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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Tuning of PID Controllers by £h-Sensitivity

Lien, I-Sheng 16 August 2001 (has links)
Since uncertainty exists inevitably in control systems, it is questionable whether the controller, designed to compensate a nominal plant well, still guarantees the criteria of robust stability and robust H¡Û performance for the perturbed plant. In this thesis, controller parameters tuning based on the sensitivity concept of structured singular value, called £g-sensitivity, will be adopted to do the parameter adjustment so that, when the influence of uncertainty is considered, the robust stability and robust performance properties of the nominal closed-loop system will be preserved. In view of the time consuming effect of numerical computation and the misjudgment due to discontinuity problem involved in the £g-sensitivity analysis, this thesis proposes the sensitivity concept of skewed structured singular value, called £h-sensitivity, to remedy these drawbacks. Finally, the feasibility of the £h-sensitivity based controller parameters tuning technique is verified by the simulation results of two examples.
112

Design of Variable Structure Controllers for Perturbed Descriptor Systems

Chen, Chang-Chun 30 June 2003 (has links)
Based on the Lyapunov stability theorem, two different variable structure controllers are proposed in this thesis for two different classes of multi-variable descriptor systems subject to matched nonlinear perturbations. The integral variable structure controller is proposed first for solving the stabilization problems, and model reference variable structure controller is the second for solving the state tracking problems. Both proposed control schemes can guarantee the trajectories of the controlled systems to lie in the sliding surface from initial time, so that the properties of regularity, impulse free, and stability can be obtained. Two numerical examples are given for demonstrating the feasibility of the proposed control schemes.
113

Maximum power tracking control scheme for wind generator systems

Mena Lopez, Hugo Eduardo 10 October 2008 (has links)
The purpose of this work is to develop a maximum power tracking control strategy for variable speed wind turbine systems. Modern wind turbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor speed measurements as control variable inputs. The dependence on the accuracy of the measurement devices makes the controller less reliable. The proposed control scheme is based on the stiff system concept and provides a fast response and a dynamic solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier, a dc/dc boost converter, a current controlled voltage source inverter, and a microcontroller that commands the dc/dc converter to control the generator for maximum power extraction. The microcontroller will also be able to control the current output of the three-phase inverter. In this work, the aerodynamic characteristics of wind turbines and the power conversion system topology are explained. The maximum power tracking control algorithm with a variable step estimator is introduced and the modeling and simulation of the wind turbine generator system using the MATLAB/SIMULINK® software is presented and its results show, at least in principle, that the maximum power tracking algorithm developed is suitable for wind turbine generation systems.
114

Implementation of Hierarchical Architecture of Basic Memory Modules

Yang, Shang-da 11 September 2008 (has links)
In system-on-chip designs, memory designs store data to be accessed by processing modules. Memory access time can affect overall system performance significantly. In this research, we implemented a configurable architecture of a basic memory module and its design composition, including memory interface, memory controller, memory array, row buffer, row decoder and column decoder. We explore various memory module designs. Utilizing the configurable architecture, we can effectively reduce design time and improve access time of memory module designs. We also realized these functionalities in SystemC language and performed configurability experiments.
115

SmartMedia-controller på chip / SmartMedia controller on chip

Bengtsson, Carl Johan January 2002 (has links)
<p>This report deals with the design of a controller for SmartMedia™ flash memory cards, based on a hardware description found in the SmartMedia™ Interface Library - SMIL. </p><p>The design was made on logic gate level, using standard cells in OrCAD Capture. After simulation of the design in PSpice A/D, it was exported as an EDIF netlist, which was used to make a chip layout in L-Edit, a layout tool for making integrated circuits. The layout was made using a method called Standard Place and Route - SPR, where the layout tool places standard cells from a library and connects them according to the EDIF netlist. </p><p>A netlist which could be simulated in PSpice was extracted from the finished chip layout to verify that the function of the design was the same as before the transition from schematic to layout. </p><p>The standard cells in the library used to make the chip layout have to meet certain criteria in order for both SPR and extraction to work and this is also discussed.</p>
116

Modelling and control of a Buck converter

Yang, Shun January 2011 (has links)
DC/DC buck converters are cascaded in order to generate proper load voltages. Rectified line voltage is normally converted to 48V, which then, by a bus voltage regulating converter also called the line conditioner converter, is converted to the bus voltage, e.g. 12V. A polynomial controller converter transforms the 12V into to a suitable load voltage, a fraction of or some few voltages. All cascaded converters are individually controlled in order to keep the output voltage stable constant. In this presentation focusing on the polynomial controller converter implemented as Ericsson’s buck converter BMR450. In this paper modeling, discretization and control of a simple Buck converter is presented. For the given DC-DC-Converter-Ericsson BMR 450 series, analyzing the disturbance properties of a second order buck converter controllers by a polynomial controller. The project is performed in Matlab and Simulink. The controller properties are evaluated for measurement noise, EMC noise and for parameter changes. / +46-762795822
117

Ökad förståelse för controllerollen : Dess styrning, dubbelsidighet och funktion inomorganisationsstrukturen / A deeper understanding of the controller role : Its control, dual responsibilities and function within theorganizational structure

Holmert, Josefine, Juvon, Jacob January 2015 (has links)
The controller role is a principal part of all bigger organizations and through the years ithas been discussed whether the controllers main responsibility is towards the highermanagement or if its priorities should be towards the local management. The differentinterests can in its turn be incompatible which leads to the view that the controller canbe seen as having problematic dual responsibilities. As a result the role has been definedin many different ways in regards to its involvement in management control as well asits work content. A problematic discussion regarding the dual responsibilities arisewhen a controller is to balance commitments towards both the higher management aswell as its own division, and also the handling of these responsibilities within thecompany. The aim of the study is to shed a light on, and increase the understanding, of thecontroller role in a Swedish, multinational industrial company regarding itsresponsibilities and work content. A contributing aim of the study is to create anunderstanding of the interplay between the controller, its organizational counterpartsand the management of these interactions. The study is conducted with a qualitative method due to an interest towards a greaterunderstanding of the controller role. To better comprehend the controllers’ ownunderstandings of the role, a case study with six semi-structured interviews have beenconducted with active controllers. The results of the study indicate that the role of the controller isn’t affected by the issuesregarding its dual responsibilities as the discourse suggest. A close cooperation with thedivision as well as a hierarchical distance from the higher management results in thecontroller having a supporting role rather than a controlling one. Finally the study pointsto a great deal of significance regarding the controller role and its placement within theorganizational structure of the company. / Controllerrollen utgör en central del inom alla större organisationer och med tiden hardet inom litteraturen diskuterats huruvida controllerrollens huvudsakliga ansvar är atttillgodose intresset hos den högre ledningen inom en organisation eller om den iställetska prioritera den lokala ledningens intressen. Dessa olika intressen kan i sin tur varaoförenliga vilket leder till att controllern på så sätt kan ses ha en dubbelsidig roll medavseende på dess ansvarsområden. Controllern har som en följd beskrivits med enmängd olika benämningar inom litteraturen och det råder således en övergripandeproblematik kring controllerrollen och forskningen på området är inte överens huruvidadubbelsidigheten även är ett problem för controllern i praktiken. Syftet med studien är att skapa en ökad förståelse för controllerrollen inom ett svenskt,multinationellt industriföretag med avseende på controllerns arbetsinnehåll ochansvarsfördelning. Syftet med studien är även att belysa samspelet mellancontrollerrollen och de olika relationer som råder i anslutning till rollen. Undersökningen utgår från ett kvalitativt metodsynsätt då en ökad förståelse förcontrollerrollen är av intresse. För att fånga controllerns egen uppfattning av rollengenomfördes en fallstudie bestående av sex semistrukturerade intervjuer medverksamma controllers. Resultaten av studien indikerar att controllerrollen inte innehar problematik angåendedubbelsidigheten på samma sätt som den beskrivs i den rådande diskussionen påområdet. Genom ett nära samarbete med den egna divisionen och ett hierarkiskt avstånd till den högre ledningen innehar controllern snarare en stödjande funktion än enstyrande. Avslutningsvis pekar studiens resultat på den stora vikt som ligger påorganisationsstrukturen och controllerns placering inom denna.
118

Vad prioriteras, eleverna eller budgeten? : En fallstudie av en kommunal verksamhet

Lagerholm, Alexandra, Lindgren, Hedvig January 2012 (has links)
Sammanfattning       Ämnesfördjupande arbete Ekonomihögskolan, Civilekonomprogrammet, Controllerfördjupningen Linnéuniversitetet, Växjö Titel: Vad prioriteras, eleverna eller budgeten? - En fallstudie av en kommunal verksamhet Författare: Alexandra Lagerholm &amp; Hedvig Lindgren Handledare: Anders Jerreling Examinator: Fredrik Karlsson En begränsad ekonomi och ökade statliga krav har bidragit till att kommuner idag tvingas prioritera hårdare än tidigare. Dessa prioriteringar förtydligas i kommunens budget. Ett flertal kommunpolitiker har uppmärksammat en omfattande konflikt mellan kommunens budget och de lagar de tvingas följa till förmån för bland annat elevers hälsa och uppfyllande av kunskapskrav. Om kommunen ska klara sig med sina begränsade ekonomiska resurser, med minskade skatteintäkter, kommer det leda till att de tvingas bryta mot lagar. Skolorna kan inte leva upp till de krav som ställs i skollagen, om de ska följa budgeten. Arbetets syfte är att beskriva och förklara hur budgetprocessen är uppbyggd i en kommun, för att vidare undersöka vilka prioriteringar som görs om det uppstår konflikter mellan lagar och kommunens budget. Avsikten är att utifrån detta analysera vilken styreffekt budgeten har i en kommunal verksamhet. Studien genomförs som en kvalitativ studie i form av en fallstudie av Sölvesborgs kommun. Semi-strukturerade intervjuer med ekonomer, nämndordförande och en rektor inom kommunen utgör studiens empiriska underlag. Slutsatsen av studien är att budgetens styreffekt i Sölvesborgs kommun är svag, till stor del på grund av de lagar som styr en kommunal verksamhet. Lagarna stämmer inte alltid överens med budgetens resursramar, vilket får till följd att budgeten prioriteras bort till förmån för lagen.
119

New-generation Fully Programmable Controller for Functional Electrical Stimulation Applications

Agnello, Davide 11 August 2011 (has links)
Functional electrical stimulation (FES) systems have been developed to help restore various neuromuscular functions in individuals with neurological disorders leading to paralysis. Most of the current FES systems are designed for specific neuroprosthesis applications (i.e., walking, grasping, bladder voiding, coughing, etc.) and when one intends to use them in other custom made applications they are very limited due to a lack of functionality and flexibility in hardware and programmability. This prevents effective and efficient development of customized neuroprostheses. Research and development efforts at the Rehabilitation Engineering Laboratory at the University of Toronto were being carried out with an objective to produce a new, fully programmable and portable FES system. This thesis presents a novel proof-of-concept prototype controller for use in the new FES system. The controller subsystem manages and controls the overall FES system including the real-time decoding and execution of stimulation, data acquisition, external systems interfaces and user interface.
120

Design and FPGA implementation of a log-domain high-speed fuzzy control system

Razib, Md Ali Unknown Date
No description available.

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