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1
Hughes, Christopher Scott. "Variable Sampling Rate Control Charts for Monitoring Process Variance." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/37643.
Full textAbstract:
Industrial processes are subject to changes that can adversely
affect product quality. A change in the process that increases
the variability of the output of the process causes the output to
be less uniform and increases the probability that individual
items will not meet specifications.
Statistical control charts for monitoring process variance can be
used to detect an increase in the variability of the output of a
process so that the situation can be repaired and product
uniformity restored. Control charts that increase the sampling
rate when there is evidence the variance has changed gather
information more quickly and detect changes in the variance more
quickly (on average) than fixed sampling rate procedures. Several
variable sampling rate procedures for detecting increases in the
process variance will be developed and compared with fixed
sampling rate methods.
A control chart for the variance is usually used with a separate
control chart for the mean so that changes in the average level
of the process and the variability of the process can both be
detected. A simple method for applying variable sampling rate
techniques to dual monitoring of mean and variance will be
developed. This control chart procedure increases the sampling
rate when there is evidence the mean or variance has changed so
that changes in either parameter that will negatively impact
product quality will be detected quickly.Ph. D.
2
Ginsberg, David W. "Variable structure control systems." Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/18787.
Full textAbstract:
The primary aims of this thesis, is to provide a body of knowledge on variable structure system theory and to apply the developed design concepts to control practical systems. It introduces the concept of a structure. The main aim in designing variable structure controllers, is to synthesize a variable structure system from two or more single structure systems, in such a way that the ensuing system out-performs its component structures. When a sliding mode is defined, the ensuing closed loop behaviour of the system is invariant to plant parameter changes and external disturbances. A variable structure controller was designed for a servo motor and successfully applied to the system. In practice, the phase plane representative point does not slide at infinite frequency with infinitesimal amplitude along the switching surface(s). Thus, the concept of a quasi-sliding regime was introduced. For high performance system specifications, the phase plane representative point could cycle about the origin. In some instances, sliding could be lost. For high speed applications, a novel design modification ensured that the system did not lose sliding. In addition, the controller could track a rapidly changing set point. Successful results support the developed theory.
3
Amin, Raid Widad. "Variable sampling interval control charts." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/82617.
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Process control charts are widely used to display sample data from a process for purposes of determining whether a process is in control, for bringing an out-of-control process into control, and for monitoring a process to make sure that it stays in control. The usual practice in maintaining a control chart is to take samples from the process at fixed length sampling intervals. This research investigates the modification of the standard practice where the sampling interval or time between samples is not fixed but can vary depending on what is observed from the data. Variable sampling interval process control procedures are considered for monitoring the outcome of a production process. The time until the next sample depends on what is being observed in the current sample. Sampling is less frequent when the process is at a high level of quality and vise versa. Properties such as the average number of samples until signal, average time to signal and the variance of the time to signal are developed for the variable sampling interval Shewhart and cusum charts. A Markov chain is utilized to approximate the average time to signal and the corresponding variance for the cusum charts. Properties of the variable sampling interval Shewhart chart are investigated through Renewal Theory and Markov chain approaches for the cases of a sudden and gradual shift in the process mean respectively. Also considered is the case of a shift occurring in the time between two samples without the simplifying assumption that the process mean remains the same from time zero onward. For such a case, the adjusted time to signal is developed for both the Shewhart and cusum charts in addition to the variance of the adjusted time to signal.
Results show that the variable sampling interval control charts are considerably more efficient than the corresponding fixed sampling interval control charts. It is preferable to use only two sampling intervals which keeps the complexity of the chart to a reasonable level and has practical implications. This feature should make such charts very appealing for use in industry and other fields of application where control charts are used.Ph. D.
4
Wang, Longke. "Adaptive control of variable displacement pumps." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43654.
Full textAbstract:
Fluid power technology has been widely used in industrial practice; however, its energy efficiency became a big concern in the recent years. Much progress has been made to improve fluid power energy efficiency from many aspects. Among these approaches, using a valve-less system to replace a traditional valve-controlled system showed eminent energy reduction. This thesis studies the valve-less solution-pump displacement controlled actuators- from the view of controls background.
Singular perturbations have been applied to the fluid power to account for fluid stiffness; and a novel hydraulic circuit for single rod cylinder has been presented to increase the hydraulic circuit stabilities. Recursive Least Squares has been applied to account for measurement noise thus the parameters have fast convergence rate, square root algorithm has further applied to increase the controller's numerical stability and efficiency. It was showed that this technique is consistent with other techniques to increase controller's robustness. The developed algorithm is further extended to a hybrid adaptive control scheme to achieve desired trajectory tracking for general cases.
A hardware test-bed using the invented hydraulic circuit was built up. The experimental results are presents and validated the proposed algorithms and the circuit itself. The end goal of this project is to develop control algorithms and hydraulic circuit suitable for industrial practice.
5
Reay, Donald S. "Variable structure control of industrial robots." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257514.
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6
Sethuraman, Shanthi. "Variable sampling interval control strategies for a process control problem." Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/40313.
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7
Woodham, Catherine Anne. "Eigenvalue placement for variable structure control systems." Thesis, University of Sheffield, 1992. http://etheses.whiterose.ac.uk/14793/.
Full textAbstract:
Variable Structure Control is a well-known solution to the problem of deterministic control of uncertain systems, since it is invariant to a class of parameter variations. A central feature of vsc is that of sliding motion, which occurs when the system state repeatedly crosses certain subspaces in the state space. These subspaces are known as sliding hyperplanes, and it is the design of these hyperplanes which is considered in this thesis. A popular method of hyperplane design is to specify eigenvalues in the left-hand half-plane for the reduced order equivalent system, and to design the control matrix to yield these eigenvalues. A more general design approach is to specify some region in the left-hand half-plane within which these eigenvalues must lie. Four regions are considered in this thesis, namely a disc, an infinite vertical strip, a sector and a region bounded by two intersecting sectors. The methods for placing the closed-loop eigenvalues within these regions all require the solution of a matrix Riccati equation : discrete or continuous, real or complex. The choice of the positive definite symmetric matrices in these Riccati equations affects the positioning of the eigenvalues within the region. suitable selection of these matrices will therefore lead to real or complex eigenvalues, as required, and will influence their position within the chosen region. The solution of the hyperplane design problem by a more general choice of the closed-loop eigenvalues lends itself to the minimization of the linear part of the control. A suitable choice of the position of the eigenvalues within the required region enables either the 2-norm of the linear part of the control, or the condition number of the linear feedback to be minimized. The choice of the range space eigenvalues may also be used, more effectively, in this minimization.
8
Yallapragada, Subbarao. "Variable structure control and output feedback systems." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/13303.
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9
Ingvast, Johan. "Quadruped robot control and variable leg transmissions." Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-600.
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Licari, John. "Control of a variable speed wind turbine." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/46516/.
Full textAbstract:
Stop signal task of response inhibition, I find that response inhibition (stopping) is slowed in the presence of angry facial expressions, and such slowing is greater in individuals high in trait neuroticism. Further, as predicted, the influence of neuroticism is moderated by individual differences in emotion regulation, such that good emotion regulation ‘buffers’ the impact of neuroticism. The implications of these findings for current cognitive models of threat-processing are discussed.
11
Eriksson, Ludvig, and Ilango Lourdudoss. "SKUGGA: Sunglasses with Variable Electronic Tint Control." Thesis, KTH, Maskinkonstruktion (Inst.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-198153.
Full textAbstract:
Tillsammans med den svenska design och ingenjörsbyrån, Top Notch Design & Engineering, har ett par solglasögon, under namnet SKUGGA, med elektriskt justerbar toning tagits fram. Ett av målen var att förverkliga en teknologiskt avancerad produkt med en icke-teknisk design. Den slutgiltiga produkten bestod av flera tekniska komponenter och funktioner, som Bluetooth, ljussensor, UV-mätare och Induktionsladdning (Trådlös laddning). Den justerbara toningen är möjligt tack vare LC Tecs Liquid Crystal (LC) filter. Med en elektrisk spänning kan ljusinsläppet (transmittansen) justeras och nivån bestäms av spänningens styrka. Även om all teknik som används i solglasögonen redan finns är användningsområdet nytt och därför ses produkten som ny. Solglasögonen har inga knappar eller avancerade inställningar och kontrolleras med en telefonapplikation genom Bluetooth. I det automatiska läget, följer toningen av solglasögonen omgivningens ljusstyrka med hjälp av en ljussensor. I manuellt läge kan toningen bestämmas med hjälp av telefonapplikationens reglage och anpassas till användarens ljuskänslighet. Genom applikationen finns även möjligheten att logga och hålla koll på daglig UV exponering. SKUGGA har ett 100 % UV filter som skyddar ögonen mot både UVA- och UVB-strålning. Eftersom användare med synfel var en stor målgrupp, designades solglasögonen för möjligheten att sätta in linser med styrka. Två modeller togs fram, båda med en könsneutral design för att tilltala både män och kvinnor. Projektet resulterade i en Kickstarter kampanj med ett mål på 1 MSEK. Tråkigt nog så togs beslutet att avsluta kampanjen i förtid efter att ha samlat in 15 % av målet. Därför kunde inte den slutgiltiga produkten bli utvärderad.Together with the Swedish design and engineering agency, Top Notch Design & Engineering, a pair of sunglasses, named SKUGGA, with variable electronic tint control was developed. One ofthe goals was to realize a high-tech product with a non-tech design. The finished product included several technical features and components, such as Bluetooth, ambient light sensor, UV meter and induction charging (wireless charging). The electronic tint is possible due to LC Tec’s LC (Liquid crystal) filter. When applying an external voltage the transmittance change dependently to the amount of voltage applied. Even though all technologies exist the product itself can be considered as new. The sunglasses have no buttons or complex settings and are controlled by a smartphone application through Bluetooth. When in auto mode, the tint of the sunglasses can be adjusted according to the current lightning conditions with help of the ambient light sensor. In manual mode, the user can modify the settings in the smartphone application so the tint will customized according to the user’s light sensitivity. Inside the smartphone application it is also possible to log and keep track of the daily UV exposure. SKUGGA has a 100 % UV filter that protects the eyes from rays, both UVA and UVB. Since users of prescriptions lenses were a major target group, the frames were design to make it possible to integrate prescription lenses if needed. Two different models were developed, both with unisex design to appeal both sexes. The project resulted in a Kickstarter campaign with a funding goal of 1 MSEK. Unfortunately, the campaign was cancelled after achieving 15% of the goal. Therefore the final product could not be evaluated.
12
Mostafa, Osama A. "Variable structure control system maneuvering of spacecraft /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487267546980772.
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13
Maggiore, Manfredi. "Output feedback control : a state-variable approach /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488203552780374.
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Ramtharan, Gnanasambandapillai. "Control of variable speed wind turbine generators." Thesis, University of Manchester, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556174.
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Shekhar, Rohan Chandra. "Variable horizon model predictive control : robustness and optimality." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/244210.
Full textAbstract:
Variable Horizon Model Predictive Control (VH-MPC) is a form of predictive control that includes the horizon length as a decision variable in the constrained optimisation problem solved at each iteration. It has been recently applied to completion problems, where the system state is to be steered to a closed set in finite time. The behaviour of the system once completion has occurred is not considered part of the control problem. This thesis is concerned with three aspects of robustness and optimality in VH-MPC completion problems. In particular, the thesis investigates robustness to well defined but unpredictable changes in system and controller parameters, robustness to bounded disturbances in the presence of certain input parameterisations to reduce computational complexity, and optimal robustness to bounded disturbances using tightened constraints. In the context of linear time invariant systems, new theoretical contributions and algorithms are developed. Firstly, changing dynamics, constraints and control objectives are addressed by introducing the notion of feasible contingencies. A novel algorithm is proposed that introduces extra prediction variables to ensure that anticipated new control objectives are always feasible, under changed system parameters. In addition, a modified constraint tightening formulation is introduced to provide robust completion in the presence of bounded disturbances. Different contingency scenarios are presented and numerical simulations demonstrate the formulation’s efficacy. Next, complexity reduction is considered, using a form of input parameterisation known as move blocking. After introducing a new notation for move blocking, algorithms are presented for designing a move-blocked VH-MPC controller. Constraints are tightened in a novel way for robustness, whilst ensuring that guarantees of recursive feasibility and finite-time completion are preserved. Simulations are used to illustrate the effect of an example blocking scheme on computation time, closed-loop cost, control inputs and state trajectories. Attention is now turned towards mitigating the effect of constraint tightening policies on a VH-MPC controller’s region of attraction. An optimisation problem is formulated to maximise the volume of an inner approximation to the region of attraction, parameterised in terms of the tightening policy. Alternative heuristic approaches are also proposed to deal with high state dimensions. Numerical examples show that the new technique produces substantially improved regions of attraction in comparison to other proposed approaches, and greatly reduces the maximum required prediction horizon length for a given application. Finally, a case study is presented to illustrate the application of the new theory developed in this thesis to a non-trivial example system. A simplified nonlinear surface excavation machine and material model is developed for this purpose. The model is stabilised with an inner-loop controller, following which a VH-MPC controller for autonomous trajectory generation is designed using a discretised, linearised model of the stabilised system. Realistic simulated trajectories are obtained from applying the controller to the stabilised system and incorporating the ideas developed in this thesis. These ideas improve the applicability and computational tractability of VH-MPC, for both traditional applications as well as those that go beyond the realm of vehicle manœuvring.
16
Yoon, Hyungjoo. "Spacecraft Attitude and Power Control Using Variable Speed Control Moment Gyros." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4850.
Full textAbstract:
A Variable Speed Control Moment Gyro (VSCMG) is a recently
introduced actuator for spacecraft attitude control.
As its name implies, a VSCMG is essentially a single-gimbal
control moment gyro (CMG) with a flywheel allowed to have variable spin
speed. Thanks to its extra degrees of freedom, a
VSCMGs cluster can be used to achieve additional objectives, such
as power tracking and/or singularity avoidance, as well as
attitude control.
In this thesis, control laws for an integrated power/attitude
control system (IPACS) for a satellite using VSCMGs are
introduced.
The power tracking objective is achieved by storing or releasing the kinetic energy
in the wheels. The proposed control algorithms perform both the attitude
and power tracking goals simultaneously.
This thesis also provides a singularity analysis and avoidance method using
CMGs/VSCMGs. This issue is studied for both the cases of attitude tracking with and without a power
tracking requirement. A null motion method to avoid singularities is
presented, and a criterion is developed to determine the momentum region
over which this method will successfully avoid singularities.
The spacecraft angular velocity and attitude control problem using a single
VSCMG is also addressed.
A body-fixed axis is chosen to
be perpendicular to the gimbal axis, and it is controlled to aim at an arbitrarily given inertial direction,
while the spacecraft angular velocity is stabilized.
Finally, an adaptive control algorithm for the spacecraft attitude tracking in case
when the actuator parameters, for instance the spin axis directions, are uncertain is developed.
The equations of motion in this case
are fully nonlinear and represent a Multi-Input-Multi-Output (MIMO) system.
The smooth projection algorithm is applied to keep the parameter estimates inside
a singularity-free region.
The design procedure can also be easily applied to general MIMO dynamical systems.
17
Dridi, Hocine. "Microprocessor control of a DC variable speed drive." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319962.
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Milman, Ruth. "Adaptive backstepping control of the variable reluctance motor." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28848.pdf.
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Whittington, William Grant. "Cooperative control of systems with variable network topologies." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49107.
Full textAbstract:
Automation has become increasingly prevalent in all forms of society. Activities that are too difficult for a human or to dangerous can be done by machines which do not share those downsides. In addition, tasks can be scheduled more precisely and accurately. Increases in the autonomy have allowed for a new level of tasks which are completed by teams of automated agents rather than a single one, called cooperative control. This has many benefits; but comes at the cost of increased complexity and coordination. The main thrust of research in this field is problem based, considering communication issues as a secondary feature. There is a gap considering problems in which many changes occur as rapidly as communication and the issues that arise as a result. This is the main motivation.
This research presents an approach to cooperative control in highly variable systems and tackles some of the issues present in such a system. One of the most important issues is the communication network itself, which is used as an indicator for how healthy the system is an how well it may react to future changes. Therefore using the network as an input to control allows the system to navigate between conservative and aggressive techniques to improve performance while still maintaining robustness.
Results are based on a test bed designed to simulate a wide variety of problem types based on: network type; numbers of actors; frequency of changes; impact of changes and method of change. The developed control method is compared to the baseline case ignoring cooperation as well as an idealized case assuming perfect system knowledge. The baseline represents sacrifices coordination to achieve a high level of robustness at reduced performance while the idealized case represents the best possible performance. The control techniques developed give a performance at least as good as the baseline case if not better for all simulations.
20
Larbes, Cherif. "Boost modulation : control of AC variable speed drives." Thesis, Lancaster University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304281.
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Biswas, Md Israfil. "Internet congestion control for variable-rate TCP traffic." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=182264.
Full textAbstract:
The Transmission Control Protocol (TCP) has been designed for reliable data transport over the Internet. The performance of TCP is strongly influenced by its congestion control algorithms that limit the amount of traffic a sender can transmit based on end-to-end available capacity estimations. These algorithms proved successful in environments where applications rate requirements can be easily anticipated, as is the case for traditional bulk data transfer or interactive applications. However, an important new class of Internet applications has emerged that exhibit significant variations of transmission rate over time. Variable-rate traffic poses a new challenge for congestion control, especially for applications that need to share the limited capacity of a bottleneck over a long delay Internet path (e.g., paths that include satellite links). This thesis first analyses TCP performance of bursty applications that do not send data continuously, but generate data in bursts separated by periods in which little or no data is sent. Simulation analysis shows that standard TCP methods do not provide efficient support for bursty applications that produce variable-rate traffic, especially over long delay paths. Although alternative forms of congestion control like TCP-Friendly Rate Control and the Datagram Congestion Control Protocol have been proposed, they did not achieve widespread deployment. Therefore many current applications that rely upon User Datagram Protocol are not congestion controlled. The use of non-standard or proprietary methods decreases the effectiveness of Internet congestion control and poses a threat to the Internet stability. Solutions are therefore needed to allow bursty applications to use TCP. Chapter three evaluates Congestion Window Validation (CWV), an IETF experimental specification that was proposed to improve support for bursty applications over TCP. It concluded that CWV is too conservative to support many bursty applications and does not provide an incentive to encourage use by application designers. Instead, application designers often avoid generating variable-rate traffic by padding idle periods, which has been shown to waste network resources. CWV is therefore shown to not provide an acceptable solution for variable-rate traffic. In response to this shortfall, a new modification to TCP, TCP-JAGO, is proposed. This allows variable-rate traffic to restart quickly after an inactive (i.e., idle) period and to effectively utilise available network resources while sending at a lower rate than the available rate (i.e., during an application-limited period). The analysis in Chapter five shows that JAGO provides faster convergence to a steady-state rate and improves throughput by more efficiently utilising the network. TCP-JAGO is also shown to provide an appropriate response when congestion is experienced after restart. Variable-rate TCP traffic can also be impacted by the Initial Window algorithm at the start or during the restart of a session. Chapter six considers this problem, where TCP has no prior indication of the network state. A recent proposal for a larger initial window is analysed. Issues and advantages of using a large IW over a range of scenarios are discussed. The thesis concludes by presenting recommendations to improve TCP support for bursty applications. This also provides an incentive for application designers to choose TCP for variable-rate traffic.
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Lloyd, Simon H. "Variable speed control of a small wind turbine." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/14376.
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An electronic controller has been developed for a wind turbine which uses a passive pitching mechanism and a permanent magnet generator. The turbine rotor is a 3 bladed, down wind horizontal axis design with a diameter of 3.4m. The machine, manufactured by Proven Engineering Ltd., produces 2.2kW at a wind speed of 12m/ s and a rotor speed of 30Orpm. Passive regulation is achieved through a variation of blade pitch controlled by balancing the aerodynamic, centrifugal and spring forces acting on each blade. A production machine has been instrumented and laboratory and field test data collected; from this data a mathematical model has been derived. A power electronic interface (DC-DC booster) was designed and built to transform the generator voltage to a fixed DC voltage. A controlled load is used together with feedback to the booster to set an appropriate load resistance according to operating conditions. Current demand from the generator (used in the control) is derived either from the difference between the rotor speed and a reference speed, or directly as a function of the rotor speed (feed-forward control). This thesis deals with the design and testing of the 3 compensators which govern the wind turbine control using both simulated and measured results. The overall objective of the controller is to maximise the energy yield from the wind turbine, subject to realistic constraints imposed by the power electronic design in the context of this particular design.
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Fleder, Michael (Michael S. ). "Affordance-based control of a variable-autonomy telerobot." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/85221.
Full textAbstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis. "September 2012."
Includes bibliographical references (pages 37-38).
Most robot platforms operate in one of two modes: full autonomy, usually in the lab; or low-level teleoperation, usually in the field. Full autonomy is currently realizable only in narrow domains of robotics-like mapping an environment. Tedious teleoperation/joystick control is typical in military applications, like complex manipulation and navigation with bomb-disposal robots. This thesis describes a robot "surrogate" with an intermediate and variable level of autonomy. The robot surrogate accomplishes manipulation tasks by taking guidance and planning suggestions from a human "supervisor." The surrogate does not engage in high-level reasoning, but only in intermediate-level planning and low-level control. The human supervisor supplies the high-level reasoning and some intermediate control-leaving execution details for the surrogate. The supervisor supplies world knowledge and planning suggestions by "drawing" on a 3D view of the world constructed from sensor data. The surrogate conveys its own model of the world to the supervisor, to enable mental-model sharing between supervisor and surrogate. The contributions of this thesis include: (1) A novel partitioning of the manipulation task load between supervisor and surrogate, which side-steps problems in autonomous robotics by replacing them with problems in interfaces, perception, planning, control, and human-robot trust; and (2) The algorithms and software designed and built for mental model-sharing and supervisor-assisted manipulation. Using this system, we are able to command the PR2 to manipulate simple objects incorporating either a single revolute or prismatic joint.
by Michael Fleder.
M. Eng.
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Dadashnialehi, Ehsan. "Modeling And Control of Variable Speed Wind Turbines." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1356372607.
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Kilander, Johanna, and Madeleine Frisell. "Variable expiration control for an intensive care ventilator." Thesis, Linköpings universitet, Institutionen för medicinsk teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157761.
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Critical care patients are often connected to ventilators, to support or replace their breathing. The ventilators deliver a mixture of gas to the patient by applying a specific volume or pressure, and then the patient exhales passively. This thesis is based of the hypothesis that a slower reduction of the expiration pressure could benefit intensive care patients connected to a ventilator. To enable research within the area, a device which can control the expiration is needed. In this thesis project, an expiration valve was controlled to create different pressure patterns during expiration. To facilitate the research and the usage of the expiration control, an application software was created with the purpose to simulate relevant pressure, flow and volume curves. The prototype is an expiration cassette created for the ventilator Servo-i by Maquet Getinge Group. To enable flexibility, the prototype is external and no information is transmitted from or to the ventilator. The prototype has its own flow and pressure sensors. The different pressure patterns which the prototype uses are designed as a linear decrease and as if a constant resistance was added to the system. The user can also create their own pressure pattern, by deciding 20 pressure points in the duration of two seconds. The simulation application was designed with the ability to simulate the same pressure patterns available with the prototype. By using a lung model, it is possible to simulate the ideal pressure, flow and volume in the lungs which can be expected from the chosen expiration control. During the implementation, two different types of lung models were evaluated in order to determine the specificity required. The prototype was tested with settings which were chosen to challenge the performance of the control. Some problematic areas were detected, such as high pressures or large volumes. However, the prototype was judged to perform well enough to be used in animal trials. The lung model used for the simulation application was a simple model of the lung, consisting of a resistor and a capacitor in series. The simulations were compared with the real system with the purpose to get an indication on the difference between theory and reality. The application presents the expected behavior when using the expiration control. However, it should be kept in mind by the user that the application represents a theoretical model.
26
Zhu, Chaoying. "Induction motor speed sensing and control." Thesis, University of Sussex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358985.
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Goodfellow, David. "Variable speed operation of wind turbines." Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/7822.
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This work describes a control system in which a cycloconverter is connected between the secondary windings of a three phase induction machine and the a. c. mains supply to give variable speed sub- and super –synchronously. In order to control the system smoothly in an asynchronous mode a secondary emf signal generator has been designed, which enables the cycloconverter to operate in synchronism with the emf induced in the secondary windings of the machine. A computer programme has been written which calculates the required firing angles for the cycloconverter to produce secondary current in phase with the secondary emf in the machine. An electronic system has been built which ensures that these firing angles are used by the cycloconverter during actual operation. A cycloconverter has been built, using an effective six phases of mains supply, and has been successfully operated over a range of 20% about synchronous speed in both generating and motoring modes. Results show the ability of the cycloconverter to drive the machine up from standstill as a motor to just below 20% subsynchronous speed. An on-line computer simulation of a wind turbine has been developed which enables an assessment of variable speed generation applied to wind turbines to be achieved. This simulation, in connection with a d. c. machine and thyristor controller, can be used to drive the shaft of the induction machine and assess operation of the cycloconverter control scheme under actual wind turbine operating conditions.
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Myslicki, Stefan Leopold 1953. "A VARIABLE SAMPLING FREQUENCY CUMULATIVE SUM CONTROL CHART SCHEME." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276503.
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This study uses Monte Carlo simulation to examine the performance of a variable frequency sampling cumulative sum control chart scheme for controlling the mean of a normal process. The study compares the performance of the method with that of a standard fixed interval sampling cumulative sum control chart scheme. The results indicate that the variable frequency sampling cumulative sum control chart scheme is superior to the standard cumulative sum control chart scheme in detecting a small to moderate shift in the process mean.
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Kypuros, Javier Angel. "Variable structure model synthesis for switched systems /." Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008373.
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Lewin, Paul Leonard. "Microprocessor control of a switched reluctance motor." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262359.
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Maugham, Robin. "Dilution torque control of a gasoline engine." Thesis, University of Bath, 2002. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268735.
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McKenna, Paul. "Delta operator : modelling, forecasting and control." Thesis, Lancaster University, 1997. http://eprints.lancs.ac.uk/65542/.
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Interest in the delta operator as a tool in the development of robust approaches to modelling and control has been revived in the last decade, principally following the work of Goodwin (1985). The use of this discrete differential operator provides improved numerical properties particularly when modelling or implementing control at high sampling frequencies or under finite wordlength restraints. The delta operator also provides for the alliance of continuous time designs and discrete time application, linking traditional control theory with modern implementation through digital computing. In this thesis, a delta operator Simplified Refined Instrumental Variable (SRIV) approach to model estimation is employed, together with model order identification tools, to provide delta operator models for use in control and forecasting. The True Digital Control (TDC) design theory is adopted to develop a delta operator Proportional-Integral-Plus (PIP) controller. The construction of realisable control filters enables implementation of the PIP controller, the structure of which can prove operationally significant. A number of refinements to the standard PIP controller are developed and applications are presented for engineering and environmental examples. The development of a recursive delta operator Kalman filter is presented and incorporated within a forecasting framework. The resulting algorithm is applied to historical data to generate real time stochastic forecasts of river flows from an effective rainfall-flow model.
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Cho, Gyo-Young. "Multivariate control charts for the mean vector and variance-covariance matrix with variable sampling intervals." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/37242.
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Flores-Cerrillo, Jesus MacGregor John F. "Quality control for batch processes using multivariate latent variable methods /." *McMaster only, 2003.
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Guo, Wei Horn Joseph F. "Flight control design for rotorcraft with variable rotor speed." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4647/index.html.
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Bergström, Andreas. "Torque Modeling and Control of a Variable Compression Engine." Thesis, Linköping University, Department of Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1821.
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The SAAB variable compression engine is a new engine concept that enables the fuel consumption to be radically cut by varying the compression ratio. A challenge with this new engine concept is that the compression ratio has a direct influence on the output torque, which means that a change in compression ratio also leads to a change in the torque. A torque change may be felt as a jerk in the movement of the car, and this is an undesirable effect since the driver has no control over the compression ratio.
The aim of this master's thesis work is to develop a torque control strategy for the SAAB variable compression engine. Where the main control objective is to make the output torque behave in a desirable way despite the influence of compression ratio changes.
The controller is developed using a design method called Internal Model Control, which is a straightforward way of both configuring a controller and determining its parameters. The controller has been implemented and evaluated in a real engine, and has proved to be able to reduce the effect of compression ratio disturbance.
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Chen, Wei-Jen, and 陳威仁. "Multi-Variable Control of Variable-Frequency Air Conditioner." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/50615414725387915463.
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碩士國立臺灣大學
機械工程學研究所
104
The main purpose of the present research is to develop a variable-frequency air conditioner system. By modifying the frequency of the compressor and the opening of the electronic expansion valve, we can precisely control room temperature and superheat temperature. The multi-variable control system is simplified to two individual single variable control systems, while the interaction is treated as the disturbance process of the control system. A prototype of variable-frequency air conditioner system was built and tested. The experiment results show that the room temperature error is less than 0.1℃ and the superheat temperature error is less than 1℃. The performance of the designed variable-frequency air conditioner system is shown satisfactory.
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Huang, Tung-Chuan, and 黃東川. "Control of Variable Reluctance Motors." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/18544094856535785268.
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碩士國立交通大學
機械工程研究所
86
The purpose of this thesis is to design a high performace velocity controller for vaiable reluctance motors (VRM) based on an adaptive feedback linearization method. The nonlinear adaptive controller developed in this thesis contains two parts, one part compensates all the non-linearities between inputs and putputs, the other part contains a linear controller for motion tracking. With this controller, the asymptotic convergence of both the parameter estimation errors and command tracking errors are guaranteed. Furthermore, this adaptive controller is combined with a balanced commutator to reduce the torque ripple due to the salient structure in the VRM. Simulation result show that both the parameter estimation and the velocity tracking performance are excellent even when the disturbance load is present.
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Huang, Chin-Ching, and 黃智清. "Control of Hydrostatic Variable Transmission." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/854pnb.
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碩士國立虎尾科技大學
機械與機電工程研究所
98
In this research, a new hydrostatic-transmission with shift control scheme is developed. Coupled with a 2-DOF planetary gear set, a hydraulic package of a reversible variable-displacement hydraulic pump/motor and accumulator is used to replace the conventional continuously variable transmission (CVT) to optimize energy economy. With this hydrostatic system, nearly all of the energy typically lost during vehicle braking is captured and used to propel the vehicle the next time it needs to accelerate. Compare with conventional CVT system, the benefits of hydrostatic-transmission system include: better energy economy, better acceleration, less brake maintenance, and longer battery life. In this study, the prime task is to analyze the operating characteristics and performance of the hydrostatic-transmission system and derive an optimal control strategy for power shift. Then, a test bench of hydrostatic-transmission system is arranged to perform operating tests for verifying the performances of the developed systems. For optimizing energy economy and smoothing shift control, a genetic algorithm (GA) based adaptive neural sliding mode control (GANSMC) is proposed to control the hydrostatic -transmission system. The control parameters of GANSMC can be properly adjusted by using online parameters tuning algorithm derived from GA. Compare with PI controller, the experimental results show that this novel controller has good control performance, stability, and robustness.
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Liu, Hung-Hsi, and 劉洪禧. "FPGA implements variable gains control of the variable gain amplifier." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/01974566430523855947.
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碩士中原大學
電子工程研究所
97
Field Programmable Gate Array (FPGA) can be used to implement complex logic function and provide rapid field re-programmable ability in a single chip design application. This thesis describes the use of hardware design language Verilog and the implementation of a variable gain controller in a Variable Gain Amplifier. A top-down methodology is applied in this design to make the design clearer and easier for maintenance. A look up table (LUT) mechanism is applied to realize faster computing and simplify the design complexity. The design is simulated by Modelsim and implemented by Altera FPGA EP1C6.
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Jon, Yon-Huei, and 鍾勇輝. "Variable Structure Control and Fuzzy Control Applied to Flight Control Systems." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/09484883841764827724.
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碩士國立交通大學
控制工程系
82
The purpose of the thesis is to design flight controller to make aircraft to fulfill the following maneuvers:level flight, climbing ,level turn and level acceleration. The flight controller is designed with variable structure control law and fuzzy control law for a practical flight control system. For the attitude and altitude hold control system,variable structure controller is used to help the aircraft to reject the matching type uncertainty . For the velocity hold control system, we use fuzzy control law to design the thrust controller,it could avoid the "precise modeling" problem. When the aircraft takes an accelerating flight from subsonic to supersonic,the conventional flight controller must use the gain- scheduling approach to overcome the parameter variations due to the change of the velocity. It always increase the complexity for design. The advantage of variable structure controller is its robustness for such time-varying system and its simplicity in design. Because of the nonlinearity and complexity of the engine system,variable structure controller is not suitable. Here we may treat the fuzzy controller as a nonlinear PI- controller,there exists the suitable velocity performance for engine in every different velocity.
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"Multi-variable control techniques for greenhouses." Thesis, 2012. http://hdl.handle.net/10210/5421.
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M.Ing.This research project is dedicated to the automation of environmental control within greenhouses. To create an optimal climate in the greenhouse, the main environmental parameters that need to be controlled are temperature, humidity and light intensity. As a result of process dead times and the extreme interdependence of these parameters, the control problem can be classified as non-linear and multi-variable. In the past, most greenhouse environmental control systems depended on the decision making of an experienced human operator. This often gave rise to trial and error, especially when new species were established. With the current advances in "intelligent" control systems and high accuracy sensors, more and more of the decisions involved in greenhouse control can be automated. In this way more emphasis can be placed on emulating the abilities of an expert operator, by means of a computerbased automatic control system. In this research project, "intelligent" as well as "non-intelligent" control techniques, for addressing the problem of automated climate control in a greenhouse, are investigated. These include PID-control as a "non-intelligent" technique, and rule-based fuzzy logic control and self-learning fuzzy logic control as two "intelligent" control techniques. These techniques are all applied to experimental greenhouse which is equipped with management mechanisms, such as fans, heaters, sprinklers and lights. The results of the experiments are evaluated according to two performance parameters: the Control Performance Index (CPI) and the Mean Square Error (MSE). The three techniques are not only assessed for their efficiency, but also for their applicability to the greenhouse environmental problem. Each of the control techniques has a unique characteristic response to the non-linear, non-stationary, multi-variable problem of environmental control and are subsequently addressed in the respective chapter.
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Shy, Kuen-Yih, and 施昆毅. "Multi-variable Discrete Sliding Mode Control." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/14276621274076315197.
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碩士淡江大學
機械工程學系
90
A Sliding Model Control (SMC) is proposed for the temperature control of the thermal barrel in plastic molding processes. Firstly, derive a linear approximate model for the thermal barrel and treat the nonlinear term as an uncertainty or noise. Usually this uncertainty is a matched noise corresponding to the input. Since the Sliding Mode Control is robust to a matched noise, it is appropriate to design a digital sliding mode controller for a nonlinear system. Secondly, time delay of heat transferred in the thermal barrel results in oscillation at the output temperature. A grey prediction control is proposed to solve the problem caused by the time delay. According to literatures, forward grey prediction control decreases the overshoot of step response; on the other hand, backward grey prediction control increases the response speed. Finally, an on-line self-tuning SMC is developed in this paper to prevent extra work on estimation of the system parameters. Meanwhile, the adaptation of the self-tuning SMC extends the application of the controller to a large parameter range. The developed system is applied to thermal control for a plastic molding machine. Two experiments including temperature step response and trapezoid curve following are tested to evaluate the performance of the proposed methodology.
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溫為閔. "Construction of Control Chart for Variable." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/55607122851723028886.
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碩士明志技術學院
工程管理研究所
92
Statistical process control（SPC） is the method that monitor process quality characteristic. Through control charts, one can detect whether the present process malfunction. However, as one use it, one need choose different control charts in order to match different quality characteristic. But nowadays, any control chart can''t effectively monitor quality characteristic under variable circumstances. According to the aforementioned, that a quality engineer need choose different control charts under different processes will bring annoyance in using it. So, it is necessary to develop a control chart which has good detective effect to different process quality characteristic. Our research uses wavelet transformation drawing wavelet control chart under single quality characteristic. Time series models whose process observation is independent to another, which has first-order autoregressive processes（AR1）, use average run length（ARL） to compare with Shewhart control chart, EWMA control chart, SCC ,and EWMA Control Chart of residual. After simulation, we find that, when process observation is independent to another, the efficiency of wavelet control chart detective abnormality is better than EWMA control chart, and the more the mean shift is, the better the detective efficiency is. When the process is AR(1) time series model and its autoregressive parameter is less than 0.5, wavelet control chart still has fine detective efficiency. When is more than 0.5, the detecting efficiency of traditional SCC is better than wavelet control chart. According to the result of instances, we find that wavelet control chart indeed has better detective efficiency in our research.
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Chau, Jan, and 詹超. "Piezomechanics Using Intelligent Variable Structure Control." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/51252293446675360235.
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碩士大同工學院
機械工程研究所
86
The so-called piezomechanics contains three parts: piezoelectric translator, carriage mechanism and control system. It is well-known that a piezoelectric translator consists of the following advantages: (i) unlimited resolution, (ii) no moving parts, (iii) high efficiency, (iv) large forces, and (v) fast response. However, three drawbacks of piezomechanics: (i) it should only be load axially, (ii) it contains hysteresis feature, and (iii) the expansion is dependent on temperature, must be tackled. The first drawback is solved by the carriage mechanism design. The thesis focuses on the secondand third drawbacks by using an intelligent variable structure control (IVSC).First, a neural-network, including two different nonlinear gains and a lineardynamic system, is employed to learn the dynamics of piezomechanism. Then a forward control based on this learned model is used to achieve an acceptabletracking result. Because the tracking performance using forward control cannot be guaranteed as the system is subject to uncertainties, a discrete-time variable structure control (DVSC) is then synthesized with the previous forward control to improve the tracking performance. No state estimator is required for the proposed control. The stability of the overall system is verified by the Lyapunov stability criterion and the experiment is also presented to confirmthe usefulness of the proposed control.
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Huang, Chiue-Yan, and 黃雀燕. "Variable Control Charts with Fuzzy Data." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/69175868493387419101.
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碩士國立高雄應用科技大學
工業工程與管理系
99
Traditionally, variable control charts are constructed based on precise data collected from well-defined quality characteristics of manufacturing products. However, in the real world there are many occasions the stated quality characteristic of products such as surface roughness of optical lens or light transmittance of touch screens contains somewhat degree of imprecise information so that their readings inevitably gather as fuzzy numbers (data). In this situation, the traditional method for constructing the variable control charts exists a limitation of dealing with fuzzy data when the average and variance of underlying quality characteristic are monitored. Therefore, in this paper we propose and control charts with fuzzy data, whose fuzzy control limits are obtained on the basis of employing two well-known principles, so called resolution identity and extension principle, in the fuzzy theory. Furthermore, for comparing fuzzy observations and fuzzy control limits, a fuzzy ranking method is presented to classify the underlying manufacturing process condition. Finally, a practical example is provided to demonstrate the applicability of our proposed methodologies.
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Hwa, Lan Chii, and 藍啟華. "The Position Control of Electrohydraulic Servomechanism via Variable Structure Control." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/62170237469227713471.
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碩士大同工學院
機械工程研究所
81
There are many distinct advantages of a hydraulic control system, such as a higher speed of response with fast motions, a higher torque stiffness, and a higher output power per unit weight. The hydraulic control system becomes the most common form of precise manipulation system. However, some nonlinear phenomena, such as the relationship between input current and output flow, the fluid compressibility, and the deadband due to internal leakage and hysteresis, make the control of hydraulic system difficult. This paper is divided into two part: Part 1 :The trajectory tracking of electrodraulic servomechanism via a sliding mode controller. Part 2 :The position control of electrohydraulic servomechanism via a variable structure control with a second-order sliding condition.
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Costa, Válter de Sousa. "LLC resonant charger with variable inductor control." Master's thesis, 2016. http://hdl.handle.net/10400.26/18421.
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The present work pretends to study the operation and behavior of the LLC resonant converter
topology considering a battery charging application, using the traditional switching frequency
control and a new control variable, the variable inductance, provided by a current controlled
device, the Variable Inductor (VI).
During this work, a brief state of the art regarding general types of power converters and
resonant power converters is presented. The LLC resonant converter topology and its
advantages and disadvantages are described. The VI principle of operation and structure is
presented and discussed and, in the end some information about batteries and its behavior
under charging and discharging conditions is presented. The considered batteries
characteristics for the studied battery charger are shown and the adopted charging profile is
presented.
In the following chapters, a theoretical analysis of the LLC resonant converter operation and
behavior under switching frequency or VI control is performed and presented. A design
methodology is proposed for the converter considering both switching frequency and VI
control, separately or simultaneously. Simulations of the converter operation under open-loop
condition were made, and simulation results were obtained and discussed.
A prototype was built and test results were obtained. The prototype uses a SiC MOSFET
(Silicon Carbide Metal Oxide-Semiconductor Field Effect Transistor) based inverter working
at 100 kHz controlled with fiber optic drivers. To build the prototype, Printed Circuit Boards
(PCB) were designed, manufactured and built. An high-frequency transformer and a VI were
also design and built. Finally, theoretical, simulation and experimental results are confronted
in order to reach conclusions regarding to the proposed design methodology and the prototype
operation. This final analysis allows validating the LLC-VI resonant converter as a good
option for a battery charger.
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黃信仁. "Synthetic Control Charts with Variable Sampling Intervals." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/01371998781853508264.
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博士國立清華大學
工業工程與工程管理學系
93
Statistical process control (SPC) techniques have been greatly implemented in industries for improving product quality and saving production costs. As a primary tool among these techniques, control charts are widely used to detect the occurrence of assignable causes. Recently proposed synthetic control charts perform well for monitoring process mean, fraction nonconforming and mean of interarrival times. For monitoring other types of process parameters conveniently, this study proposes a general model of synthetic control chart with regard to non-specified process parameter monitored. The chart is a combination of the Shewhart chart and conforming run length (CRL) chart. The variable sampling intervals (VSI) schemes of the synthetic chart are constructed for improving chart performance further. The Shewhart chart, VSI Shewhart chart, and synthetic chart can be regarded as special cases of the VSI synthetic chart. The general model of synthetic control chart and its VSI schemes are then, respectively, applied to three kinds of parameters of a normally distributed process: process variability, process mean and variability, and process mean vector. These synthetic charts are composed of Shewhart sample range (R) chart or sample standard deviation (S) chart, Shewhart Max chart, and Shewhart chi-squared ( ) chart or T-squared ( ) chart, and CRL chart, respectively. The operation, design, performance comparisons with other types of control charts such as Shewhart chart with runs rules, Shewhart chart with warning line, cumulative sum (CUSUM) chart and exponentially weighted moving average (EWMA) chart, and numerical example are described. Tables of optimally designed synthetic charts can assist the users to design the chart, and the presented VSI schemes can be implemented to further improve the chart performance if the current one is unsatisfactory.
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Lee, Rong-Chyang, and 李榮全. "Specific designs in variable structure control systems." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/61197268993633047466.
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