Set-Membership Estimation Improvement Applying HOSM Differentiators

International audienceThis work is devoted to design of interval observers for a class of Linear-Parameter-Varying (LPV) systems. Applying High Order Sliding Mode (HOSM) techniques it is possible to decrease the initial level of uncertainty in the system, which leads to improvement of set-membership estimates generated by an interval observer. In addition, it is shown that HOSM techniques may relax the applicability conditions of the interval observer design methods. The efficiency of the proposed approach is demonstrated through computer simulations

Contribution au développement des techniques ensemblistes pour l'estimation de l'état et des entrées des systèmes à temps continu (application à la détection de défauts)

Cette thèse traite du problème d'observation et d'estimation des variables caractéristiques des systèmes dynamiques. Il s agit d une problématique fondamentale qui est au cœur de nombreux domaines relavant des sciences de l'ingénieur. Les travaux sont conduits dans un contexte ensembliste. Les techniques développées pour l estimation de l état et des variables d entrées ont pour objectif final le contrôle de cohérence des systèmes non linéaires à temps continu. Une première approche conjugue les relations de parité et les différentiateurs à modes glissants pour l estimation des entrées d un système non linéaire. Les domaines des entrées compatibles avec les mesures sont alors reconstruits grâce à l analyse par intervalles et aux techniques de satisfaction de contraintes. Il est montré que la relaxation des contraintes de stabilité/coopérativité pour la construction d un observateur intervalle peut se faire grâce à des changements de base déterminés de différentes manières et pouvant être variants ou invariants dans le temps. Des simulations numériques illustrent les techniques proposées. Une application à un système aéronautique est également présentée à l aide d un jeu de données réelles.This thesis deals with the problem of a dynamical system observation and the estimation of its characteristic variables; the latter point constitutes the core element in many engineering science fields. The final aim is to build a general framework for integrity control and fault detection of such systems within a bounded error context. The developments offered herein make use of parity relations, sliding mode differentiators, interval observers and constraint satisfaction problems. Input reconstruction techniques are developed for a general class of nonlinear continuous-time systems. Domains are reconstructed for the input values which are consistent with the measurements using interval analysis and constraint satisfaction techniques. It is shown that time-varying or invariant coordinate changes may relax the applicability conditions (stability/cooperativity) of the interval observer design methods. Sliding mode differentiators were also used to enhance interval observer accuracy. The proposed approaches are illustrated through computer simulations and they have been applied to aircraft servo loop control surface for robust and early detection of abnormal positions.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Set-Membership Estimation Improvement Applying HOSM Differentiators

International audienceThis work is devoted to design of interval observers for a class of Linear-Parameter-Varying (LPV) systems. Applying High Order Sliding Mode (HOSM) techniques it is possible to decrease the initial level of uncertainty in the system, which leads to improvement of set-membership estimates generated by an interval observer. In addition, it is shown that HOSM techniques may relax the applicability conditions of the interval observer design methods. The efficiency of the proposed approach is demonstrated through computer simulations

Control Theory in Engineering

The subject matter of this book ranges from new control design methods to control theory applications in electrical and mechanical engineering and computers. The book covers certain aspects of control theory, including new methodologies, techniques, and applications. It promotes control theory in practical applications of these engineering domains and shows the way to disseminate researchers’ contributions in the field. This project presents applications that improve the properties and performance of control systems in analysis and design using a higher technical level of scientific attainment. The authors have included worked examples and case studies resulting from their research in the field. Readers will benefit from new solutions and answers to questions related to the emerging realm of control theory in engineering applications and its implementation

Indigenous Firm Performance in a Small Late Developing State : A Case-study of the Role and Contribution of Public Venture Capital in Ireland.

Domestic market size constraints in small late developing states are expected to influence the economic growth process in general and indigenous firm performance in particular. The role and contribution of policy-makers in overcoming these constraints can therefore be significant. This thesis evaluates the role and contribution of public venture capital - as a significant industrial policy initiative - to shareholder value creation in growth-oriented indigenous firms in Ireland. Three main themes are investigated. Firstly the rationale and context for micro-level industrial policy interventions in Ireland is considered. Secondly, the role and contribution of public venture capital to indigenous firm performance and thirdly the factors differentiating between performing and non-performing firms are explored. Using mixed methods research this study finds that in a small late developing state such as Ireland, 'job creation' has been elevated from an industrial policy perspective to the de facto national objective. Enterprise policy development for indigenous industry however remains largely emergent and fluid, fifty-four years on from the advent of the national export-oriented industrial policy. In the absence of a deliberately-stated enterprise policy, this emergent micro-level approach has led the states' economic development agency into areas outside its originally intended remit. This goes some way to explaining the plethora of micro-level policy instruments available in Ireland to growth-oriented indigenous firms. Further, this study also finds no conclusive evidence that an 'equity gap' existed in the analysis period. However, as a consequence of attempting to close this perceived gap, the Irish state now finds itself with an investment portfolio of over nine hundred direct share investments in indigenous firms. The Irish State, through its economic development agency, has thus become the largest venture capital company in Europe. The portfolio of state-selected firms in the analysis (n = 51) for public venture capital investment are found not to perform as anticipated by the theory of change mapped out in the study. A quantitative model developed for the study also finds that there is no statistically significant association between firm performance as measured in the study and the value of the public venture capital invested in each firm. The crosscase and contribution analysis in the study further confirm that the contribution of public venture capital to indigenous firm performance in Ireland was marginal at best. The primary barrier to profitable growth for the indigenous firms receiving public venture capital support in the analysis period was the firms 'Limited endowments of managerial resources' (Penrose, 1959) to manage the growth process and not a lack of risk capital as perceived by agents of the State. Policy implications of the findings are also considered in the study