Unstationnary control of a launcher using observer-based structures

This paper deals with the design of a gain-scheduled controller for the attitude control of a launcher during atmospheric flight. The design is characterized by classical requirements such as phase/gain margins and flexible mode attenuations as well as time-domain constraints on the response of angle of attack to a worstcase wind profile. Moreover, these requirements must be fulfilled over the full atmospheric flight envelope and must be robust against parametric uncertainties. In order to achieve this goal, we propose a method based on minimal observer-based realizations of arbitrary stabilizing compensators. An original technique to assign the closed-loop dynamics between the state-feedback dynamics and the state-estimation dynamics is presented for the H∞ compensators case. The structure is used to mix various specifications through the Cross Standard Form(CSF) and to perform a smooth gain scheduling interpolation through an Euler-Newton algorithm of continuation

De l'utilisation de la structure estimation/commande pour le pilotage instationnaire d'un lanceur spatial

Dans cet article, nous nous intéressons au développement de techniques ayant trait à la mise sous forme LQG équivalente de correcteurs stabilisants. Dans un premier temps nous nous concentrerons plus particulièrement sur la transformation de correcteurs issus d'une synthèse Hinfinty. Nous proposons une méthode originale pour effectuer le choix des dynamiques d'estimation et de commande du correcteur équivalent en s'appuyant sur les résultats d'une synthèse H2. Puis nous proposerons une définition en temps discret de la Forme Standard de Passage (CSF) qui s'appuie également sur la paramétrisation de Youla sur la structure estimation /commande. Nous la présenterons en tant qu'outil méthodologique pour la mise en forme d'un problème multi-objectif. Nous mettrons en application la CSF sur le problème de pilotage d'un lanceur et nous montrerons l'intérêt de l'utilisation de la structure estimation/commande dans le cadre de l'inter-polation de correcteur pour le pilotage instationnaire

Launcher attitude control: some additional design and optimization tools

This paper deals with the launcher attitude control during atmospheric flight. A two step approach combining an H1 control design and an optimization procedure is proposed. The first step is multi-objective stationary H1 design based on the Cross Standard Form. It provides easily a first rough solution from a few physical tuning parameters. The second step is a fine tuning using an multi-constraint satisfaction algorithm. This algorithm enables the certification criteria computed on the validation model to be met and is also used to propagate the nominal tuning to the full flight envelope

A convergent entropy diminishing finite volume scheme for a cross-diffusion system

We study a two-point flux approximation finite volume scheme for a cross-diffusion system. The scheme is shown to preserve the key properties of the continuous systems, among which the decay of the entropy. The convergence of the scheme is established thanks to compactness properties based on the discrete entropy-entropy dissipation estimate. Numerical results illustrate the behavior of our scheme

Launcher attitude control: discrete-time robust design and gain-scheduling

In this paper, a robust multi-objective design for the control of a launcher during atmospheric flight is investigated. This approach is based on the Cross Standard Form formulation which allows to incorporate the various specifications of the launcher problem in a streamlined manner. An important feature of this approach is that a non-conventional LQG/LTR approach, required to satisfy time-domain specifications, can be embedded into a more general standard problem in order to account for frequency-domain robustness constraints. The specific form of this standard problem is also very interesting for gain scheduling

La demande d’éducation des jeunes québécois

Ce mémoire porte sur les déterminants qui sont à la base de la décision de poursuivre ses études chez un groupe de jeunes Québécois. Le modèle utilisé s’inspire de la théorie de l’investissement en capital humain. Parmi les facteurs retenus et analysés, on peut relever des caractéristiques personnelles de l’élève, son milieu familial, un ensemble de variables scolaires, l’expérience antérieure sur le marché du travail, ainsi que des caractéristiques plus générales de ce marché. L’ensemble des résultats met en relief l’importance du milieu familial mais il est également compatible avec des thèses qui montrent l’influence du manque à gagner.This paper reports empirical evidence on the determinants of the decision to stay in school for a group of young Quebecers. The model used is derived from the theory of investment in human capital. The independent variables refer to personal characteristics, family environment, school environment, early labour market experience and more general characteristics of this market. Empirical results show the influence of family variables but they are also fully consistent with theories that emphasize the importance of foregone earnings in the determination of the demand for education

La demande d’éducation des jeunes québécois

This paper reports empirical evidence on the determinants of the decision to stay in school for a group of young Quebecers. The model used is derived from the theory of investment in human capital. The independent variables refer to personal characteristics, family environment, school environment, early labour market experience and more general characteristics of this market. Empirical results show the influence of family variables but they are also fully consistent with theories that emphasize the importance of foregone earnings in the determination of the demand for education. Ce mémoire porte sur les déterminants qui sont à la base de la décision de poursuivre ses études chez un groupe de jeunes Québécois. Le modèle utilisé s’inspire de la théorie de l’investissement en capital humain. Parmi les facteurs retenus et analysés, on peut relever des caractéristiques personnelles de l’élève, son milieu familial, un ensemble de variables scolaires, l’expérience antérieure sur le marché du travail, ainsi que des caractéristiques plus générales de ce marché. L’ensemble des résultats met en relief l’importance du milieu familial mais il est également compatible avec des thèses qui montrent l’influence du manque à gagner.

A numerical analysis focused comparison of several finite volume schemes for an unipolar degenerated drift-diffusion model

In this paper, we consider an unipolar degenerated drift-diffusion system where the relation between the concentration of the charged species c and the chemical potential h is h(c) = log c/1-c. We design four different finite volume schemes based on four different formulations of the fluxes. We provide a stability analysis and existence results for the four schemes. The convergence proof with respect to the discretization parameters is established for two of them. Numerical experiments illustrate the behaviour of the different schemes

A numerical analysis focused comparison of several finite volume schemes for an unipolar degenerated drift-diffusion model

In this paper, we consider an unipolar degenerated drift-diffusion system where the relation between the concentration of the charged species c and the chemical potential h is h(c) = log c/1-c. We design four different finite volume schemes based on four different formulations of the fluxes. We provide a stability analysis and existence results for the four schemes. The convergence proof with respect to the discretization parameters is established for two of them. Numerical experiments illustrate the behaviour of the different schemes