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Dissertations / Theses on the topic 'Sampled-data control systems'
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Langari, Ali. "Sampled-data repetitive control systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27986.pdf.
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Dullerud, Geir Eirik. "Control of uncertain sampled-data systems." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320110.
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Mathew, Michael Ian. "Design of nonlinear sampled-data systems." Thesis, Coventry University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.480606.
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Galloway, Peter Richard. "Direct continuous-time control of sampled-data systems." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341740.
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Goucem, Ali. "Computer aided design of nonlinear sampled data systems." Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328341.
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Cantoni, Michael William. "Linear periodic systems : robustness analysis and sampled-data control." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415264.
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Bridgett, Nicholas Arthur. "Design and analysis of nonlinear sampled-data control systems." Thesis, Coventry University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303000.
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Wu, Buzhou. "Sampled-data control of a class of nonlinear systems." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493558.
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Su, Wu-Chung. "Implementation of variable structure control for sampled-data systems /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu148785431487298.
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Zheng, Ying. "Sampling rates and the stability of nonlinear sampled-data systems." Thesis, University of Sheffield, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359483.
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Yame, Joseph. "Contribution to the mathematical theory of sampled-data control systems." Doctoral thesis, Universite Libre de Bruxelles, 2001. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211597.
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Martin, Gregory A. "Modeling, control, and observation of sampled-data nonlinear systems under delayed control and sensing." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/13914.
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Kurudamannil, Jubal J. "Improved Robust Stability Bounds for Sampled Data Systems with Time Delayed Feedback Control." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1419012522.
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Mulay, Siddharth Pradeep. "Robustness Bounds For Uncertain Sampled Data Systems With Presence of Time Delays." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365971507.
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Ben, Jemaa Lamia. "Performance limitations in the robust servomechanism control problem for discrete and sampled data systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58957.pdf.
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Hayakawa, Yoshikazu, Shinji Hara, and Yutaka Yamamoto. "H∞type problem for sampled-data control systems : a solution via minimum energy characterization." IEEE, 1994. http://hdl.handle.net/2237/6811.
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Zafiriou, Evanghelos Doyle John Comstock. "A methodology for the synthesis of robust control systems for multivariable sampled-data processes /." Diss., Pasadena, Calif. : California Institute of Technology, 1987. http://resolver.caltech.edu/CaltechETD:etd-05052006-140832.
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Sanfridson, Martin. "Quality of control and real-time scheduling : allowing for time-variations in computer control systems." Doctoral thesis, KTH, Machine Design, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3785.
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The majority of computers around us are embedded in productsand dedicated to perform certain tasks. A specific task is thecontrol of a dynamic system. The computers are ofteninterconnected by communication networks forming a distributedsystem. Vehicles and manufacturing equipment are two types ofmechatronic machines which often host dedicated computercontrol systems. A research problem is how the real-timebehaviour of the computer system affects the application,especially the control of the dynamic system.
If the internal or external conditions varies over time, itbecomes difficult to assign a fixed resource reservation thatwill work well in all situations. In general, the more time anapplication gets of a resource, the better its gauged orperceived quality will be. A strategy is to alter the resourcereservation when the condition changes. This can be constructedas a negotiation between competing applications, a method forwhich the termquality of control, QoC, has been coined. Scalability isthe ability to change the structure and configuration of asystem. It promotes evolving systems and a can help manage acomplex product family. An architecture for a QoC middleware ontop of a scalable computer system, has been proposed.
As aquality measureof a control application, the well-knownweighted quadratic loss function used in optimal control, hasbeen revised to encompass a subset of the so called timingproperties. The timing properties are the periods and thedelays in the control loop, including time-varying period anddelay. They are the interface between control and computerengineering, from a control engineering viewpoint. The qualitymeasure can be used both offline and on-line given a model ofthe sampled-data system and an appropriate description of thetiming properties.
In order to use a computer system efficiently and toguarantee its responsiveness, real-time scheduling is a must.In fixed priority scheduling each task arrives periodically andhas a fixed priority. A task with a high priority can preempt alow priority task and gain access to the resource. Thebest-case response time characterizes the delays in the system,which is useful from a control viewpoint. A new algorithm tocalculate thebest-caseresponsetime has been derived. It is based on ascheduling scenario which yields a recurrence equation. Themodel is dual to the well-known worst-case response timeanalysis.
Besides the dynamic fixed priority scheduling algorithm,optimal control usingstatic schedulinghas been studied, assuming a limitedcommunication. In the static schedule, which is constructedpre-runtime, each task is assigned a time window within aschedule repeated in eternity. The optimal scheduling sequenceis sought by optimizing the overall control performance. Aninteresting aspect is that the non-specified control periodfalls out as a result of theoptimal schedule. The time-varying delay is accountedfor in the control design.
Keywords:Real-time scheduling, sampled-data control,performance measure, quality of control, limited communication,time-varying delay, jitter.
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Tanasa, Valentin. "Development of theoretical and computational tools for the design of control strategies for nonlinear sampled-data systems." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00763971.
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This thesis is concerned with the sampled-data control of non-linear continuous-time systems. Sampled-data systems are present in all computer controlled, hybrid or embedded systems. The design and computation of suitable digital controllers represent unavoidable tasks since both continuous and discrete-time components interact. The basic framework of this work takes part of a wide research activity performed by S. Monaco and D. Normand-Cyrot regarding non-linear sampled-data systems. The underlying idea is to design digital controllers that recover certain continuous-time properties that are usually degraded through sampling as it is the case when continuous-time controllers are implemented by means of zero-order holder devices (emulated control). This thesis brings contributions into three different directions. The first one regards theoretical developments: a new digital backstepping-like strategy design for strict-feedback systems is proposed. This method is compared with other strategies proposed in the literature. The second contribution is the development of a control designer and of a simulation toolbox (in Matlab) for non-linear sampled-data systems. This toolbox includes different digital design strategies such as: multi-rate control, input-output/Lyapunov matching, digital backstepping design, etc. The third contribution concerns several case studies conducted to highlight the performances of the sampled-data controller designs, computed by the means of the software toolbox. Experimental and simulation results are described for various real examples especially in the area of electrical and mechanical processes.
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Wang, Chao. "Aircraft autopilot design using a sampled-data gain scheduling technique." Ohio : Ohio University, 1999. http://www.ohiolink.edu/etd/view.cgi?ohiou1175280078.
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Tanaka, Shunji. "Studies on Sampled-Data Control Systems -the H[∞] Problem of Discrete Linear Periodically Time-Varying Systems and Nonuniform Sampling Problems." Kyoto University, 1999. http://hdl.handle.net/2433/77928.
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ZAREH, ESHGHDOUST MEHRAN. "Consensus in multi-agent systems with time-delays." Doctoral thesis, Università degli Studi di Cagliari, 2015. http://hdl.handle.net/11584/266600.
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Different consensus problems in multi-agent systems have been addressed in this thesis. They represent improvements with respect to the state of the art. In the first part of the thesis in luding Chapters 2, 3, and 4, the state of the art of the representation and stability analysis of consensus problems, time-delay systems, and sampled-data systems have been presented. Novel contributions have been illustrated in Chapters 5-8. Particularly, in Chapter 5 we reported the results of Zareh et al. (2013b), where we investigated the consensus problem for networks of agents with double integrator dynamics affected by time-delay in their coupling. We provided a stability result based on the Lyapunov-Krasovskii functional method and a numerical proc edure based on an LMI condition which depends only on the algebraic connectivity of the considered network topologies, thus reducing greatly the computational complexity of the procedure. Obviously, this result implies the existence of a minimum dwell time such that the proposed consensus protocol is stable for slow swit things between network topologies with suffient algebraic connectivity. Future work will involve actually computing such a dwell time by adopting a multiple Lyapunov function method and evaluating the worst case sider only delayed relative measurements instead of delayed absolute values of the neighbors' state variables. The results of Zareh et al. (2013a) were addressed in Chapter 6, in which a on- tinuous time version of a consensus on the average protocol for arbitrary strongly connected directed graphs is proposed and its convergence properties with respect to time delays in the local state update are characterized. The convergenc e properties of this algorithm depend upon a tuning parameter that an be made arbitrary small to prove stability of the networked system. Simulations have been presented to corroborate the theoretical results and show that the existenc e of a small time delay an a tually improve the algorithm performance. Future work will include an extension of the mathematical characterization of the proposed algorithm to consider possibly heterogeneous or time-varying delays. In Chapter 7 we proposed a PD-like consensus algorithm for a second-order multi- agent system where, at non-periodic sampling times, agents transmit to their neighbors information about their position and veloc ity, while each agent has a perfect knowledge of its own state at any time instant. Conditions have been given to prove onsensus to a ommon xed point, based on LMIs verification. Moreover, we also show how it is possible to evaluate an upper bound on the de ay rate of exponential convergence of stable modes. In Chapter 8, mainly based on our paper Zareh et al. (2014b), we considered the same problem as in Chapter 7. The main contribution consists in proving consensus to a common fixed point, based on LMIs verification, under the assumption that the network topology is not known and the only information is an upper bound on the connectivity. Two are the main directions of our future research in this framework. First, we want to compute analytically an upper bound on the value of the second largest eigenvalue of the weighted adjacency matrix that guarantees consensus, as a function of the other design parameters. Second, we plan to study the case where agents do not have a perfect knowledge of their own state.
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Almér, Stefan. "Control and Analysis of Pulse-Modulated Systems." Doctoral thesis, KTH, Optimeringslära och systemteori, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4713.
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The thesis consists of an introduction and four appended papers. In the introduction we give an overview of pulse-modulated systems and provide a few examples of such systems. Furthermore, we introduce the so-called dynamic phasor model which is used as a basis for analysis in two of the appended papers. We also introduce the harmonic transfer function and finally we provide a summary of the appended papers. The first paper considers stability analysis of a class of pulse-width modulated systems based on a discrete time model. The systems considered typically have periodic solutions. Stability of a periodic solution is equivalent to stability of a fixed point of a discrete time model of the system dynamics. Conditions for global and local exponential stability of the discrete time model are derived using quadratic and piecewise quadratic Lyapunov functions. A griding procedure is used to develop a systematic method to search for the Lyapunov functions. The second paper considers the dynamic phasor model as a tool for stability analysis of a general class of pulse-modulated systems. The analysis covers both linear time periodic systems and systems where the pulse modulation is controlled by feedback. The dynamic phasor model provides an $\textbf{L}_2$-equivalent description of the system dynamics in terms of an infinite dimensional dynamic system. The infinite dimensional phasor system is approximated via a skew truncation. The truncated system is used to derive a systematic method to compute time periodic quadratic Lyapunov functions. The third paper considers the dynamic phasor model as a tool for harmonic analysis of a class of pulse-width modulated systems. The analysis covers both linear time periodic systems and non-periodic systems where the switching is controlled by feedback. As in the second paper of the thesis, we represent the switching system using the L_2-equivalent infinite dimensional system provided by the phasor model. It is shown that there is a connection between the dynamic phasor model and the harmonic transfer function of a linear time periodic system and this connection is used to extend the notion of harmonic transfer function to describe periodic solutions of non-periodic systems. The infinite dimensional phasor system is approximated via a square truncation. We assume that the response of the truncated system to a periodic disturbance is also periodic and we consider the corresponding harmonic balance equations. An approximate solution of these equations is stated in terms of a harmonic transfer function which is analogous to the harmonic transfer function of a linear time periodic system. The aforementioned assumption is proved to hold for small disturbances by proving the existence of a solution to a fixed point equation. The proof implies that for small disturbances, the approximation is good. Finally, the fourth paper considers control synthesis for switched mode DC-DC converters. The synthesis is based on a sampled data model of the system dynamics. The sampled data model gives an exact description of the converter state at the switching instances, but also includes a lifted signal which represents the inter-sampling behavior. Within the sampled data framework we consider H-infinity control design to achieve robustness to disturbances and load variations. The suggested controller is applied to two benchmark examples; a step-down and a step-up converter. Performance is verified in both simulations and in experiments.QC 20100628
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Rehbinder, Henrik. "State Estimation and Limited Communication Control for Nonlinear Robotic Systems." Doctoral thesis, KTH, Mathematics, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3250.
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Ajwad, Syed Ali. "Distributed control of multi-agent systems under communication constraints : application to robotics." Thesis, Poitiers, 2020. http://www.theses.fr/2020POIT2264.
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Les Systèmes Multi-Agents (SMA) ont gagné en popularité en raison de leur vaste gamme d'applications. Les SMA sont utilisés pour atteindre des objectifs complexes qui ne pourraient être atteints par un seul agent. La communication et l'échange d'informations entre les agents d'un SMA sont essentiels pour contrôler son comportement coopératif. Les agents partagent leurs informations avec leurs voisins pour atteindre un objectif commun, ils n'ont donc pas besoin d'unité centrale de surveillance. Cependant, la communication entre les agents est soumise à diverses contraintes pratiques. Ces contraintes incluent des périodes d'échantillonnage irrégulières et asynchrones et la disponibilité d'états partiels uniquement. Ces contraintes posent des défis théoriques et pratiques importants. Dans cette thèse, nous étudions deux problèmes fondamentaux liés au contrôle coopératif distribué, à savoir le consensus et le contrôle de formation pour un SMA à double intégrateur sous ces contraintes. On considère que chaque agent du réseau ne peut mesurer et transmettre son état de position qu'à des instants d'échantillonnage non uniformes et asynchrones. De plus, la vitesse et l'accélération ne sont pas disponibles. Dans un premier temps, nous étudions le problème du contrôle distribué du suivi de consensus. Un algorithme de suivi de leader basé sur l'observateur à temps discret continu est proposé. L'observateur estime la position et la vitesse de l'agent et de son voisin en temps continu à partir des données de position échantillonnées disponibles. Ces états estimés sont ensuite utilisés pour le calcul de l'entrée de commande. Les scénarios de topologie fixe et de topologie commutée sont discutés. Deuxièmement, un protocole de suivi de formation distribué basé sur le consensus est conçu pour réaliser des modèles de formation fixes et variant dans le temps. Le problème d'évitement de collision est également étudié dans cette thèse. Un mécanisme d'évitement de collision basé sur la fonction de potentiel artificiel (APF) est incorporé à l'algorithme de suivi de formation pour empêcher les collisions entre les agents tout en convergeant vers la position souhaitée. Enfin, les algorithmes proposés sont appliqués sur un réseau multi-robots, composé de robots à entraînement différentiel utilisant Robot Operating System (ROS). Un nouveau schéma est proposé pour faire face aux contraintes non holonomiques du robot. L'efficacité des algorithmes sont démontrées à la fois par des résultats de simulation et des expérimentationsMulti-agent systems (MAS) have gained much popularity due to their vast range of applications. MAS is deployed to achieve more complex goals which could not be realized by a single agent alone. Communication and information exchange among the agents in a MAS is crucial to control its cooperative behavior. Agents share their information with their neighbors to reach a common objective, thus do not require any central monitoring unit. However, the communication among the agents is subject to various practical constraints. These constraints include irregular and asynchronous sampling periods and the availability of partial states only. Such constraints pose significant theoretical and practical challenges. In this thesis, we investigate two fundamental problems related to distributed cooperative control, namely consensus and formation control, of double-integrator MAS under these constraints. It is considered that each agent in the network can measure and transmit its position state only at nonuniform and asynchronous sampling instants. Moreover, the velocity and acceleration are not available. First, we study the problem of distributed control of leader-following consensus. A continuous-discrete time observer based leader-following algorithm is proposed. The observer estimates the position and velocity of the agent and its neighbor in continuous time from the available sampled position data. Then these estimated states are used for the computation of the control input. Both fixed and switching topology scenarios are discussed. Secondly, a consensus based distributed formation tracking protocol is designed to achieve both fixed and time-varying formation patterns. Collision avoidance problem is also studied in this thesis. An Artificial Potential Function (APF) based collision avoidance mechanism is incorporated with the formation tracking algorithm to prevent collisions between the agents while converging to a desired position. Finally, the proposed algorithms are applied on a multi-robot network, consisting of differential drive robots using Robot Operating System (ROS). A new scheme is proposed to deal with nonholonomic constraints of the robot. Efficiency of the designed algorithms and their effectiveness in real world applications are shown through both simulation and hardware results
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Findeisen, Rolf. "Nonlinear model predictive control a sampled data feedback perspective /." [S.l. : s.n.], 2004.
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Ricciardi, Celsi Lorenzo. "Commande non linéaire multi-agents : applications aux systèmes en réseau." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS017/document.
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L'objectif de cette thèse de doctorat est (i) d'étudier et de développer des méthodes d’analyse et de commande de systèmes de contrôle en réseau linéaires et non linéaires et (ii) de montrer le potentiel de ces approches dans des applications complexes pertinentes. À cet égard, la théorie des systèmes à plusieurs agents, la théorie des graphes algébriques et le consensus sont des outils méthodologiques les plus intéressants. Une attention particulière est accordée à la caractérisation des relations entre, d'une part, la topologie du graphe de communication qui sous-tend l'évolution du système à plusieurs agents considéré et, d'autre part, les propriétés spectrales de la matrice Laplacienne associée au graphe lui-même. Le contrôle d'un groupe d'agents autonomes est étudié sous différents angles. Le principal objectif de contrôle est de s’assurer que les agents travaillent ensemble de manière coopérative, où la coopération représente la relation étroite entre tous les agents de l'équipe, le partage de l'information jouant un rôle important. En particulier, beaucoup de problèmes de consensus/accord/ synchronisation /rendez-vous sont étudiés afin de guider un groupe d’agents vers un état commun. Le consensus est étudié dans un contexte à temps discret parce que la dynamique du système est en général continue alors que les mesures et les entrées de contrôle sont des données échantillonnées. En outre, la théorie des jeux est utilisée pour faire face aux problèmes de coordination distribués à plusieurs agents, avec une application aux réseaux connus sous le nom de Software Defined Networks. À cet égard, on peut montrer que, sous des protocoles correctement conçus, les joueurs convergent vers un équilibre unique de Wardrop. On concentre l’attention sur le contrôle distribué, car cette approche présente des avantages évidents par rapport à la centralisation, comme l'évolutivité et la robustesse. Pourtant, le contrôle distribué a également ses propres inconvénients : avant tout, un inconvénient est que chaque agent ne peut pas prédire efficacement le comportement global du groupe en se basant uniquement sur des informations locales. Une certaine attention est également accordée à la nécessité de sécuriser les réseaux électriques contre le danger des attaques cyber-physiques grâce au développement de technologies d'intelligence distribuée. À cet égard, sur la base de topologies de réseaux d'énergie réalistes, nous présentons brièvement la conception d'un schéma de protection contre les attaques dynamiques à un point et à points multiples en boucle fermée. Nous formulons et résolvons un problème d'optimisation non convexe soumis à une contrainte de stabilité de Lyapunov pour la représentation à plusieurs agents autonome d'un réseau électrique obtenue après la linéarisation et l'application des lois d’attaque et de contrôle de fréquence. Finalement, nous présentons des résultats obtenus sur : le pilotage exact de la dynamique non linéaire finie à données échantillonnées avec des retards sur les entrées, au sujet de la stabilisation à données échantillonnées et de la poursuite de l'orbite quasi-halo autour du point de libration translunaire L₂, et au sujet des algorithmes heuristiques basés sur des méthodes d'apprentissage par renforcement à plusieurs agents capables d'effectuer un contrôle adaptatif optimal de qualité de service / qualité de l’expérience dans des scénarios sans modèleThe objective of this PhD thesis is (i) to investigate and develop methods for the analysis and design of linear and nonlinear networked control systems and (ii) to show the potential of such approaches in relevant complex applications. In this respect, multi-agent systems theory, algebraic graph theory and consensus are the most interesting methodological tools, and specific attention is paid to the characterization of the relationships between, on the one hand, the topology of the communication graph that underlies the evolution of the considered multiagent system and, on the other hand, the spectral properties of the Laplacian matrix associated with the graph itself. The control of a group of autonomous agents is investigated from different perspectives. The main control objective is to make sure that the agents work together in a cooperative fashion, where cooperation accounts for the close relationship among all agents in the team, with information sharing playing an important role. In particular, various problems regarding consensus/agreement/synchronization/rendezvous are investigated with the specific aim of driving a group of agents to some common state. Consensus is investigated in a discrete-time setting due to the fact that the system dynamics is normally continuous while the measurements and control inputs might only be made in a sampled-data setting. Moreover, game theory is relied upon in order to cope with distributed multi-agent coordination problems, with application to Software Defined Networks. In this respect, it can be shown that, under properly designed protocols, the players converge to a unique Wardrop equilibrium. We focus on distributed control, since this approach shows obvious benefits over centralization, such as scalability and robustness. Yet, it also has its own drawbacks: among all, one drawback is that each agent cannot effectively predict the overall group behaviour based on only local information. Some attention is also devoted to the need for securing power grids against the danger of cyber-physical attacks through the development of distributed intelligence technologies accompanied by appropriate security enforcements. In this respect, based on realistic power network topologies, we briefly present the design of a protection scheme against closed-loop single-point and multi-point dynamic load altering attacks. This is done by formulating and solving a non-convex optimization problem subject to a Lyapunov stability constraint for the autonomous multiagent representation of a power system obtained after linearization and application of the attack and frequency control laws. Eventually, we show some other results achieved in terms of the exact steeering of finite sampled nonlinear dynamics with input delays, of sampled-data stabilization and quasi-halo orbit following around the L₂ translunar libration point, and of heuristic algorithms based on multi-agent reinforcement learning methods capable of performing optimal adaptive Quality of Service/Quality of Experience control in model-free scenarios
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Isfoula, Fayrouz. "Une approche du suivi de consensus pour les systèmes multi-agents." Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2303.
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Un système multi-agents est composé d’un ensemble d’agents interagissant entre eux et avec leur environnement, un agent étant vu comme un système dynamique autonome. La force des SMA repose sur la capacité des agents à coopérer entre eux pour atteindre un objectif qu’un agent seul ne pourrait atteindre. Chaque agent partage ses informations avec ses voisins, ce qui permet à l’ensemble des agents de s’accorder sur un objectif commun sans qu’il y ait pour autant une centralisation de l’information et de l’objectif. En ce sens, un système multi-agents peut être vu comme un réseau dans lequel l’information est distribuée. L’intérêt croissant pour le contrôle distribué et la coordination des réseaux constitués d’agents autonomes est motivé par l’absence de centralisation de l’information et la possibilité d’avoir une topologie du réseau variable. Les algorithmes de contrôle déployés sur ces réseaux sont de nature distribuée puisqu’ils s’appuient sur des informations locales, et sont robustes vis-à-vis des variations de topologie et de taille du réseau. Le problème le plus étudié dans le cadre de ces systèmes multi-agents est celui du consensus, qui peut être résumé ainsi : étant donné des conditions initiales pour chaque agent, quelles sont les conditions pour que les agents s’accordent asymptotiquement sur une valeur commune en n’échangeant que des informations entre agents voisins. Cette thèse traite du développement de commandes permettant d’atteindre ce consensus pour des topologies fixes et variables, en présence ou non d’un leader (suivi de consensus), et sur la qualité des informations transitant dans le réseau. En suivi de consensus, la notion de leader perceptif est développée et une commande est proposée pour une topologie fixe et variableAn agent is an autonomous dynamics system that can coordinate with the environment as well as with other agents. A group of these autonomous agents working in coordination is called a Multi-agent system (MAS). A MAS has several advantages over single agent operation. The main objective of MAS is to achieve a complex goal which is hard to achieve by a single agent. In MAS, each agent shares its information (states) to the neighbors only to complete the task hence no centralized monitoring systems is required. We can define a multi-agent system as a network in which information is distributed. The interest of researchers in the study of distributed control and distributed coordination of autonomous agent networks is motivated by the fact that it has the ability to cope with the problems associated with centralized communication network and also allow the switching network topologies.The algorithms for distributed networks only use local information, and are robust to variations of network topology and can accommodate network with large size.One of the most studied problems in the field of MAS is the consensus, which can be defined as: for any initial conditions for all agent, what are the conditions that should hold in order that the agents agree on a common value asymptotically while only information is exchanged between neighboring agents.This thesis deals with the development of control law to achieve the consensus for fixed and switching topologies, with or without a leader (consensus tracking). It also investigates the problem of the quality of information in the network. In consensus tracking, the notion of perceptive leader is developed and a control law is proposed for a fixed and switching topology
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Griesing-Scheiwe, Fritjof. "Irregularly Sampled Data in the Design of a Soft Sensor System: Some Preliminary Results." Master's thesis, Pontificia Universidad Católica del Perú, 2018. http://tesis.pucp.edu.pe/repositorio/handle/123456789/13295.
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In modern industrial applications, sensors are an expensive part of installed systems. Nevertheless, many system variables cannot be measured sufficiently frequently or accurately. Thus, soft sensors have been developed to estimate those variables without the expense of additional hardware. The use of a soft sensor with a bias update term has shown to perform well for disturbed systems with time delays and multirate sampling times. In industrial application, the time delay and sampling times often vary. Yet, the case of variation of the time delay and sampling time in the bias update term has not been considered in previous publications. This thesis tests a soft sensor with bias update term in simulation and gives a modification yielding better performance. It is shown that the tested method gives unstable results. Hence, a more general method with a bias update term that considers all possible sampling times in each step is proposed, giving stable results in simulation. Furthermore, the stability of the general method is proven mathematically by building a state space representation and applyingTesis
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Lindert, Sven-Olaf. "Beiträge zur Steuerung und Regelung von mehrvariablen linearen zeitinvarianten Systemen in polynomialer Darstellung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-24944.
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In dieser Arbeit werden lineare zeitinvariante endlichdimensionale Systeme (LTI-Systeme) mit m > 1 Eingängen und p > 1 Ausgängen untersucht (MIMO-Systeme). Diese lassen sich darstellen durch lineare Gleichungen mit Matrizen, deren Einträge Polynome im Ableitungsoperator d/dt sind. Bei Nutzung der Laplace-Transformation handelt es sich um Polynome in s. Algebraisch bilden diese einen Euklidischen Ring. Durch Überführung der Matrizen in die Hermitesche Normalform werden m Basisgrößen definiert. Die Verläufe oder Trajektorien der Basisgrößen lassen sich frei vorgegeben. Damit werden die Trajektorien sämtlicher übrigen Signale, insbesondere die der erforderlichen Eingangssignale, festgelegt und können ohne Integration berechnet werden. Ein linksteilerfremdes (auch steuerbar genanntes) Modell ist dabei nicht zwingend erforderlich. Damit eignen sich die Basisgrößen besonders zur Planung von Trajektorien. Genauer untersucht wird die Planung mit Polynomen in der Zeit als Ansatzfunktionen und die Planung von Trajektorien, die ein quadratisches Kostenfunktional minimieren. In der technischen Praxis werden die Systeme stets von den geplanten Trajektorien abweichen. Insbesondere bei instabilen Regelstrecken ist deshalb ein stabilisierender Folgeregler unentbehrlich. Die Struktur der Folgeregelung wird eingeführt und es wird deutlich gemacht, dass jede Methode zum Entwurf linearer Regler angewendet werden kann. Die Nullstellenzuweisung durch dynamische Ausgangsrückführung mit Reglern vorgegebener möglichst geringer dynamischer Ordnung wird detailliert untersucht und eine neue Lösungsmöglichkeit aufgezeigt. Durch Nutzung der modifizierten z-Transformation lässt sich die Theorie auf ein hybrides System, bestehend aus einer zeitkontinuierlichen Regelstrecke und einer zeitdiskreten digitalen Steuerung und Regelung, ausdehnen. Dabei werden die Verläufe der Signale zwischen den Abtastzeitpunkten in die Planung einbezogen. Zum Schluss werden die linearen Beobachter im Licht der polynomialen Matrizendarstellung neu untersucht. Es wird gezeigt, dass die polynomiale Matrizendarstellung einen theoretischen Rahmen bietet, in dem sich sämtliche linearen Beobachter mit einer Methode entwerfen lassen. - (Die Dissertation ist veröffentlicht in der Reihe Fortschritt-Berichte VDI, Reihe 8 - Mess-, Steuerungs- und Regelungstechnik, Band 1164 im VDI Verlag GmbH, Düsseldorf, ISBN 978-3-18-516408-8)In this thesis linear time invariant lumped systems (LTI-systems) with m>1 inputs and p > 1 outputs (MIMO-systems) are investigated. These systems can be represented by linear equations with matrices, whose entries are polynomials in the differential operator d/dt. If Laplace-transform is employed, the polynomials are in s. Algebraically polynomials form a Euclidean ring. The conversion of the matrices to the Hermite form leads to defining m basic variables. The trajectories of the basis variables may be chosen arbitrarily. With that choice the trajectories of all remaining variables and especially the input variables are determined and can be calculated without integration. A left coprime (also called controllable) model is not required. Hence basis variables are particularly useful for planning trajectories. Special attention is paid to planning trajectories with polynomials in time as basic functions and planning trajectories which minimise a quadratic functional of costs. In engineering practice the systems will always differ from the planed trajectories. Especially with unstable plants a stabilising tracking controller is compulsory. The structure of the tracking control is introduced. It becomes apparent that every linear theory for the design of closed loop controllers is suitable. Pole assignment by dynamic output feedback with low order controllers of a fixed structure is looked at in more detail. A new approach to this problem is presented. Using the modified z-transform the theory is extended to hybrid systems consisting of a digital or discrete time controller and a plant in continuous time. Thereby the course of the signals between the sampling moments is taken into account. Finally linear observers are reinvestigated using the polynomial matrix representation. It is shown that the polynomial matrix representation provides a theoretical framework in which all linear observers can be designed
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Palmeira, Alessandra Helena Kimura. "Estabilidade de sistemas amostrados com atuadores saturantes em magnitude e taxa de variação." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/127742.
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Neste trabalho, aborda-se o problema de estabilidade de sistemas com dados amostrados periodicamente, na presença de atuadores saturantes em posição e em taxa de variação. Os atuadores são modelados como sistemas de primeira ordem com saturação de entrada (saturação de magnitude) e do estado (saturação de taxa de variação). No modelo, considera-se que o sinal de controle é mantido constante entre dois instantes de amostragem consecutivos, enquanto as dinâmicas da planta linear e do atuador saturante são em tempo contínuo, i.e., não é feita discretização do sistema. O efeito da amostragem aperiódica é considerado através de um looped -funcional, derivado do funcional de Lyapunov-Krasovskii. O método desenvolvido relaciona uma função quadrática de Lyapunov e o funcional, considerando a amostragem assíncrona e o atuador saturante. Assim, se a derivada temporal do funcional ao longo das trajetórias do sistema for definida negativa, verifica-se que a função de Lyapunov é estritamente decrescente nos instantes de amostragem. Os efeitos das saturações são considerados por meio do uso da condição de setor generalizada. A partir do looped-funcional, da função de Lyapunov e das relações de setor generalizadas, são formuladas condições que permitem caracterizar a estabilidade e projetar ganhos estabilizantes da origem do sistema amostrado, em contexto local e global, através de algoritmos baseados na solução de LMIs. São propostas condições para maximização da estimativa da região de atração da origem ou, dado um conjunto de condições iniciais, para maximização do limite superior do intervalo de amostragem. As condições estabelecidas são válidas para o sistema com acesso a todos os estados, como também, no caso dos estados do atuador não estarem disponíveis `a medição.This work addresses the problems of stability and stabilization of sampled-data systems taking into account aperiodic sampling and magnitude and rate saturating actuactors. The actuators are represented by a first-order system subject to input (magnitude saturation) and state (rate) saturation. In the considered model, the control signal is assumed to be constant between two successive sampling instants, while the dynamics of the linear plant and the saturating actuator are in continuous-time, i.e., no discretization is performed. The aperiodic sampling is taken into account from the method based on the input delay approach via looped-functional, derived from a time-dependent Lyapunov-Krasovskii functional. The developed method is based on a particular functional, that is related to a Lyapunov function. It is shown that if the time derivative of the looped- functional along the trajectories of the continuous-time system is strictly negative, then the Lyapunov function is strictly decreasing at sampling instants. The actuator saturations are taken into account from the use of a generalized sector condition. From the looped-functional, the Lyapunov function and the generalized sector conditions, the developed results lead to conditions that can be solved as LMI prob- lems for asymptotic stability assessment and stabilization local or global of the origin of the sampled-data system. Convex optimization problems are developed to com- pute an estimate of the region of attraction or, given a set of admissible initial conditions, compute the maximal admissible inter-sampling time for which the con- vergence of the trajectories to the origin is ensured. Theorical results are valid for systems with access to all the states, and also for the case that actuator states are not available to the measurement.
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Fiter, Christophe. "Contribution à la commande robuste des systèmes à échantillonnage variable ou contrôlé." Phd thesis, Ecole Centrale de Lille, 2012. http://tel.archives-ouvertes.fr/tel-00773127.
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Cette thèse est dédiée à l'analyse de stabilité des systèmes à pas d'échantillonnage variable et à la commande dynamique de l'échantillonnage. L'objectif est de concevoir des lois d'échantillonnage permettant de réduire la fréquence d'actualisation de la commande par retour d'état, tout en garantissant la stabilité du système.Tout d'abord, un aperçu des récents défis et axes de recherche sur les systèmes échantillonnés est présenté. Ensuite, une nouvelle approche de contrôle dynamique de l'échantillonnage, "échantillonnage dépendant de l'état", est proposée. Elle permet de concevoir hors-ligne un échantillonnage maximal dépendant de l'état défini sur des régions coniques de l'espace d'état, grâce à des LMIs.Plusieurs types de systèmes sont étudiés. Tout d'abord, le cas de système LTI idéal est considéré. La fonction d'échantillonnage est construite au moyen de polytopes convexes et de conditions de stabilité exponentielle de type Lyapunov-Razumikhin. Ensuite, la robustesse vis-à-vis des perturbations est incluse. Plusieurs applications sont proposées: analyse de stabilité robuste vis-à-vis des variations du pas d'échantillonnage, contrôles event-triggered et self-triggered, et échantillonnage dépendant de l'état. Enfin, le cas de système LTI perturbé à retard est traité. La construction de la fonction d'échantillonnage est basée sur des conditions de stabilité L2 et sur un nouveau type de fonctionnelles de Lyapunov-Krasovskii avec des matrices dépendant de l'état. Pour finir, le problème de stabilisation est traité, avec un nouveau contrôleur dont les gains commutent en fonction de l'état du système. Un co-design contrôleur/fonction d'échantillonnage est alors proposé
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Braslavsky, Julio Hernán. "Frequency domain analysis of sampled-data control systems." 1995. http://www.newcastle.edu.au/services/library/adt/public/adt-NNCU20021218.164930/index.html.
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Braslavsky, Julio Hernán. "Frequency domain analysis of sampled-data control systems /." Diss., 1995. http://www.newcastle.edu.au/services/library/adt/public/adt-NNCU20021218.164930/index.html.
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Thesis (Ph. D.)--University of Newcastle, 1995."The Department of Electrical and Computer Engineering, the University of Newcastle." Includes bibliographical references (p. [137]-143) and index. Also available online.
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蔡清雄. "Robust control synthesis of sampled-data systems." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/37105900928772853024.
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Braslavsky, Julio Hernan. "Frequency domain analysis of sampled-data control systems." 1996. http://hdl.handle.net/1959.13/24783.
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This thesis is aimed at analysis of sampled-data feedback systems. Our approach is in the frequency-domain, and stresses the study of sensitivity and complementary sensitivity operators. Frequency-domain methods have proven very successful in the analysis and design of linear time-invariant control systems, for which the importance and utility of sensitivity operators is well-recognized. The extension of these methods to sampled-data systems, however, is not straightforward, since they are inherently time-varying due to the intrinsic sample and hold operations. In this thesis we present a systematic frequency-domain framework to describe sampled-data systems considering full-time information. Using this framework, we develop a theory of design limitations for sampled-data systems. This theory allows us to quantify the essential constraints in design imposed by inherent open-loop characteristics of the analog plant. Our results show that: (i) sampled-data systems inherit the difficulty imposed upon analog feedback design by the plant's non-minimum phase zeros, unstable poles, and time-delays, independently of the type of hold used; (ii) sampled-data systems are subject to additional design limitations imposed by potential non-minimum phase zeros of the hold device; and (iii) sampled-data systems, unlike analog systems, are subject to limits upon the ability of high compensator gain to achieve disturbance rejection. As an application, we quantitatively analyze the sensitivity and robustness characteristics of digital control schemes that rely on the use of generalized sampled-data hold functions, whose frequency-response properties we describe in detail. In addition, we derive closed-form expressions to compute the L2-induced norms of the sampled-data sensitivity and complementary sensitivity operators. These expressions are important both in analysis and design, particularly when uncertainty in the model of the plant is considered. Our methods provide some interesting interpretations in terms of signal spaces, and admit straightforward implementation in a numerically reliable fashion.PhD Doctorate
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patrick and 楊東峰. "On H∞ Control for Nonlinear Sampled-Data Systems." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/92067917450835952427.
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碩士國立海洋大學
電機工程學系
87
This thesis studies the H∞ control problem for more general nonaffine nonlinear systems with sampled measurements. Sufficient conditions for existence of a family of H∞ controllers built from sampled measurements are presented. State-space formulas for such a family of H∞ controllers are also derived. It is proved that the family of controllers thus obtained has the structure of a discrete-time system followed by a generalized hold function. The results extend recent achievements in the literature.
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Braslavsky, Julio H. "Frequency domain analysis of sampled-data control systems." Thesis, 1996. http://hdl.handle.net/1959.13/24783.
Full textAbstract:
This thesis is aimed at analysis of sampled-data feedback systems. Our approach is in the frequency-domain, and stresses the study of sensitivity and complementary sensitivity operators. Frequency-domain methods have proven very successful in the analysis and design of linear time-invariant control systems, for which the importance and utility of sensitivity operators is well-recognized. The extension of these methods to sampled-data systems, however, is not straightforward, since they are inherently time-varying due to the intrinsic sample and hold operations. In this thesis we present a systematic frequency-domain framework to describe sampled-data systems considering full-time information. Using this framework, we develop a theory of design limitations for sampled-data systems. This theory allows us to quantify the essential constraints in design imposed by inherent open-loop characteristics of the analog plant. Our results show that: (i) sampled-data systems inherit the difficulty imposed upon analog feedback design by the plant's non-minimum phase zeros, unstable poles, and time-delays, independently of the type of hold used; (ii) sampled-data systems are subject to additional design limitations imposed by potential non-minimum phase zeros of the hold device; and (iii) sampled-data systems, unlike analog systems, are subject to limits upon the ability of high compensator gain to achieve disturbance rejection. As an application, we quantitatively analyze the sensitivity and robustness characteristics of digital control schemes that rely on the use of generalized sampled-data hold functions, whose frequency-response properties we describe in detail. In addition, we derive closed-form expressions to compute the L2-induced norms of the sampled-data sensitivity and complementary sensitivity operators. These expressions are important both in analysis and design, particularly when uncertainty in the model of the plant is considered. Our methods provide some interesting interpretations in terms of signal spaces, and admit straightforward implementation in a numerically reliable fashion.PhD Doctorate
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Chen, Xi. "Sampled-data synchronization control of multi-agent systems." Thesis, 2015. http://hdl.handle.net/1959.13/1294248.
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Research Doctorate - Doctor of Philosophy (PhD)The collective control of multi-agent systems has attracted more and more researcher's attention in past decades due to its wide applications in different areas. This thesis mainly studies two aspects of the collective control problems of multi-agent systems, specifically, consensus of linear multi-agent systems and synchronizarion of nonlinear and heterogenous multi-agent systems. Moreover, the controllers designed throughout the whole thesis are in sampled-data versions. For consensus of linear multi-agent systems, I firstly establish a general linear dynamic for each individual, and assume that the communication topology among the agents is fixed. After proposing the sampled-data controller, it is shown that the consensus problem is equivalent to a stability problem of a continuous-time system with a time-varying time delay. Lyapunov-Razumikbin approach is used to deal with the stability problem. I then further consider a more general case where only the union of the communication topologies has a smapping tree and only the measurement output infomration of the agents are available for the controller in sampled-data setup. This problem is proved to be equivalent to a stability problem of a discrete-time system. Lyapunov-based approach is applied to solve it. For synchronization of nonlinear and heterogeneous multi-agents, I solve the problem by two steps. The first step is to design a linear reference model for each individual and to make the reference models reach consensus under the designed controllers. The second step is to design a sampled-data controller for each individual to make the output traching its own reference model. The analysis for consensus of linear MASs can be used directly for step one, thus, I am only concerned with the step two for synchronization of nonlinear and heterogenous multi-agents, and I call this problem in a two-step mannar, that is, I firstly design a continuous dynamic controller and discretize it to the sampled-data version. Throughout the thesis, the aforementioned two main problems will be stated in five chapters. Moreover, the Introduction and Conclusion are at the beginning and the end of the thesis, respectively. The effectiveness of control design framework is supported tepretically by rigorous proof and practically validated by numerical simulation.
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Madievski, Anton. "Sampled-data and reduced order controller implementation." Phd thesis, 1995. http://hdl.handle.net/1885/143967.
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HASSAN, MARWA AHMED. "Nonlinear and sampled data control with application to power systems." Doctoral thesis, 2018. http://hdl.handle.net/11573/1157428.
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Sampled data systems have come into practical importance for a variety of reasons.
The earliest of these had primarily to do with economy of design. A more recent surge of interest
was due to increase utilization of digital computers as controllers in feedback systems. This thesis
contributes some control design for a class of nonlinear system exhibition linear output. The
solution of several nonlinear control problems required the cancellation of some intrinsic dynamics
(so-called zero dynamics) of the plant under feedback. It results that the so-dened control will
ensure stability in closed-loop if and only if the dynamics to cancel are stable. What if those
dynamics are unstable? Classical control strategies through inversion might solve the problem while
making the closed loop system unstable. This thesis aims to introduce a solution for such a problem.
The main idea behind our work is to stabilize the nonminimum phase system in continuous- time
and undersampling using zero dynamics concept. The overall work in this thesis is divided into
two parts. In Part I, we introduce a feedback control designs for the input-output stabilization
and the Disturbance Decoupling problems of Single Input Single Output nonlinear systems. A
case study is presented, to illustrate an engineering application of results. Part II illustrates the
results obtained based on the Articial Intelligent Systems in power system machines. We note
that even though the use of some of the AI techniques such as Fuzzy Logic and Neural Network
does not require the computation of the model of the application, but it will still suer from some
drawbacks especially regarding the implementation in practical applications. An alternative used
approach is to use control techniques such as PID in the approximated linear model. This design
is very well known to be used, but it does not take into account the non-linearity of the model. In
fact, it seems that control design that is based on nonlinear control provide better performances.
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"Sampled-data control of high-speed trains." MIT Electronic Systems Laboratory, 1968, 2002. http://hdl.handle.net/1721.1/1241.
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Chen, Po-Ming, and 陳博銘. "Optimal Control of Sampled-Data Systems and Digital Redesign." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/34474507174224870772.
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Sheen, Ing-Eh, and 沈應鍔. "Control of Sampled-Data Systems: Optimal Digital Redesign Approach." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/54525654045551585301.
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Moarref, Miad. "Sampled-data Networked Control Systems: A Lyapunov-Krasovskii Approach." Thesis, 2013. http://spectrum.library.concordia.ca/978128/1/Moarref_PhD_S2014.pdf.
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The main goal of this thesis is to develop computationally efficient methods for stability analysis and controller synthesis of sampled-data networked control systems. In sampled-data networked control systems, the sensory information and feedback signals are exchanged among different components of the system (sensors, actuators, and controllers) through a communication network. Stabilization of sampled-data networked control systems is a challenging problem since the introduction of multirate sample and holds, time-delays, and packet losses into the system degrades its performance and can lead to instability. A diverse range of systems with linear, piecewise affine (PWA), and nonlinear vector fields are studied in this thesis. PWA systems are a class of state-based switched systems with affine vector field in each mode. Stabilization of PWA networked control systems are even more challenging since they simultaneously involve switches due to the hybrid vector fields (state-based switching) and switches due to the sample and hold devices in the network (event-based switching).
The objectives of this thesis are: (a) to design controllers that guarantee exponential stability of the system for a desired sampling period; (b) to design observers that guarantee exponential convergence of the estimation error to the origin for a desired sampling period; and (c) given a controller, to find the maximum allowable network-induced delay that guarantees exponential stability of the sampled-data networked control system. Lyapunov-Krasovskii based approaches are used to propose sufficient stability and stabilization conditions for sampled-data networked control systems. Convex relaxation techniques are employed to cast the proposed stability analysis and controller synthesis criteria in terms of linear matrix inequalities that can be solved efficiently.
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Yuz, Eissmann Juan Ignacio. "Sampled-data models for linear and nonlinear systems." Thesis, 2006. http://hdl.handle.net/1959.13/24852.
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Continuous-time systems are usually modelled by differential equations arising from physical laws. However, the use of these models in practice requires discretisation. In this thesis we consider sampled-data models for linear and nonlinear systems. We study some of the issues involved in the sampling process, such as the accuracy of the sampled-data models, the artifacts produced by the particular sampling scheme, and the relations to the underlying continuous-time system. We review, extend and present new results, making extensive use of the delta operator which allows a clearer connection between a sampled-data model and the underlying continuous-time system. In the first part of the thesis we consider sampled-data models for linear systems. In this case exact discrete-time representations can be obtained. These models depend, not only on the continuous-time system, but also on the artifacts involved in the sampling process, namely, the sample and hold devices. In particular, these devices play a key role in determining the sampling zeros of the discrete-time model. We consider robustness issues associated with the use of discrete-time models for continuous-time system identification from sampled data. We show that, by using restricted bandwidth frequency domain maximum likelihood estimation, the identification results are robust to (possible) under-modelling due to the sampling process. Sampled-data models provide a powerful tool also for continuous-time optimal control problems, where the presence of constraints can make the explicit solution impossible to find. We show how this solution can be arbitrarily approximated by an associated sampled-data problem using fast sampling rates. We also show that there is a natural convergence of the singular structure of the optimal control problem from discrete- to continuous-time, as the sampling period goes to zero. In Part II we consider sampled-data models for nonlinear systems. In this case we can only obtain approximate sampled-data models. These discrete-time models are simple and accurate in a well defined sense. For deterministic systems, an insightful observation is that the proposed model contains sampling zero dynamics. Moreover, these correspond to the same dynamics associated with the asymptotic sampling zeros in the linear case. The topics and results presented in the thesis are believed to give important insights into the use of sampled-data models to represent linear and nonlinear continuous-time systems.PhD Doctorate
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Yuz, Eissmann Juan Ignacio. "Sampled-data models for linear and nonlinear systems." 2006. http://hdl.handle.net/1959.13/24852.
Full textAbstract:
Continuous-time systems are usually modelled by differential equations arising from physical laws. However, the use of these models in practice requires discretisation. In this thesis we consider sampled-data models for linear and nonlinear systems. We study some of the issues involved in the sampling process, such as the accuracy of the sampled-data models, the artifacts produced by the particular sampling scheme, and the relations to the underlying continuous-time system. We review, extend and present new results, making extensive use of the delta operator which allows a clearer connection between a sampled-data model and the underlying continuous-time system. In the first part of the thesis we consider sampled-data models for linear systems. In this case exact discrete-time representations can be obtained. These models depend, not only on the continuous-time system, but also on the artifacts involved in the sampling process, namely, the sample and hold devices. In particular, these devices play a key role in determining the sampling zeros of the discrete-time model. We consider robustness issues associated with the use of discrete-time models for continuous-time system identification from sampled data. We show that, by using restricted bandwidth frequency domain maximum likelihood estimation, the identification results are robust to (possible) under-modelling due to the sampling process. Sampled-data models provide a powerful tool also for continuous-time optimal control problems, where the presence of constraints can make the explicit solution impossible to find. We show how this solution can be arbitrarily approximated by an associated sampled-data problem using fast sampling rates. We also show that there is a natural convergence of the singular structure of the optimal control problem from discrete- to continuous-time, as the sampling period goes to zero. In Part II we consider sampled-data models for nonlinear systems. In this case we can only obtain approximate sampled-data models. These discrete-time models are simple and accurate in a well defined sense. For deterministic systems, an insightful observation is that the proposed model contains sampling zero dynamics. Moreover, these correspond to the same dynamics associated with the asymptotic sampling zeros in the linear case. The topics and results presented in the thesis are believed to give important insights into the use of sampled-data models to represent linear and nonlinear continuous-time systems.PhD Doctorate
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Wei, Chao-Peng, and 魏朝鵬. "Control of Sampled-Data Time-Delayed Systems: Digital Redesign Approaches." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/12382742453316096370.
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博士國立成功大學
電機工程學系
89
In this dissertation, several issues are studied: digital redesign of continuous-time state-feedback controlled systems with input and/or state delays, digital modelling of continuous-time uncertain state-delayed/input-delayed systems, robust control of sampled-data uncertain state-delayed systems using digitally redesigned state-feedback controllers, and robust control of sampled-data uncertain input-delayed systems using digitally redesigned observer-based controllers. Based on the Law of Mean from the integral calculus, we derive the new digitally redesigned controllers from available analog controllers. Using the new digitally redesigned controllers, the resulting states of digitally controlled sampled-data time-delayed systems are able to closely match those of original analogously controlled continuous-time time-delayed systems. Moreover, we construct the digital uncertain models of continuous-time uncertain state-delayed and input-delayed systems by using the trapezoidal-rule approximation method and the Chebyshev quadrature method, respectively. The proposed new approaches are effective for designing the digital controllers of sampled-data time-delayed systems. Furthermore, the developed discrete-time uncertain time-delayed models are also helpful for digital simulation, analysis and design of continuous-time uncertain state-delayed/input-delayed systems.
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Sung, Tin-Wen, and 宋廷文. "Sampled-Data Tracking Control for Polynomial Fuzzy Time-delay Systems." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8xr269.
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碩士國立臺北科技大學
自動化科技研究所
105
The H∞ sampled-data tracking control problem for polynomial fuzzy time-delay system is investigated in this thesis. The sampled-data state feedback and output feedback tracking controllers for polynomial fuzzy time-delay system are proposed to stabilize the polynomial fuzzy time-delay system state and drive it to follow those of a stable reference model subject to an H∞ performance. In addition, based on the Lyapunov theorem, the sum-of-squares-based stabilization conditions are obtained to guarantee the stability of the polynomial fuzzy time-delay system and facilitate the controller synthesis. Lastly, four examples are illustrated to show the effectiveness and feasibility of the proposed results.
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MORESCHINI, ALESSIO. "Modeling and control of discrete-time and sampled-data port-Hamiltonian systems." Doctoral thesis, 2021. http://hdl.handle.net/11573/1550161.
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Modeling and control of port-Hamiltonian systems are extensively studied in the continuous-time literature as powerful tools for network modeling and control of complex physical systems. Since controllers are unavoidably implemented through digital devices, accurate sampled-data models and control strategies are highly recommended to prevent a negative impact on the closed-loop performances under digital control. This thesis contributes to the description of new port-Hamiltonian structures both in a purely discrete-time and sampled-data framework. Then, on these bases, stabilizing and energy-based digital feedback strategies are developed. Regarding modeling, the proposed state-space forms make use of the concepts of Difference/Differential Representation (DDR) of discrete-time dynamics and the discrete gradient function. The proposed models exhibit a Dirac structure that properly defines the storing, resistive and external elements of the concerned port-Hamiltonian system. For stabilization purposes, the u-average passivity property has been essential for properly discussing passivity-based-control (PBC) strategies such as damping output feedback and Interconnection and Damping Assignment (IDA-PBC) both in discrete time and under sampling. Three case studies from different physical domains aim to illustrate the computational aspects related to the modeling and control design and further we validate their performances by means of simulations.