Browsing by Author "Rehm, Ansgar"

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    An engineering perspective on nonlinear H∞ control
    (1994) Allgöwer, Frank; Rehm, Ansgar; Gilles, Ernst Dieter
    The focus is on the question whether meaningful practical control problems for nonlinear systems can be expressed and solved in the nonlinear H∞ framework. Approximate I/O-linearization of a realistic chemical reactor, that cannot be I/O-linearized exactly, is given.
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    H∞-control of differential-algebraic-equation systems
    (1998) Rehm, Ansgar; Allgöwer, Frank
    In this paper H∞ control of high index and non-regular linear differential-algebraic-equation systems is addressed. Based on a generalization of the bounded real lemma (BRL) to index one systems, all linear output feedback controllers in standard, ie non-descriptor, state space form solving the H∞ control problem can be characterized via biaffine matrix inequalities (BMIs). In a second step a congruence transformation and a subsequent change of variables show that certain linear matrix inequalities (LMIs) necessarily must hold in order to admit a solution of the H∞ control problem. However, these conditions are not sufficient. Necessary and sufficient conditions for the existence of a controller solving the H∞ control problem are derived as BMIs of reduced order compared to the original characterization via the BRL. The approach is illustrated by a simple example.