Systems and Control Seminar
2019/06/12: Dr.-Ing. Sören Weinrich, Deutsches Biomasseforschungszentrum
- 2019/06/12: Dr.-Ing. Sören Weinrich (Deutsches Biomasseforschungszentrum) will give a talk on Model-based control for demand-oriented power supply of anaerobic digestion plants at 3:30 pm in 2/W185.
- Abstract: The changing conditions within the energy sector in Germany force biogas plants to meet new requirements. Demand-oriented power supply to compensate the divergence between electricity production and consumption by uncontrolled sources like wind and solar power defines one option for future plant operation. Dynamic models of the anaerobic digestion process are essential tools to predict the progression of various process variables and to guarantee secure and optimized plant operation under highly dynamic or demand-oriented feeding. However, due to the high number of state variables and unknown model parameters complex models such as the established Anaerobic Digestion Model No.1 (ADM1) still cannot be applied in practice. Thus, the development of simplified model structures is of great importance for a standardized application of model-based monitoring and control systems at anaerobic digestion plants. The presentation will focus on the systematic simplification and comparison of available model structures of the anaerobic digestion process. Based on the derived model structures a model predictive control (MPC) concept was developed to provide optimal feeding strategies and enable demand-oriented power supply of anaerobic digestion plants. Full-scale application showed high intraday flexibility ranging as far as 30 to 130% of the average gas production rate and high process stability during demand-oriented feeding. The gas storage demand could be reduced significantly by up to 45% in comparison to steady state operation.
- Curriculum Vitae: Sören Weinrich studied agriculture and environmental science at the professorship of 'Abfall- und Stoffstromwirtschaft' at the university of Rostock and received his PhD in 2017. He has since been working at the DBFZ in Leipzig. His research topics focus around modeling and control of biogas plants.
2019/05/08: Prof. Dr.-Ing. Dr. h. c. Oliver Sawodny, University of Stuttgart
- 2019/05/08: Prof. Dr.-Ing. Dr. h. c. Oliver Sawodny (University of Stuttgart) will give a talk on System Dynamic Methods for Optimization in Electric Vehicles at 3:30 pm in 2/W020.
- Abstract: The powertrain of an all-electric vehicle has changed radically compared to a conventional combustion vehicle. With this change new challenges but also new possibilities arise in terms of system integration and system control. Even though battery technologies continuously improve in capacity and price, one of the main challenges and customer concerns is the overall range. Consequently, founding is mostly directed to research in the field of battery capacity and battery management. However, several essential questions seek to improve the all-electric range by means of advanced driver assistant systems. Research activities at the Institute for System Dynamics thus focus on operating as well as energy management strategies for electric powertrain architectures based on software solutions and the consideration of additional environmental data. Latter is obtained from a constantly increasing number of vehicle sensors and increasing vehicle connectivity and is used for example in loss minimizing control strategies of electric drive modules or in cycle and driver specific range predictions. In this context, estimating and optimizing battery lifetime is also essential for energy management. In most automotive applications, the battery can be represented by an electrical equivalent circuit. Lifetime effects are covered by adding empirical aging relations. Li-ion cell measurements are therefore essential and aging tests are exemplarily described for a LiMn2O4 cell. Based on the derived models, an optimization framework for battery lifetime extension is described for a given scenario. As last aspect the thermal management in EV's is discussed. Therefore, model-based approaches to describe the thermal circuits are introduced and methods to optimize the operational strategy and the design presented.
- Curriculum Vitae: Professor Sawodny received his Dipl.-Ing. degree in electrical engineering from the University of Karlsruhe, Karlsruhe, Germany, in 1991 and his Ph.D. degree from the University of Ulm, Ulm, Germany, in 1996. In 2002, he became a Full Professor at the Technical University of Ilmenau, Ilmenau, Germany. Since 2005, he has been the Director of the Institute for System Dynamics, University of Stuttgart, Stuttgart, Germany. His current research interests include methods of differential geometry, trajectory generation, and applications to mechatronic systems. He received important paper awards in major control application journals such as Control Engineering Practice Paper Prize (IFAC, 2005) and IEEE Transaction on Control System Technology Outstanding Paper Award (2013). He is a senior member of IEEE and senior editor of Mechatronics.
2019/04/12: Prof. Jean Lévine, MINES ParisTech
- 2019/04/12: Prof. Jean Lévine (MINES ParisTech) will give a talk on An introduction to flatness with emphasis on computational aspects at 3:30 pm in 2/W017.
- Abstract: The notion of differentially flat (or shortly flat) system concerns a particular class of nonlinear systems often encountered in practice. It has been introduced in the early 90's by Michel Fliess, Philippe Martin, Pierre Rouchon and the author, and has shown to be most useful in motion planning and tracking of nonlinear systems. In this presentation, we recall the basics of this theory and show, as an example, that aircraft dynamics are flat, giving rise to an autopilot design that is different and much simpler than the traditional AFCS's. We also present various applications, in particular to mechatronics and robotics. We conclude our presentation by some remarks on computer algebraic as well as numerical sides of flatness, and on global aspects of this theory versus singularities.
- Curriculum Vitae: Jean Lévine obtained his 'Doctorat d' État' in Mathematics in 1984 for which he was awarded the Best Thesis AFCET Prize, section Theory, in 1985. He has held various professorship positions, has been a Director of Research with MINES-ParisTech, PSL Research University, since 2006 and is in charge of the Systems and Control Doctoral Studies. He is presently an Emeritus Director of Research and joined the 'Fondation Sciences Mathématiques de Paris' (FSMP) at the Institut Henri Poincaré in 2016 as a Math-Industries special adviser. He contributed to many research fields, including Differential Games, Nonlinear filtering and Nonlinear control. He is one of the founders of differential flatness theory and of the notion of barrier in state constrained nonlinear systems. He also contributed to the transfer of advanced control know-how to the industry through many collaborations with French and international companies on applications such as distillation columns, chemical reactors, food and bio-engineering processes, aircraft control, car equipments, crane control, machine tools, magnetic bearings, high-precision positioning systems and web-to-web machines.
2018/12/12: Prof. Dr. Lars Grüne, University of Bayreuth
- 2018/12/12: Prof. Dr. Lars Grüne (University of Bayreuth) will give a talk on Computing nonsmooth control Lyapunov functions on a grid at 1:45 pm in 2/N001.
- Abstract: Control Lyapunov functions play an important role for controller design for nonlinear control systems. They can be interpreted as a road map, which for each point of the state space indicates a set of good directions towards the target from which the value of the controller can be computed.
Lyapunov functions can be represented as sub- or supersolutions of certain partial differential equations (PDEs) and due to this fact various numerical schemes for computing Lyapunov functions have been designed based on discretization schemes for PDEs. However, most of these schemes require appropriate smoothness of the function to be computed. It is known from seminal works of Artstein, Clarke, Sontag and others in the 1980s and 1990s that Control Lyapunov functions are in general not smooth.
The talk explains a new way to cope with this problem. It is based on joint work with Robert Baier, Philipp Braun, and Chris Kellett.
- Curriculum Vitae: Lars Grüne has been Professor for Applied Mathematics at the University of Bayreuth, Germany, since 2002. He received his Diploma and Ph.D. in Mathematics in 1994 and 1996, respectively, from the University of Augsburg and his habilitation from the J.W. Goethe University in Frankfurt/M in 2001. He held visiting positions at the Universities of Rome 'Sapienza' (Italy), Padova (Italy), Melbourne (Australia), Paris IX - Dauphine (France) and Newcastle (Australia). Prof. Grüne is Editor-in-Chief of the journal Mathematics of Control, Signals and Systems (MCSS) and Associate Editor of several other journals, including the Journal of Optimization Theory and Applications (JOTA) and the IEEE Control Systems Letters. His research interests lie in the area of mathematical systems and control theory with a focus on numerical and optimization-based methods for nonlinear systems.
2018/12/05: Prof. Dr.-Ing. habil. Dipl.-Math. Klaus Röbenack, TU Dresden
- 2018/12/05: Prof. Dr.-Ing. habil. Dipl.-Math.Klaus Röbenack (TU Dresden) will give a talk on Lösung regelungstechnischer Probleme mittels Quantorenelimination at 3:30 pm in 2/W021.
- Abstract: Zahlreiche regelungstechnisch relevante Entwurfsaufgaben lassen sich als Entscheidungsprobleme formulieren und mittels Quantorenelimination lösen. Im Vortrag wird eine Auswahl dieser Probleme behandelt und deren Lösung mittels Quantorenelimination vorgestellt.
-Entwurf statischer Ausgangsrückführungen: Für lineare zeitinvariante Zustandsraummodelle sind sowohl Bedingungen für Polplatzierbarkeit bzw. Stabilisierbarkeit mittels Zustandsrückführung als auch die konkrete Berechnung des jeweiligen Regelgesetzes hinlänglich bekannt. Im Fall einer statischen Ausgangsrückführung sind die Existenzbedingungen und die Berechnung wesentlich schwieriger. Sowohl Polplatzierbarkeit als auch Stabilisierbarkeit können als Entscheidungsprobleme formuliert werden.
-Globale Stabilitätsuntersuchungen: Für globale Stabilitätsuntersuchungen bietet sich die zweite Methode von Ljapunov an. Die für den Stabilitätsnachweis benötigten Bedingungen hinsichtlich der Definitheit lassen sich ebenfalls als Entscheidungsprobleme formulieren.
Bei den genannten Problemen treten Aussagen auf, die Quantoren enthalten. Für den Entwurf bzw. die Auslegung einer Regelungseinrichtung sind äquivalente Formulierungen der jeweiligen Stabilitätsbedingungen ohne Quantoren erforderlich. Dieser Übergang von einer Aussage mit Quantoren zu einer äquivalenten quantorenfreien Aussage erfolgt mittels Quantorenelimination. Alfred Tarski zeigte, dass eine solche über dem Körper der reellen Zahlen grundsätzlich möglich ist. Zu ihrer praktischen Durchführung wurden in den letzten Jahrzehnten verschiedene algorithmische Verfahren entwickelt bzw. implementiert. Die zunehmend effizienter werdenden Algorithmen ermöglichen die Anwendung von Quantorenelimination auf praktisch und theoretisch interessante Fragestellungen der Regelungstechnik.
- Curriculum Vitae: Klaus Röbenack hat Elektrotechnik und Mathematik an der TU Dresden studiert, an der er im Jahr 1999 auch erfolgreich zum Thema Beitrag zur Analyse von Deskriptorsystemen promovierte. Nach seiner Habilitation an der Fakultät Elektrotechnik und Informationstechnik im Jahr 2005 wurde Klaus Röbenack 2009 zum Professor für Regelungs- und Steuerungstheorie an der TU Dresden berufen. Momentan ist er dort als Institutsdirektor des Instituts für Regelungs- und Steuerungstheorie tätig. Er ist ein Fachgutachter bei zahlreichen wissenschaftlichen Tagungen und Zeitschriften wie Automatica, Journal of Computational and Applied Mathematics, sowie IEEE Transactions on Automatic Control. Seine Forschungsinteressen reichen von der nichtlinearen Regelungstechnik bis zu algorithmischen Methoden in der Regelungstheorie.
2018/11/07: Prof. Dr.-Ing. Christian Ebenbauer, University of Stuttgart
- 2018/11/07: Prof. Dr.-Ing. Christian Ebenbauer (University of Stuttgart) will give a talk on To commute or not to commute? The role of geometric control in optimization algorithms at 2:15 pm in 2/W014.
- Abstract: Optimization algorithms are often used in control to solve decision making problems. Control methods, however, are used much less in optimization, despite the facts that control is dedicated to the analysis and design of dynamical systems and that optimization algorithms are dynamical systems. In recent years, however, the research about employing feedback ideas in optimization algorithm design has gained some momentum. In this talk, we present some recent results in this direction, in which we specifically employ fundamental ideas from geometric control to develop optimization algorithms. In particular, we show how non-commutative effects in vector fields and maps give rise to novel classes of extremum seeking, derivative-free and distributed optimization algorithms.
- Curriculum Vitae: Christian Ebenbauer received his MS (Dipl.-Ing.) in Telematics (Electrical Engineering and Computer Science) from Graz University of Technology, Austria, in 2000 and his PhD (Dr.-Ing.) in Mechanical Engineering from the University of Stuttgart, Germany, in 2005. After having completed his PhD, he was a Postdoctoral Associate and an Erwin Schrödinger Fellow at the Laboratory for Information and Decision Systems, Massachusetts Institute of Technology (MIT), USA. Since April 2009, he is a full professor at the Institute for Systems Theory and Automatic Control, University of Stuttgart, Germany. His research interests lie in the areas of dynamical systems, control theory, optimization and computation. Recent research projects focus on system-theoretic approaches to optimization algorithms, extremum seeking control, MPC and MHE algorithms.