07 Fakultät Konstruktions-, Produktions- und Fahrzeugtechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/8
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Item Open Access Multivariable controller design for an industrial distillation column(1992) Allgöwer, Frank; Raisch, JörgIn this paper, we report our experience with the design of linear multivariable controllers for a staged binary distillation column with 40 trays. Controller design methods include H∞-minimization, DNA-design, CL-design and H2minimization. Results obtained at the real plant are shown.Item Open Access A systems science view on cell death signalling(2007) Eißing, Thomas; Allgöwer, Frank (Prof. Dr.-Ing.)This thesis provides new insight into cellular signal transduction by integrating biological knowledge into mathematical models, which are subsequently analysed using systems theoretic methods. Signal transduction has been dissected using molecular and genomic approaches providing exciting insight into the biochemistry of life. However, a detailed understanding of its dynamic properties remains elusive. The application of systems science ideas to biology is promising to put the pieces of molecular information back together, as important properties of life arise at the system level only. For example, certain signalling pathways convert graded input signals into all-or-none output signals constituting biological switches. These are implicated in cellular memory and decisions. One such decision is whether or not to undergo programmed cell death (apoptosis). Apoptosis is an important physiological process crucially involved in the development and homoeostasis of multicellular organisms. Switches, such as in apoptosis, can be represented by ordinary differential equation models showing bistable behaviour. Different biochemical mechanisms generating bistability in reaction schemes as encountered in apoptosis are presented and compared in this thesis. Bifurcation studies reveal structural and parametric requirements for bistability. In combination with reported kinetic information, inconsistencies in the literature view of apoptosis signalling in humans are revealed. An additional regulatory mechanism is proposed, which is now supported by experimental evidence. Extended robustness analyses indicate that the cell has achieved a favourable robustness-performance trade-off, imposed by network structure and evolutionary constraints. On the one hand, inhibitors of apoptosis function as noise filters and reduce variability caused by the stochastic nature of reactions. Further, qualitative properties such as bistability are comparably robust to parameter changes supporting proper decisions. On the other hand, quantitative aspects are comparably sensitive. This allows for variability in a population, as observed in experiments, and which is likely important for physiological function as recently indicated in immunological studies. The analyses further indicate that the trade-off leads to fragilities. For example, an up-regulation of inhibitors of apoptosis, as observed in certain cancers, can not only desensitise cells to apoptotic stimuli, as also suggested by experimental studies, but can contribute to cancer aggressiveness and progression through additional mechanisms. Thereby, the analyses provide insight of pharmaceutical relevance. Several results presented in this thesis are not restricted to apoptosis signalling only, but are conceptually relevant to various other signal transduction pathways.Item Open Access Control of uncertain systems with l1 and quadratic performance objectives(2007) Rieber, Jochen M.; Allgöwer, Frank (Prof. Dr.-Ing.)This thesis presents novel analysis and synthesis concepts for linear control systems with parametric uncertainties. Different performance objectives such as L1, H-infinity, H2, and quadratic performance are considered. In the analysis section, upper bounds on the L-infinity-gain (or the L1-norm) of uncertain systems are developed. These bounds exhibit different degrees of computational effort and accuracy. In particular, a new direct approach for determining the robust L-infinity-gain is proposed. The synthesis sections introduce an efficient formulation of H-infinity and H2 constraints in a general linear multi-objective control framework. Moreover, a novel control structure for the design of parameter-varying controllers is developed. Using this structure, a scheme for the synthesis of linear parameter-varying output-feedback controllers in the L1 control framework is presented for the first time. In addition, it is shown how the control structure is applicable to other norm-based frameworks like quadratic performance control and in particular H-infinity control. The analysis and synthesis conditions proposed in this thesis are expressed as computationally tractable optimization problems, in particular in form of linear matrix inequalities, semi-definite programs, or iterations thereof. Several detailed examples, including a flight control problem with time-varying dynamics, demonstrate the properties and the applicability of the proposed methods.Item Open Access Schneller sehen durch Regelungstechnik - Moderne Bildgebung in der Nanotechnologie(2004) Rieber, Jochen M.; Allgöwer, Frank; Stemmer, AndreasDie Nanotechnologie, also die Wissenschaft von Untersuchungen und Manipulationen im Nanometermaßstab, wird als eine der Schlüsseltechnologien des 21. Jahrhunderts angesehen. Wichtige Komponenten dieses aktuellen Forschungszweiges sind das Rastertunnelmikroskop und das Rasterkraftmikroskop, die den Blick in die Nanowelt erlauben. Dieser Artikel gibt einen einführenden Einblick in die Bildgebung der Nanowelt und versucht, den Beitrag von Systemtheorie und Regelungstechnik für die Nanotechnologie anhand der Regelung von Rasterkraftmikroskopen allgemeinverständlich zu beschreiben.Item Open Access Chemical process control: a german perspective(1992) Allgöwer, FrankThis paper focuses on developments in controller design that we think can have a significant impact on the solution of practical process control problems, and try to summarize the discussion in Germany on this subject.Item Open Access Versuchsstand Flexibler Roboter: Modellierung und Beobachterentwurf(2009) Burkhardt, MarkusDiese Arbeit befasst sich mit der Modellbildung und dem Beobachterentwurf eines zweigelenkigen, ebenen Roboters mit flexiblen Verbindungselementen. Der Roboter wird dabei als ein flexibles Mehrkörpersystem betrachtet, um die Elastizitäten in den Verbindungen zu berücksichtigen. Durch die Variation der Anzahl an Moden und durch eine unterschiedliche Berücksichtigung der auftretenden Reibung werden mehrere verschiedene Modelle erstellt und anschließend miteinander verglichen. Um eine Zustandsrückführung zu ermöglichen, wird ein Beobachter entworfen. Dabei kommt ein Extended Kalman Filter zum Einsatz. Dabei gilt die Zielvorgabe, dass das Extended Kalman Filter echtzeitfähig ist. Die Implementierung am Versuchsstand erfolgt als C Mex S-Function. Nachdem verschiedene Varianten miteinander verglichen wurden und die geeignetste Variante gewählt wurde, wird das Konvergenzverhalten überprüft.Item Open Access Kinetic instabilities in heterogeneously catalyzed reactions. Pt. 1, Rate multiplicity with Langmuir-type kinetics(1978) Eigenberger, GerhartThis paper is concerned with the occurrence of rate multiplicities (ignition-extinction phenomena). It is shown that rate multiplicity can be caused by the competing chemisorption of A and B upon the same active sites of the catalyst. Rate multiplicity can occur if at least one of the chemisorption or reaction steps is of second order. No rate multiplicity can be expected, if either A or B reacts via an Eley-Rideal type mechanism.Item Open Access Uncertainty and robustness analysis of biochemical reaction networks via convex optimisation and robust control theory(2009) Waldherr, Steffen; Allgöwer, Frank (Prof. Dr.-Ing.)In the area of systems biology, dynamical models of biochemical reaction networks are used to derive model-based predictions about the related biological processes. This thesis provides new methods to study how parametric uncertainty affects such predictions. The focus of this study is on predictions about the steady states and the type of dynamical behaviour, such as bistability or oscillations. Concerning steady states, the problem of uncertainty analysis is investigated. For a given extent of parametric uncertainty, the objective is to compute bounds on the variations in the steady states. In view of an underlying feasibility problem, a method based on semidefinite programming is developed to solve this problem. The approach is also applied to compute a measure for the robustness of the location of steady states in the presence of parametric uncertainty. Regarding the effect of parametric uncertainty on the type of dynamical behaviour, the robustness problem is considered. A robustness measure is defined by the extent of parametric uncertainty for which no local bifurcations occur. An approach to solve the robustness problem with frequency domain methods is investigated. The proposed feedback loop breaking method allows to characterise parametric uncertainties for which the type of dynamical behaviour is robust. On the one hand, a lower bound on the corresponding robustness measure is computed by providing Positivstellensatz infeasibility certificates for the underlying equations. On the other hand, the feedback loop breaking concept is adopted for the design of a bifurcation search algorithm in a high-dimensional parameter space. The results of the search algorithm thereby provide an upper bound on the robustness measure. In addition, the novel concept of kinetic perturbations is introduced. This is a class of specific parametric uncertainties which are particularly useful for the analysis of biochemical reaction networks. It is shown that a robustness analysis is performed efficiently for kinetic perturbations by use of the structured singular value. As a side result, the direct relation between kinetic perturbations and changes to the sensitivity of steady states in a biochemical reaction network is demonstrated. To complement the methodological results, a novel model for a specific biochemical signal transduction system within the TNF induced signalling network is constructed. The model is analysed with methods developed in this thesis. In addition to an illustrative application of the new methods, the findings of this analysis also provide new biological insight into TNF signal transduction.Item Open Access Nonlinear control of an industrial distillation column by exact linearization(1989) Allgöwer, Frank; Sax, Antonius; Gilles, Ernst Dieter-Item Open Access Nichtlinearer Reglerentwurf auf der Grundlage exakter Linearisierungstechniken(1993) Allgöwer, Frank; Gilles, Ernst DieterDem nichtlinearen Reglerentwurf mittels exakter Linearisierung liegt eine Zweischritt-Philosophie zugrunde: zuerst wird die nichtlineare Regelstrecke durch eine nichtlineare Rückführung exakt in ein lineares System überführt. Das exakt linearisierte System kann im zweiten Schritt mit linearen Reglerentwurfsverfahren so geregelt werden, daß Stabilität und gutes Regelverhalten erreicht werden. In diesem Übersichtsbeitrag wird eine Einführung und ein Überblick über das Gebiet der exakten Linearisierung gegeben. Anhand von Beispielen werden die Vorteile und Grenzen der Verfahren diskutiert.
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