Dans ce travail de thèse, on s’intéresse au problème de déplacement et de la localisation d'un robot mobile autonome dans son environnement local. La première partie du manuscrit les deux tâches de mouvement de base : c'est-à-dire, la stabilisation et le suivi de trajectoire. Deux stratégies de commande ont été traitées: le mode de glissement intégral, et la méthode dite «Immersion et Invariance». La deuxième partie porte sur l'asservissement visuel, les deux techniques 2D et 3D d'asservissement visuel ont été appliquées. Les moments d'image ont été choisis comme indices visuels car ils sont moins sensibles au bruit d'image et autres erreurs de mesure. Une nouvelle approche de l'asservissement visuel qui repose sur l'image est ici proposée. Elle est basée sur la génération de trajectoires sur le plan de l'image directement (calcul des valeurs des primitives d’image correspondantes à une trajectoire cartésienne donnée). Cette approche garantit que la robustesse et la stabilité bien connues de l'asservissement 2D ont été étendues en raison du fait que les emplacements initial et désiré de la caméra sont proches. Les trajectoires obtenues garantissent aussi que la cible reste dans le champ de vue de la caméra et que le mouvement du robot correspondant est physiquement réalisable. Des tests expérimentaux ont été effectués et des résultats satisfaisants ont été obtenus à partir des implémentations des stratégies de commande et d'asservissement visuel. Bien qu'ils soient développés et expérimentés dans le cadre spécifique d'un robot de type unicycle, ces travaux sont assez génériques pour être appliqués sur autres types de véhicules. / This thesis focuses on the problem of moving and localizing an autonomous mobile robot in its local environments. The first part of the manuscript concerns two basic motion tasks, namely the stabilization and trajectory tracking. Two control strategies were discussed: the integral sliding mode, and the method known as “Immersion and Invariance” for nonlinear control. The second part focuses on both 2D and 3D visual servoing techniques. Image moments were chosen as visual features as they provide a more geometric and intuitive meaning than other features, and they are less sensitive to image noise and other measurement errors. A new approach to visual servoing based on image is herein proposed. It is based on the generation of trajectories directly on the image plane (Calculation of the image features corresponding to a given Cartesian path). This approach ensures that the robustness and stability are extended due to the fact that the initial and desired locations of the camera are close. The trajectories obtained guarantee that the target remains in the field of view of the camera and the corresponding movement of the robot is physically feasible. Experimental tests have been conducted, and satisfactory results have been obtained from both implementations regarding motion control and visual servoing strategies. Although developed and tested in the specific context of a unicycle type robot, this work is generic enough to be applied to other types of vehicles.

Jia Peng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 85-87). / Abstracts in English and Chinese. / Abstract --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview of Output Regulation Problem --- p.2 / Chapter 1.2 --- Attitude Tracking Control of Rigid Spacecraft --- p.3 / Chapter 1.3 --- Overview of Continuous-time Nonlinear H∞ Control --- p.4 / Chapter 1.4 --- Overview of Discrete-time Nonlinear Hq∞ Control --- p.6 / Chapter 1.5 --- Flight Control in Windshears --- p.8 / Chapter 1.6 --- Nonlinear Benchmark System --- p.9 / Chapter 1.7 --- Outline of the Work --- p.11 / Chapter 2 --- Attitude Control and Asymptotic Disturbance Rejection of Rigid Spacecraft --- p.12 / Chapter 2.1 --- Model Description --- p.12 / Chapter 2.2 --- Problem Formulation --- p.16 / Chapter 2.3 --- Preliminaries of General Framework for Global Robust Output Regulation --- p.17 / Chapter 2.4 --- Application of Global Robust Output Regulation --- p.21 / Chapter 2.4.1 --- Case I: without unknown parameters --- p.21 / Chapter 2.4.2 --- Case II: with unknown parameters --- p.26 / Chapter 2.5 --- Simulation --- p.34 / Chapter 2.5.1 --- Case I: without unknown parameters --- p.34 / Chapter 2.5.2 --- Case II: with unknown parameters --- p.36 / Chapter 2.6 --- Conclusions --- p.38 / Chapter 3 --- Application of Approximation Continuous-time Nonlinear H∞ Control Law --- p.45 / Chapter 3.1 --- Preliminaries of Approximation Continuous-time Nonlinear Hq∞ Control Law --- p.45 / Chapter 3.2 --- Disturbance Attenuation of Flight Control System in Windshears --- p.50 / Chapter 3.2.1 --- Design of Control Law --- p.51 / Chapter 3.2.2 --- Computer Simulation --- p.56 / Chapter 3.3 --- Conclusions --- p.57 / Chapter 4 --- Application of Approximation Discrete-time Nonlinear H∞ Control Law --- p.65 / Chapter 4.1 --- Preliminaries of Approximation Discrete-time Nonlinear H∞ Control Law --- p.66 / Chapter 4.2 --- Explicit Expression of u --- p.69 / Chapter 4.3 --- Disturbance Attenuation of RTAC System --- p.73 / Chapter 4.4 --- Computer Simulation --- p.78 / Chapter 4.5 --- Conclusions --- p.80 / Chapter 5 --- Conclusions --- p.83 / Bibliography --- p.85 / A Programs --- p.88 / Vita --- p.112

Lan Weiyao. / "December 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 163-172). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Cette thèse étudie les aspects de contrôle d'applications optique adaptative, une technologie utilisée pour améliorer la performance des systèmes optiques en réduisant l'effet des distorsions de front d'onde, à l'imagerie haute résolution angulaire. Le problème Adaptive Optics contrôle est présenté à travers une revue de la littérature. Par conséquent, la conception d'un contrôleur de rétroaction est adressée, d'un point de vue moderne de contrôle, au moyen de la méthode de contrôle Linéaire Quadratique Gaussienne. L'approche proposée met l'accent sur la capacité de la boucle d'optique adaptative de rejeter l'aberration atmosphérique. On dérive un système de représentation diagonale état-espace qui sépare nettement la dynamique de la plante (miroir déformable et le capteur de front d'onde) de la dynamique des perturbations (modèle atmosphérique). Cette représentation facilite la résolution numérique du problème. Une analyse de fréquence est effectuée pour vérifier les spécifications de performance et de robustesse de la multiple-input multiple-système de rétroaction de sortie. De plus, nous analysons les performances et la robustesse de LQG contrôle basé par rapport au témoin intégrante classique, au moyen de bout en bout des simulations et en considérant les différents niveaux de bruit du capteur de front d'onde. Durant le-ciel observations, l'énergie turbulente et la vitesse relative de chaque couche de l'atmosphère peut changer rapidement dégrader l'estimation de front d'onde. Pour cette raison, un algorithme de modèle numérique de conception garantissant une performance satisfaisante rejet de perturbations, même dans le cas de variables dans le temps caractéristique de la turbulence est dérivé. Expériences numériques en utilisant les CAOS du progiciel ont été menées pour démontrer la robustesse de chaque approche proposée. Compte tenu de la conviction auteur que l'avenir de l'optique adaptative repose également sur le développement d'un plus sophistiqués (par exemple, non linéaire) des modèles, une quantité importante de travail a été consacrée à l'étude de deux classes de méthodes de reconnaissance des formes répandues. À savoir Support Vector Machines et méthodes du noyau, dont la régression des capacités sont exploitées dans la solution du problème non linéaire suivi optimal. En ce qui concerne Support Vector Machines, grâce à la théorie du contrôle optimal singulier, les contraintes se relâchent permettant une résolution plus facile et plus rapide numérique du problème d'optimisation. Alors que, dans le cas totalement déterministe du contrôleur Support Vector résulte plus simple à synthétiser. En référence aux méthodes du noyau, une tentative originale de réunir leurs forces de régression avec le concept de contrôle adaptatif inverse est présentée. Le noyau récursif des moindres carrés algorithme est utilisé pour mettre en œuvre un contrôleur adaptatif inverse capable de forcer une dynamique non linéaire appropriés pour suivre une sortie désirée. Cette méthode très peut également être utilisé pour vérifier si une trajectoire donnée arbitraire est une sortie admissible pour le système non linéaire à l'étude. Un tel algorithme innovant pourrait être utilement appliquée dans les travaux futurs, le contrôle de Tip-Tilt miroirs. Finalement, une première esquisse du cadre théorique soutenant l'utilisation du contrôle adaptatif inverse pour la solution du problème de suivi général est donné. Après l'introduction de la formulation mathématique du problème de suivi et les définitions nécessaires mathématiques, des conditions suffisantes et nécessaires (cas linéaire) et des conditions suffisantes (cas non-linéaire) de l'existence de la solution sont dérivés. / His thesis investigates the control aspects of Adaptive Optics applications, a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions, to high angular resolution imaging. The Adaptive Optics control problem is presented through a survey of the literature. Consequently, the design of a feedback controller is addressed, from a modern control point of view, by means of the Linear Quadratic Gaussian control methodology. The proposed approach emphasizes the ability of the adaptive optics loop to reject the atmospheric aberration. We derive a diagonal state-space system representation which clearly separates the dynamics of the plant (deformable mirror and wavefront sensor) from the disturbance dynamics (atmospheric model). This representation facilitates the numerical resolution of the problem. A frequency analysis is carried out to check the performance and robustness specifications of the multiple-input multiple-output feedback system. Moreover, we analyze the performance and the robustness of LQG-based control compared to classic integral control, by means of end-to-end simulations and by considering different levels of wavefront sensor noise. During on-sky observations, the turbulent energy and relative speed of each atmospheric layer can change rapidly degrading the wavefront estimate. For this reason, a numerical model design algorithm guaranteeing satisfactory disturbance rejection performance even in the case of time-varying turbulence's characteristic is derived. Numerical experiments using the Software Package CAOS have been conducted to demonstrate the robustness of every proposed approach. Given the author firm belief that the future of Adaptive Optics also relies on the development of more sophisticated (i.e., nonlinear) models, a substantial amount of work was dedicated to the study of two classes of widespread pattern recognition methods. Namely Support Vector Machines and Kernel Methods, whose regression capabilities are exploited in the solution of the nonlinear optimal tracking problem. Concerning Support Vector Machines, thanks to the singular optimal control theory, constraints are loosened permitting an easier and faster numerical resolution of the optimization problem. So that, in the fully deterministic case the Support Vector controller results simpler to synthesize. With reference to Kernel Methods, an original attempt to bring together their regression strengths with the concept of Adaptive Inverse Control is presented. The Kernel Recursive Least-Square algorithm is used to implement an adaptive inverse controller capable of forcing a suitable nonlinear dynamics to follow a desired output. This very method can also be used to check if a given arbitrary trajectory is an admissible output for the nonlinear system under study. Such an innovative algorithm could be fruitfully applied, in future works, to the control of Tip-Tilt mirrors. Eventually, a first sketch of the theoretical framework supporting the use of Adaptive Inverse Control for the solution of the general tracking problem is given. After introducing the mathematical formulation of the tracking problem and the needed mathematical definitions, sufficient and necessary conditions (linear case) and sufficient (nonlinear case) conditions to the existence of the solution are derived.

Este trabalho apresenta a aplicação da teoria de controle robusto não linear por modos deslizantes a sistemas de posicionamento dinâmico para embarcações flutuantes, com validação experimental. O objetivo do sistema de controle projetado é manter a embarcação próxima a uma posição pré-ajustada (set-point) ou a uma trajetória preestabelecida (pathfollowing), por meio das forças geradas nos propulsores, mesmo estando o sistema na presença de distúrbios externos, ou seja, vento, ondas e correnteza. A princípio, realizaram-se simulações numéricas com o sistema projetado a fim de verificar o seu desempenho. O simulador utilizado foi implementado em ambiente Matlab/Simulink, considerando a dinâmica da embarcação e dos agentes ambientais. As simulações consistiram de manobras realizadas em condições nominais e na ausência de esforços ambientais, com embarcação cheia (plena) e vazia (lastro). Para validação do algoritmo implementado realizaram-se ensaios de manobra em condição de calmaria e na presença de vento, com a embarcação em plena carga e vazia. Os ensaios foram administrados no laboratório do Departamento de Engenharia Naval e Oceânica da USP (DENO). O algoritmo de controle por modos deslizantes demonstrou-se robusto a variações de condições ambientais (vento), mantendo o desempenho e estabilidade. Verificou-se que o ajuste dos parâmetros do controlador pode ser feito de forma intuitiva, utilizando-se fórmulas matemáticas. Além disso, a estrutura não linear do controlador e suas propriedades de robustez asseguram o desempenho e estabilidade para uma grande gama de condições ambientais e manobras realizadas com a embarcação. / This paper presents the application of the robust and nonlinear sliding mode control theory to the dynamic positioning systems for floating vessel, with experimental validation. The objective of the control system designed is to keep the vessel next a specific position (set-point) or follow a pre-defined trajectory (pathfollowing) through the action of propellers, in the presence of wind, waves and current external disturbances. In principle numerical simulations were carried out with the system designed to verify its performance. The simulator used was implemented in a Matlab / Simulink, considering the dynamics of the vessel and environmental agents. The simulations consisted of maneuvers carried out in nominal condition and in the absence of environmental efforts, with the vessel full and empty (ballasted). In order to validate the algorithm, small scale experiments were done, considering maneuvers in both calm and windy conditions, with the vessel at full or ballasted load. The tests were conducted at the laboratory of the Naval and Ocean Engineering Department (DENO) of the University of São Paulo. The sliding mode control was robust to variations in environmental conditions (wind), keeping the performance and stability. It was verified that the adjustment of controller parameters can be easily done, using mathematical equations. Moreover, the nonlinear structure of the controller and its robustness properties ensure the performance and stability for a large range of environmental conditions and maneuvers carried out with the vessel.

Cette thèse traite du problème de la stabilisation d'un système de lancement aéroporté (éventuellement non habité) pour satellites. Le lancement aéroporté consiste à ramener, à l'aide d'un avion, un satellite et son lanceur (fusée) à une certaine hauteur, et d'exécuter son lancement dans les airs (souvent en larguant la fusée). Ceci est similaire au lancement d'un missile par un avion chasseur. La plus grande différence réside dans le rapport de masse entre l'avion et le lanceur qui est beaucoup plus proche de l'unité (fusée lourde comparée à la masse de l'avion). Le système est composé de deux étages: le premier étage est dit avion porteur qui est un véhicule aérien automatisé. Il porte le lanceur qui constitue le deuxième étage (la fusée). Dans la première partie, sont proposées des approches de modélisation pour le système de largage pendant et après le largage. La première approche considère que la phase de séparation est instantanée, mais imparfaite. Par conséquent le système est vu comme un modèle d'aéroplane dont les variables d'état sont avec des larges conditions initiales dues à la séparation imparfaite. Une deuxième approche considère la séparation elle-même, représentée par une forte perturbation (un extrême cas) sur les forces et couples aérodynamiques du modèle au cours d'un intervalle de temps. Dans la deuxième partie, afin de stabiliser le système de largage après la séparation, la commande à intégrateur conditionnel modifié est développée dans un premier temps pour une classe des systèmes non-linéaires multi-entrées multi-sorties, avec comme point de départ la théorie introduite par Khalil et co-auteurs pour des systèmes mono entrée mono sortie. Cette commande a été ensuite étendue pour la commande à servo-compensateur conditionnel modifié pour une classe de systèmes non-linéaires multi-entrées multi-sorties. Les deux stratégies ont été appliquées pour stabiliser le système de largage pendant et après la phase de séparation. Ces techniques ont l'avantage d'être robustes et de pouvoir utiliser des modèles approximatifs. D'un autre côté, il était important d'examiner la possibilité d'obtenir de meilleures performances en utilisant de meilleurs modèles. Pour cette raison, la commande de linéarisation par bouclage dynamique a été étudiée. Finalement, les performances de toutes ces méthodes de commande (ainsi que certaines commandes de base additionnelles) ont été illustrées par des simulations sous Matlab/Simulink sur un modèle non-linéaire de F-16. / This thesis addresses the problem of the stabilization of an (unmanned) airlaunch system. Air launching consists in bringing a satellite and its launcher (rocket) to a certain height using an aircraft, and then launching it from the air (often by dropping the rocket), in a similar way of launching a missile from a fighter. The main difference is that the envisaged mass ratio is much closer to one (heavy rocket compared to aircraft mass). It is then composed of two stages: the first stage called carrier aircraft consists of an <unmanned> aerial vehicle that carries the launcher which constitutes the second stage (rocket). This thesis starts by introducing the problem and objectives, continues by presenting several approaches to model the airlaunch system, and ends by developing different advanced control methods to stabilize it after the launching phase. In the modeling part we propose a firstly approach called the initial condition model which assumes that the separation phase is instantaneous, and then the airlaunch system is composed of an aircraft model after the launching phase but with large initial conditions on its state variables, caused by a non-perfect split phase. A second approach assumes that the separation phase itself is modeled by a disturbance on aerodynamic forces and moments (from a worst case) during a time interval. In the control part a modified conditional integrator controller for a class of nonlinear multi-input multi-output systems is first developed starting from the conditional integrator theory developed by Khalil and co-workers. It is then extended to a modified conditional servocompensator control for a class of nonlinear multi-input multi-output systems. Both control strategies were then applied to stabilize the airlaunch system after the separation phase. They have the advantage of being very robust, and they don't depend so much on reliable models. Even if these control strategies gave good results, it was investigated in this thesis another control approach much more dependent on detailed and reliable models. This approach was based on dynamic feedback linearization theory, and the main idea is to obtain better performance in trade off better models. Finally, all proposed control methods (plus some standard ones) were compared and illustrated by simulations under Matlab/Simulink on a nonlinear F-16 model. These simulations have shown that the results were as expected, and that each control strategy was well fit for a particular situation.

In this work we address the problem of friction compensation in a pneumatic control valve. It is proposed a nonlinear control law that uses algebraic estimators in its structure, in order to adapt the controller to the aging of the valve. For that purpose we estimate parameters related to the valve\'s Karnopp model, necessary to friction compensation, online. The estimators and the controller are validated through simulations. / Nessa pesquisa, estudamos o problema de compensação de atrito em válvulas pneumáticas. É proposta uma lei de controle não linear que tem estimadores algébricos em sua estrutura, para adaptar o controlador ao envelhecimento da válvula. Para isso, estimam-se os valores de parâmetros relacionados ao modelo de Karnopp da válvula, necessários à compensação do atrito, de maneira online. Os estimadores e o controlador são validados através de simulações.

Faults and failures in system components are the two main reasons for the instability and the degradation in control performance. In recent decades, fault-tolerant control (FTC) approaches were introduced to improve the resiliency of the control system against faults and failures. In general, FTC techniques are classified into two major groups: passive and active. Passive FTC systems do not rely on the fault information to control the system and are closely related to the robust control techniques while an active FTC system performs based on the information received from the fault detection and isolation (FDI) system, and the fault problem will be tackled more intelligently without affecting other parts of the system. This dissertation technically reviews fault and failure causes in control systems and finds solutions to compensate for their effects. Recent achievements in FDI approaches, and active and passive FTC designs are investigated. Thorough comparisons of several different aspects are conducted to understand the advantages and disadvantages of different FTC techniques to motivate researchers to further developing FTC, and FDI approaches. Then, a novel active FTC system framework based on online FDI is presented which has significant advantages in comparison with other state of the art FTC strategies. To design the proposed active FTC, a new FDI approach is introduced which uses the artificial neural network (ANN) and a model based observer to detect and isolate faults and failures in sensors and actuators. In addition, the extended Kalman filter (EKF) is introduced to tune ANN weights and improve the ANN performance. Then, the FDI signal combined with a nonlinear dynamic inversion (NDI) technique is used to compensate for the faults in the actuators and sensors of a nonlinear system. The proposed scheme detects and accommodates faults in the actuators and sensors of the system in real-time without the need of controller reconfiguration. The proposed active FTC approach is used to design a control system for three different applications: Unmanned aerial vehicle (UAV), load frequency control system, and proton exchange membrane fuel cell (PEMFC) system. The performance of the designed controllers are investigated through numerical simulations by comparison with conventional control approaches, and their advantages are demonstrated.

Differential geometric nonlinear control of a multiple stage evaporator system of the liquor burning facility associated with the Bayer process for alumina production at Alcoa Wagerup alumina refinery, Western Australia was investigated.Mathematical models for differential geometric analysis and nonlinear controller synthesis for the evaporator system were developed. Two models, that were structurally different from each other, were used in the thesis for simulation studies. Geometric nonlinear control structure, consisting of nonlinear state feedback control laws and multi-loop single-input single-output proportional-integral controllers, were designed for the industrial evaporator system. The superiority of the geometric nonlinear control structure for regulatory control of the evaporator system was successfully demonstrated through computer simulations and real-time simulator implementation. The implementation trial has verified the practicality and feasibility of these type of controllers. It also re-solved some practical issues of the geometric nonlinear control structure for industrial control applications. In addition, the implementation trial also established a closer link between the academic nonlinear control theory and the industrial control practices.Geometric nonlinear output feedback controller, consisting of the geometric nonlinear control structure and reduce-order observer was proposed for actual plant implementation on the evaporator system on-site. Its superior performance was verified through computer simulations, but its feasibility on the evaporator system on-site has yet to be investigated either through simulator implementation or actual plant implementation. This investigation was not performed due to the time constraint on the preparation of this thesis and the inavailability of the plant personnel required for this implementation.Robust ++ / nonlinear control structures that are simple and computationally efficient have been proposed for enhancing the performance of geometric nonlinear controllers in the presence of plant/model mismatch and/or external disturbances. The robust nonlinear control structures are based on model error compensation methods. Robustness properties of the proposed robust nonlinear control structures on the evaporator system were investigated through computer simulations and the results indicated improved performance over the implemented geometric nonlinear controller in terms of model uncertainty and disturbance reductions.A software package was developed in MAPLE computing environment for the analysis of nonlinear processes and the design of geometric nonlinear controllers. This developed symbolic package is useful for obtaining fast and exact solutions for the analysis and design of nonlinear control systems. Procedures were also developed to simulate the geometric nonlinear control systems. It was found that MAPLE, while it is superior for the analyses and designs, is not viable for simulations of nonlinear control systems. This was due to limitation of MAPLE on the physical, or virtual, memory management. The use of both symbolic and numeric computation for solutions of nonlinear control system analysis, design and simulation is recommended.To sum up, geometric nonlinear controllers have been designed for an industrial multiple stage evaporator system and their simplicity, practicality, feasibility and superiority for industrial control practices have been demonstrated either through computer simulations or real-time implementation. It is hoped that the insights provided in this thesis will encourage more industry-based projects in nonlinear control, and thereby assist in closing the widening gap between academic nonlinear control theory and industrial control ++ / practice.Keywords: geometric nonlinear control, input-output linearization, multiple stage evaporator, robust geometric nonlinear control, control performance enhancement.

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Sciences, Electrical Engineering Department. / Includes bibliographical references.