<div>Traction control (TC) systems have become quite common in on-road passenger vehicles in recent years. However, for vehicles in other applications, they are not as widely available.</div><div>This work presents a methodology for the proper design and implementation of a traction control system for heavy duty off-road machines, using a wheel loader as a reference vehicle.</div><div><br></div><div><div>A simulation model was developed, using standard vehicle dynamics constructs, including equations of motion and a description of the distribution of weight between the axles for different operating conditions. This model contains considerations for resistive forces acting on the machine implement, such as that generated by a work pile. The simulation also incorporates a detailed representation of the slip-friction characteristics between the vehicle tires and the road surface. One objective of this research was to model this interaction accurately, because the system traction behavior is dependent on it. Therefore, a series of tests was run using a state estimator to generate data on the slip-friction relationship at various ground conditions, and the results were incorporated into the simulation model. The dynamics of the machine braking system pressure were also modeled to give a more accurate description of the system response. The result is a mathematical model capable of accurately reproducing the behavior of the real-world system.</div></div><div><br></div><div><div>One of the primary goals of this work was the description of the traction control strategy itself, which should work as effectively and efficiently as possible. Several different aspects of the system were taken into consideration in generating this control structure. First, a relatively simple controller based on a PID control law was created. This controller was updated to account for peculiarities of the traction control system, as well as aspects like time delay. From there, more advanced controllers were created to address certain aspects of the system in greater detail. First, a self-tuning controller based on real-time optimization strategies was developed, to allow the controller to quickly adapt to changes in ground condition. Then, different nonlinear controllers were synthesized which were designed to address the theoretical behavior of the system. All of these controllers were simulated using the system model and then some were run in experiments to show their potential for improving system performance. To improve system efficiency, the machine drivetrain itself was also examined to develop a more efficient control algorithm. By designing a more efficient methodology, traction control congurations which had previously seen increases in fuel consumption of 16% were now able to actually reduce fuel usage by 2.6%.</div></div><div><br></div><div><div>Another main goal of this work was the development of a prototype system capable of implementing the formulated control strategies. The reference machine was modied so that the brakes could be controlled electronically and independently for implementation of the TC system. The vehicle was instrumented using a wide array of sensors, and estimation methodologies for accurately determining vehicle speed and implement forces were designed. The velocity estimator designed in this work is more accurate and more reliable than an industry standard sensor, which is important for traction control implementation. The implement force estimate was also quite accurate, achieving payload estimate errors of less than 2.5%, comparable to commercially-available measurement systems. This setup allowed for tests to be accurately compared, to assess the traction control performance.</div></div><div><br></div><div><div>With the objective of performing experiments on the traction control system, many tests were run to assess its capabilities in various situations. These tests included experiments for characterizing the vehicle behavior so that the simulation model could be updated to accurately reflect the physical machine performance. Another task for the experimental work was the generation of useful metrics for quantifying traction control performance. Laboratory experiments which were very controlled and repeatable were also run for generating data to improve the system model and for comparing traction control performance results side-byside. The test metrics proposed for these experiments provided for accurate, repeatable comparisons of pushing force, tire wear, and brake consumption. For each of these tests, the traction control system saw an increase in pushing force of at least 10% when compared with the stock machine, with certain operating conditions showing increases as high as 60%. Furthermore, every test case showed a decrease in wheel slip of at least 45% (up to 73% for some cases), which translates into increased tire longevity.</div></div><div><br></div><div><div>Other tests were conducted in the eld, designed to mimic the real-world operating conditions of the wheel loader. Various performance comparisons were made for different congurations in which traction control could provide potential benets. These included parameters for comparing overall vehicle performance in a typical truck loading cycle, such as tire wear, fuel consumption, and material moved per load. Initial results for this testing showed a positive result in terms of wheel slip reduction, but other performance parameters such as fuel consumption were negatively impacted. Therefore, the control structure was reexamined extensively and new methods were added to improve those results. The final control implementation saw a 12% reduction in tire slip, while also reducing fuel consumption by 2.6% compared to the stock system. These results show signicant potential for traction control as a technology for maximizing the performance output of construction machines.</div></div>

With the promise to shape the future of industry, multi-agent robotic technologies have the potential to change many aspects of daily life. Over the coming decade, they are expected to impact transportation systems, military applications such as reconnaissance and surveillance, search-and-rescue operations, or space missions, as well as provide support to emergency first responders. Motivated by the latest developments in the field of robotics, this thesis contributes to the evolution of the future generation of multi-agent robotic systems as they become smarter, more accurate, and diversified in terms of applications. But in order to achieve these goals, the individual agents forming cooperative robotic systems need to be specialized in what they can accomplish, while ensuring accuracy and preserving the ability to perform diverse tasks. This thesis addresses the problem of task allocation in swarm robotics in the specific context where specialized capabilities of the individual agents are considered. Based on the assumption that each individual agent possesses specialized functional capabilities and that the expected tasks, which are distributed in the surrounding environment, impose specific requirements, the proposed task allocation mechanisms are formulated in two different spaces. First, a rudimentary form of the team members’ specialization is formulated as a cooperative control problem embedded in the agents’ dynamics control space. Second, an advanced formulation of agents’ specialization is defined to estimate the individual agents’ task allocation probabilities in a dedicated specialization space, which represents the core contribution of this thesis to the advancement and practice in the area of swarm robotics. The original task allocation process formulated in the specialization space evolves through four stages of development. First, a task features recognition stage is conceptually introduced to leverage the output of a sensing layer embedded in robotic agents to drive the proposed task allocation scheme. Second, a matching scheme is developed to best match each agent’s specialized capabilities with the corresponding detected tasks. At this stage, a general binary definition of agents’ specialization serves as the basis for task-agent association. Third, the task-agent matching scheme is expanded to an innovative probabilistic specialty-based task-agent allocation framework to generalize the concept and exploit the potential of agents’ specialization consideration. Fourth, the general framework is further refined with a modulated definition of the agents’ specialization based on their mechanical, physical structure, and embedded resources. The original framework is extended and a prioritization layer is also introduced to improve the system’s response to complex tasks that are characterized based on the recognition of multiple classes. Experimental validation of the proposed specialty-based task allocation approach is conducted in simulation and on real-world experiments, and the results are presented and discussed in light of potential applications to demonstrate the effectiveness and efficiency of the proposed framework.

Dans les dernières années, le respect de l’environnement est devenu une des grandes préoccupations des clients du secteur automobile. Les constructeurs cherchent à réduire les émissions carbones de ses produits et les véhicules hybrides ou purement électriques apparaissent comme une alternative viable aux véhicules thermiques. Un des éléments importants de la réussite de la commercialisation des véhicules électriques est la recharge de la batterie qui peut être effectuée par différents moyens, avec des chargeurs embarqués/débarqués, à domicile ou sur la voie-publique. Dans ce domaine un système de charge performant doit notamment être robuste vis-à-vis des contraintes extérieures( perturbations réseaux, impédances de ligne, charges de plusieurs véhicules en même temps), avoir un bon rendement entre la puissance puisée à la prise et celle délivrée à la batterie, maitriser les courants harmoniques rejetés sur le réseau électrique (respect des différentes contraintes réglementaires liées aux perturbations émises). Pour répondre à ces exigences les travaux de cette thèse proposent des commandes innovantes des convertisseurs de puissance contenus dans les chargeurs électriques. Dans un premier temps, la modélisation des convertisseurs de puissance est réalisée en moyenne à la période de commutation et en moyenne généralisée pour d´écrire le processus de génération des harmoniques des courants et tensions des convertisseurs. Des lois de commande non-linéaire fondées sur la théorie de stabilité au sens de Lyapunov sont proposées de fac¸on à induire un comportement en boucle fermée satisfaisant les exigences souhaitées pour les convertisseurs de puissance. La partie commande est complétée par une partie d’observation nécessaire pour l’estimation des signaux non-mesurés et pour l’extraction harmonique. Enfin dans la dernière partie de la thèse, les différentes stratégies de commande sont validées par rapport aux exigences via une co-simulation en reproduisant l’architecture de logiciel model in the loop utilisée dans l’industrie / In the last few years the question of respecting the environment became a central concern of car users. The electric cars respond to the public trend of reducing the toxic emissions of conventional cars. The success of electric cars depends on the charging of the batteries, charging done either at home or on the public domain.The charging system has to respond to the following performance criteria:-robustness to exterior constraints: network perturbations, line impedance, multiple simultaneous charging of vehicles.-a good efficiency for the power transfer between the received power and the power delivered to the battery.-respecting the power distributer constrains for network harmonic pollution.These three points impose the need for efficient control laws for the battery charger. In this context, the power converters (AC / DC - DC / DC) are key components in electrical chargers , an improved control law of these elements can provide a better level of performance for the charger.This work is a continuation of previous work that resulted in several theses with CIFRE funding, in collaboration with Renault in the context of the electric car (but not only):- From an industrial viewpoint, the doctoral student will draw on the expertise, experience and Renault's test facilities in the field of electric traction in the automotive transport.- From an academic point of view the work will benefit from the skills of the working group 'System control’ within the L2S laboratory, in the field of multi-physics modelling, design of control laws and optimization.Supervision will be provided by:- Emmanuel Godoy (Professor, HDR, advisor) and Dominique Beauvois (professor, co-director) of the academic point of view.- Pedro Kvieska (Engineer, Doctor, Ecole Centrale de Nantes) for industrial management within Renault.Objectives of the thesisThe first two years of thesis work will focus on methodological studies of dedicated control laws. During the third year the work will be focused on the implementation of the proposed architectures and control strategies by: implementing of the new control strategies as prototypes on test bench and on the transferability of the proposed control approaches.A big part of the last year will naturally be devoted to the writing of the doctoral thesis and the preparation of the defence.

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No / An adaptive iterative learning control approach is proposed for a class of single-input single-output uncertain nonlinear systems with completely unknown control gain. Unlike the ordinary iterative learning controls that require some preconditions on the learning gain to stabilize the dynamic systems, the adaptive iterative learning control achieves the convergence through a learning gain in a Nussbaum-type function for the unknown control gain estimation. This paper shows that all tracking errors along a desired trajectory in a finite time interval can converge into any given precision through repetitive tracking. Simulations are carried out to show the validity of the proposed control method.

No description available.

This dissertation presents a discussion of the optimal feedback control for nonliner systems (both discrete and ODE) and nonquadratic cost functions in order to achieve improved performance and larger regions of asymptotic stability in the nonlinear system context. The main work of this thesis is carried out in two parts; the first involves development of nonlinear, nonquadratic theory for nonlinear recursion equations and formulation, proof and application of the stable manifold theorem as it is required in this context in order to obtain the form of the optimal control law. The second principal part of the dissertation is the development of nonlinear, nonquadratic theory as it relates to nonautonomous systems of a particular type; specifically periodic time varying systems with a fixed, time invariant critical point. / Ph. D.

Compte tenu de la forte croissance du trafic aérien aussi bien dans les pays émergents que dans les pays développés soutenue durant ces dernières décennies, la satisfaction des exigences relatives à la sécurité et à l’environnement nécessite le développement de nouveaux systèmes de guidage. L’objectif principal de cette thèse est de contribuer à la synthèse d’une nouvelle génération de lois de guidage pour les avions de transport présentant de meilleures performances en terme de suivi de trajectoire. Il s’agit en particulier d’évaluer la faisabilité et les performances d’un système de guidage utilisant un référentiel spatial. Avant de présenter les principales approches utilisées pour le développement de lois de commande pour les systèmes de pilotage et de guidage automatiques et la génération de directives de guidage par le système de gestion du vol, la dynamique du vol d’un avion de transport est modélisée en prenant en compte d’une manière explicite les composantes du vent. Ensuite, l’intérêt de l’application de la commande adaptative dans le domaine de la conduite automatique du vol est discuté et une loi de commande adaptative pour le suivi de pente est proposée. Les principales techniques de commande non linéaires reconnues d’intérêt pour le suivi de trajectoire sont alors analysées. Finalement, une loi de commande référencée dans l’espace pour le guidage vertical d’un avion de transport est développée et est comparée avec l’approche temporelle classique. L’objectif est de réduire les erreurs de poursuite et mieux répondre aux contraintes de temps de passage en certains points de l’espace ainsi qu’à une possible contrainte de temps d’arrivée / Safety and environmental considerations in air transportation urge today for the development of new guidance systems with improved accuracy for spatial and temporal trajectory tracking.The main objectives of this thesis dissertation is to contribute to the synthesis of a new generation of nonlinear guidance control laws for transportation aircraft presenting enhanced trajectory tracking performances and to explore the feasibility and performances of a flight guidance system developed within a space-indexed reference with the aim of reducing tracking errors and ensuring the satisfaction of overfly time constraints as well as final arrival time constraint. Before presenting the main approaches for the design of control laws for autopilots and auto-guidance systems devoted to transport aircraft and the way current Flight Management Systems generates guidance directives, flight dynamics of transportation aircraft, including explicitly the wind components, are presented. Then, the interest for adaptive flight control is discussed and a self contained adaptive flight path tracking control for various flight conditions taking into account automatically the possible aerodynamic and thrust parametric changes is proposed. Then, the main recognized nonlinear control approaches suitable for trajectory tracking are analyzed. Finally an original vertical space-indexed guidance control law devoted to aircraft trajectory tracking is developed and compared with the classical time-indexed approach

Les problématiques de recherche abordées dans cette thèse concernent la conceptualisation, la modélisation et la commande générique des robots mobiles lors de leur évolution en milieux extérieurs et en présence de glissement pour des applications de suivi de précision. Ainsi, ce mémoire synthétise dans un premier temps les développements et résultats obtenus lors du suivi de trajectoire (localisation absolue), puis synthétise ensuite ceux obtenus lors de suivi de structure et de cible (localisation relative). Une dernière partie introduit un concept de plateforme robotique reconfigurable et sa commande associée pour adapter l’assiette et les dimensions du châssis en fonction de la topographie du terrain.Pour chaque application de suivi, ce mémoire présente un panel de lois de commande originales pour des robots différentiels, à un train et à deux trains directeurs. Chaque modalité de commande est présentée en quatre étapes : modélisation, estimation, commande et expérimentations. La première contribution majeure de la thèse concerne l’estimation du glissement. Cette dernière est adaptative et basée modèle. Elle intègre la modélisation cinématique étendue seule ou couplée à la modélisation dynamique du robot mobile pour assurer une estimation intègre quels que soient la vitesse, les phénomènes dynamiques rencontrés et la nature du sol. La seconde contribution majeure concerne le développement d’une stratégie de commande générique pour les robots mobiles. Cette stratégie est basée sur le principe de la commande en cascade (ou par backstepping) et est déclinée dans ce mémoire à travers un panel de lois de commande. Cette méthodologie de commande, lorsqu’elle est associée à l’observation du glissement précédent, permet d’obtenir des performances de suivi accrues quel que soit le contexte rencontré. L’ensemble des algorithmes ont été validés en simulation et/ou expérimentalement à l’aide de différentes plateformes robotiques en contextes réels. / This work is focused on the conceptualization, the modeling and the genericcontrol of mobile robots when moving in off-road contexts and facing slipperyterrains, especially for very accurate tracking and following applications. Thisthesis summarizes the proposed methods and the obtained results to addressthis research issue, first for path following applications (absolute localization)and then for edge and target tracking applications (relative localization). A finalsection of this thesis introduces an adaptive robotic concept and its associatedcontroller allowing the adaptation of the pose (position and orientation) of thechassis with respect to the environment topography.For each application, this thesis introduces a panel of innovative control algorithmsfor controlling skid-steering, two-wheel steering and four-wheel steeringmobile robots. Each algorithm of the panel is described, in this thesis, infour steps : modeling, estimation, control and experiments.The first main contribution of this thesis deals with the slippage estimation.The latter is adaptive and model-based. It also includes the extended kinematicmodeling only or together with the dynamic modeling of the mobile robot toensure a robust estimation of the slippage whatever the speed of the robot, encountereddynamic phenomena or even ground characteristics.The second main contribution deals with the design of a generic control approachfor mobile robots when path following and target tracking. The proposedstrategy is mostly based on a backstepping method and is illustrated inthis thesis via a panel of control laws. When combining this proposed controlapproach with the slippage estimation described above, significant improvedtracking and following performances are obtained (in term of stability, repeatability,accuracy and robustness) whatever the encountered context.All algorithms have been tested and validated through simulations and/orfull-scale experiments, indoor and off-road, with different mobile robots.

Les systèmes électroniques commutés sont de plus en plus utilisés dans plusieurs domaines domestiques ou industriels: les écrans à cristaux liquides, les appareils électroménagers, l'éclairage, les ordinateurs personnels, les centrales électriques, les véhicules de transport et ainsi de suite. L'efficacité des opérations de toutes les applications dépend du travail essentiel réalisé par des systèmes électroniques à commutation, dont le comportement est déterminé par une interconnexion et un contrôle appropriés des dispositifs analogiques et numériques. Comme motivation de ce travail, nous considérons les convertisseurs DC-DC de puissance. Cette thèse contribue à fournir des solutions aux problèmes de contrôle hybrides et non linéaires des plusieurs types de convertisseurs de puissance. Dans la première partie nous intéressons au problème de la régulation de la tension des convertisseurs de puissance fonctionnant dans le mode de conduction discontinue. Deux convertisseurs de puissance sont considérés: le convertisseur boost et le convertisseur buck-boost. L'objectif de commande est la génération d'une orbite périodique. Notre principale contribution est un algorithme simple et robuste qui donne des formules explicites pour les temps de commutation sans approximations. Les résultats de simulation et expérimentaux sont présentés. Dans la deuxième partie une classe de convertisseurs de puissance qui peut être globalement stabilisé avec un contrôleur PI a été identifiée. Par ailleurs, nous allons prouver que l'observateur I&I peut être combiné avec le contrôleur PI tout en préservant les propriétés de stabilité asymptotique globale de la boucle fermé. La classe se caractérise par une inégalité matricielle linéaire simple. Le nouveau contrôleur est illustré avec le convertisseur très - populaire, et difficile à contrôler, le SEPIC, pour lequel les résultats de simulation et expérimentaux sont présentés. / Switched electronic systems are used in a huge number of everyday domestic and industrial utilities: liquid crystal displays, home appliances, lighting, personal computers, power plants, transportation vehicles and so on. Efficient operations of all such applications depend on the essential “hidden work" done by switched electronic systems, whose behavior is determined by a suitable interconnection and control of analog and digital devices. As a motivation of this work, we consider the DC-DC power converters. This thesis contributes to provide hybrid and nonlinear control problem solutions to several types of power converters. In the first part we are interested in the problem of voltage regulation of power converters operating in discontinuous conducting mode. Two power converters are considered: the boost converter and the buck-boost converter. The system does not admit a (continuous--time) average model approximation, hence is a hybrid system where the control objective is the generation of a periodic orbit and the actuator commands are switching times. Our main contribution is a simple robust algorithm that gives explicit formulas for the switching times without approximations. Simulation and experimental results that illustrate the robustness of the scheme to parameter uncertainty, as well as performance comparisons with current practice, are presented. In the second part a class of power converters that can be globally stabilized with an output-feedback PI controller has been identified. Moreover, we will prove that the I&I observer can be combined with the PI controller preserving the GAS properties of the closed-loop. The class is characterized by a simple linear matrix inequality. The new controller is illustrated with the widely-popular, and difficult to control, single-ended primary inductor converter, for which simulation and experimental results are presented.