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Maiolini, Jacopo. "On delay compensation control for systems with distributed input delay." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Questa tesi riguarda lo sviluppo di una nuova tecnica di controllo chiamata Delay Compensation per sistemi scalari che presentano un ritardo distribuito nei canali di ingresso. Lo scopo principale è di compensare realmente il lag intrinseco del sistema per un dato instante T_0. Esistono, infatti, alcune tecniche già utilizzate in questo ambito, chiamate predictor-like, che assegnano uno spettro stabile in closed-loop solamente dopo che il sistema è stato soggetto a tutto il ritardo presente in ingresso, non riuscendo perciò a compensarlo esattamente. L'obbiettivo secondario è dovuto a delle approssimazioni scaturite dall'implementazione in controllori real-time di questi controlli. Tutte le tecniche di cui sopra, inclusa Delay Compensation, necessitano infatti di un controllo anch'esso distribuito. Quando ci si scontra con la realtà, l'integrale di controllo deve essere approssimato tramite un integrazione numerica. Negli anni questa non idealità è stata ampiamente studiata, in particolar modo per il controllo Finite Spectrum Assignment (FSA) che verrà, nel caso di ritardi distribuiti di ingresso, relazionato con la tecnica Delay Compensation qui introdotta. Differenti metodi di quadratura verranno utilizzati e confrontati, per l'approssimazione dell'integrale di controllo, effettuando un analisi sia nel dominio del tempo sia nel dominio delle frequenze. Verrà poi effettuata un'estensione della tecnica nel caso di sistemi vettoriali, con dimostrazione annessa della validità nell'utilizzo del controllo Delay Compensation in questo frangente. Anche se non è presente una dimostrazione rigorosa dell'applicabilità del controllo Delay Compensation anche nel caso di un sistema Multi-Input, nella tesi sono presenti alcuni risultati considerando una semplificazione nel sistema controllato. La tesi si conclude elencando gli aspetti positivi e negativi derivanti dall'applicazione della tecnica Delay Compensation qui presentata e da un'indicazione di futuri sviluppi.
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Iwanaga, Mauricio Kiotsune. "Development of a virtual pipe test rig for testing acoustic correlators for leak detection in buried water pipes /." Ilha Solteira, 2019. http://hdl.handle.net/11449/183466.
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Orientador: Michael John BrennanResumo: Vazamentos em tubulações de água enterradas são considerados um importante problema já que uma grande quantidade de água é desperdiçada entre a planta de tratamento e os consumidores. Para lidar com tal problema, companhias de saneamento utilizam dispostivos para localizar vazamentos nas tubulações. Dispositivos de escuta e correlacionadores de ruídos são os equipamentos mais utilizados em campo pelas companhias de sanemaneto ao redor do mundo. Correlacionadores de ruídos são dispositivos usados na localização de vazamentos em tubulações enterradas através da estimativa do tempo de atraso entre os sinais medidos pelos sensores posicionados em ambos os lados de um suposto vazamento. Uma vez que as companhias de saneamento devem decidir qual tipo de correlacionador é o mais compatível com a sua rede de tubulações, elas devem realizar alguns testes para ajudar em tal decisão e para treinar os funcionários que operam estes dispositivos, os quais devem ser expostos a diferentes condições, tais como tubos de diferentes materiais e geometrias, diferentes tipos de solo, vazamentos com diferentes intensidades, etc. Neste contexto, o principal objetivo desta pesquisa é contribuir com esta necessidade através da elaboração de um dispositivo de bancada capaz de reproduzir as vibrações de um tubo causadas por um vazamento. O dispositivo, chamado de simulador virtual de vazamentos, é composto por um computador, um amplificador de potência com dois canais e dois shakers. Ruídos de vazamento... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Leakage in buried water pipes is an important problem since a large amount of water is wasted between the treatment plant and the consumers. To deal with such a problem, water companies have used some devices to localize leaks in the pipe network. Listening devices and leak noise correlators are the most popular equipment used in the field by the water companies around the world. Leak noise correlators are important devices used to localize leaks in buried pipes by calculating the time delay between the signals measured by the sensors positioned either side of a suspected leak. Since water companies have to decide which leak noise correlator is more suitable for each pipe network, they have to carry out some field tests to assist in this decision and to train the personnel that handles such a device, which ideally must be exposed to different conditions, such as pipes with different materials and geometries, different types of soil, different leak strengths, etc. The main objective of this research project is to contribute with the necessity of the water companies by designing an indoor bench-top device capable to reproduce the pipe vibrations generated by a leak in the field. The device, called virtual pipe test rig, comprises a computer and a dual-channel power amplifier supplying two shakers. In the computer, leak noise is synthesized by using a model of a buried leaking pipe implemented using the software Matlab®. Since the systems, composed by the power amplifiers and th... (Complete abstract click electronic access below)
Mestre
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Kwok, Wilfred. "Automating Radiotherapy: Parameterizations of Sensor Time Delay Compensators and the Separation Principle." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/954.
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Motivated by recent research to automate radiotherapy, this thesis looks into feedback control problems where the feedback sensor imposes considerable time delay. The use of an asymptotic estimator is considered as a method to compensate for the time delay. Properties and parameterizations of asymptotic estimators are analyzed. It is shown that if such a delay compensation scheme is adopted, a separation principle holds, which allows for independent design of the feedback controller and the time delay compensator. The radiotherapy problem is used as a case study to show how asymptotic estimators may be designed, exploiting the separation principle. Lastly, the thesis considers multivariable versions of asymptotic estimators.
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Moraes, Vitor Mateus. "Delay-dependent output feedback compensators for a class of networked control systems." reponame:Repositório Institucional da UFSC, 2014. https://repositorio.ufsc.br/xmlui/handle/123456789/128874.
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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2014Made available in DSpace on 2015-02-05T20:26:24Z (GMT). No. of bitstreams: 1 330228.pdf: 1707908 bytes, checksum: e9e7656943afa359919bcdb455b78423 (MD5) Previous issue date: 2014
Sistemas de controle via rede (NCS, do inglês Networked Control Systems) são uma classe especial de sistemas amostrados digitalmente, nos quais os dispositivos do sistema de controle se comunicam através de uma rede de comunicação (como mostrado na Fig. I). Significantes avanços tecnológicos tem levado a um maior interesse tanto na utilização de NCS em ambiente industrial (MOYNE; TILBURY, 2007), quanto em pesquisas relacionadas ao assunto (HESPANHA; NAGHSHTABRIZI; XU,2007; HEEMELS; WOUW, 2010; ZHANG; GAO; KAYNAK, 2013). Algumas das vantagens oferecidas por tais sistemas, com relação a sistemas de controle tradicionais, compreendem menor custo de implementação, flexibilidade e facilidade de manutenção. Apesar disso, inerentemente alguns efeitos indesejados também podem ocorrer, tais como atrasos na comunicação e intervalos de amostragem variantes, ocasionando degradação no desempenho do sistema em malha fechada. Devido a esses efeitos, a análise de estabilidade e também o projeto de controladores para NCS tornam-se mais desafiadores (TANG; YU, 2007). De modo geral, os estudos sobre NCS podem ser divididos em duas grandes áreas: controle da rede e controle via rede (GUPTA; CHOW, 2010). A primeira está mais interessada em proporcionar uma melhor qualidade no serviço de transmissão de dados realizado pela rede de comunicação, enquanto a segunda objetiva uma melhor qualidade do desempenho dos sistemas de controle sob determinadas condições induzidas pelos efeitos da utilização da rede. Embora tipicamente tratadas de forma separada, recentemente alguns esforços têm sido empreendidos de modo a integrar algumas características de ambas as áreas em fase de projeto, as chamadas estratégias de co-design (TORNGREN et al., 2006). Uma abordagem integrada é necessária de modo a se obter uma maior compreensão do funcionamento de um NCS, podendo assim obter um melhor desempenho geral do sistema. Neste contexto, especialmente levando em consideração que o uso rede de comunicação é limitado, tal recurso deve ser corretamente distribuído entre os sistemas de controle de modo a garantir um funcionamento adequado. Além disso, requisitos de desempenho individuais de cada planta também devem ser cumpridos, mesmo sujeitos a tais restrições de limites de recursos.
Abstract: Networked control system (NCS) is a special class of sampled-data system where control systems devices are interconnected through a communication network. Despite the advantages, such as lower cost, flexibility and easy of maintenance compared to a more traditional implementation, some undesired effects may be induced by the use of a shared medium in the feedback loop, for instance, time-varying sampling intervals and delays. Due to the multidisciplinary nature of an NCS, the analysis and design of such systems also demand a more comprehensive approach. Thus, the main objective of this thesis is to propose some strategies for the synthesis of dynamic output feedback compensators, assuming an industrial network control system environment with temporal behavior features and requirements. Throughout this document, the NCS is modeled considering unknown time-varying delays, which leads to an uncertain system representation, later overapproximated by a convex polytope with additional norm-bounded uncertainty. Based on parameter dependent Lyapunov functions, closed-loop stability conditions are provided, which can be verified in terms of feasibility of a set of linear matrix inequalities (LMIs). The control designs are then promptly derived from the stability conditions, leading to delay-dependent compensators. Furthermore, an integrated control design and resource management strategy is proposed, taking into account the controller design while also addressing the shared nature of the communication network. This co-design strategy assumes that a supervisor task has the knowledge of all devices that access the network, as well as their allocated bandwidths. Numerical examples and simulations are provided to illustrate the effectiveness of the proposed design methodologies.
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Lim, Hee Jin. "Facilitatory neural dynamics for predictive extrapolation." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1759.
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Chen, Liang. "Design of decoupling control and time-delay compensation for a CFSTR." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29469.
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This thesis is concerned with the design of a decoupling compensator and a time-delay compensator for a nonisothermal continuous flow stirred tank reactor (CFSTR). An expression for the analysis of interaction of the two-variable CFSTR was theoretically derived by using the relative gain method (RGM). For the purpose of improving the stability of the decoupling control system, undercompensation for a decoupled CFSTR system was suggested and the robustness test of such undercompensation decoupler to the modelling error was studied. On the other hand, the proposed time-delay compensation method, unlike conventional Smith's scheme, can rely on the basic property of gain-invariant time-delay. The stability of this time-delay compensation method is not affected by the CFSTR control system time-variant time-delay, while its compensation structure has the same features as the Smith compensator.
The design of a decoupler and that of a time-delay compensator are independent of each other. All compensation structures are physically realizable.
The theoretical results are supported by simulation. Simulation results for a CFSTR demonstrate that the undercompensation decoupling control can tolerate a relatively wide modelling error and reduce the sensitivity of the CFSTR process to parameter variations and unwanted disturbances. Also, simulation results show that the proposed time-delay compensator can provide an improvement over the conventional Smith compensator.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Hoang, Trong bien. "Switched observers and input-delay compensation for anti-lock brake systems." Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-00994114.
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Many control algorithms for ABS systems have been proposed in the literature since the introduction of this equipment by Bosch in 1978. In general, one can divide these control algorithms into two different types: those based on a regulation logic with wheel acceleration thresholds that are used by most commercial ABS systems; and those based on wheel slip control that are preferred in the large majority of academic algorithms. Each approach has its pros and cons [Shida 2010]. Oversimplifying, one can say that the strength of the first ones is their robustness; while that of the latter ones their short braking distances (on dry grounds) and their absence of limit cycles. At the midpoint of this industry/academy dichotomy, based on the concept of extended braking stiffness (XBS), a quite different class of ABS control strategies has been proposed by several researchers (see, e.g., [Sugai 1999] and [Ono 2003]). This concept combines the advantages from both the industrial and academic approaches. Nevertheless, since the slope of the tyre characteristic is not directly measurable, it introduces the question of real-time XBS estimation. The first part of this thesis is devoted to the study of this estimation problem and to a generalization of the proposed technique to a larger class of systems. From the technological point of view, the design of ABS control systems is highly dependent on the ABS system characteristics and actuator performance. Current ABS control algorithms on passenger cars, for instance the Bosch ABS algorithm, are based on heuristics that are deeply associated to the hydraulic nature of the actuator. An interesting observation is that they seem to work properly only in the presence of a specific delay coming from the hydraulic actuation [Gerard 2012]. For brake systems that have different delays compared to those of hydraulic actuators, like electric in-wheel motors (with a smaller delay) or pneumatic trailer brakes (with a bigger delay), they might be no longer suitable [Miller 2013]. Therefore, adapting standard ABS algorithms to other advanced actuators becomes an imperative goal in the automobile industry. This goal can be reached by the compensation of the delays induced by actuators. The second part of this thesis is focused on this issue, and to the generalization of the proposed technique to a particular class of nonlinear systems. Throughout this thesis, we employ two different linearization techniques: the linearization of the error dynamics in the construction of model-based observers [Krener 1983] and the linearization based on restricted state feedback [Brockett 1979]. The former is one of the simplest ways to build an observer for dynamical systems with output and to analyze its convergence. The main idea is to transform the original nonlinear system via a coordinate change to a special form that admits an observer with a linear error dynamics and thus the observer gains can be easily computed to ensure the observer convergence. The latter is a classical method to control nonlinear systems by converting them into a controllable linear state equation via the cancellation of their nonlinearities. It is worth mentioning that existing results for observer design by error linearization in the literature are only applied to the case of regular time scalings ([Guay 2002] and [Respondek 2004]). The thesis shows how to extend them to the case of singular time scalings. Besides, the thesis combines the classical state feedback linearization with a new method for the input delay compensation to resolve the output tracking problem for restricted feedback linearizable systems with input delays.
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Leonard, Theresa Ann. "Time delay compensation of distributed multiple microphones in recording : an experimental evaluation." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61154.
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In the search for improved reproduction of a classical music performance, the technique of time delay compensation is shown to be a useful tool for balance in recording. This paper investigates the importance and validity of small time adjustments in recordings to compensate for variation in distance between spot microphones and a main stereo pair. Conventional recording techniques, psychoacoustic considerations and technological aspects of the use of delays are researched in order to determine their validity in timbral improvement.Multiple microphone set-ups are used to record both large orchestral works and smaller-scale classical compositions where auxiliary microphones may be needed to ensure an optimum balance in the final mix. Small time delays are derived from calculations involving the distances between microphones, the speed of sound, and humidity and temperature readings from the hall. Proper synchronization of these delays is desirable to preserve phase coherence and combat comb-filter effects. Precise delay units are used to compile musical exerpts for listening tests.
The results reveal any change in sound quality and provide a basis for investigating both the positive and negative effects through objective study of the value of time delay compensation in the live recording reproduction of classical music performances.
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Moon, Seung Ryul. "Hybrid PWM Update Method for Time Delay Compensation in Current Control Loop." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/84929.
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A novel hybrid pulse-width modulation (PWM) update method is proposed to eliminate the effect of the one-step control time delay Td one without losing the full duty cycle range. Without the Td one to cause linear phase shifts that limit the control bandwidth and affect closed-loop stability, a very high quality digital current control can be achieved, such as a high closed current loop bandwidth, strong robustness against disturbances, ability to reach a very high fundamental frequency compared to switching frequency, etc.
In a conventional digital control implementation, a sampling period (Tsamp) is allocated for the execution of samplings and computations, and the update of PWM outputs is delayed until the beginning of the following sampling period. This delayed PWM update method is the cause of the Td one. Instead of the delayed PWM update, if the PWM outputs are updated immediately after algorithm computations, then the effect of the Td one can be eliminated; however, the computation time delay Td comp from the current sampling instant through algorithm computations to the PWM update instant causes a reduced duty cycle range. Each of these two conventional PWM update methods has some shortcomings.
A hybrid PWM update method is proposed to circumvent the aforementioned shortcomings and to incorporate only the advantages. The proposed method improves the performance by updating the PWM outputs multiple times during a Tsamp, whereas the PWM outputs are updated only one time during a Tsamp in the conventional methods. In spite of the simplicity of the proposed method, the performance improvements in stability, robustness and response characteristics are significant. On the other hand, the proposed method can be easily applied to many PWM based digital controls because of its simplicity.
Additional to the hybrid PWM update method, a hybrid control method is proposed to optimize the sequence of control operations. It maximizes the current loops' robustness and minimizes the delay from the sampling of outer control loops' variables, such as voltage and speed, to the duty cycle update instant. The minimum delay enables the maximization of the outer control loops' bandwidth. Additionally, a corrective neutral offset voltage injection method is proposed to correct small PWM output deviations that may occur with the hybrid PWM update method.
Utilizing a three-phase voltage source inverter with a permanent magnet synchronous machine as the platform, a deadbeat current control and a high speed ac drive experiments have been conducted to demonstrate the feasibility and validity. Notable results include a closed current loop response of one Tsamp with the deadbeat control and a 500 Hz current fundamental frequency with 1 kHz switching frequency in the high speed ac drive.Ph. D.
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Moctezuma, Andres. "CPM Equalization to Compensate for ISI due to Band Limiting Channels." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34559.
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In modern wireless communication systems, such as satellite communications and wireless networks, the need for higher data rates without the need for additional transmit power has made Continuous Phase Modulation (CPM) one of the most attractive modulation schemes in band limited channels. However, as the data rates keep increasing, the spectral width of the CPM signal increases beyond the channel bandwidth and performance becomes constrained by the intersymbol interference (ISI) that results from band-limiting filters. We propose two approaches to the problem of equalization of band-limited CPM signals. First, our efforts are focused on shortening the channel impulse response so that we can use a low complexity MLSE equalizer. We implement the channel truncation structure by Falconer and Magee and adapt it to work with CPM signals. This structure uses a, a more derivable, pre-filter to shape the overall response of the channel, so that its impulse response is of shorter duration. Simulation results show that near-MLSE performance can be obtained while dramatically reducing MLSE equalizer complexity.
In our second approach, we focus on eliminating the group-delay variations inside the channel passband using an FIR pre-filter. We assume the channel to be time-invariant and provide a method to design an FIR filter so that -when convolved with the band limiting filter - it results in more constant group-delay over the filter passband. Results show that eliminating the group-delay variations in the band limiting filter passband reduce the amount of ISI and improve bit error rate performance.
Master of Science
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Kovach, Bob. "TEMPORAL ALIGNMENT OF TELEMETRY STREAMS WITH DIVERSE DELAY CHARACTERISTICS." International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/605597.
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International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaIn many test ranges, it is often required to acquire a number of telemetry streams and to process the data simultaneously. Frequently, the streams have different delay characteristics, requiring temporal alignment before the processing step. It is desired to have the capability to align these streams so that the events in each stream are coincident in time. Terawave Communications has developed technology to perform temporal alignment for a number of streams automatically. Additionally, the algorithm performs the delay compensation independent of the source data rate of each stream. Terawave will present the algorithm and share the results of their testing in a test installation.
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Snickars, Carlo. "Design of a wirelessHART simulator for studying delay compensation in networked control systems." Thesis, KTH, Reglerteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105893.
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Borrego, Dulce Armonía. "Value Equivalency Analysis: Quantity Compensation, Distance Decay, And Time Treatment." Doctoral thesis, Universitat Autònoma de Barcelona, 2011. http://hdl.handle.net/10803/42010.
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La compensación ambiental se refiere a la provisión adicional de recursos naturales, servicios ecológicos o de bienestar social a través de proyectos de reparación que son equivalentes en magnitud a las pérdidas producidas por daños ambientales. En la Unión Europea, la Directiva de Responsabilidad Medioambiental establece el marco legal para introducir responsabilidad ambiental debido a daños producidos al medio ambiente por actividades industriales. La responsabilidad ambiental establece que los recursos naturales dañados deben devolverse al estado que hubieran tenido de no producirse el daño en cuestión (restauración primaria) así como la provisión de una compensación por pérdidas acumuladas (o pérdidas provisionales) producidas desde el momento en que ha ocurrido el incidente hasta que el medio ambiente ha vuelto a su estado original (restauración compensatoria). Los Análisis de Equivalencia representan un instrumento que se utiliza para determinar la cuantía por daños al medio ambiente. Esta investigación aplica una metodología de análisis de equivalencia conocida como método valor-a-valor como una herramienta para escalar la cantidad de remediación requerida y de esta manera estimar la cantidad de reparación para compensar las pérdidas ambientales producidas tras un incendio forestal ocurrido en el noreste de España. Para efectos del Análisis de Equivalencia de Valor (AEV) se ha diseñado un ejercicio de Valoración Contingente (VC) que estima la media de la cantidad mínima de compensación física requerida para compensar los daños producidos según las preferencias sociales. A continuación, el estudio explora cuestiones que tienen que ver con la localización del proyecto de remediación cuando éste se sitúa a cierta distancia del sitio dañado. Intuitivamente, la idea de que la ubicación de un proyecto de restauración se encuentre alejado de la ubicación inicial (la zona dañada) podría implicar una mayor cantidad de compensación en comparación a un proyecto de reparación localizado más próximo al sitio del daño. Para este fin se ha diseñado un ejercicio adicional que utiliza modelos de elección que permite estimar la cantidad de compensación requerida cuando el proyecto de reparación se localiza en un sitio distinto al de la zona afectada. Finalmente, la última parte de esta investigación explora los efectos en la disposición a pagar de la información proporcionada en el cuestionario relacionada con los pagos de un programa de reparación; específicamente, cómo pagarán por el programa y si los pagos corresponden a valores nominales o reales. Con el fin de analizar este tema la pregunta de valoración toma una forma dicotómica simple en la cual los pagos deben hacerse anualmente, durante diez años, y con incrementos anuales de acuerdo a la inflación.Environmental compensation implies the provision of additional natural resources, services or social welfare through restoration projects that are scaled to equal the losses due to environmental damage. The Environmental Liability Directive provides legal framework in the European Union for introducing environmental liability due to damages to the environment caused by industrial operators. Environmental liability requires that harmed natural resources be restored to baseline conditions (primary restoration) and compensated for the accumulated losses (interim losses) produced from the time of the incident until the environment reaches baseline conditions (compensatory restoration). Equivalency Analysis is a methodology used to determine compensation for environmental damage. This study uses an Equivalency Analysis (EA) approach namely the value-to-value approach as a tool to scale remediation and to estimate the amount of compensatory restoration to off-set an environmental damage following a wild forest fire in the northeast of Spain. Value Equivalency Analysis (VEA) is undertaken by a Contingent Valuation (CV) exercise to determine the welfare loss from the initial damage and interim loss and then a remediation project that can be established based on that information. The study elicits the minimum amount of compensation required to make individuals as well off as they would be in the baseline situation. After this the study explores remediation located at a geographical distance from the site of damage. In some cases displacement between damaged resources and restored resources is allowed, this study explores whether longer distance from the damaged site could imply a larger amount of compensation to offset the change in natural resource location. For this, an additional exercise was designed to estimate the trade-off rate for compensating in a farther away site using choice experiment techniques. Finally, the last section focuses on the information provided to respondents regarding payments in the survey instrument. This includes informing respondents how they would pay for the restoration program and whether payments correspond to nominal or real values. The survey instrument takes the form of a single bounded dichotomous choice where the payments are to be made every year over a ten year period and they would go up every year according to inflation.
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Shivaprasad, Mala A. "Dynamic Dealy Compensation and Synchronisation Services for Continuous Media Streams." Thesis, Indian Institute of Science, 1995. http://hdl.handle.net/2005/144.
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Multimedia' nature of an application refers to the presence of several media streams in parallel. Whether it is receiving real-time data or retrieving stored data, there exists an end-to-end delay in data transfer from source to destination over the network. This delay experienced can be split into a fixed part and a variable part. Data processing time like coding and decoding at the source and destination are the fixed delays experienced. The variable delay occurs mainly due to queuing at the intermediate nodes during its flow through the network. The variable or unequal delays introduce gaps or discontinuities within a stream. In multi-stream applications where each stream may flow on different routes based on the bandwidth availability experiencing different delays, mismatch between them can also occur. These discontinuities and skews result in poor quality of playout. Clock drift and variations in drift rates between the source/s and destination/s, clock also lead to poor quality of play out. To eliminate these skews and discontinuities, there must be mechanisms, viz., and synchronisation services to convey, reintroduce and maintain the temporal relationship between the media streams for presentation throughout the playout, at the destination. The reintroduction of this lost temporal relationship within a stream and between various media streams for presentation at the destination is the object of multimedia synchronisation and is the subject matter of this thesis.
In the presence of synchronised clocks, the main cause of asynchronies between media streams is the difference in delays experienced and the jitter. In this work, to convey the temporal relationship between streams of an application to the playout site, each stream is assigned a priority л, based on its importance to the user. The media streams are then divided into synchronisation units called 'Groups' based on that stream's characteristics which has the highest priority л. A group may therefore consist of one video frame and other data which were generated in that interval. Or may consist of silence and talk-spurt periods of the voice stream with data units of other streams generated in the same interval.
Since the quality of playout of temporally related delay-sensitive streams depends upon the delay-experienced, the concept of QoS can be extended to describe the presentation requirements of uch data. Depending on the user perception and the delay experienced, an application can have a range of playout times, giving the best performance. The presentation of many real-time applications can be considered satisfactory even when the delay bound is exceeded by a small amount for a short period of time under varying network conditions. This property can be exploited by defining two sets of QoS parameters, namely QoS optimum and QoSlimit for each real-time application. As the delay and its variations increase, the optimum playout time range
decreases. QoS optimum specifies the performance parameters required to perceive 'realtime'. Multimedia data can be played out at its QoSlimit with a deterioration in quality under poor network conditions still maintaining the synchronisation between streams. To control the playout at two levels of QoS, and maintain intra-media and inter-media synchronisation, stream controllers and super stream controllers have been used.
The dynamic delay compensation algorithm and synchronisation services were simulated using network delay models and performances studied. It is shown that the proposed algorithm not only synchronised media streams and smoothened jitter but also optimised buffer space and buffer occupancy time while meeting the desired quality of service requirements
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Böhm, Michael, Jörg-Uwe Pott, José Borelli, Phil Hinz, Denis Defrère, Elwood Downey, John Hill, et al. "OVMS-plus at the LBT: disturbance compensation simplified." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622509.
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In this paper we will briefly revisit the optical vibration measurement system (OVMS) at the Large Binocular Telescope (LBT) and how these values are used for disturbance compensation and particularly for the LBT Interferometer (LBTI) and the LBT Interferometric Camera for Near-Infrared and Visible Adaptive Interferometry for Astronomy (LINC-NIRVANA). We present the now centralized software architecture, called OVMS+, on which our approach is based and illustrate several challenges faced during the implementation phase. Finally, we will present measurement results from LBTI proving the effectiveness of the approach and the ability to compensate for a large fraction of the telescope induced vibrations.
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Sandström, Marlene. "Investigation of and Compensation for Time-Delays in Driveline Control Systems." Thesis, KTH, Optimeringslära och systemteori, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-143783.
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Time-delays occur in all real-time control systems. The driveline control system considered in this thesis is such a system. It is of interest to know if it is possible to move the cruise control from the engine management system to another control unit that communicates with the engine using CAN (Communication Area Network). Since the amount of data sent over CAN is increasing, it is of concern how large time-delays a controller can handle and if there is any simple method to compensate for time-delays while maintaining good performance. Measurements of time-delays between the control units of the engine and the gearbox have been done in a Scania heavy truck. The results show that the time-delays are very small and that a few percent of the sent messages are overwritten due to the time-delays varying in length and the clocks drifting in relation to each other. Four different methods for compensation of time-delays have been studied and compared to a prototype cruise controller from Scania. Three of the alternative controllers are PID controllers and the fourth is a Smith predictor. All of them are more robust to time-delays than the prototype, but all except one also have the disadvantage of not eliminating the impact of a load disturbance in a reasonably short time, which the prototype does. Since the time-delays on the concerned CAN bus are very small and the prototype controller is robust to time-delays of significantly larger magnitude, the conclusion is that it is probably safe to move the cruise control to another control unit that communicates with the engine using CAN, without compensating for time-delays. If compensation for time-delays were to be required in the future, there is no obvious choice out of the compensation methods evaluated in this work. They all have drawbacks but they might be applicable after some modifications to improve their performance.Tidsfördröjningar förekommer i alla realtidsstyrsystem. Drivlinestyrsystemet som behandlas i denna uppsats är ett sådant system. Det är av intresse att utreda om det är möjligt att flytta hastighetsregleringen från motorns styrenhet till en annan styrenhet som kommunicerar med motorn via CAN (Communication Area Network). Då mängden data som skickas över CAN ökar är det angeläget att ta reda på hur stora tidsfördröjningar en regulator klarar av och om det finns någon enkel metod att kompensera för tidsfördröjningar med som även ger god prestanda. Mätningar av tidsfördröjningar mellan motorns och växellådans styrenheter har genomförts i en Scanialastbil och resultaten visar att tidsfördröjningarna är mycket små samt att par procent av de skickade meddelandena skrivs dock över på grund av att tidsfördröjningarnas längd varierar och att styrenheternas klockkristaller driver i förhållande till varandra. Fyra olika metoder för kompensering av tidsfördröjningar har undersökts och jämförts med en prototyphastighetsregulator från Scania. Tre av de alternativa regulatorerna är PID-regulatorer och den fjärde är en Smithregulator. Samtliga är robustare mot tidsfördröjningar än prototypen men alla utom en dras med nackdelen att inte kunna eliminera en laststörning inom rimlig tid, vilket prototypen gör. Eftersom tidsfördröjningarna på den aktuella CAN-bussen är mycket små och prototypregulatorn är robust mot betydligt större tidsfördröjningar, så är slutsatsen att det troligtvis är säkert att flytta hastighetsregleringen till en annan styrenhet som kommunicerar med motorn via CAN utan att kompensera för tidsfördröjningar. Om kompensation för tidsfördröjningar skulle behövas i framtiden så finns inget självklart val av de kompenseringsmetoder som utretts i detta arbete. Alla har brister men skulle eventuellt kunna användas efter vissa modifikationer för att förbättra deras prestanda.
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Jain, Saurabh. "LTCP-RC: RTT compensation technique to scale high-speed protocol in high RTT links." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2528.
Full textAbstract:
In this thesis, we propose a new protocol named Layered TCP with RTT Compensation
(LTCP-RC, for short). LTCP-RC is a simple modification to the congestion
window response of the high-speed protocol, Layered TCP (LTCP). In networks characterized
by large link delays and high RTTs, LTCP-RC makes the LTCP protocol
more scalable. Ack-clocked schemes, similar to TCP, suffer performance problems
like long convergence time and throughput degradation, when RTT experienced by
the flow increases. Also, when flows with different RTTs compete, the problem of
unfairness among competing flows becomes worse in the case of high-speed protocols.
LTCP-RC uses an RTT Compensation technique in order to solve these problems.
This thesis presents a general framework to decide the function for RTT Compensation
factor and two particular design choices are analyzed in detail. The first
algorithm uses a fixed function based on the minimum RTT observed by the flow.
The second algorithm uses an adaptive scheme which regulates itself according to
the dynamic network conditions. Evaluation of the performance of these schemes is
done using analysis and ns-2 simulations. LTCP-RC exhibits significant performance
improvement in terms of reduced convergence time, low drop rates, increased utilization
in presence of links with channel errors and good fairness properties between
the flows,. The scheme is simple to understand, easy to implement on the TCP/IP
stack and does not require any additional support from the network resources. The choice of parameters can be influenced to tune the RTT unfairness of the scheme,
which is not possible in TCP or other high-speed protocols. The flexible nature of
the analysis framework has laid the ground work for the development of new schemes,
which can improve the performance of the window based protocols in high delay and
heterogeneous networks.
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Álvarez, Rodrigo [Verfasser]. "Characterization of New Press-Pack IGBTs and Automated Delay Time Compensation of Parallel Connected IGBTs / Rodrigo Álvarez." München : Verlag Dr. Hut, 2012. http://d-nb.info/1021719404/34.
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Schwartz, Paul D., and Christopher B. Hersman. "A HIGH SPEED REAL TIME SPACE QUALIFIED TIME DIVISION MULTIPLEXED DATA FORMATTER." International Foundation for Telemetering, 1994. http://hdl.handle.net/10150/608564.
Full textAbstract:
International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, CaliforniaA system to generate a contiguous high speed time division multiplexed (TDM) spacecraft downlink data stream has been developed. The 25 MBPS downlink data stream contains high rate real time imager data, intermediate rate subsystem processor data, and low rate spacecraft housekeeping data. Imager data is transferred directly into the appropriate TDM downlink data window using control signals and clocks generated in the central data formatter and distributed to the data sources. Cable and electronics delays inherent in this process can amount to several clock periods, while the uncertainty and variations in those delays (e.g. temperature effects) can exceed the clock period. Unique (patent pending) electronic circuitry has been included in the data formatter to sense the total data gathering delay for each high speed data source and use the results to control series programmable delay elements to equalize the delays from all sources and permit the formation of a contiguous output data stream.
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Bhadauriya, Sonal. "Relaxation Behaviour of Patterned Composite Polymer Surfaces and Underlying Compensation Phenomenon." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1577984063649952.
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Schuwerk, Clemens [Verfasser], Eckehard [Akademischer Betreuer] [Gutachter] Steinbach, and Subhasis [Gutachter] Chaudhuri. "Client/Server-Based Shared Haptic Virtual Environments: Perceptual Data Reduction, Communication, and Delay Compensation / Clemens Schuwerk ; Gutachter: Subhasis Chaudhuri, Eckehard Steinbach ; Betreuer: Eckehard Steinbach." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1125018208/34.
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Neumann, Niels. "Signal processing with optical delay line filters for high bit rate transmission systems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-64036.
Full textAbstract:
In den letzten Jahrzehnten ist das globale Kommunikationssystem in einem immer größerem Maße ein integraler Bestandteil des täglichen Lebens geworden. Optische Kommunikationssysteme sind die technologische Basis für diese Entwicklung. Nur Fasern können die riesige benötigte Bandbreite bereitstellen. Während für die ersten optischen Übertragungssysteme die Faser als "flacher" Kanal betrachtet werden konnte, machen Wellenlängenmultiplex und steigende Übertragungsraten die Einbeziehung von immer mehr physikalischen Effekten notwendig. Bei einer Erhöhung der Kanaldatenrate auf 40 Gbit/s und mehr ist die statische Kompensation von chromatischer Dispersion nicht mehr ausreichend. Die intrinsische Toleranz der Modulationsformate gegenüber Dispersion nimmt quadratisch mit der Symbolrate ab. Daher können beispielsweise durch Umwelteinflüsse hervorgerufene Dispersionsschwankungen die Dispersionstoleranz der Modulationsformate überschreiten. Dies macht eine adaptive Dispersionskompensation notwendig, was gleichzeitig auch Dispersionsmonitoring erfordert, um den adaptiven Kompensator steuern zu können. Vorhandene Links können mit Restdispersionskompensatoren ausgestattet werden, um sie für Hochgeschwindigkeitsübertragungen zu ertüchtigen. Optische Kompensationstechniken sind unabhängig von der Kanaldatenrate. Daher wird eine Erhöhung der Datenrate problemlos unterstützt. Optische Kompensatoren können WDM-fähig gebaut werden, um mehrere Kanäle auf einmal zu entzerren. Das Buch beschäftigt sich mit optischen Delay-Line-Filtern als eine Klasse von optischen Kompensatoren. Die Filtersynthese von solchen Delay-Line-Filtern wird behandelt. Der Zusammenhang zwischen optischen Filtern und digitalen FIR-Filtern mit komplexen Koeffizienten im Zusammenhang mit kohärenter Detektion wird aufgezeigt. Iterative und analytische Methoden, die die Koeffizienten für dispersions- und dispersions-slope-kompensierende Filter produzieren, werden untersucht. Genauso wichtig wie die Kompensation von Dispersion ist die Schätzung der Dispersion eines Signals. Mit Delay-Line-Filtern können die Restseitenbänder eines Signals genutzt werden, um die Dispersion zu messen. Alternativ kann nichtlineare Detektion angewandt werden, um die Pulsverbreiterung, die hauptsächlich von der Dispersion herrührt, zu schätzen. Mit gemeinsamer Dispersionskompensation und Dispersionsmonitoring können Dispersionskompensatoren auf die Signalverzerrungen eingestellt werden. Spezielle Eigenschaften der Filter zusammen mit der analytischen Beschreibung können genutzt werden, um schnelle und zuverlässige Steueralgorithmen zur Filtereinstellung bereitzustellen. Schließlich wurden Prototypen derartiger faseroptischen Kompensatoren von chromatischer Dispersion und Dispersions-Slope hergestellt und charakterisiert. Die Einheiten und ihr Systemverhalten wird gezeigt und diskutiertOver the course of the past decades, the global communication system has become a central part of people's everyday lives. Optical communication systems are the technological basis for this development. Only fibers can provide the huge bandwidth that is required. Where the fiber could be regarded as a flat channel for the first optical transmission systems wavelength multiplexing and increasing line rates made it necessary to take more and more physical effects into account. When the line rates are increased to 40 Gbit/s and higher static chromatic dispersion compensation is not enough. The modulation format's intrinsic tolerance for dispersion decreases quadratically with the symbol rate. Thus, environmentally induced chromatic dispersion fluctuations may exceed the dispersion tolerance of the modulation formats. This makes an adaptive dispersion compensation necessary implying also the need for a monitoring scheme to steer the adaptive compensator. Legacy links that are CD-compensated by DCFs can be upgraded with residual dispersion compensators to make them ready for high speed transmission. Optical compensation is independent from the line rate. Hence, increasing the data rates is inherently supported. Optical compensators can be built WDM ready compensating multiple channels at once. The book deals with optical delay line filters as one class of optical compensators. The filter synthesis of such delay line filters is addressed. The connection between optical filters and digital FIR filters with complex coefficients that are used in conjunction with coherent detection could be shown. Iterative and analytical methods that produce the coefficients for dispersion (and also dispersion slope) compensating filters are researched. As important as the compensation of dispersion is the estimation of the dispersion of a signal. Using delay line filters, the vestigial sidebands of a signal can be used to measure the dispersion. Alternatively, nonlinear detection can be used to estimate the pulse broadening which is caused mainly by dispersion. With dispersion compensation and dispersion monitoring, dispersion compensators can be adapted to the signal's impairment. Special properties of the filter in conjunction with an analytical description can be used to provide a fast and reliable control algorithm for setting the filter to a given dispersion and centering it on a signal. Finally, prototypes of such fiber optic chromatic dispersion and dispersion slope compensation filters were manufactured and characterized. The device and system characterization of the prototypes is presented and discussed
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Vengattaramane, Kameswaran. "Efficient Reconstruction of Two-Periodic Nonuniformly Sampled Signals Applicable to Time-Interleaved ADCs." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6253.
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Nonuniform sampling occurs in many practical applications either intentionally or unintentionally. This thesis deals with the reconstruction of two-periodic nonuniform signals which is of great importance in two-channel time-interleaved analog-to-digital converters. In a two-channel time-interleaved ADC, aperture delay mismatch between the channels gives rise to a two-periodic nonuniform sampling pattern, resulting in distortion and severely affecting the linearity of the converter. The problem is solved by digitally recovering a uniformly sampled sequence from a two-periodic nonuniformly sampled set. For this purpose, a time-varying FIR filter is employed. If the sampling pattern is known and fixed, this filter can be designed in an optimal way using least-squares or minimax design. When the sampling pattern changes now and then as during the normal operation of time-interleaved ADC, these filters have to be redesigned. This has implications on the implementation cost as general on-line design is cumbersome. To overcome this problem, a novel time-varying FIR filter with polynomial impulse response is developed and characterized in this thesis. The main advantage with these filters is that on-line design is no longer needed. It now suffices to perform only one design before implementation and in the implementation it is enough to adjust only one variable parameter when the sampling pattern changes. Thus the high implementation cost is decreased substantially.
Filter design and the associated performance metrics have been validated using MATLAB. The design space has been explored to limits imposed by machine precision on matrix inversions. Studies related to finite wordlength effects in practical filter realisations have also been carried out. These formulations can also be extended to the general M - periodic nonuniform sampling case.
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Hamza-Lup, Felix George. "DYNAMIC SHARED STATE MAINTENANCE IN DISTRIBUTED VIRTUAL ENVIRONMENTS." Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4407.
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Advances in computer networks and rendering systems facilitate the creation of distributed collaborative environments in which the distribution of information at remote locations allows efficient communication. Particularly challenging are distributed interactive Virtual Environments (VE) that allow knowledge sharing through 3D information. In a distributed interactive VE the dynamic shared state represents the changing information that multiple machines must maintain about the shared virtual components. One of the challenges in such environments is maintaining a consistent view of the dynamic shared state in the presence of inevitable network latency and jitter. A consistent view of the shared scene will significantly increase the sense of presence among participants and facilitate their interactive collaboration. The purpose of this work is to address the problem of latency in distributed interactive VE and to develop a conceptual model for consistency maintenance in these environments based on the participant interaction model. A review of the literature illustrates that the techniques for consistency maintenance in distributed Virtual Reality (VR) environments can be roughly grouped into three categories: centralized information management, prediction through dead reckoning algorithms, and frequent state regeneration. Additional resource management methods can be applied across these techniques for shared state consistency improvement. Some of these techniques are related to the systems infrastructure, others are related to the human nature of the participants (e.g., human perceptual limitations, area of interest management, and visual and temporal perception). An area that needs to be explored is the relationship between the dynamic shared state and the interaction with the virtual entities present in the shared scene. Mixed Reality (MR) and VR environments must bring the human participant interaction into the loop through a wide range of electronic motion sensors, and haptic devices. Part of the work presented here defines a novel criterion for categorization of distributed interactive VE and introduces, as well as analyzes, an adaptive synchronization algorithm for consistency maintenance in such environments. As part of the work, a distributed interactive Augmented Reality (AR) testbed and the algorithm implementation details are presented. Currently the testbed is part of several research efforts at the Optical Diagnostics and Applications Laboratory including 3D visualization applications using custom built head-mounted displays (HMDs) with optical motion tracking and a medical training prototype for endotracheal intubation and medical prognostics. An objective method using quaternion calculus is applied for the algorithm assessment. In spite of significant network latency, results show that the dynamic shared state can be maintained consistent at multiple remotely located sites. In further consideration of the latency problems and in the light of the current trends in interactive distributed VE applications, we propose a hybrid distributed system architecture for sensor-based distributed VE that has the potential to improve the system real-time behavior and scalability.Ph.D.
School of Computer Science;
Engineering and Computer Science;
Engineering and Computer Science
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Carlini, Alessandro. "Prédire le passé et le futur : rôle des représentations motrices dans l'inférence du mouvement." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00834893.
Full textAbstract:
L'efficacité du système visuel est permise par un complexe réseau d'élaboration, qui s'appuie sur des structures corticales, sous-corticales et périphériques. Le but de la présente recherche est de mieux comprendre le processus de perception visuelle du mouvement, et réaliser un modèle computationnel capable de reproduire les fonctionnalités humaines du tracking (suivi) d'un objet en mouvement. Ce travail de thèse comprend une ample recherche bibliographique, ainsi qu'une série d'expérimentations ; la thèse se compose de deux parties :La première partie a pour objet la détermination des performances dans l'inférence " vers le passé ", d'un mouvement partiellement visible. Il s'agit de définir l'implication des informations exogènes (les signaux rétiniens) et endogènes (les modèles internes de l'action observée) dans la reconstruction de la cinématique d'une cible en mouvement et partiellement occultée. Nos résultats supportent l'hypothèse que le Système Nerveux Central adopte un mécanisme basé sur le recours aux modèles internes dans la reconstruction du passé de cinématiques biologiques. La deuxième partie complémente la première, et vise à identifier la structure et les caractéristiques fonctionnelles du système de poursuite, ainsi que à comprendre l'origine des erreurs systématiques présentes dans la localisation d'une cible chez l'homme. Nous avons développé un modèle computationnel en langage Matlab, basé sur le mécanisme d'extrapolation du mouvement, qui est capable de reproduire les données expérimentales dans la tâche de localisation
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Jansson, J. P. (Jussi-Pekka). "A stabilized multi-channel CMOS time-to-digital converter based on a low frequency reference." Doctoral thesis, Oulun yliopisto, 2012. http://urn.fi/urn:isbn:9789514299322.
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Abstract The aim of this work was to improve the performance and usability of a digital time-to-digital converter (TDC) in CMOS technology. The characteristics of the TDC were improved especially for the needs of pulsed laser time-of-flight (TOF) distance measurement, where picosecond-level precision with a long µs-level measurement range is needed in order to approach mm-level measurement accuracy. Stability in the face of process, voltage and temperature variations, multiple measurement channels, alternative measurement modes, a high integration level, standard interfaces and simple usage were the main features for development. The measurement architecture is based on counter and timing signal interpolation on two levels. The counter counts the full reference clock cycles between the timing signals, while a new recycling delay line developed in this thesis interpolates within the reference clock cycle. This technique utilizes a short delay line several times per reference clock cycle, which minimizes the interpolation nonlinearity. The same structure also makes the use of a low, MHz-level reference frequency possible, and thus only a crystal is needed as an external oscillator component. The parallel load capacitor-scaled delay line structure acts as the second, sub-gate-delay interpolation level. The INL does not accumulate in elements connected in parallel, and the load capacitance differences enable high, ps-level resolution to be achieved. Four TDC circuits in 0.35 µm CMOS technology were designed and tested in the course of this work, of which the latest, a 7-channel TDC, is able to measure the time intervals between the start pulse and three separate stop pulses in one measurement and to resolve the pulse widths or rise times at the same time. In laser TOF distance measurement this functionality can be used when several echoes arrive at the receiver, and also to compensate for the detection threshold problem known as timing walk error. The TDC achieves 8.9 ps interpolation resolution within the cycle time of a 20 MHz reference clock using only 8 delay elements on the first interpolation level and 14 delay elements on the second. A measurement precision better than 9 ps was achieved without using result post-processing or look-up tables. This work shows that versatile, high performance TDCs can be created in standard CMOS technologyTiivistelmä Väitöskirjatyön tavoitteena oli parantaa CMOS-aika-digitaalimuuntimien suorituskykyä ja käytettävyyttä. Muuntimen ominaisuuksia kehitettiin erityisesti laseretäisyysmittauksen tarpeita ajatellen, missä millimetritason mittaustarkkuus laajalla mittausaluella edellyttää aika-digitaalimuuntimelta pikosekuntitason tarkkuutta mikrosekuntien mittausalueella. Stabiilius prosessiparametri-, jännite- ja lämpötilavaihteluita vastaan, useat mittauskanavat, useat mittausmoodit, korkea integraatioaste, standardoidut liitäntäväylät ja helppo käytettävyys olivat erityisesti kehityksen kohteina. Suunniteltu mittausarkkitehtuuri koostuu laskurista ja kaksitasoisesta ajoitussignaali-interpolaattorista. Laskuri laskee kokonaiset referenssikellojaksot ajoitussignaalien välillä ja työssä kehitetty referenssiä kierrättävä viivelinjarakenne rekistereineen interpoloi ajoitussignaalien paikat referenssikellojaksojen sisältä. Referenssinkierrätystekniikka hyödyntää lyhyttä viivelinjaa useampaan kertaan kellojakson aikana, mikä minimoi epälineaarisuuden interpoloinnissa. Sama rakenne mahdollistaa myös MHz-tason referenssitaajuuden, jolloin matalataajuista kidettä voidaan käyttää referenssilähteenä. Toinen interpolointitaso koostuu rinnakkaisista kapasitanssiskaalatuista viive-elementeistä, mitkä mahdollistavat alle porttiviiveen mittausresoluution. Rinnakkaisessa rakenteessa elementtien epälineaarisuudet eivät summaudu, mikä mahdollistaa pikosekuntitason mittaustarkkuuden. Väitöskirjatyössä suunniteltiin ja toteutettiin neljä aikavälinmittauspiiriä käyttäen 0,35 µm CMOS-teknologiaa, joista viimeisin, 7-kanavainen muunnin kykenee mittaamaan aikavälin useampaan pulssiin yhdellä kertaa sekä voi selvittää samalla pulssien leveydet tai nousuajat. Laseretäisyysmittauksessa monikanavaisuutta voidaan käyttää kun useita kaikuja lähetetystä pulssista saapuu vastaanottimeen sekä kompensoimaan mittauksessa esiintyviä muita virhelähteitä. Käytettäessä 20 MHz:n kidettä referenssilähteenä muunnin saavuttaa alle 9 ps:n interpolointiresoluution ja tarkkuuden ilman epälineaarisuudenkorjaustaulukoita. Työ osoittaa, että edullisella CMOS-teknologialla voidaan toteuttaa monipuolinen ja erittäin suorituskykyinen aika-digitaalimuunnin
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Lin, Sheng-Wen, and 林聖文. "PID Controller Design Based on Smith-type Compensator for Stable/Integrating Processes with Inverse Response and Time Delay." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/jd987h.
Full textAbstract:
碩士國立臺北科技大學
化學工程研究所
99
In chemical industry, it is general to encounter great difficulties in process control when the system contains inverse response and time delay. To this circumstance, this thesis presents the design concepts and tuning rules for PID controller for stable/integrating processes with inverse response and time delay. The control system design is based on a Smith-type compensator for non-minimum phase (NMP) dynamics, which aims to remove these elements from the feedback loop. In this control scheme, it is necessary to factorize the process model into minimum phase and non-minimum phase portions. Different factorization methods are thus investigated and compared, and it turns out that the system resulted from direct factorization (DF) method can achieve better tradeoff between control performance and system robustness. Then, the equivalent feedback controller for the proposed configuration is approximated as a traditional PID controller by Maclaurin-series approach. The analytical tuning rules for PID parameters are developed where a single tuning controller parameter can be adjusted to make desired tradeoff between control performance and system robustness. Furthermore, the analysis of robust stability is provided. Several simulation examples have demonstrated the superiority of the proposed control design method.
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Lu, Chong-wei, and 呂崇瑋. "Easily-implemented compensation design of model reference time-delay networks with multiple time delays." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/92674884930048514306.
Full textAbstract:
碩士義守大學
電機工程學系碩士班
97
In this thesis, a class of model reference time-delay networks with multiple time delays is investigated. Based on the time-domain approach and feedback control methodolody, an easily-implemented control is proposed to realize synchronization for a class of model reference time-delay networks with multiple time delays. Furthermore, the guaranteed exponential convergence rate can be correctly estimated. Finally, several numerical examples and computer simulations are provided to illustrate the feasibility and effectiveness of the obtained results.
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CHEN, SHING-YUAN, and 陳行遠. "System Design of Flight Delay Compensation." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3334dx.
Full textAbstract:
碩士東吳大學
資訊管理學系
106
Because of the transparency of the flight information and the development of the blockchain technology in the past few years, flight delay insurance products can be redesigned. The insurance total, delay compensation details, expected time of arrival and the exact time which will cost the airliners to compensate if passed can be written into a smart contract. The blockchain technology could be applied to design a smart contract of flight delay insurance products. Although the factors that cause flight delays are difficult to predict, open and transparent flight information can help optimize flight delay insurance claims processes for automated claims. Flight on-time analysis results also help consumers make decisions and provide comprehensive insurance products services. The purpose of this research is to evaluate the possibility of designing a flight delay compensation system, and the feasibility of applying the blockchain technology to the design. Finally, we investigate the considerations in system design.
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Lin, Geng Sian, and 林耕賢. "Time Delay Compensation on Real-time Pseudo-dynamic Testing." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/nzvndy.
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碩士國立臺北科技大學
土木與防災研究所
98
In a real-time pseudo-dynamic test, time-delay occurring in the process of driving the actuator results in the difference between the measured structural recovering force in reality and the ideal one. It causes erroneous results in the test. Therefore, the study aims to develop a time-delay compensation method which can correct the error due to the time-delay. First, a delay differential equation（DDE）is used to represent the equation of motion of a system including time-delay. Based on the characteristic equation associated with the DDE, we can analytically derive the stability boundary equations which show how the dynamic stability of the system is affected by the time delay. We investigate the cases in which the time delay is considered to occur respectively and simultaneously in the recovering force and the damping force. Next, we modify Newmark explicit method such that it can solve for delay differential equations and explore how the time response of a structure is influenced by the time-delay. Finally, we derive a time-delay compensation method applied to a real-time pseudo-dynamic test through comparisons between the Newmark explicit method and the modified one. Then, the proposed compensation method is verified both numerically and experimentally if it can eliminate the error caused by the time-delay in the test.
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Lai, Chien-Liang, and 賴建良. "Networked Control Systems Design with the Time Delay Compensation." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/20724410824254882919.
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博士國立交通大學
電控工程研究所
99
Real-time network control applications have increasingly gained attentions due to the rapid development of data communication network technologies. Network systems can be conveniently and systematically maintained in industrial applications. The networked control system (NCS), which simply interconnects all sensors, actuators, and controllers through the network, is promising in the future development of industrial technologies with low integration cost. However, NCS also leads to unavoidable problems in time delays that seriously degrade control performance and stability. The characteristics of network-induced delays may be in constant, bounded, random, or unpredictable natures depending on the network protocols, nodes, software, and hardware. In this study, there are two approaches proposed for NCS design under significantly varied time delays. In the first approach, on-line estimation of the delay time is developed by processing the on-line measurement of the round-trip time (RTT) between two nodes in real network environments. Three related controllers are thus developed: (1) the adaptive Smith predictor control scheme for significantly varied time delay, (2) the robust NCS design for bounded variation of time delay and disturbance, and (3) the multi-rate design under the condition of wireless network congestion. The second approach is proposed as the model-free perfect delay compensation (PDC) scheme. This scheme effectively deals with network-induced delays requiring neither the delay time information nor the plant model. NCS with PDC is thus simply equivalent to the original closed-loop system with an additional pure time delay and it is designed without concerning the network. Therefore, the well-designed controller can be directly implemented on a network and its stability can be guaranteed without being affected by the varied time delay. The proposed approaches have been successfully applied to remote control systems under significantly time-varying delay to control an AC servo motor. Provided experimental results have further proven that both SISO and MIMO systems can be directly implemented in networking systems by including the proposed PDC to maintain its original feedback-loop characteristics.
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Lee, Peter Ming Wong. "Delay compensated fade prediction based CDMA closed loop power control." Thesis, 2004. http://hdl.handle.net/2429/15640.
Full textAbstract:
Power control is essential in Code Division Multiple Access (CDMA) systems in order to reduce the near-far effect, optimize,the system capacity, and combat the signal degradation due to fading. One problem with Closed Loop Power Control (CLPC) is the delay introduced by power measurement and round-trip delay in the power control loop. We study the impact of power control loop delays on Frame Error Rate (FER) performance under a range of channel conditions. A new CLPC algorithm with delay compensation and fade prediction is then proposed to mitigate the effects of loop delays on CLPC. Delay compensation can reduce power oscillation amplitude around the desired received power level and fade prediction can forecast an upcoming fade in order to mitigate its effect. The FER performance on the forward link of an Interim Standard - 2000 (IS-2000) CDMA system using the delay compensated fade prediction based CLPC algorithm is studied. Simulations with a detailed IS-2000 physical layer model and various Third Generation Partnership Project 2 (3GPP2) channel models are used to illustrate the performance gains of the proposed CLPC algorithm over the conventional CLPC algorithm. The performance of the proposed CLPC algorithm as a function of mobile speed, delay, and carrier frequency is analyzed. It is found that the proposed CLPC algorithm performs better than the conventional CLPC algorithm by about 1 dB for a range of mobile speeds of interest. The performance improvement obtainable by using the proposed CLPC algorithm can reduce the interference and result in an increase in the system capacity. Finally, the effect of power control bit (PCB) errors on the performance of the proposed CLPC algorithm is studied. Simulation results indicate that the proposed CLPC algorithm is still beneficial when the PCB error rate is 5%.
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Ho, Jyun-Che, and 何峻徹. "On Loop Delay Compensation Design for Continuous-Time ΣΔ ADC." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/00065990850436789392.
Full textAbstract:
碩士國立交通大學
電機與控制工程系所
96
A ΔΣ modulator is well-known as a very efficient technique for the implementation of high resolution A/D converters in low to medium bandwidth applications. Comparing with switched-capacitor (discrete-time) technique in the past, the continuous time circuitry is more suitable for today’s growing bandwidth applications. The thesis presents the implementation of a ΔΣ modulator with continuous-time techniques. Different numbers of digital delay in the ΔΣ feedback loop have been analyzed based on mathematic theorems in detail. The chip is designed with 1.8V power supply by using 0.18μm TSMC CMOS process, with power consumption 6.5mW and the core area 0.05mm2. The simulation result shows that the ADC achieves a 62dB peak signal-to-noise pulse distortion ratio (Peak-SNDR) within a 2MHz bandwidth with a sampling rate of 100MHz
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Liu, Meng-Che, and 劉孟哲. "Compensation of Nonlinear Distortion and Group Delay in OFDM Systems." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/34140765612291252547.
Full textAbstract:
碩士國立中正大學
通訊工程研究所
95
OFDM signal is very sensitive to the nonlinear distortion mainly caused by a power amplifier (PA) as a result of its high peak-to-average power ratio (PAPR). Predistortion, an effective countermeasure for balancing off the nonlinearity of a PA, is usually necessary for the sake of mitigating in-band distortion and spectrum regrowth. In the conventional schemes, a memoryless polynomial is generally used in modelling the PA characteristic or designing the predistorter. The polynomial coefficients are solved by least square (LS) estimation or adaptive identification algorithms in the time domain. However, most of the time domain schemes are not easy to implement owing to the practical difficulty in compensating the delay effect caused by the transmission filter and the receiving filter in the feedback path. In this thesis we examine this issue from frequency domain. The PA characteristic (or its inverse) can solved by least square (LS) estimation. But adaptive algorithm seem the only way to approach optimum predistorter. Due to we don’t wish to estimating the characteristic of the PA, So we can use numerical methods to solved this problem. In this thesis we propose adaptive finite difference algorithm to design predistorter, and time delay effect practically rotates the phase on frequency domain. If input signal of the PA is symmetric in frequency domain, out signal of the PA still exhibits the frequency symmetry. When delay effect occur, the phase didn’t still symmetry, thus we can use this characteristic obtain phase difference on differ frequency, consequently we can kwon delay time. Finally, the simulation of application of the proposed schemes to a 64-QAM OFDM system is presented.
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Cheng, Yao-Chung, and 鄭曜鐘. "The Minimization of Compensated Delay for Multi-Voltage Clock Tree Designs." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/3kb3k6.
Full textAbstract:
碩士中原大學
電子工程研究所
101
In modern VLSI designs, the minimization of power consumption is a very important issue. To minimize power consumption, the use of multiple voltages is a useful approach. However, in a multi-voltage design, the clock skew control becomes very complicated. Previous works use the delay compensation method to achieve always zero skew among different voltage modes. As a result, a large amount of compensated delay is often required. Based on that observation, in this paper, we try to utilize useful skew among blocks to reduce the amount of compensated delay. We propose a linear programming (LP) approach to formally draw up this problem. Compared with the previous work, experimental results show that our approach can reduce 19.08% compensated delay.
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Tang, Yu Tang, and 唐祐堂. "A Study of Nonlinear Time-Delay Compensation using Artificial Neural Network." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/39394372974812751807.
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Wang, Tse-Kai, and 王則凱. "Compensation of Project Overhead Damages for Concurrent Delay in Public Construction." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/90829726698322853295.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
101
It is generally recognized that construction delays is critical in public construction projects. Contractors may claim incurred costs for excusable and compensable delays. And it often leads to contract disputes due to the lack of effective settlement approaches. The presence of concurrent delay adds to the complexity of delay analysis as it has become the most common defense raised by owners faced with a contractor's claim for delay damages. Therefore, it is imperative to develop methods for calculating overhead claims for damages due to concurrent delay. Whatsoever, apportioning responsibilities of concurrent delay between the two parties is extremely difficult, due to the complicated nature both in the Construction programme as well as the circumstances under which methodology should be applied. The main objective of this study is thus aimed to assist in the quick and efficient calculation of the appropriate compensation due a contractor for concurrent delay. In this study, key issues and the major problems encountered in the calculation of damage of compensable delay of public construction were investigated first and guidances set up in the SCL Delay and Disruption Protocol (DDP) were examined. In addition, the existing methodologies for analysing concurrent delay claims with a view to identifying the problems associated with their current usage towards apportionment were explored. Then, seven case studies were conducted to evaluate the differences of calculating overhead claims for damages due to concurrent delay using various delay analysis techniques such as Time Impact Analysis，Snapshot Analysis and Window Analysis etc. Base on the result, guidelines of appropriate compensation for concurrent delays were established consequently.
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Lu-Zhen, Chen, and 陳陸陣. "A Study of Compensatory Policy for Travel Time Delay of TRA''s Service." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/82434591653588127866.
Full textAbstract:
碩士國立交通大學
運輸工程與管理系
88
A Study of Compensatory Policy for Travel Time Delay of TRA’s Service Student：Lu-Zhen Chen Advisor：Dr. Hsin-Li Chang Institute of Transportation Engineering and Management National Chiao Tung University ABSTRACT Punctuality is commonly recognized as an important factor affecting travelers'' mode choice decision. However, travel time delay still happens to operation sometimes due to the occurrence of expected or unexpected events. From the viewpoints of trade equity and service quality, some compensatory policies should be made to reasonably make up customers'' loss resulted from those events. Unfortunately, it lacks of systemically studies in refunds of delay in Taiwan. The operators can only deal those events by case, and a lot of quarrels have happened between travelers and operators. This study not only reviews the operation data of Taiwan Railway Administration (TRA), but also collects the opinions of railway users to the refunding policies that include conditions for refunding and alternatives of refunding. Some propositions were derived based on the analytical results from collected information. The empirical results show that half of the travelers don’t satisfy the current compensatory policy of TRA. Travelers evaluate the convenience of refunding procedure as the most important factor among all concerned factors. Most people agree that TRA should be responsible only to the travel time delays resulted from preventable events. Sixty minutes delay is suggested as the refunding threshold for travel time delay in the short term. The amount of refund is suggested to be the half value of purchased ticket. Furthermore, if discount coupon will be used as another refunding alternative, extra refund should be offered. About eighty percentages of travelers show their willingness to pay extra cost to buy better service quality. The study results not only provide valuable information for drawing appropriate refunding policies for travel time delay of railway operations, but also explore a lot of operation and quality control issues for transportation industry.
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TSENG, Chih-wei, and 曾智威. "Compensation of Project Overhead Damages for Owner Caused Delay in Public Construction." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/78d93z.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
99
It is generally recognized that construction delays is critical in public construction projects. Contractors may claim incurred costs for excusable and compensable delays. However, the compensation of overhead damages for owner caused construction delay is not specified in most public construction contacts. And it often leads to contract disputes due to the lack of effective settlement approaches. Therefore, it is imperative to develop methods for calculating overhead claims for damages due to construction delay. Unabsorbed overhead is a significant cost to contractors and needs to be addressed in an expeditious manner by owners and their representatives. The objective of this study is aimed to assist in the quick and efficient calculation of the appropriate compensation due a contractor for an owner caused increase in the project duration. In this study, key issues and the major problems encountered in the calculation of damage of compensable delay of public construction were investigated first through extensive interviews with leading experts. Then, various approaches for compensable damage with relate to the cost items that may incur due to owner caused delay are compared and analyzed. Furthermore, cases study (including 30 mediation cases and 21 litigation cases ) are conducted to explore the current practices of calculating overhead claims for damages due to project delay. It is concluded that there are significant discrepancies in mediation and litigation with regard to the determination of jobsite overhead by the over-simplified proportion method. Based on the results, guidelines of appropriate compensation for owner caused construction delay are established. Taking account of the circumstances of the construction delay and the related expenses incurred, a modified method of pricing allocable overhead for dispute resolution is developed consequently.
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SUNG, YEN-LIN, and 宋彥霖. "Compensation of Project Overhead Damages for Delay and Disruptions in Public Construction." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/48539760856763636659.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
104
Overhead damage due to delay is a very controversial issue since it is very difficult to verify the costs incurred are linked to the delay and to determine extra resources used. However, the methodology for the calculation of the expense incurred has been widely debated. There are significant discrepancies with regard to current practices of calculating prolongation costs by the over-simplified proportion method. Factors should be considered in assessing overhead damage relating to different circumstances and their effects of the delay and disruptions. The objective of this study is aimed to assist in the quick and efficient calculation of the appropriate compensation for prolongation costs to facilitate delay and disruption claims assessment and their resolution. In this study, key issues and the major problems encountered in the calculation of damage of compensable delay of public construction were investigated first through extensive interviews with leading experts. Then, case studies(including 12 mediation cases,2 arbitration and 7 litigation cases )were conducted to explore the current practices of calculating overhead damages due to project delay. And various approaches for compensable damage with relate to the cost items that may incur due to owner caused delay were compared and analyzed. It is concluded that there are significant discrepancies in mediation and litigation with regard to the determination of jobsite overhead by the over-simplified proportion method currently employeed. Guidance set up in the SCL Delay and Disruption Protocol (UK) as well as in the MLIT Ordinance (Japan) are examined. Based on the results, taking account of the circumstances of the construction delay and the related expenses incurred, a modified method of pricing allocable overhead for dispute resolution are developed consequently.
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Zhang, Zi-Yang, and 張梓洋. "Study on the RC Delay Issues for the External Compensation AMOLED Circuit." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/why4xa.
Full textAbstract:
碩士國立交通大學
光電工程研究所
106
In this paper, we study on the RC delay issues for the external compensation method of Sentinel Voltage Control for AMOLED circuit with real-time feedback. This circuit has ramping bus and sensing bus to connect the pixel and the driver IC. Ramping bus is used to pass input signal, and sensing bus is used to pass sensing current. Since there are parasitic resistors and capacitors on the ramping bus and the sensing bus, the input signal and the sensing current can be affected by the RC delay. Because the proposed external compensation circuit is a real-time feedback, the delayed signal and wrong sensing current may cause serious problems in the circuit. In order to solve the problem of input signal delay, we propose two methods. The main concept of the first method is capacitive coupling, and the driving voltage is pulled back the expected value by capacitive coupling. The concept of the second method is to add a delay block to make the delay input signal of near end and far end be the same. We also propose a method to solve the effect of RC delay on the sensing bus. The concept of the method is to add an analog computer to correct the wrong sensing current to the right value. Finally, we propose two methods that deal with the effects of RC delay on the both buses. The first method uses the look-up table and delay time adjustment. The concept is to form a table with the near end data and use it for and far end. According to the required driving current, we select the best available sensing voltage in the table and make minor adjustment in the ramp stop time with a delay block. The second method is to adjust the near-end and far-end I-V converting factor with different component. For the same driving current, the sensing currents of the near and far ends translate to the same sensing voltage through different I-V converting component. Therefore, we make the external compensation AMOLED circuit useful even with the RC delay on buses.
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Liao, Yu Jia, and 廖昱嘉. "An Active Rectifier with Time-Domain Delay Compensation to Enhance the Efficiency." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107CGU05442015%22.&searchmode=basic.
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Chang, Li-Ying, and 張立穎. "Phase Advance Compensation for Computational Time Delay of a Digital Controlled PWM Converter." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/51539441732306927684.
Full textAbstract:
碩士國立清華大學
電機工程學系
92
Recently, many power electronics applications use digital signal processors for control implementation because of their advantages in handling complex mathematics operations and easy programming. However, the inherent time delay of the digital signal processor deteriorates its control performance. For example, the filtering capability of the shunt active filter highly depends on the current control capability. The time delay of the digital signal processor reduces the current tracking capability and harmonic compensation performance. Thus, the research on the time delay of the digital controller becomes an issue. The predictive current regulator is often used for shunt active filters because it has the advantages of high current tracking capability and fixed switching frequency operation. This thesis studies the effect of the time-delay caused by digital controllers on the predictive current regulator, and proposes a compensation method. Computer simulation and laboratory test results are presented to validate the functionalities of the proposed method.
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Yu, Jen-Tsung, and 游仁宗. "A Compact Delay-Recycled Clock Skew-Compensation And/Or Duty-Cycle-Correction Circuit." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/34570195575256761660.
Full textAbstract:
碩士國立暨南國際大學
電機工程學系
99
A clock skew-compensation and/or duty-cycle correction circuit (CSADC) is indispensably required to maximize the performance of a synchronous double edge clocking system. Most conventional CSADC adopted a cascade structure that inherits a lower performance property that is causing a slower the locking procedure, meanwhile the dual loop design results in more design complexity. In this thesis, a compact delay-recycled CSADC was proposed. There are two significant design concepts in the CSADC. The first is a fast locking and low power measure-and-tuned architecture. The second is a bandwidth augmentation technique. Compared to conventional CSADCs, the proposed circuit achieves at least a 4.24 times reduction in power, a 7.93 times reduction in power bandwidth ratio, and a 1.11 times reduction in lock-in cycles. In TSMC 0.18-μm 1P6M 1.8V CMOS process, the “input signal frequency range” of the proposed CSADC from 300MHz to 2GHz, and the corrected duty cycle variation ranges from 48.41% to 55.51% are confirmed through HSPICE circuit simulation. When the clock frequency is 2GHz, the acceptable input duty cycles ranges from 30% to 70%. Besides, the aligned phase error and power consumption are 67ps and 5.87mW, respectively.
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Shenouda, Mikhail. "Temperature Effects in Optical Fiber Dispersion Compensation Modules." Thesis, 2013. http://hdl.handle.net/10012/7866.
Full textAbstract:
This thesis presents the results for the temperature variation of the Differential Group Delay (DGD) measurements of a Dispersion Compensation Module (DCM) and interprets the results with a theoretical DGD model based on glass viscoelastic properties and estimated values of some of glass parameters. The results of our analysis demonstrate the existence of long birefringence relaxation times on the order of many hours in response to temperature changes. These results could be of significance in interpreting the behavior of optical fiber systems.
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Knight, Thomas, and Henry M. Wu. "A Method for Skew-free Distribution of Digital Signals Using Matched Variable Delay Lines." 1992. http://hdl.handle.net/1721.1/5986.
Full textAbstract:
The ability to distribute signals everywhere in a circuit with controlled and known delays is essential in large, high-speed digital systems. We present a technique by which a signal driver can adjust the arrival time of the signal at the end of the wire using a pair of matched variable delay lines. We show an implemention of this idea requiring no extra wiring, and how it can be extended to distribute signals skew-free to receivers along the signal run. We demonstrate how this scheme fits into the boundary scan logic of a VLSI chip.
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Bibian, Stéphane. "Time delay compensation of digital control for switchmode DC power supplies using prediction techniques." Thesis, 1999. http://hdl.handle.net/2429/9251.
Full textAbstract:
The control of switchmode dc power supplies has been traditionally implemented in analog
electronics for its low cost, high bandwidth, and proven technology. However, the emergence of
advanced microprocessors and Digital Signal Processors (DSPs) has made it possible for power supply
manufacturers to consider digital technology a suitable option.
As compared to analog control, digital control provides a number of advantages such as reduced
susceptibility to aging and environmental variation (temperature, humidity, etc.), better noise
immunity, ability to handle complex control schemes and monitoring functions, possibility to
implement communication functions for fault and status information, and easy re-programming for
different applications. With the downward trend of microprocessor prices and the versatility of the
hardware architecture, digital control offers a cost-effective solution which can compete with analog
technology.
However, one of the major drawbacks of digital control is the limited bandwidth caused by the
inherent time delay required for A/D conversion, computation and PWM generation. Such delay
degrades the control loop performance, which makes it difficult to comply with technical
specifications in many high-performance products.
In this thesis, a simple and straightforward predictive technique based on linear extrapolation is
presented to compensate for this delay. Two predictive controllers are derived and applied to a full
bridge dc power supply. Simulation and experimental results show that the performances of the
converter with respect to dc bus ripple and load disturbances can be significantly improved. Those
schemes are characterized by a low computational cost which makes them particularly attractive in the
demanding real-time environment due to the ever increasing switching frequency of the converter.
A similar prediction concept based on a second order parabolic extrapolation is also presented. This
predictor substantially reduces the amount of calculation needed to obtain similar results to a
conventional controller, thus freeing valuable processor resources. These resources can be used for
less critical tasks such as communication and user interface. As a result, the processor is not solely
dedicated to the control of the power supply but can incorporate other functions, thus adding
functionality and expandability to the system.
Finally, this thesis assesses typical digital control issues such as word length, A/D resolution and
fixed point programming.
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Hou, Chia-wen, and 侯佳玟. "Vibration Control Performance of Pseudo Hybrid Mass Damper Systems with Optimal Time Delay Compensation." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/46361641166515714256.
Full textAbstract:
碩士國立成功大學
土木工程學系碩博士班
95
The vibration mitigation performance of a conventional tuned mass damper system (TMD) is very sensitive to the fluctuation in tuning of the designed frequency to the natural frequency of the main system. Because of the stochastic characteristics of external loading and the errors of identifying system parameters, a hybrid mass damper system (HMD) with optimal selection on control parameters can enhance the designed performance with the help of a supplementary active force acted between the main system and the mass damper. However, the control performance degradation induced by the control force application time delay should be considered and investigated before practical application. In practical consideration, using discrete time optimal control theorem involved time delay effect ,the Pesudo Hybrid Mass Damper (PHMD) systems are proposed to investigate the interactive detuning of parameter and time delay. A multiple-sampling -rate algorithm is applied to verify the control performance in time domain subjected to earthquake excitations. From numerical results of frequrncy domain and time domain, if choose optimal control designed value and optimal delay time, the good control performance provide stable modal damping and keep tuning,which better than TMD & HMD system.
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Jian, Da-Hong, and 簡達鴻. "A Time Delay Compensation System Based on Fuzzy Neural Networks and Improved Communication Disturbance Observer." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/89q5z3.
Full textAbstract:
碩士國立臺北科技大學
電機工程系研究所
100
In recent years, due to the development of the Internet, the controlled systems have become more complex. In industry and academia, traditional control has been unable to satisfy the requirement of the control performance, so the research on networked control system (NCS) is important increasingly. However, in the actual control system, especially controlled over the Internet, the time delay is an urgent problem. If the time delay is too long, the stability and performance of the whole system will be destroyed, and then it is difficult to analyze and design the systems. Therefore, this paper proposes a set of time delay compensation method, based on the architecture of communication disturbance observers (CDOB) with fuzzy theory and neural networks algorithm, and results show that it can improve the time delay system effectively. First, it replaces the traditional controller with fuzzy controller, combined with improved CDOB architecture, to study the effect of the low-pass filter in CDOB architecture. When the frequency of the disturbance signal changes, the fuzzy controller can be adapted to it. System modeling utilizes back propagation method in neural networks, by continuously training and the adjustment of weight value, the estimation is more close to the actual system, and therefore we can reduce the modeling error and improve the steady state error of the system response. From the simulation results, the proposed method in this paper can be effectively applied to the networked control systems with time delay.
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Hung, Jia-hung, and 洪嘉鴻. "Rrsearch on Compensation of Project Overhead Damages For Owner Caused Concurrent Delay of Responsibility Apportionment." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/55813952705554177848.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
98
It is generally recognized that construction delays is critical in public construction projects. Contractors may claim incurred costs for excusable and compensable delays.And it often leads to contract disputes due to the lack of effective settlement approaches.Concurrency is a contentious issue both because there are differing views on the correct approach to concurrency when analysing entitlement to EOT. The main objective of this study is thus aimed to assist in the quick and efficient calculation of the appropriate compensation due a contractor for concurrent delay. In this study, key issues and the major problems encountered in the calculation of damage of compensable delay of public construction will be investigated first through extensive interviews with leading experts and questionnaire surveys. Guidances set up in the SCL Delay and Disruption Protocol (UK) will be examined. Then, the existing methodologies for analysing concurrent delay claims with a view to identifying the problems associated with their current usage towards apportionment will be explored.