In this Master thesis a new framework for achieving fault tolerance in mechatronic systems is studied. The framework is called service-based fault tolerant control and has the advantage of being completely decentralized and modular and therefore scales very well to large system sizes. First, a method is presented for designing the signal-flow architecture of mechatronic systems of real-life size and complexity. The result is a small set of generic building blocks in the form of design patterns, a concept that has gained widespread popularity in the field of software architecture. Best practises are then established for how each of the design patterns can be extended to support fault tolerance through diagnosis and reconfiguration according to the service-based framework. These extended design patterns can be used either to aid in the construction of new and more complex mechatronic systems or as a methodology for applying service-based fault tolerant control on large existing systems. The presented methods for designing and modelling large-scale mechatronic systems have the advantages of being applicable to a large class of mechatronic systems, being easy to apply without expert knowledge, as well as having the potential for being automated in the future. Finally, a case-study demonstrates how the new methods can be used to construct a fault tolerance architecture for a real-life automotive system currently used by Scania CV AB. As a part of this study a mathematical model for the system was also constructed and implemented. The model can be used for analysis during the development phase as well as troubleshooting in a repair workshop.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The requirement of increasing the availability of plants is present in the current industrial park. The availability represents the satisfactory operation of a plant even during process failures. A system with these characteristics is defened as a system fault-tolerant. For the implementation of a fault-tolerant system is important to use automatic monitoring techniques capable of providing accurate information on the state of the process and form the basis for the recovery of the diagnosed condition. This structure functions as the main source of information for supervisory systems responsible for corrective actions to accommodate efects caused by failures. In this work, techniques for fault detection and diagnosis based on data from the plant operation and mathematical models of processes are used to monitor the state of industrial processes. The tolerant control techniques proposed in this work is based on the union of dierent strategies for process monitoring, a process and control reconfiguration and control goals adaptation to obtain new control structures. Thus, the proposed system will add features for fault tolerance by coupling fault detection and diagnosis with the structural reconfiguration of the control system. In this context, this work presents a novel fault-tolerant control scheme illustrating their successful application through case studies on PID control, optimal control and predictive control structures. / A exigência do aumento da disponibilidade de plantas industriais é cada vez mais presente no parque industrial atual. A disponibilidade representa a manutenção satisfatória da operação da planta mesmo após o aparecimento de falhas. Um sistema com essas características é definido como um sistema tolerante a falhas. Para a concretização de um sistema tolerante a falhas é importante a implementação de técnicas de monitoramento automático capazes de fornecer informações precisas sobre o estado do processo e formar a base necessária para a recuperação da condição diagnosticada. Essa estrutura de monitoramento funciona como a fonte principal de informações para sistemas de supervisão responsáveis por ações corretivas que acomodem efeitos causados por falhas. Neste trabalho, técnicas de detecção e diagnóstico de falhas baseadas em dados de operação da planta e em modelos matemáticos dos processos s~ao utilizadas para o monitoramento do estado de processos industriais. As técnicas de controle tolerante propostas neste trabalho baseiam-se na união de diferentes estratégias de monitoramento, na reconfiguração do processo ou controladores envolvidos e adaptação dos objetivos de controle para a obtenção de novas estruturas de controle. Assim, o sistema proposto adiciona características de tolerância a falhas através do acoplamento da detecção e diagnóstico de falhas a um sistema de reconfiguração estrutural do sistema de controle. Nesse contexto, este trabalho apresenta propostas de controle tolerante a falhas ilustrando com sucesso a sua aplicação através do estudo de casos em estruturas de controle PID, controle ótimo e controle preditivo. / Mestre em Engenharia Química

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-25T17:55:23Z No. of bitstreams: 1 murilloferreiradossantos.pdf: 10926905 bytes, checksum: fd28a8c6e03bce5e40e5620a6bbf1666 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-26T12:22:42Z (GMT) No. of bitstreams: 1 murilloferreiradossantos.pdf: 10926905 bytes, checksum: fd28a8c6e03bce5e40e5620a6bbf1666 (MD5) / Made available in DSpace on 2017-04-26T12:22:42Z (GMT). No. of bitstreams: 1 murilloferreiradossantos.pdf: 10926905 bytes, checksum: fd28a8c6e03bce5e40e5620a6bbf1666 (MD5) Previous issue date: 2014-07-30 / Este trabalho tem o objetivo de desenvolver o controle tolerante a falhas de um sistema de propulsão de hexacópteros, visando mante-lo em condições de voo. Inicialmente, apresenta-se a modelagem do sistema, abordando o modelo cinemático e dinâmico da aeronave para a simulação e controle do sistema onde as forças gravitacionais e de propulsão são consideradas. Falhas nos sistemas de propulsão são inseridas para que quando detectadas, o sistema seja operado com outra sintonia de controladores PID, mantendo-o em condições de voo. Por fim, os resultados são simulados e analisados onde através dos índices de desempenho IAE, ISE e ITSE seja possível realizar um estudo de viabilidade do tempo limite que uma técnica de detecção e identificação de falhas terá disponível para localizar qual sistema de propulsão se encontra com problemas. Os resultados foram satisfatórios mostrando ser uma técnica possível de se implementada na aeronave desenvolvida. / This dissertation aims to develop the fault tolerant control of a propulsion system of hexacopters, which intends to keep it in good flight conditions. Initially, it’s presented the modeling of the system, considering the kinematic and dynamic model of the aircraft where the gravitational and propulsion forces are considered. Failures in propulsion systems are inserted to the system and when detected, the system can be operated with the new PID tuning, keeping it in flight. Finally, the results are simulated and analyzed using performance indices as IAE, ISE and ITSE, making possible to perform the feasibility study of the time limit that a technique for detecting and identifying faults have available to find which propulsion system meets problems. The results were satisfactory showing to be a possible technique to be implemented in the aircraft developed.

Cette thèse s'intéresse à l'adaptation des lois de pilotage d'un avion de transport civil aux différentes incertitudes qui peuvent affecter sa dynamique. Le procédé de pilotage adaptatif est censé fonctionner en temps réel à bord de l'avion afin d'optimiser la performance boucle fermée en fonction des conditions dans lesquelles il évolue. Les incertitudes peuvent être liées à la méconnaissance des conditions de vol (par exemple la vitesse et l'altitude), à des non-linéarités aérodynamiques inconnues ou encore à la méconnaissance du pilote aux commandes. Les procédés adaptatifs qui répondent à ces problèmes se doivent d'être performants sur l'ensemble du domaine opérationnel de l'avion en présence de perturbations réalistes. D'autres contraintes spécifiques peuvent être ajoutées en fonction du contexte (par exemple des charges limites, la stabilité aéroélastique, etc.). Plusieurs méthodes adaptatives sont testées afin d'adapter le système aux larges incertitudes qui le composent. Elles associent en général un estimateur en ligne (aussi appelé loi de mise-à-jour) à une loi de commande structurée. La synthèse de ces deux éléments peut être réalisée simultanément pour les méthodes adaptatives dites " directes ", comme par exemple le Model Reference Adaptative Control qui utilise la stabilité au sens de Lyapounov. Mais cette synthèse peut aussi être découplée pour les méthodes adaptatives dites "indirectes", ce qui offre un large choix de techniques pour chaque élément (comme les Moindres Carrés pour l'estimation de paramètres physiques incertains et la synthèse sous forme LFR pour le correcteur). Le choix de la méthode dépend fortement du contexte applicatif et des nombreuses contraintes associées. Trois applications sont au cœur de ce mémoire. Elles traitent de l'ajustement de lois de guidage à un modèle pilote inconnu, du contrôle longitudinal de non-linéarités de l'avion, et de la mise au point de lois longitudinale et latérale de pilotage manuel qui s'adaptent à des conditions de vol inconnues. Des méthodes avancées d'analyse linéaire et non-linéaire (dérivées de la µ-analyse et d'algorithmes d'optimisation) sont aussi mises en place pour valider ces systèmes sophistiqués adaptatifs en temps réel. D'une façon générale, les méthodes adaptatives indirectes ont donné le plus de satisfaction. Leur performance est aussi bonne que celle des méthodes directes, mais le fait qu'elles estiment en ligne des paramètres physiques facilite la surveillance temps réel du procédé adaptatif et sa validation. / This thesis deals with adapting flight control laws of a civil transport aircraft to various incertainties which can affect its behaviour. The adaptive flight control system is supposed to run in real time onboard the airplane so that its closed-loop performance is optimized with respect to the current conditions. These incertainties may be linked to unknown flight conditions (e.g. unknown airspeed and altitude), or unknown aerodynamics non-linearities or even unknown behaviour of the pilot in command. The adaptive schemes that are derived to answer these problems must be valid on the whole flight envelope with realistic disturbances but other additional contraints may exist depending on the context (e.g. loads limits, aeroelastic stability, etc.). To accommodate for large uncertainties on the system, adaptive methods are investigated. They usually combine an online estimator (also called an update law) with a structured flight control law. The synthesis of both elements may be simultaneous on 'direct' adaptive methods, e.g. on Model Reference Adaptive Control, using Lyapunov's stability theory. But it can also be decoupled on 'indirect' adaptive methods, giving a full spectrum of techniques for both elements (such as Least-Squares for estimating unknown physical parameters and the LFR framework for designing controllers). The choice of a specific method really depends on the application context and the related constraints.Three applications are the core of this report. They deal with adjusting guidance law to the pilot's unknown behaviour, controlling a longitudinal non-linearity, and providing manual longitudinal and lateral flight control laws which adapt to unknown flight conditions. Advanced linear and non-linear analysis techniques (based on µ-analysis or on optimization algorithms) are also applied to validated these sophisticated real-time adaptive systems. Results showed that indirect adaptive schemes were generally the most satisfactory. Their performance is similar to the one of direct schemes but as indirect methods provide physical parameter estimates, real-time monitoring and offline validation seem quite easier.

Markov jump linear systems find application in many areas including economics, fault-tolerant control, and networked control. Despite significant attention paid to Markov jump linear systems in the literature, few authors have investigated Markov jump linear systems with time-inhomogeneous Markov chains (Markov chains with time-varying transition probabilities), and even fewer authors have considered time-inhomogeneous Markov chains with a priori unknown transition probabilities. This dissertation provides a formal stability and disturbance attenuation analysis for a Markov jump linear system where the underlying Markov chain is characterized by an a priori unknown sequence of transition probability matrices that assumes one of finitely-many values at each time instant. Necessary and sufficient conditions for uniform stochastic stability and uniform stochastic disturbance attenuation are reported. In both cases, conditions are expressed as a set of finite-dimensional linear matrix inequalities (LMIs) that can be solved efficiently. These finite-dimensional LMI analysis results lead to nonconservative LMI formulations for optimal controller synthesis with respect to disturbance attenuation. As a special case, the analysis also applies to a Markov jump linear system with known transition probabilities that vary in a finite set. / Ph. D.

Les travaux de recherche présentés dans ce mémoire portent sur la synthèse d'observateurs intervalles pour la commande tolérante aux fautes de systèmes incertains. La présence de défauts, d'incertitudes et de perturbations peut provoquer des réactions indésirables du système commandé. Dans ce contexte, nous avons développé deux approches de commande tolérante aux fautes basées sur des observateurs intervalles dans le cas où les défauts et les incertitudes sont inconnus mais bornés. La première approche, dite passive, permet de garantir la stabilité du système en boucle fermée y compris en présence de défauts actionneurs et/ou composants. La seconde approche, dite active, permet de compenser l'effet des défauts et d'assurer la stabilité et les performances désirées du système. Ces contributions sont validées par des simulations numériques. / The research work presented in this thesis focuses on the design of interval observers for fault-tolerant control of uncertain systems. The presence of faults, uncertainties and disturbances in automated systems often causes undesirable reactions. In this context, two approaches of fault tolerant control have been developed based on interval observers in the case where the faults and the uncertainties are unknown but bounded. The first approach is passive and consists in ensuring the closed loop system stability even in the presence of actuator and/or component faults. The second approach, an active one, compensates the fault effect and ensures the system stability and desired performances. These contributions are validated through numerical simulations.

La surveillance et l'amélioration des modes de fonctionnement des systèmes propulsifs des lanceurs représentent des défis majeurs de l'industrie aérospatiale. En effet, une défaillance ou un dysfonctionnement du système propulsif peut avoir un impact significatif pour les clients institutionnels ou privés et entraîner des catastrophes environnementales ou humaines. Des systèmes de gestion de la santé (HMS) pour les moteurs fusée à ergols liquides (LPREs), ont été mis au point pour tenir compte des défis actuels en abordant les questions de sureté et de fiabilité. Leur objectif initial est de détecter les pannes ou dysfonctionnements, de les localiser et de prendre une décision à l’aide de Redlines et de systèmes experts. Cependant, ces méthodes peuvent induire de fausses alarmes ou des non-détections de pannes pouvant être critiques pour la sécurité et la fiabilité des opérations. Ainsi, les travaux actuels visent à éliminer certaines pannes critiques, mais aussi diminuer les arrêts intempestifs. Les données disponibles étant limitées, des méthodes à base de modèles sont essentiellement utilisées. La première tâche consiste à détecter les défaillances de composants et/ou d'instruments à l'aide de méthodes de détection et de localisation de fautes (FDI). Si la faute est considérée comme mineure, des actions de « non-arrêt » sont définies pour maintenir les performances de l'ensemble du système à un niveau proche de celles souhaitées et préserver les conditions de stabilité. Il est donc nécessaire d’effectuer une reconfiguration robuste (incertitudes, perturbations inconnues) du moteur. Les saturations en entrée doivent également être prises en compte dans la conception de la loi de commande, les signaux de commande étant limités en raison des caractéristiques ou performances des actionneurs physiques. Les trois objectifs de cette thèse sont donc : la modélisation des différents sous-systèmes principaux d’un LPRE, le développement d’algorithmes de FDI sur la base des modèles établis et la définition d’un système de reconfiguration du moteur en temps réel pour compenser certains types de pannes. Le système de FDI et Reconfiguration (FDIR) développé sur la base de ces trois objectifs a ensuite été validé à l’aide de simulations avec CARINS (CNES) et du banc d’essai MASCOTTE (CNES/ONERA). / Monitoring and improving the operating modes of launcher propulsion systems are major challenges in the aerospace industry. A failure or malfunction of the propulsion system can have a significant impact for institutional or private customers and results in environmental or human catastrophes. Health Management Systems (HMS) for liquid propellant rocket engines (LPREs), have been developed to take into account the current challenges by addressing safety and reliability issues. Their objective was initially to detect failures or malfunctions, isolate them and take a decision using Redlines and Expert Systems. However, those methods can induce false alarms or undetected failures that can be critical for the operation safety and reliability. Hence, current works aim at eliminating some catastrophic failures but also to mitigate benign shutdowns to non-shutdown actions. Since databases are not always sufficient to use efficiently data-based analysis methods, model-based methods are essentially used. The first task is to detect component and / or instrument failures with Fault Detection and Isolation (FDI) approaches. If the failure is minor, non-shutdown actions must be defined to maintain the overall system current performances close to the desirable ones and preserve stability conditions. For this reason, it is required to perform a robust (uncertainties, unknown disturbances) reconfiguration of the engine. Input saturation should also be considered in the control law design since unlimited control signals are not available due to physical actuators characteristics or performances. The three objectives of this thesis are therefore: the modeling of the different main subsystems of a LPRE, the development of FDI algorithms from the previously developed models and the definition of a real-time engine reconfiguration system to compensate for certain types of failures. The developed FDI and Reconfiguration (FDIR) scheme based on those three objectives has then been validated with the help of simulations with CARINS (CNES) and the MASCOTTE test bench (CNES/ONERA).

Cette thèse propose une nouvelle approche de détection de défauts pour des systèmes linéaires soumis à des incertitudes par intervalles, des perturbations et des bruits de mesures bornés. Dans ce contexte, la détection de défauts est fondée sur une estimation ensembliste de l'état du système. Les contributions de cette thèse concernent trois directions principales :- La première partie propose une méthode d'estimation d'état ensembliste améliorée combinant l'estimation à base des zonotopes (qui offre une bonne précision) et l'estimation à base d'ellipsoïdes (qui offre une complexité réduite).- Dans la deuxième partie, une nouvelle approche d'estimation d'état ellipsoïdale fondée sur la minimisation du rayon de l'ellipsoïde est développée. Dans ce cadre, des systèmes multivariables linéaires invariants dans le temps, ainsi que des systèmes linéaires variants dans le temps ont été considérés. Ces approches, résolues à l'aide de problèmes d'optimisation sous la forme d'Inégalités Matricielles Linéaires, ont été étendues au cas des systèmes soumis à des incertitudes par intervalles.- Dans la continuité des approches précédentes, deux techniques de détection de défauts ont été proposées dans la troisième partie utilisant les méthodes d'estimation ensemblistes. La première technique permet de détecter des défauts capteur en testant la cohérence entre le modèle et les mesures. La deuxième technique fondée sur les modèles multiples permet de traiter simultanément les défauts actionneur/composant/capteur. Une commande prédictive Min-Max a été développée afin de déterminer la commande optimale et le meilleur modèle à utiliser pour le système, malgré la présence des différents défauts. / This thesis proposes a new Fault Detection approach for linear systems with interval uncertainties, bounded perturbations and bounded measurement noises. In this context, the Fault Detection is based on a set-membership state estimation of the system. The main contributions of this thesis are divided into three parts:- The first part proposes an improved method which combines the good accuracy of the zonotopic set-membership state estimation and the reduced complexity of the ellipsoidal set-membership estimation.- In the second part, a new ellipsoidal state estimation approach based on the minimization of the ellipsoidal radius is developed, leading to Linear Matrix Inequality optimization problems. In this context, both multivariable linear time-invariant systems and linear time-variant systems are considered. An extension of these approaches to systems with interval uncertainties is also proposed. - In the continuity of the previous approaches, two Fault Detection techniques have been proposed in the third part based on these set-membership estimation techniques. The first technique allows to detect sensor faults by checking the consistency between the model and the measurements. The second technique is based on Multiple Models. It deals with actuator/component/sensor faults in the same time. A Min-Max Model Predictive Control is developed in order to find the optimal control and the best model to use for the system in spite of the presence of these faults.

No description available.

<p>This thesis considers the problems of modelling and control of batch processes, a class of finite duration chemical processes characterized by their absence of equilibrium conditions and nonlinear, time-varying dynamics over a wide range of operating conditions. In contrast to continuous processes, the control objective in batch processes is to achieve a non-equilibrium desired end-point or product quality by the batch termination time. However, the distinguishing features of batch processes complicate their control problem and call for dedicated modelling and control tools. In the initial phase of this research, a predictive controller based on the novel concept of reverse-time reachability regions (RTRRs) is developed. Defined as the set of states from where the process can be steered inside a desired end-point neighbourhood by batch termination subject to input constraints and model uncertainties, an algorithm is developed to characterize these sets at each sampling instance offline; these characterizations subsequently play an integral role in the control design. A key feature of the resultant controller is that it requires the online computation of only the immediate control action while guaranteeing reachability to the desired end-point neighbourhood, rendering the control problem efficiently solvable even when using the nonlinear process model. Moreover, the use of RTRRs and one-step ahead type control policy embeds important fault-tolerant characteristics into the controller. Next, we address the problem of the unavailability of reliable and computationally manageable first-principles-based process models by developing a new data-based modelling approach. In this approach, local linear models (identified via latent variable regression techniques) are combined with weights (arising from fuzzy c-means clustering) to describe global nonlinear process dynamics. Nonlinearities are captured through the appropriate combination of the different models while the linearity of the individual models prevents against a computationally expensive predictive controller. This modelling approach is also generalized to account for time-varying dynamics by incorporating online learning ability into the model, making it adaptive. This is accomplished by developing a probabilistic recursive least squares (PRLS) algorithm for updating a subset of the model parameters. The data-based modelling approach is first used to generate data-based reverse-time reachability regions (RTRRs), which are subsequently incorporated in a new predictive controller. Next, the modelling approach is applied on a complex nylon-6,6 batch polymerization process in order to design a trajectory tracking predictive controller for the key process outputs. Through simulations, the modelling approach is shown to capture the major process nonlinearities and closed-loop results demonstrate the advantages of the proposed controller over existing options. Through further simulation studies, model adaptation (via the PRLS algorithm) is shown to be crucial for achieving acceptable control performance when encountering large disturbances in the initial conditions. Finally, we consider the problem of direct quality control even when there are limited quality-related measurements available from the process; this situation typically calls for indirectly pursuing the control objective through trajectory tracking control. To address the problem of unavailability of online quality measurements, an inferential quality model, which relates the process conditions over the entire batch duration to the final quality, is required. The accuracy of this type of quality model, however, is sensitive to the prediction of the future batch behaviour until batch termination. This "missing data" problem is handled by integrating the previously developed data-based modelling approach with the inferential model in a predictive control framework. The key feature of this approach is that the causality and nonlinear relationships between the future inputs and outputs are accounted for in predicting the final quality and computing the manipulated input trajectory. The efficacy of the proposed predictive control design is illustrated via simulations of the nylon-6,6 batch polymerization process with a different control objective than considered previously.</p> / Doctor of Philosophy (PhD)