Seminars and conferences organized by the team
- 6 February: Seminar by Masayuki Sato at 10h30, salle Europe.
- Title: "Required Technology To Realize Easy-Handling Aircraft; flight test of H_{infty} model-matching controllers and robust gain-scheduled controller design for LPV systems".
- Abstract: We introduce some of our activity in our department (flight systems technology center) in Japan Aerospace Exploration Agency (JAXA). First, we talk about flight test of flight controllers for the lateral/directional motions of our research aircraft to decrease pilot task due to gust wind and realize arbitrary handling simultaneously. For the former purpose, we design a feedback controller which achieve disturbance rejection by applying H_{infty} control, and for the latter purpose, we design a inverse system of the closed-loop system composed of plant system and the feedback controller. We show some animations of flight test to confirm that designed controllers have good performance. Next, we talk about novel stability analysis and controller design using the analysis method. (The analysis method is originally presented at ACC 2005.) The analysis method is at least as conservative as previously proposed analysis methods, which is confirmed with some numerical examples. Although we can only design inverse systems and filters with the proposed analysis method for the moment, our design methods are at least as conservative as previously proposed methods. Some numerical examples are introduced to demonstrate the effectiveness of our methods.
- 15 March: Seminar by Yukinori NAKAMURA of NAIST Nara Institute of Science and Technology, Prof. Kenji Sugimoto Laboratory (slides).
- Abstract of his institute: NAra Institute of Science and Technology (NAIST), the Excellence Student Program. In this program, NAIST encourages students to become excellent researchers by financial support. I proposed to introduce NAIST & my research in LAAS. Objective of the proposal is to seek your opinion to improve our institute/my research, and examine the foreign educational curriculum. About my institute, outline of the curriculum, facilities and so on is introduced.
- Abstract of his research: In networked control systems, transmission delay varies irregularly depending on conditions of the network. It is therefore difficult in general to realize desirable state estimation for the systems. In this presentation, I propose an observer design method for the systems with time-varying transmission delay. The method switches observer gains to estimate the present state of the plant. Then, the design of proposed observer is reduced to stabilization of switched estimation error systems. Linear matrix inequalities make it possible to design the observer multiple gains so that the stability of the error system is guaranteed even if the gains are switched randomly. Furthermore, the performance of the gain switching observer is improved by D-stability. Finally, numerical examples and an experiment illustrate the effectiveness of the proposed method.
- 24-25 April : Workshop CNRS-NSF on Biology and control theory: current challenges, LAAS-CNRS, Toulouse. Program and registration. Chairs: S. Niculescu, G. Garcia, I. Queinnec and S. Tarbouriech.
- 18 May :Workshop on Delays and robustness organized jointly by the MOSAR (Methods and Tools for Robust Analysis and Synthesis) and the SAR (Time-Delay Systems) working groups. 10h-18h, Salle Europe. Program in pdf.
- 22 May : Seminar by Matthew Turner at 2pm, salle Europe.
- Title: "Robustness in anti-windup design"
- Abstract: The issue of robustness in control system design has been studied in detail by many researchers over the last 30 years. Important advances have been made, particularly in the area of linear robust control where techniques such as H-infinity and mu-analysis/synthesis have become popular. Unfortunately, robustness has played a less prominent role in the study of linear systems subject to input saturation, particularly in anti-windup design. The guiding principle in applying anti-windup compensators so far is that robustness of the nominal linear loop implies robustness of the saturated loop. It can be demonstrated that such a conjecture is fallacious. This talk will focus on the fundamental difficulties which are encountered when trying to enforce design anti-windup compensators for uncertain systems. It will also discuss a "robustification" method which can be employed to overcome some of these difficulties at the expense of increasing the controller complexity.
- 22 Juin : Seminar by Xuan Vinh Doan, "A moment approach to some optimal data fitting and multivariate integration problems", 11am, salle Tourmalet.
- 5-7 July: 5th IFAC Symposium on Robust Control Design, ROCOND'06, Toulouse, France.
- 13 Septembrer: Seminar by Bill Helton, Professor in Mathematical Department of University of Californial San Diego (UCSD), 14h30, salle Carlit.
- Title: Optimization problems in matrix variables
- Abstract: To treat many types of systems problems whose unknowns are matrices, without disaggregating the matrices, requires developing a noncommutative analog of real algebraic geometry; especially a theory of noncommutative convexity as well as numerics.
- 20 September : Seminar by M. Etxeberria Ander and M. Sabalza Xabier from Mondragon University, 11h, salle Tourmalet.Title: "LMI Techniques for the control of flexible structures by piezo-electric components"
- 26 September: LAAS project "OLOCEP" seminar with the presence of the evaluators Hisham Abou-Kandil and Frédéric Bonnans. Salle du conseil.
- 27 September: Marten Voelker gives a talk at 10h30, salle Moore.
- Title: "Systematic Development of a Control Concept for a Reactive Distillation Column"
- Abstract: The presentation deals with the systematic design of a linear multivariable controller for a medium-scale reactive distillation column that is operated in semi-batch mode. This is a challenging problem because of the time-varying and strongly nonlinear dynamics of the process and considerable deviations of the behavior of the real plant from the rigorous model used for process design. The design procedure consists of three steps:
- - In the first step, a rigorous nonlinear process model is employed for analysis as well as for optimization purposes. A suitable control structure that enables the operation of the column near the economically optimal operating point is proposed, also taking into account a nonlinearity analysis of the process model.
- - In the second step, a linear model of the column is identified from experiments and used to compute the best attainable control performance for the chosen control structure. In this step, actuator limitations and model uncertainties described by confidence intervals that were obtained in the identification procedure are considered by a multiobjective controller synthesis approach based on Youla parametrization and finite gridding in the frequency domain as well as in the time domain. Instead of attacking the numerical optimization by semidefinite programming, a novel sequence of simpler quadratic problems, for which convergence could be proved, is proposed. An empiric evaluation of randomized optimization problems indicates an increase in the solution efficiency relative to standard LMI techniques.
- - In the third step, the resulting high-order controller is approximated by a low-order controller that gives nearly the same performance and preserves robust stability for the computed uncertainty bounds. The controller performance is demonstrated in a series of experiments that were performed at the real reactive distillation column.
- 19 October : Seminar by Jan Willems at 14h30, salle Europe.
- Title: Distributed dissispative systems.
- Abstract: The notion of a dissipative dynamical system was introduced in the early 1970's. It generalizes the idea of a Lyapunov function to 'open' dynamical systems. This concept has found applications in diverse areas of systems and control, for example, in stability theory, system norm estimation, and robust control. A central problem that emerges is the construction of a storage function. It is this problem that brought LMI's to the foreground. The main topic of this talk is distributed dissipative systems. First sorne basic system theoretic concepts for systems described by linear constant coefficient PDE's are discussed, within the behavioral framework. Issues as sub-module characterizations, elimination, and controllability and observability are introduced. Subsequently, dissipative systems described by linear PDE's and supply rates that are quadratic expressions in the system variables and their partial derivatives are defined. The dissipation inequality for such systems involves, in addition to the storage function, also the flux. The construction of the storage and the flux reduces to the factorization of polynomial matrices in many variables. This leads straight to Hilbert's 17-th problem regarding the sum-of-squares representation of nonnegative polynomials in many variables. Throughout the talk, Maxwell's equations will be used as the paradigmatic example.
- 26 October : Seminar by Emmanuelle Crepeau (universite de Versailles en detachement INRIA Rocquencourt), salle Europe at 11h00.
- Title: Modèles de pression sanguine de type solitons-windkessel
- Abstract: Dans cette présentation on développera un modèle simplifié de pression sanguine faisant intervenir des solitons de KdV pour la partie rapide et un modèle de windkessel pour la partie lente. On proposera pour résoudre le problème d'identification des paramètres la méthode de Scattering direct et inverse, basée sur l'étude spectrale d'un opérateur de Schrodinger.
Ph.D. defence
- 25 October : PhD defence of Bo GAO
- Title: Contribution à la Synthèse de Commandes Référencées Vision 2D Multi-critères
- Jury: Michel de Mathelin (universite de Strasbourg) : rapporteur ; Edson Roberto de Pieri (universite federale de Santa Catarina, Bresil) : rapporteur ; Jamal Daafouz (Institut National Polytechnique de Lorraine) : examinateur ; Jean-Marc Biannic (ONERA) : invité ; Jean-Louis Calvet (universite Paul Sabatier) : examinateur ; Philippe Soueres : directeur de these ; Sophie Tarbouriech : Co-directeur de these.
- Abstract: This thesis presents the design of multicriteria 2D image-based controllers to position a 3-DOF camera with respect to a fixed or mobile target. The camera is supposed to be supported by a robotic system which allows any horizontal translations and rotations about the vertical axis. The frequency and the quality of information delivered by the CCD cameras which equip today the robots make indeed possible the direct alimentation of the loops of control by visual measurements of the environment. The model considered is defined in the framework of the task function approach and is based on the concept of screw of interaction which allows linking up the movement of the camera with the variation of the visual indices. The objective of this work is to propose control laws to stabilize the camera on the basis of two-dimensional information resulting from the image, despite the uncertainty on the depth of the target points, the constraints of visibility and the limits on the camera velocity and acceleration. The proposed method implements advanced control techniques. It is based on the satisfaction of a modified sector condition to take into account the saturation of acceleration and the description of the closed-loop system via a polytopic model of uncertainties. This approach allows formulating constructive conditions which can be expressed in the form of Matrix Linear Inequalities (LMIs). From this formulation, some LMI-based convex optimization schemes are considered for computing the feedback gain that leads to the maximization of the size of the associated region of stability. The technique, initially applied to the positioning problem of the camera with respect to a fixed target, is then extended to track a moving target by regarding the unknown target velocity as a disturbance limited in energy. Then, the interest of the approach for designing control strategies, to link dynamically a sequence of sensor-based tasks for the problem of navigation of a mobile robot, is shown. Several examples of sequences of tasks are considered and simulated on the basis of a model of car-like robot equipped with the sensors of proximity and supporting a camera mounted on a directional pan-platform in azimuth.
- Keywords: 2D visual servoing, saturation control, multicriteria control, visibility, L2 disturbances, task sequencing, task function, target tracking, mobile robot.
- 6 December : PhD defence by Christophe FARGES
- Title: Robust Analysis and Design Methods for Linear Periodic Systems
- Jury: Patrizio Colaneri (Politecnico di Milano) : rapporteur ; Gilles Duc (Supelec) : rapporteur ; Régis Bertrand (CNES) : examinateur ; Michel Courdesse (universite Paul Sabatier) : examinateur ; Jamal Daafouz (Institut National Polytechnique de Lorraine) : examinateur ; Alain Théron (LAAS) : invité ; Denis Azelier (LAAS) directeur de these ; Dimitri Peaucelle (LAAS) : directeur de these.This thesis addresses robustness problems for a linear periodic systems.
- Abstract : These correspond to a special case of linear time-varying systems with periodic dynamics. Such periodic processes arise in numerous domains such as aeronautics, celestial mechanics or communication systems.
Systematics procedures for robust analysis and synthesis are proposed. The adopted framework is based on the Lyapunov theory and uses the linear matrix inequalities (LMI) formalism. Uncertainties are supposed to affect not only the system but the controller itself. This last problem is treated by the synthesis of convex sets of controllers ensuring a given level of performances for the closed-loop system. The question of the time structure of the controller is formulated. Does the controller need to be of the same periodicity as the system? Is it possible to reduce the number of parameters to be stored inside the controller? The class of time-structured controller is defined and dedicated synthesis methods are developed.
Theoretical results are illustrated on the problem of the stationkeeping for a spacecraft on a low earth orbit subject to different disturbance accelerations (atmospheric drag, effect of the non spheric mass repartition of the Earth). Different feedback control laws are computed with performance requirements such as minimizing the amount of maneuvering propellant or the effect of additional unknown disturbance accelerations. Their efficiency is evaluated by the mean of non linear simulations.
Visitors
- 12-18 March: Yukinori NAKAMURA with NAIST Nara Institute of Science and Technology, Prof. Kenji Sugimoto Laboratory, is visiting MAC team.
- 21-26 May: Matthew Turner, University of Leicester, UK, is visiting MAC team to work on anti-windup strategies.
- 19 June - 7 July: J.M. Gomez Da Silva (UFRGS, Porto Alegre, Brésil) is at LAAS for a cooperation with MAC team.
- 8 Juin - 8 Juillet : Boris Andrievsky (IMPE-RAS, St Petersburg, Russia) is in MAC team for a CNRS - Russian Academy of Sciences cooperation No 19134.
- 1 Juin - 20 Juillet : Xuan Vinh Doan, PhD au MIT, is in MAC team and works with J.-B. Lasserre.
- 18 July - 7 August: P.L.D. Peres (Campinas University, Brazil) is at for a cooperation with MAC team (CNRS-FAPESP funding).
- 20 September - 3 Octobrer: Marten Voelker from Dortmund University is visiting MAG group.
- 18-20 October : Jan Willems (Katholieke Universiteit Leuven) is visiting MAC team.
- till November: One year long term visit of Masayuki Sato in MAC team.
- 4-7 December: Fuwen Yang researcher at King's College, London, is visiting MAC group, his site.
Conferences
- 9-13 January: J.-B. Lasserre is invited speaker at the workshop "Semidefinite Programming and its Applications" of the Institute of Mathematical Sciences, Singapour.
- 29 March - 6 April : S. Tarbouriech and I. Queinnec are at UFRGS in Porto Alegre, Brazil. I. Queinnec participates to IFAC Adchem Congress and choirs the invited session "Optimization and Control of Biological Systems".
- 26-28 April : D. Arzelier, C. Farges, G. Garcia, D. Henrion, C. Prieur and S. Tarbouriech attend the IFAC Workshop on Control Applications of Optimisation, Cachan.
- April: J.-B. Lasserre is Conférencier plénier at "Conférence Internationale sur les Mathématiques de l'Optimisation et de la Décision", University of Antilles Guyane.
- 30-31 May : I. Queinnec is at CIFA'06, Bordeaux.
- 25 - 28 June: J.-B. Lasserre is at the SIAM conference on Discrete Mathematics (Vancouver).
- 24 - 28 July: D. Arzelier, C. Prieur and D. Peaucelle are at MTNS'06 conference in Kyoto, Japan.
- 30 July - 4 August: J.-B. Lasserre is semi-plenary speaker at triennal "ISMP 2006" (International Symposium of Mathematical Programming, Rio de Janeiro).
- 4-6 October : D. Henrion and D. Peaucelle attend the IEEE CCA/CACSD/ISIC conference in Munich.
- 7-12 October: J.-B. Lasserre is Invited speaker at the workshop "Positive polynomials and optimization" at the Banff International Research Station.
- 13-15 December: F. Gouaisbaut, C. Prieur, I. Queinnec and S. Tabouriech attend the CDC'06 in San Diego.
Other
- 16-17 January: S. Tarbouriech and G. Garcia are in Stockholm for a GARTEUR meeting, FM(AG15) "Pilot-in-the-loop Oscillations Analysis and Test Techniques for their prevention", half term evaluation by the GARTEUR Flight Mechanics Group of Responsables. The meeting is organized by FOI (The Swedish Defense Research Agency) and includes participants from: EADS, NLR, DLR, SAAB, FOI, STRAERO, DUT, Universite of Leicester, LAAS-CNRS.
- 18-19 Janvier : D. Henrion is in Limoges for a seminar.
- 13-19 Février : D. Henrion is at Technical University of Prague for an ECONET project "Polynomial Optimization for Complex Systems".
- 17 Mars : D. Arzelier and C. Prieur are at SupElec for the workshop GTMOSAR. Christophe gives a talk entitled "Robust control of mirrors in adaptive optics sytems: An EDP approach".
- 24 March: C. Prieur gives a talk at the INRIA Sophia-Antipolis, Nice, entitled "Robust stabilization of nonlinear control systems by means of hybrid feedbacks".
- 21-28 March 2006 : S. Tarbouriech and I. Queinnec are at UFSC in Florianopilis, Brazil.
- 21 March - 5 April : D. Peaucelle is at IPME-RAS, St Petersbourg, Russia, for a bilateral cooperation CNRS-Russian Acadeny of Sciences.
- 15-19 May: C. Prieur gives a lecture at the "Formation d'Automatique de Paris" on "Control Hybrid Systems".
- 1-2 June : D. Henrion is at Katholieke Universiteit Leuven, Belgium, for a lecture "on LMI optimization with applications in control".
- 21 May - 29 June: C. Prieur is at Campinas University (Brazil) for a CNRS-FAPESP cooperation.
- 25-27 October : D. Henrion is at Dortmund University for a course on LMIs.
- 9-10 November : D. Arzelier, B. Gao, W. Gilbert, T. Loquen, D. Peaucelle, and C. Prieur attend the MOSAR meeting dedicated to "Robotics and Control Theory" at LIRMM, Montepellier.
- 25 September - 25 November : S. Tabouriech and I. Queinnec are inited professors at Dept. Ing. de Sistemas y Automatica, Escuela Superior de Ingenieros, Universidad de Sevilla, Spain, and will work with Teodoro Alamo and Eduardo F. Camacho.
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