Seminars Winter 2006

Le Laboratoire d’Automatique de l’EPFL a le plaisir de vous inviter aux séminaires selon la liste ci-après. Une mise à jour régulière des informations concernant ces séminaires est disponible à l’adresse sur cette page. En particulier, il est conseillé aux visiteurs externes de vérifier que les séminaires soient dispensés comme prévu ci-dessous.

Where: Salle de séminaire LA-EPFL, ME C2 405 (2è étage), 1015 Lausanne

When: Friday at 10h15

Winter 2006 seminars

Vibration Control of Flexible Structures using Shunted Piezoelectric Transducers

01.09.2006 – Prof. Moheimani – University of Newcastle, Australia

Research on shunted piezoelectric transducers, conducted mainly over the past fifteen years, provides new opportunities for control of vibration and damping in flexible structures. This is made possible by the strong electromechanical coupling associated with modern piezoelectric transducers. In vibration control applications a piezoelectric transducer is bonded to, or embedded in a base structure. As the structure deforms, the piezoelectric element strains and converts a portion of the structural vibration energy into electrical energy. By shunting the piezoelectric transducer to an electrical impedance, a part of the induced electrical energy can be dissipated. Hence, the impedance acts as a means of extracting mechanical energy from the base structure. This talk presents an overview of recent research related to the use of shunted piezoelectric elements for vibration damping and control. It will be demonstrated that the problem of piezoelectric shunt damping can be viewed as a feedback control problem with a specific feedback structure, and a number of high performance impedance structures will be introduced. Furthermore, an effective method for implementing such impedances will be presented.

Application of NIR Spectroscopy to Food Analysis

03.11.2006 – Dr. R. Nzabonimpa – Nestlé Research Center, Lausanne

During the last decades, Near Infrared Spectroscopy (NIR) spectroscopy has proven to be an easy-to-use and powerful tool for identification of incoming raw materials and quantification of food components. These measurements are non-invasive and non-destructive. Moreover, since they do not necessitate sample preparation, NIR spectroscopy can be considered to be an environmentally friendly technology. Chemical characteristics are determined by comparing the sample spectrum to spectra of known samples. This talk will give a broad overview of state-of-the-art NIR applications in process control, with emphasizes on (i) the identification of incoming raw material and the quantification of components as indicators for process control, and (ii) the use of fiber technology for on-line control of liquids, powders and granulates.

Teaching Hands-On Introductory Controls with LEGO Mindstorms

17.11.2006 – Prof. C. Rogers – Department of Mechanical Engineering, Tufts University, Medford, MA

A group of us at the Center for Engineering Education Outreach ( at Tufts University have spent the last 8 years working with LEGO on developing a LabVIEW interface for LEGO Mindstorms called ROBOLAB. ROBOLAB has entered classrooms around the world and is being used by thousands of teachers to teach math and science through engineering and robotics. It has also led us to start one of the first engineering education programs in the U.S. to better understand gender differences, age differences, and issues of self-confidence in learning engineering. Recently, with the release of ROBOLAB 2.9, the RCX (and the new NXT) are fast enough to allow students to learn simple and complex controls in a hands-on way. I will show how a group of us changed the way we taught introductory controls, going from a class that starts with dynamics and ends with MATLAB simulations, to one that starts with the students building a LEGO car that drives exactly 1 meter and ends with them developing accurate simulations of their LEGO constructions, including building a LEGO Segway.

Convex Optimization over Linear Matrix Inequalities for Fixed-Order H-infinity Controller Design

01.12.2006 – Dr. D. Henrion – Laboratoire d’Analyse et d’Architecture des systèmes, CNRS, Toulouse, France.

First, we describe simple sufficient linear matrix inequality (LMI) conditions for stability of a polynomial matrix in the Laplace variable. The conditions are derived from basic results on positivity of polynomials, and they are parameterized around a given central polynomial. Then, we show how these conditions can be extended to cope with closed-loop H-infinity design specifications, resulting in a flexible methodology to design fixed-order or structured H-infinity suboptimal controllers. Numerical experiments with convex optimization solvers illustrate how the choice of the central polynomial can be an alternative to the choice of weighting functions in standard H-infinity control. If time permits, we explain how these results can be extended to linear parameter varying (LPV) controller design, using recent results of real algebraic geometry.

Control of Hybrid Systems: Theory, Computation and Applications

08.12.2006 – Prof. M. Morari – Automatic Control Laboratory, ETHZ, Zürich, Switzerland.

Theory, computation and applications define the evolution of the field of control. This premise is illustrated with the emerging area of hybrid systems, which can be viewed, loosely speaking, as dynamical systems with switches. Many practical problems can be formulated in the hybrid system framework. Power electronics are hybrid systems by their very nature, systems with hard bounds and/or friction can be described in this manner and problems from other domains, as diverse as driver assistance systems, anesthesia and active vibration control can be put in this form. We will highlight the theoretical developments and mention the extensive software that helps to bring the theory to bear on the practical examples. We will close with an outlook for hybrid systems and control more generally.

Modeling and Control in Biological and Biotechnological Systems

15.12.2006 – Prof. S. Jørgensen – Department of Chemical, Technical University of Denmark, Lyngby, Denmark

The challenge in technological systems is to optimize productivity, while meeting quality and sustainability constraints. The challenge in microbial cells, on the other hand, is to ensure survival under all conditions. In both types of systems, control is applied, to a significant extent, for ensuring robustness. It is of great interest to understand how natural living organisms have been incorporating control during their development. There is still a long way to go to obtain a detailed understanding of regulatory networks in microorganisms, even though some aspects are already clear at a higher level for certain classes of microorganisms. An interesting analogy between technological and natural systems will be pinpointed before progressing into approaches to actually dealing with control of biotechnological processes at the present level of understanding. Progressing from basic aspects of biological systems, some monitoring and control designs may be developed based on modern control theory. These designs will be illustrated on pilot and industrial examples, including continuous and batch bioreactors.

An Actuator Fault Detection and Isolation System for a Reconfigurable Flight Controller of a Small UAV

12.01.2007 – G. Ducart – Measurement and Control Laboratory, ETHZ

The extended multiple model adaptive estimation method (EMMAE) combines the ability of the multiple model adaptive estimation method (MMAE) to detect faults based on a predefined hypothesis and the parameter-estimating ability of an extended Kalman filter (EKF). It results in an efficient fault detection and isolation (FDI) approach, which can estimate on-line the state of the system as well as the deflection of the failed control surface, without adding sensors on the actuators. A supervision module has been designed to enhance the performance of the EMMAE method and to appropriately change settings in a control allocation module. This control allocation module allows for easy reconfiguration, for fast operation and low computational load. The complete system has been successfully demonstrated on a nonlinear model of an aircraft.

Teaching Process Control with Scilab and Scicos

26.01.2007 – Dr. P. Tona – Direction Technologie, Informatique et Mathématiques Appliquées, IFP, Lyon, France

Most process control courses rely on MATLAB/Simulink to fulfill, at least partially, their simulation needs. Although this choice represents a standard and rather satisfactory solution, the availability of such commercial software in academia should not be taken for granted. In this talk we will show that, with some adjustments and moderate additional effort, teaching material developed with MATLAB/Simulink can be successfully replaced by equivalent material developed with Scilab/Scicos, a free and open-source computing environment.

Semi-Automatic Modeling of Reaction Systems

02.02.2007 – Prof. R. King – Institut für Prozess- und Anlagentechnik, Technische Universität Berlin, Germany

Model-based methods, such as optimization, monitoring and control can significantly improve the performance of many processes. The application of these methods, however, is limited in some areas – as in reaction engineering – by the modeling process itself. Up to now modeling is mostly done by a human expert in an iterative and therefore time-intensive way. In this talk, the software tool TAM-B is introduced which automates parts of this iterative procedure and therefore makes the modeling process easier and more efficient. It is based on a combination of qualitative and quantitative methods to allow an efficient testing of even large numbers of automatically postulated model candidates. Compared to the classical manual modeling procedure, a significant amount of time is saved. Moreover, many more possible model candidates are tested and automatically documented compared to what a human modeler is able to do. Therefore, the methods proposed here should not only help the inexperienced modeler but the modeling expert as well.