Dissertations / Theses on the topic 'Dynamic output feedback'

This thesis is concerned with robust control of an offshore steel jacket platform subject to nonlinear wave-induced forces. Since time delay and uncertainty are inevitably encountered for an offshore structure and their existence may induce instability, oscillation and poor performance, it is very significant to study on how the delay and uncertainty affect the offshore structure. In this thesis, a memory robust control strategy is, for the first time, proposed to reduce the internal oscillations of the offshore structure under wave-induced forces, so as to ensure the safety and comfort of the offshore structure. Firstly, when the system's states are adopted as feedback, memory state feedback controllers are introduced for the offshore structure. By using Lyapunov-Krasovskii stability theory, some delay-dependent stability criteria have been established, based on which, and by combining with some linearization techniques, memory state feedback controllers are designed to control the offshore structure. The simulation results show that such controllers can effectively reduce the internal oscillations of the offshore structure subject to nonlinear wave-induced forces and uncertainties. On the other hand, a new Lyapunov-Krasovskii functional is introduced to derive a less conservative delay-dependent stability criterion. When this criterion is applied to the offshore structure, an improved memory state feedback controller with a small gain is obtained to control the system more effectively, which is sufficiently shown by the simulation. Secondly, when the system's outputs are adopted as feedback, memory dynamic output feedback controllers are considered for the offshore structure. By employing a projection theorem and a cone complementary linearization approach, memory dynamic output feedback controllers are derived by solving some nonlinear minimization problem subject to some linear matrix inequalities. The simulation results show that the internal oscillations of the offshore structure subject to nonlinear wave-induced forces are well attenuated. Finally, robust H control is fully investigated for the offshore structure. By employing Lyapunov-Krasovskii stability theory, some delay-dependent bounded real lemmas have been obtained, under which, via a memory state feedback controller or a dynamic output feedback controller, the resulting closed-loop system is not only asymptotically stable but also with a prescribed disturbance attenuation level. The simulation results illustrate the validity of the proposed method.

To meet the exponentially increasing traffic data driven by the rapidly growing mobile subscriptions, both industry and academia are exploring the potential of a new genera- tion (5G) of wireless technologies. An important 5G goal is to achieve high data rate. Small cells with spectrum sharing and multiple-input multiple-output (MIMO) techniques are one of the most promising 5G technologies, since it enables to increase the aggregate data rate by improving the spectral efficiency, nodes density and transmission bandwidth, respectively. However, the increased interference in the densified networks will in return limit the achievable rate performance if not properly managed. The considered setup can be modeled as MIMO interference networks, which can be classified into the K-user MIMO interference channel (IC) and the K-cell MIMO interfering broadcast channel/multiple access channel (MIMO-IBC/IMAC) according to the number of mobile stations (MSs) simultaneously served by each base station (BS). The thesis considers two physical layer (PHY) resource allocation problems that deal with the interference for both models: 1) Pareto boundary computation for the achiev- able rate region in a K-user single-stream MIMO IC and 2) grouping-based interference alignment (GIA) with optimized IA-Cell assignment in a MIMO-IMAC under limited feedback. In each problem, the thesis seeks to provide a deeper understanding of the system and novel mathematical results, along with supporting numerical examples. Some of the main contributions can be summarized as follows. It is an open problem to compute the Pareto boundary of the achievable rate region for a K-user single-stream MIMO IC. The K-user single-stream MIMO IC models multiple transmitter-receiver pairs which operate over the same spectrum simultaneously. Each transmitter and each receiver is equipped with multiple antennas, and a single desired data stream is communicated in each transmitter-receiver link. The individual achievable rates of the K users form a K-dimensional achievable rate region. To find efficient operating points in the achievable rate region, the Pareto boundary computation problem, which can be formulated as a multi-objective optimization problem, needs to be solved. The thesis transforms the multi-objective optimization problem to two single-objective optimization problems–single constraint rate maximization problem and alternating rate profile optimization problem, based on the formulations of the ε-constraint optimization and the weighted Chebyshev optimization, respectively. The thesis proposes two alternating optimization algorithms to solve both single-objective optimization problems. The convergence of both algorithms is guaranteed. Also, a heuristic initialization scheme is provided for each algorithm to achieve a high-quality solution. By varying the weights in each single-objective optimization problem, numerical results show that both algorithms provide an inner bound very close to the Pareto boundary. Furthermore, the thesis also computes some key points exactly on the Pareto boundary in closed-form. A framework for interference alignment (IA) under limited feedback is proposed for a MIMO-IMAC. The MIMO-IMAC well matches the uplink scenario in cellular system, where multiple cells share their spectrum and operate simultaneously. In each cell, a BS receives the desired signals from multiple MSs within its own cell and each BS and each MS is equipped with multi-antenna. By allowing the inter-cell coordination, the thesis develops a distributed IA framework under limited feedback from three aspects: the GIA, the IA-Cell assignment and dynamic feedback bit allocation (DBA), respec- tively. Firstly, the thesis provides a complete study along with some new improvements of the GIA, which enables to compute the exact IA precoders in closed-form, based on local channel state information at the receiver (CSIR). Secondly, the concept of IA-Cell assignment is introduced and its effect on the achievable rate and degrees of freedom (DoF) performance is analyzed. Two distributed matching approaches and one centralized assignment approach are proposed to find a good IA-Cell assignment in three scenrios with different backhaul overhead. Thirdly, under limited feedback, the thesis derives an upper bound of the residual interference to noise ratio (RINR), formulates and solves a corresponding DBA problem. Finally, numerical results show that the proposed GIA with optimized IA-Cell assignment and the DBA greatly outperforms the traditional GIA algorithm.

This thesis develops dynamic models for the two-mode FWD EVT, develops a control system based on those models that is capable of meeting driver torque demands and performing synchronous mode shifts between different EVT modes while also accommodating preferred engine operating points. The two-input two-output transmission controller proposed herein incorporates motor-generator dynamics, is based on a general state-space integral control structure, and has feedback gains determined using linear quadratic regulator (LQR) optimization. Dynamic modeling of the vehicle is categorized as dynamic modeling of the mechanical and electrical subsystems where the mechanical subsystem consists of the planetary gear sets, the transmission and the engine whereas the electrical subsystem consists of the motor-generator units and the battery pack. A discussion of load torque is also considered as part of the mechanical subsystem. With the help of these derived dynamic models, a distinction is made between dynamic output torque and steady-state output torque. The overall control system consisting of multiple subsystems such as the human driver, power management unit (PMU), friction brakes, combustion engine, transmission control unit (TCU) and motor-generator units is designed. The logic for synchronous mode shifts between different EVT modes is also detailed as part of the control system design. Finally, the thesis presents results for responses in individual operating modes, EVT mode shifting and a full UDDS drive cycle simulation.

Les systèmes à commutations constituent un cas particulier des systèmes dynamiques hybrides. Ils sont composés d'une famille de systèmes et d'une loi de commutation qui détermine quel mode est activé à chaque instant. Ces systèmes représentent une large gamme de systèmes concrets. L'étude de la stabilité de ceux-ci a déjà été longuement abordée. Les travaux de cette thèse portent sur l'analyse de performance des systèmes à commutations linéaires en temps discret et sur la synthèse de différentes lois de commande pour ces systèmes en tenant compte de contraintes de performances. L'analyse de stabilité de ces systèmes a été étendue pour tenir compte de l'aspect performance qui a été modélisée par un critère quadratique. La valeur du critère dépendant des commutations, l'analyse porte sur le coût garanti des performances. Grâce à la résolution d'un problème d'optimisation sous des contraintes sous la forme d'inégalités matricielles linéaires, un majorant du coût garanti est déterminé. Une approche est proposée pour évaluer la qualité du majorant trouvé. Un deuxième point abordé est la conception de contrôleurs qui tiennent compte de l'aspect performance. Des méthodes de synthèse de différents contrôleurs (retour d'état, retour d'état reconstruit par observateur et retour de sortie dynamique) sont proposées dans ce cadre. Enfin, nos résultats ont été appliqués au cas des systèmes contrôlés en réseau
Switched systems are a specific case of dynamical hybrid systems. They are made up of a family of subsystems and of a switching law which defines the activated subsystem at each instant. These systems depict a wide range of real systems. Stability's study has been intensely studied. This Ph.D. thesis deals with performance analysis for discrete-time switched linear systems and synthesis of different control laws by taking into account performance constraints. Stability's analysis for these systems was spread in order to taking into account performance aspect, modeled by a quadratic criterion. As the value of the criterion depends on commutations, the analysis is done for the guaranteed cost of performances. By solving an optimization problem under constraints in the form of linear matrices inequalities, an upper bound of the guaranteed cost is found. An approach is proposed to certificate the upper bound. An other tackled point is the synthesis of controllers which take into account performance aspect. Methods of synthesis of different controllers (state feedback, state feedback based on observer and dynamic output feedback) are proposed. Last, our results are applied to networked controlled systems

Les systèmes à commutations constituent un cas particulier des systèmes dynamiques hybrides. Ils sont composés d'une famille de systèmes et d'une loi de commutation qui détermine quel mode est activé à chaque instant. Ces systèmes représentent une large gamme de systèmes concrets. L'étude de la stabilité de ceux-ci a déjà été longuement abordée. Les travaux de cette thèse portent sur l'analyse de performance des systèmes à commutations linéaires en temps discret et sur la synthèse de différentes lois de commande pour ces systèmes en tenant compte de contraintes de performances. L'analyse de stabilité de ces systèmes a été étendue pour tenir compte de l'aspect performance qui a été modélisée par un critère quadratique. La valeur du critère dépendant des commutations, l'analyse porte sur le coût garanti des performances. Grâce à la résolution d'un problème d'optimisation sous des contraintes sous la forme d'inégalités matricielles linéaires, un majorant du coût garanti est déterminé. Une approche est proposée pour évaluer la qualité du majorant trouvé. Un deuxième point abordé est la conception de contrôleurs qui tiennent compte de l'aspect performance. Des méthodes de synthèse de différents contrôleurs (retour d'état, retour d'état reconstruit par observateur et retour de sortie dynamique) sont proposées dans ce cadre. Enfin, nos résultats ont été appliqués au cas des systèmes contrôlés en réseau
Switched systems are a specific case of dynamical hybrid systems. They are made up of a family of subsystems and of a switching law which defines the activated subsystem at each instant. These systems depict a wide range of real systems. Stability's study has been intensely studied. This Ph.D. thesis deals with performance analysis for discrete-time switched linear systems and synthesis of different control laws by taking into account performance constraints. Stability's analysis for these systems was spread in order to taking into account performance aspect, modeled by a quadratic criterion. As the value of the criterion depends on commutations, the analysis is done for the guaranteed cost of performances. By solving an optimization problem under constraints in the form of linear matrices inequalities, an upper bound of the guaranteed cost is found. An approach is proposed to certificate the upper bound. An other tackled point is the synthesis of controllers which take into account performance aspect. Methods of synthesis of different controllers (state feedback, state feedback based on observer and dynamic output feedback) are proposed. Last, our results are applied to networked controlled systems

La commande à transmissions événementielles est une approche dans laquelle les instants de transmission sont définis selon un critère dépendant de l'état du système et non plus d'une horloge à l'instar des implantations périodiques. Dans cette thèse, nous nous concentrons sur la synthèse de telles lois de commande par retour de sortie. Les contributions sont les suivantes : (i) nous proposons une méthode de synthèse dite par émulation pour des systèmes non linéaires; (ii) nous présentons une méthode de synthèse jointe de la loi de commande et de la condition de déclenchement pour les systèmes linéaires; (iii) nous nous intéressons au cas de systèmes non linéaires singulièrement perturbés et nous construisons le contrôleur à partir d’approximation de la dynamique lente uniquement
Event-triggered control is a sampling paradigm in which the sequence of transmission instants is determined based on the violation of a state-dependent criterion and not a time-driven clock. In this thesis, we deal with event-triggered output-based controllers to stabilize classes of nonlinear systems. The contributions of the presented material are threefold: (i) we stabilize a class of nonlinear systems by using an emulation-based approach; (ii) we develop a co-design procedure to simultaneously design the output feedback law and the event-triggering condition for linear systems; (iii) we propose stabilizing event-triggered controllers for nonlinear systems whose dynamics have two-time scales (in particular, we only rely on the knowledge of an approximate model of the slow dynamics)

Dans cette étude on s'intéresse à la dynamique d'une classe de systèmes non-linéaires décrits par des équations aux dérivées partielles (EDP) du type hyperbolique. L'objectif de l'étude est de construire des lois de contrôle par feedback dynamique de la sortie afin de stabiliser le système autour d'un point d'équilibre d'une part, et, d'autre part, de réguler la sortie vers le point de consigne. Nous considérons la classe des systèmes gouvernés par des EDP quasi-linéaires du type hyperbolique à deux variables indépendantes (une variable temporelle et une variable spatiale). Pour le bien-posé du système dynamique non seulement l'état initial mais aussi certaines conditions frontières doivent être prescrites en cohérence avec les EDP. Nous supposons que l'observation et le contrôle sont ponctuels. Autrement dit l'action du contrôle intervient dans le système via les conditions frontières et l'observation est effectuée aux points de la frontière. Notre étude est motivée par l'observation que de nombreux processus physiques sont modélisés par ce type d'équations EDP. Nous citons, par exemple, des processus tels que flux trafique en transport, flux de gaz dans un réseau de pipeline, échangeurs thermiques en génie des procédés, équations de télégraphe dans des lignes de transmission, canaux d'irrigation en génie civil etc. Nous commençons l'étude par une EDP non-linéaire scalaire. Dans ce cas-là nous proposons un correcteur intégral stabilisant qui assure la régulation de la sortie avec l'erreur statique nulle. Nous prouvons la stabilisation locale du système non-linéaire par le correcteur intégral en construisant une fonctionnelle de Lyapunov appropriée. La conception des correcteurs proportionnels et intégraux (PI) que nous proposons est étendue dans un cadre de systèmes de deux EDP. Nous prouvons la stabilisation du système en boucle fermée à l'aide d'une nouvelle fonctionnelle de Lyapunov. La synthèse des correcteurs PI stabilisants se poursuit dans un cadre de réseaux formés d'un nombre fini de systèmes à deux EDP : réseau étoilé et réseau série en cascade. Les contrôles et les observations se trouvent localisés aux différents nœuds de connexion. Pour ces configurations nous présentons un ensemble de correcteurs PI stabilisants qui assurent la régulation vers le point de consigne. Les correcteurs PI que nous concevons sont validés par des simulations numériques à partir des modèles non-linéaires EDP. La contribution de la thèse, par rapport à la littérature existante, consiste en l'élaboration de nouvelles fonctionnelles de Lyapunov pour une classe de systèmes stabilisés par correcteur PI. En effet une grande quantité de résultats ont été obtenus sur la stabilisation des systèmes hyperboliques par feedback statique de la sortie. Toutefois il existe encore peu de résultats sur la stabilisation de ces systèmes par feedback dynamique de la sortie. L'étude de la thèse est consacrée sur l'élaboration des fonctionnelles de Lyapunov permettant d'obtenir des correcteurs PI stabilisants. L'approche de Lyapunov direct que nous avons proposée a pour l'avantage de permettre d'étudier la robustesse des lois de feedback de la sortie PI vis-à-vis de la non-linéarité. Une autre contribution de la thèse consiste en la construction des programmes de Malab permettant d'effectuer des simulations numériques pour la validation des correcteurs conçus. Pour la résolution numérique des EDP hyperboliques nous avons discrétisé nos systèmes par le schéma numérique de Preissmann. Nous avons chaque fois un système d'équations algébriques non-linéaires à résoudre de façon récurrente. L'apport des simulations numériques nous permet de mieux comprendre la méthodologie applicative de la théorie du contrôle en dimension infinie
In this study we are interested in the dynamics of a class of nonlinear systems described by partial differential equations (PDE) of the hyperbolic type. The aim of the study is to construct control laws by dynamic feedback of the output in order to stabilize the system around an equilibrium point on the one hand and to regulate the output to the set-point. We consider the class of systems governed by hyperbolic PDEs with two independent variables (one time variable and one spatial variable). For the well-posed dynamic system not only the initial state but also certain boundary conditions must be prescribed in coherence with the PDEs. We assume that observation and control are punctual. In other words, the action of the control intervenes in the system via the boundary conditions and the observation is carried out at the points of the border. Our study is motivated by the observation that many physical processes are modeled by this type of PDE equations. Examples include processes such as traffic flow in transportation, gas flows in a pipeline network, heat exchangers in process engineering, telegraph equations in transmission lines, civil engineering irrigation channels, to cite but a few.We begin the study with a scalar nonlinear PDE. In this case we propose a stabilizing integral controller which ensures the regulation of the output with zero static error. We prove the local stabilization of the nonlinear system by the integral controller by constructing an appropriate Lyapunov functional. The design of the proportional and integral (PI) controllers that we propose is extended in a framework of two PDE systems. We prove the stabilization of the closed-loop system with a new Lyapunov functional. The synthesis of stabilizing PI controllers is carried out in a framework of networks formed by a finite number of two PDE systems: star network and serial network in cascade. Controls and observations are located at the different connection nodes. For these configurations we present a set of stabilizing PI controllers that regulate the output to the set-point. The PI controllers that we design are validated by numerical simulations from the nonlinear PDE models. The contribution of the thesis compared to the existing literature consists in the development of new Lyapunov functionals for the class of systems looped by a PI controller. Indeed, a large number of results have been obtained from the stabilization of hyperbolic systems by static feedback of the output. However, there are still few results with the stabilization of these systems by the output dynamic feedback. The study of the thesis is devoted to the development of the Lyapunov functional to obtain stabilizing PI controllers. The direct Lyapunov approach that we have proposed has the advantage of allowing to study the robustness of the output dynamic feedback laws in the form of PI controllers with respect to the nonlinearity. Another contribution of the thesis consists of the Malab program construction allowing to carry out numerical simulations for the validation of the conceived controllers. For the numerical resolution of hyperbolic PDEs, we have discretized our systems using the Preissmann numerical scheme. Each time moment we have a system of non-linear algebraic equations to be solved in a recurring way. The contribution of numerical simulations allows us to better understand the application methodology of the infinite dimension control theory

La commande à transmissions événementielles est une approche dans laquelle les instants de transmission sont définis selon un critère dépendant de l'état du système et non plus d'une horloge à l'instar des implantations périodiques. Dans cette thèse, nous nous concentrons sur la synthèse de telles lois de commande par retour de sortie. Les contributions sont les suivantes : (i) nous proposons une méthode de synthèse dite par émulation pour des systèmes non linéaires; (ii) nous présentons une méthode de synthèse jointe de la loi de commande et de la condition de déclenchement pour les systèmes linéaires; (iii) nous nous intéressons au cas de systèmes non linéaires singulièrement perturbés et nous construisons le contrôleur à partir d’approximation de la dynamique lente uniquement
Event-triggered control is a sampling paradigm in which the sequence of transmission instants is determined based on the violation of a state-dependent criterion and not a time-driven clock. In this thesis, we deal with event-triggered output-based controllers to stabilize classes of nonlinear systems. The contributions of the presented material are threefold: (i) we stabilize a class of nonlinear systems by using an emulation-based approach; (ii) we develop a co-design procedure to simultaneously design the output feedback law and the event-triggering condition for linear systems; (iii) we propose stabilizing event-triggered controllers for nonlinear systems whose dynamics have two-time scales (in particular, we only rely on the knowledge of an approximate model of the slow dynamics)

Orientador: Edvaldo Assunção
Banca: Marcelo Carvalho Minhoto Teixeira
Banca: José Paulo Fernandes Garcia
Banca: Cristiano Quevedo Andrea
Banca: Márcio Roberto Covacic
Resumo: Neste trabalho sao propostas metodologias de modificacao de zeros para solucionar o problema do rastreamento do sinal de referencia em sistemas discretos determinısticos, sistemas discretos incertos e sistemas discretos nao-lineares considerando-se uma entrada de perturbacao na planta. Em um primeiro momento e projetado um controlador discreto para minimizar a norma H∞ entre a entrada ex'ogena e o sinal de saıda com o objetivo de reduzir o efeito da perturbacao sobre a saıda do sistema determinıstico. Posteriormente, minimiza-se a norma H∞ entre o sinal de referencia e o erro de rastreamento atraves da modificacao otima de zeros do sistema discreto, constituindo desta maneira o rastreador de sinal de referencia. Essa nova estrutura de projeto do controlador e estendida para o projeto do controlador robusto H∞, supondo incertezas politopicas na planta e tambem para sistemas nao-lineares. No caso de sistemas com incertezas politopicas na planta, um controlador discreto e projetado para minimizar o custo garantido H∞ entre a entrada exogena e o sinal de saıda com o objetivo de reduzir o efeito da perturbacao sobre a saıda do sistema discreto incerto. Posteriormente e projetado um rastreador para sinais de referˆencia em sistemas com incertezas politopicas, utilizando-se modificacao de zeros. Por fim, estende-se a metodologia de rastreamento do sinal de referencia com rejeicao do disturbio para sistemas nao-lineares. A formulacao do projeto e descrita na forma de inequacoes matriciais lineares, pois estas permitem a descricao de problemas de otimizacao convexa
Abstract: The tracking problems in uncertain, deterministic and nonlinear discrete time systems, with the presence of a disturbance signal in the plant, are solved in this work proposing a zero variation methodology. A discrete state feedback controller is designed in order to minimize the H∞-norm between the exogen input and the output signal, such that the effect of the disturbance is attenuated in deterministic systems. After, the tracking problem is solved using the variation of the zeros minimizing the H∞-norm from the reference input signal to the error tracking signal. This new structure is extended to design of H∞ robust controller, supposing politopic uncertainties and other one supposing nonlinearities in the plant. In uncertain systems case, a discrete controller is designed in order to minimize the H∞ guaranteed cost between the exogen input and the output signal such that the effect of the disturbance is attenuated in uncertain systems. Then, the tracking problem in uncertain systems is solved using the variation of the zeros minimizing the H∞ guaranteed cost from the reference input signal to the error tracking signal. Finally, the zero variation methodology is extended to nonlinear systems. The design is formulated in the Linear Matrix Inequalities (LMI) framework, such that the optimal solution of the stated control problem is obtained when feasible solution exists
Doutor

Functional Electrical Stimulation (FES) is a technique that applies electrical currents to nervous tissue in order to actively induce muscle contraction. Recent research has shown that FES provides a promising treatment to restore functional tasks due to paralysis caused by spinal cord injury, head injury, and stroke, to mention a few. Therefore, the overarching goal of this research work is to develop FES controllers to enable patients with movement-disorder to control their limbs in a desired manner and, in particular, to aid Parkinson's patients to suppress hand tremor. In our effort to develop strategies for muscle stimulation control, we first implement a model-based control technique assuming that all the states are measurable. The Hill-type muscle model coupled with a simplified 2DoF model of the arm is used to study the performance of our proposed adaptive sliding mode controller for simulation purpose. However, in the more practical situations, human limb dynamics are extremely complicate and it is inadequate to use model based controllers, especially considering there are still technical limitations that allow in vivo measurements of muscle activity. To tackle these challenges, we have developed output feedback adaptive control approaches for a class of unknown multi-input multi-output systems. Such control strategies are first developed for linear systems, and then extended to the nonlinear case. The proposed controllers, supported by experimental results, require minimum knowledge of the system dynamics and avoid many restrictive assumptions typically found in the literature. Therefore, we expect that the results introduced in this dissertation can provide a solution for a wide class of nonlinear uncertain systems, with focus on practical issues such as partial state measurement and the presence of mismatched uncertainties.
Ph. D.

This thesis presents decentralized model reference adaptive control techniques for systems with full-state feedback and systems with output feedback. The controllers are strictly decentralized, that is, each local controller uses feedback from only local subsystems and no information is shared between local controllers. The full-state feedback decentralized controller is effective for multi-input systems, where the dynamics matrix and control-input matrix are unknown. The decentralized controller achieves asymptotic stabilization and command following in the presence of sinusoidal disturbances with known spectrum. We present a construction technique of the reference-model dynamics such that the decentralized controller is effective for systems with arbitrarily large subsystem interconnections. The output-feedback decentralized controller is effective for single-input single-output subsystems that are minimum phase and relative degree one. The decentralized controller achieves asymptotic stabilization and disturbance rejection in the presence of an unknown disturbance, which is generated by an unknown Lyapunov-stable linear system.

The presented research concerns the control of unmanned vehicles. The results introduced in this dissertation provide a solid control framework for a wide class of nonlinear uncertain systems, with a special emphasis on issues related to implementation, such as control input amplitude and rate saturation, or partial state measurements availability. More specifically, an adaptive control framework, allowing to enforce amplitude and rate saturation of the command, is developed. The motion control component of this framework, which works in conjunction with a saturation algorithm, is then specialized to different types of vehicles. Vertical take-off and landing aerial vehicles and a general class of autonomous marine vehicles are considered. A nonlinear control algorithm addressing the tracking problem for a class of underactuated, non-minimum phase marine vehicles is then introduced. This motion controller is extended, using direct and indirect adaptive techniques, to handle parametric uncertainties in the system model. Numerical simulations are used to illustrate the efficacy of the algorithms. Next, the output feedback control problem is treated, for a large class of nonlinear and uncertain systems. The proposed solution relies on a novel nonlinear observer which uses output measurements and partial knowledge of the systemâ s dynamics to reconstruct the entire state for a wide class of nonlinear systems. The observer is then extended to operate in conjunction with a full state feedback control law and solve both the output feedback control problem and the state observation problem simultaneously. The resulting output feedback control algorithm is then adjusted to provide a high level of robustness to both parametric and structural model uncertainties. Finally, in a natural extension of these results from motion control of a single system to collaborative control of a group of vehicles, a cooperative control framework addressing limited communication issues is introduced.
Ph. D.

Made available in DSpace on 2014-06-11T19:30:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-11-12Bitstream added on 2014-06-13T20:40:35Z : No. of bitstreams: 1 mendes_rat_dr_ilha.pdf: 2326436 bytes, checksum: 60aa15eb5fb66a63b31662bee7904bfa (MD5)
Neste trabalho sao propostas metodologias de modificacao de zeros para solucionar o problema do rastreamento do sinal de referencia em sistemas discretos determinısticos, sistemas discretos incertos e sistemas discretos nao-lineares considerando-se uma entrada de perturbacao na planta. Em um primeiro momento e projetado um controlador discreto para minimizar a norma H∞ entre a entrada ex´ogena e o sinal de saıda com o objetivo de reduzir o efeito da perturbacao sobre a saıda do sistema determinıstico. Posteriormente, minimiza-se a norma H∞ entre o sinal de referencia e o erro de rastreamento atraves da modificacao otima de zeros do sistema discreto, constituindo desta maneira o rastreador de sinal de referencia. Essa nova estrutura de projeto do controlador e estendida para o projeto do controlador robusto H∞, supondo incertezas politopicas na planta e tambem para sistemas nao-lineares. No caso de sistemas com incertezas politopicas na planta, um controlador discreto e projetado para minimizar o custo garantido H∞ entre a entrada exogena e o sinal de saıda com o objetivo de reduzir o efeito da perturbacao sobre a saıda do sistema discreto incerto. Posteriormente e projetado um rastreador para sinais de referˆencia em sistemas com incertezas politopicas, utilizando-se modificacao de zeros. Por fim, estende-se a metodologia de rastreamento do sinal de referencia com rejeicao do disturbio para sistemas nao-lineares. A formulacao do projeto e descrita na forma de inequacoes matriciais lineares, pois estas permitem a descricao de problemas de otimizacao convexa
The tracking problems in uncertain, deterministic and nonlinear discrete time systems, with the presence of a disturbance signal in the plant, are solved in this work proposing a zero variation methodology. A discrete state feedback controller is designed in order to minimize the H∞-norm between the exogen input and the output signal, such that the effect of the disturbance is attenuated in deterministic systems. After, the tracking problem is solved using the variation of the zeros minimizing the H∞-norm from the reference input signal to the error tracking signal. This new structure is extended to design of H∞ robust controller, supposing politopic uncertainties and other one supposing nonlinearities in the plant. In uncertain systems case, a discrete controller is designed in order to minimize the H∞ guaranteed cost between the exogen input and the output signal such that the effect of the disturbance is attenuated in uncertain systems. Then, the tracking problem in uncertain systems is solved using the variation of the zeros minimizing the H∞ guaranteed cost from the reference input signal to the error tracking signal. Finally, the zero variation methodology is extended to nonlinear systems. The design is formulated in the Linear Matrix Inequalities (LMI) framework, such that the optimal solution of the stated control problem is obtained when feasible solution exists

This thesis presents rules that characterize the root locus for polynomials that are nonlinear in the root-locus parameter k. Classical root locus applies to polynomials that are affine in k. In contrast, this thesis considers polynomials that are quadratic or cubic in k. In particular, we focus on constructing the root locus for linear feedback control systems, where the closed-loop denominator polynomial is quadratic or cubic in k. First, we present quadratic root-locus rules for a controller class that yields a closed-loop denominator polynomial that is quadratic in k. Next, we develop cubic root-locus rules for a controller class that yields a closed-loop denominator polynomial that is cubic in k. Finally, we extend the quadratic root-locus rules to accommodate a larger class of controllers. We also provide controller design examples to demonstrate the quadratic and cubic root locus. For example, we show that the triple integrator can be high-gain stabilized using a controller that yields a closed-loop denominator polynomial that is quadratic in k. Similarly, we show that the quadruple integrator can be high-gain stabilized using a controller that yields a closed-loop denominator polynomial that is cubic in k.

碩士
國立中央大學
機械工程研究所
99
In this thesis, three topics are addressed. First, we investigate a general control problem via the Circle criterion borrowed from system theory; We show a fuzzy version of Circle criterion and then provide a synthesis result based on the Circle criterion, establishing closed-loop stabilizability for dynamic output feedback controllers and state-feedback controllers. Second, we show how to solve LMI representation numerically by SOSTOOLS. Third, we solve a stabilization problem for systems with sector-bounded nonlinearities at their input. Then, based on dissipative control and Circle criterion, we get the same stabilization conditions for a state feedback stabilizing controller. Finally, we integrate Circle theorem and dissipative control theorem into one unified structure.

碩士
國立高雄應用科技大學
電機工程系博碩士班
101
The design problem of sliding mode output feedback controller for uncertain multivariable systems are studied in this thesis. Based on the sufficient and necessary conditions for the existence of a sliding mode output feedback controller, the output feedback controller for the certain part of a system is constructed from the state feedback controller for that system using linear matrix inequalities(LMI). Meanwhile, an additional condition is added in the LMI so that the output feedback controller become a sliding mode output feedback controller for the uncertain multivariable system. This method can design sliding mode output feedback controllers of any order and improve the design method in the literature. Simulation examples are provided to demonstrate the effectiveness of the proposed method.

碩士
國立高雄應用科技大學
電機工程系博碩士班
101
In preview study , there are not easy methods for the design of sliding mode output feedback controller for uncertain multivariable systems. In this thesis, the design problem of sliding mode output feedback controller for uncertain multivariable systems are studied. There are Based on the sufficient and necessary conditions for the existence of a sliding mode output feedback controller, (the interactive linear matrix inequality ILMI) method is used to design the output feedback controller for the certain part of a system. Meanwhile, an additional condition is added during the iteration of ILMI so that the output feedback controller become a sliding mode output feedback controller for the uncertain multivariable system. This method can design sliding mode output feedback controllers of any order and improve the design method in the literature. Finally the simulation examples are provided to demonstrate the effectiveness of the proposed method.

碩士
義守大學
電機工程學系碩士班
93
In this dissertation, we will consider the guaranteed cost control problem of uncertain dynamic systems, state feedback, static output feedback, and observer-based control. Exponential stabilization uncertain dynamic systems will be guaranteed via of linear matrix inequality (LMI) optimization approach. Optimal guaranteed cost controls which minimize the guaranteed cost are provided. The robust guaranteed cost observer-based controls for uncertain time-delay systems are considered. Linear matrix inequality (LMI) optimization approach is used to design the feedback controls. Optimal guaranteed cost feedback controls which minimize the upper bound of cost function are provided.

博士
國立成功大學
電機工程研究所
82
Two indirect routes used to prepare the densely sintered In this dissertation, we discuss the dynamic output feedback control and the sliding-mode control (SMC) for the singularly perturbed systems. The compensator-type dynamic output feedback controllers are designed for the robustness of the reduced system via the two-time-scale design. The design methodology of static output feedback control is applied to determine gain matrices via the separate control design of the fast subsystem and the so-called auxiliary system of the slow subsystem. It is shown that there is no restriction on the strict properness of the robust controller concluded in some papers. Next, the design of the near-optimal observer-based controller for the singularly perturbed discrete system is investigated. The minimum value of the performance index of the system under the composite control is $O(\varepsilon^{2})$ close to that of the optimal control. An application to a twin-engine aircraft model is used to illustrate the near-optimal results. The upper bound of the singular perturbation parameter of the controlled closed- loop systems is also calculated. Then the application of the SMC to singularly perturbed systems with inaccessible states is studied. The reaching conditions determined for the fast and slow switching surfaces are verified for the full-order system. And, the error between the response of the fast and slow sliding dynamics and that of the full-order system is proved to be $O(\varepsilon)$. Besides the condition to achieve the robust dynamic SMC design is found, the design technique of the static output feedback control is applied to the design procedure. Finally, the SMC is designed by state feedback for singularly perturbed discrete system. In addition to the existence condition, the convergence condition is also considered on the stability condition of the quasi-sliding mode in the discrete system.

碩士
國立成功大學
電機工程學系碩博士班
100
In this thesis, a new indirect digital redesign method is presented for multi-rate sampled-data control systems with cascaded and dynamic output feedback controllers. These analog controllers are often predesigned based on desirable frequency specification, such as the bandwidth, the natural angular frequency, etc. To take advantages of the digital controller over the analog controller, digital implementations of these analog controllers are often desirable. As only measured input-output signals are available, an ideal state reconstructing algorithm is utilized to obtain the multi-rate discrete-time states of the original continuous-time system. Based on the Chebyshev quadrature method, the gains of the multi-rate cascaded and the output feedback digital controllers are determined from their continuous-time counterparts according to the different sampling rates employed in the different parts of the closed-loop system. As a result, the respective analog controllers with the high-frequency and low-frequency characteristics can be implemented using the respective fast-rate sampling and slow-rate sampling digital controllers. Unlike the classical direct bilinear transform method which is an open-loop direct digital redesign method, the proposed digital controllers take into account the state-matching of the original continuous-time closed-loop system and the digitally redesigned sampled-data closed-loop system. To further improve the state-matching performance, an improved digital redesign approach is also developed to construct the multi-rate cascaded and dynamic output feedback digital controllers. Illustrative examples are given to demonstrate the effectiveness of the developed methods.

碩士
大同大學
電機工程學系(所)
92
This thesis presents an H∞ fuzzy output feedback control design method for fuzzy dynamic systems based on a piecewise Lyapunov function. First, we use the fuzzy dynamic model to represent a complex continuous-time system. Next, based on the fuzzy dynamic model, a fuzzy observer-based H∞ controller is developed to construct controllers for the fuzzy dynamic systems in such a way that a piecewise continuous Lyapunov function can be used to establish the global stability with a desired H∞ disturbance rejection constraint. By the proposed decoupling technique and two-stage procedure, the overall fuzzy observer-based H∞ control problems are parameterized in terms of two linear matrix inequalities (LMIs)— one for controller and the other for observer. The LMIs can be solved very efficiently using commercially available software. Finally, we apply the fuzzy observer-based H∞ controller to control a ball-beam system (BB-system) and an inverted pendulum system, the simulation results demonstrate the applicability of the proposed method.

碩士
大同大學
電機工程研究所
92
This thesis presents an H∞ fuzzy output feedback control design method for fuzzy dynamic systems based on a piecewise Lyapunov function. First, we use the fuzzy dynamic model to represent a complex continuous-time system. Next, based on the fuzzy dynamic model, a fuzzy observer-based H∞ controller is developed to construct controllers for the fuzzy dynamic systems in such a way that a piecewise continuous Lyapunov function can be used to establish the global stability with a desired H∞ disturbance rejection constraint. By the proposed decoupling technique and two-stage procedure, the overall fuzzy observer-based H∞ control problems are parameterized in terms of two linear matrix inequalities (LMIs)─one for controller and the other for observer. The LMIs can be solved very efficiently using commercially available software. Finally, we apply the fuzzy observer-based H∞ controller to control a ball-beam system (BB-system) and an inverted pendulum system, the simulation results demonstrate the applicability of the proposed method.

碩士
國立高雄應用科技大學
電機工程系博碩士班
96
The design task of the dynamic controller for linear neutral systems with state and input delays is usually not easy. Based on new Lyapunov functional, new time-dependent linear matrix inequalities are derived to solve the dynamic output feedback controller problems for linear neutral systems with state and input delays in this thesis. This derivation is different from that in the literature, these new linear matrix inequalities, contain the length of delay time. Closed-loop responses in the simulations show the effectiveness of the method in this thesis.

碩士
淡江大學
電機工程學系碩士班
100
In the future, Renewable energy is become a major topic for discussion. Good power transformation is very important for renewable energy system. In this thesis, we will focus on power change control part where is basic on Grid-connect system. The power change part have DC-DC Boost Converter and DC-AC Inverter. Due to the operation is a nonlinear condition. So before control, we need to discuss the modeling of nonlinear systems into linear-like systems with state –dependent parameters. In the controller design part, because DC-DC Boost Converter need to has stability output voltage. According to objective, we use robust output tracking/regulation for converter. However, due to converter operation is nonlinear system, so we need adopting well-known linear regulator theory to do. The robust output tracking/regulation stability analysis can into LMIs. The matlab LMIs is powerful numerical toolboxes solve for observer/controller gains. Finally, we design a practical experiments on the basis on Digital Signal Processor 1104 (DSP1104), then carried out on converter. Through the experiment, we can verify the proposed methodology.

To meet the exponentially increasing traffic data driven by the rapidly growing mobile subscriptions, both industry and academia are exploring the potential of a new genera- tion (5G) of wireless technologies. An important 5G goal is to achieve high data rate. Small cells with spectrum sharing and multiple-input multiple-output (MIMO) techniques are one of the most promising 5G technologies, since it enables to increase the aggregate data rate by improving the spectral efficiency, nodes density and transmission bandwidth, respectively. However, the increased interference in the densified networks will in return limit the achievable rate performance if not properly managed. The considered setup can be modeled as MIMO interference networks, which can be classified into the K-user MIMO interference channel (IC) and the K-cell MIMO interfering broadcast channel/multiple access channel (MIMO-IBC/IMAC) according to the number of mobile stations (MSs) simultaneously served by each base station (BS). The thesis considers two physical layer (PHY) resource allocation problems that deal with the interference for both models: 1) Pareto boundary computation for the achiev- able rate region in a K-user single-stream MIMO IC and 2) grouping-based interference alignment (GIA) with optimized IA-Cell assignment in a MIMO-IMAC under limited feedback. In each problem, the thesis seeks to provide a deeper understanding of the system and novel mathematical results, along with supporting numerical examples. Some of the main contributions can be summarized as follows. It is an open problem to compute the Pareto boundary of the achievable rate region for a K-user single-stream MIMO IC. The K-user single-stream MIMO IC models multiple transmitter-receiver pairs which operate over the same spectrum simultaneously. Each transmitter and each receiver is equipped with multiple antennas, and a single desired data stream is communicated in each transmitter-receiver link. The individual achievable rates of the K users form a K-dimensional achievable rate region. To find efficient operating points in the achievable rate region, the Pareto boundary computation problem, which can be formulated as a multi-objective optimization problem, needs to be solved. The thesis transforms the multi-objective optimization problem to two single-objective optimization problems–single constraint rate maximization problem and alternating rate profile optimization problem, based on the formulations of the ε-constraint optimization and the weighted Chebyshev optimization, respectively. The thesis proposes two alternating optimization algorithms to solve both single-objective optimization problems. The convergence of both algorithms is guaranteed. Also, a heuristic initialization scheme is provided for each algorithm to achieve a high-quality solution. By varying the weights in each single-objective optimization problem, numerical results show that both algorithms provide an inner bound very close to the Pareto boundary. Furthermore, the thesis also computes some key points exactly on the Pareto boundary in closed-form. A framework for interference alignment (IA) under limited feedback is proposed for a MIMO-IMAC. The MIMO-IMAC well matches the uplink scenario in cellular system, where multiple cells share their spectrum and operate simultaneously. In each cell, a BS receives the desired signals from multiple MSs within its own cell and each BS and each MS is equipped with multi-antenna. By allowing the inter-cell coordination, the thesis develops a distributed IA framework under limited feedback from three aspects: the GIA, the IA-Cell assignment and dynamic feedback bit allocation (DBA), respec- tively. Firstly, the thesis provides a complete study along with some new improvements of the GIA, which enables to compute the exact IA precoders in closed-form, based on local channel state information at the receiver (CSIR). Secondly, the concept of IA-Cell assignment is introduced and its effect on the achievable rate and degrees of freedom (DoF) performance is analyzed. Two distributed matching approaches and one centralized assignment approach are proposed to find a good IA-Cell assignment in three scenrios with different backhaul overhead. Thirdly, under limited feedback, the thesis derives an upper bound of the residual interference to noise ratio (RINR), formulates and solves a corresponding DBA problem. Finally, numerical results show that the proposed GIA with optimized IA-Cell assignment and the DBA greatly outperforms the traditional GIA algorithm.

"This thesis is concerned with robust control of an offshore steel jacket platform subject to nonlinear wave-induced forces. Since time delay and uncertainty are inevitably encountered for an offshore structure and their existence may induce instability, oscillation and poor performance, it is very significant to study on how the delay and uncertainty affect the offshore structure. In this thesis, a memory robust control strategy is, for the first time, proposed to reduce the internal oscillations of the offshore structure under wave-induced forces, so as to ensure the safety and comfort of the offshore structure. Firstly, when the system's states are adopted as feedback, memory state feedback controllers are introduced for the offshore structure. By using Lyapunov-Krasovskii stability theory, some delay-dependent stability criteria have been established, based on which, and by combining with some linearization techniques, memory state feedback controllers are designed to control the offshore structure. The simulation results show that such controllers can effectively reduce the internal oscillations of the offshore structure subject to nonlinear wave-induced forces and uncertainties. On the other hand, a new Lyapunov-Krasovskii functional is introduced to derive a less conservative delay-dependent stability criterion. When this criterion is applied to the offshore structure, an improved memory state feedback controller with a small gain is obtained to control the system more effectively, which is sufficiently shown by the simulation. Secondly, when the system's outputs are adopted as feedback, memory dynamic output feedback controllers are considered for the offshore structure. By employing a projection theorem and a cone complementary linearization approach, memory dynamic output feedback controllers are derived by solving some nonlinear minimization problem subject to some linear matrix inequalities. The simulation results show that the internal oscillations of the offshore structure subject to nonlinear wave-induced forces are well attenuated. Finally, robust H control is fully investigated for the offshore structure. By employing Lyapunov-Krasovskii stability theory, some delay-dependent bounded real lemmas have been obtained, under which, via a memory state feedback controller or a dynamic output feedback controller, the resulting closed-loop system is not only asymptotically stable but also with a prescribed disturbance attenuation level. The simulation results illustrate the validity of the proposed method." -- abstract.