs i samband med testerna skapas en beräkningsmodell som presenterar teoretiska värden för slagtiderna. Denna beräkningsmodell stämmer kvalitativt överens med de experimentella tester som också genomförs i detta arbete. Testerna genomförs först på en enkel pneumatisk cylinder vilket bidrar till kunskaper om slagkarakteristik och slagtider. Denna kunskap är till hjälp för utveckling av beräkningsmodellen. Under testerna mäts bland annat slagtid, kammartryck och kolvens förflyttning vid en mängd olika driftförhållanden. Testerna visar att en av de mest kritiska parametrarna för beräkningsmodellen är C-värdet, en parameter som beskriver flödeskarakteristiken för pneumatiska komponenter. För att få beräkningsmodellen att fungera väl behöver ett så korrekt C-värde som möjligt användas. Beräkningsmetodiken består i stora drag av samband för fyllning och tömning av pneumatiska volymer samt tryckförändringar i cylinderkamrarna vid kompression och expansion. Med en kombination av dessa ekvationer är det möjligt att beräkna slagtiden. Eftersom beräkningsmodellen vill hållas relativt enkel görs ett antal antaganden om systemets parametrar. Dessa antaganden utvärderas efter deras påverkan på slagtiden. Validering mot experimentella resultat visar att beräkningsmodellen generellt fungerar bättre vid höga matningstryck och kritiska flöden. När matningstrycket är lågt och underkritiska flöden erhålls påverkas slagtiden av många fler parametrar, vilket gör att beräkningsmodellen får något sämre precision. Detta resultat är inte helt oväntat eftersom sambandet för kritiskt flöde är relativt enkelt.This thesis work describes the development of a calculation model for stroke times of pneumatic cylinders and actuators. The stroke time of an actuator can be determined by experimental tests. To facilitate and reduce the time required in connection with the tests, a calculation model is created which presents theoretical values of the stroke time. This calculation model is qualitatively consistent with the experimental tests carried out in this work. The tests are first carried out on a simple pneumatic cylinder, which contributes to knowledge of stroke characteristics and stroke times. This knowledge is helpful for the development of the calculation model. During the tests the stroke time, chamber pressure and piston movement are measured in a variety of operating conditions. The tests show that one of the most critical parameters for the calculation model is the C value, a parameter that describes the flow characteristics of pneumatic components. To make the calculation model reliable, a reasonable C value need to be used. The calculation method consists largely of equations for filling and emptying of pneumatic volumes as well as pressure changes in the cylinder chambers during compression and expansion. With a combination of these equations it is possible to calculate the stroke time. Since the calculation model wants to be kept relatively simple, several assumptions are made about parameters in the system. These assumptions are evaluated according to their potential and impact on the stroke time. Validation experiments show that the calculation model generally works better at high supply pressures and critical flows. When the supply pressure is low and subcritical flow are obtained, the stroke time is affected by many more parameters, which lower the precision of the calculation model. This result is not entirely unexpected since the critical flow equations are relatively simple.