In the automotive industry, a Control Engineer must design a unique control law that is then tested and validated on a single prototype with a level of reliability high enough to to meet a number of complex specifications on various systems. In order to do this, the Engineer uses an experimental iterative process (Trial and Error phase) which relies heavily on his or her experience. This book looks to optimise the methods for synthesising servo controllers ny making them more direct and thus quicker to design. This is achieved by calculating a final controller to directly tackle the high-end system specs.
The loop-shaping approach consists of obtaining a specification in relation to the open loop of the control from specifications regarding various closed loop transfers, because it is easier to work on a single transfer (in addition to the open loop) than on a multitude of transfers (various loopings such as set point/error, disturbance/error, disturbance/control, etc.). The simplicity and flexibility of the approach make it very well adapted to the industrial context. This book presents the loop-shaping approach in its entirety, starting with the declension of high-level specifications into a loop-shaping specification. It then shows how it is possible to fully integrate this approach for the calculation of robust and efficient correctors with the help of existing techniques, which have already been industrially tried and tested, such as H-infinity synthesis. The concept of a gap metric (or distance between models) is also presented along with its connection with the prime factors of a set of systems shaping a ball of models, as well as its connections with robust synthesis by loop-shaping, in order to calculate efficient and robust correctors. As H-infinity loop-shaping is often demanding in terms of the order of correctors, the author also looks at loop-shaping synthesis under an ordering constraint. Two further promising lines of research are presented, one using stochastic optimization, and the other non-smooth optimization. Finally, the book introduces the concept of correction with two degrees of freedom via the formalism of prime factorization. Avenues for future work are also opened up by the author as he discusses the main drawbacks to loop-shaping synthesis, and how these issues can be solved using modern optimization techniques in an increasingly competitive industrial context, in accordance with ever more complex sets of functional specifications, associated with increasingly broad conditions of usage. Contents Introduction 1. The Loop-shaping Approach 2. Loop-shaping H-infinity Synthesis 3. Two Degrees-of-Freedom Controllers 4. Extensions and Optimizations Appendix 1. Demonstrative Elements on the Optimization of Robust Stabilization with Order Constraint Appendix 2. Establishment of Real LMIs for the Quasi-Convex Problem of Optimization of the Weighting Functions About the Authors Philippe Feyel is an R&D Engineer for the high-tech company Sagem Défense Sécurité, part of the defence and security business of the SAFRAN group, in Paris, France.
In the automotive industry, a Control Engineer must design a unique control law that is then tested and validated on a single prototype with a level of reliability high enough to to meet a number of complex specifications on various systems. In order to do this, the Engineer uses an experimental iterative process (Trial and Error phase) which relies heavily on his or her experience. This book looks to optimise the methods for synthesising servo controllers ny making them more direct and thus quicker to design. This is achieved by calculating a final controller to directly tackle the high-end system specs.
L’approche loop-shaping consiste en l’obtention d’une spécification relative à la boucle ouverte de l’asservissement à partir de spécifications relatives à divers transferts en boucle fermée. Parce qu’il est plus simple de travailler sur un unique transfert (la boucle ouverte) plutôt que sur une multitude de transferts bouclés, cette approche s’avère particulièrement adaptée au contexte industriel. Cet ouvrage se concentre sur la déclinaison des spécifications de haut niveau vers une spécification de type loop-shaping, puis sur les techniques permettant d’intégrer pleinement cette démarche pour le calcul de correcteurs robustes et performants, en particulier par la synthèse H?. Modelage de la boucle ouverte escomptée, la synthèse H? par loop-shaping permet par ailleurs de stabiliser toute une boule de modèles grâce à la notion de gap métrique, ce qui s’avère particulièrement intéressant pour la prise en compte de contraintes industrielles. La volonté accrue de réaliser des asservissements à moindre coût et de plus en plus performants mène à l’optimisation de cette technique, la rendant indispensable à son domaine.
Few individuals made such an impact on nineteenth-century French politics as Louis-Auguste Blanqui (1805-1881). Political organiser, leader, propagandist and prisoner, Blanqui was arguably the foremost proponent of popular power to emerge after the French Revolution. Practical engagement in all the major uprisings that spanned the course of his life – 1830, 1848, 1870-71 – was accompanied by theoretical reflections on a broad range of issues, from free will and fatalism to public education and individual development. Since his death, however, Blanqui has not been simply overlooked or neglected; his name has widely become synonymous with theoretical misconception and practical misadventure. Auguste Blanqui and the Politics of Popular Empowerment offers a major re-evaluation of one the most controversial figures in the history of revolutionary politics. The book draws extensively on Blanqui's manuscripts and published works, as well as writings only recently translated into English for the first time. Through a detailed reconstruction and critical analysis of Blanqui's political thought, it challenges the prevailing image of an unthinking insurrectionist and rediscovers a forceful and compelling theory of collective political action and radical social change. It suggests that some of Blanqui's fundamental assumptions – from the insistence on the primacy of subjective determination to the rejection of historical necessity – are still relevant to politics today.
The application of Bayesian Networks (BN) or Dynamic Bayesian Networks (DBN) in dependability and risk analysis is a recent development. A large number of scientific publications show the interest in the applications of BN in this field. Unfortunately, this modeling formalism is not fully accepted in the industry. The questions facing today's engineers are focused on the validity of BN models and the resulting estimates. Indeed, a BN model is not based on a specific semantic in dependability but offers a general formalism for modeling problems under uncertainty. This book explains the principles of knowledge structuration to ensure a valid BN and DBN model and illustrate the flexibility and efficiency of these representations in dependability, risk analysis and control of multi-state systems and dynamic systems. Across five chapters, the authors present several modeling methods and industrial applications are referenced for illustration in real industrial contexts.
The first part of the book defines the concept of uncertainties and the mathematical frameworks that will be used for uncertainty modeling. The application to system reliability assessment illustrates the concept. In the second part, evidential networks as a new tool to model uncertainty in reliability and risk analysis is proposed and described. Then it is applied on SIS performance assessment and in risk analysis of a heat sink. In the third part, Bayesian and evidential networks are used to deal with important measures evaluation in the context of uncertainties.
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