Jacqueline Scherpen

Normalized coprime factorizations and balancing for unstable nonlinear systems

In this paper we first study the normalized right and left coprime factorizations of a nonlinear system from a state-space point of view. In order to do so, we introduce the notion of inner and co-inner nonlinear systems. Secondly we deal with balancing for unstable nonlinear systems. For linear systems there are several ways to approach this problem, and we generalize the ideas of balancing the normalized coprime factorization and of LQG balancing to the nonlinear case. LQG balancing can be seen as measuring the influence of a state component on a certain future and past energy function. We extend this interpretation to the nonlinear case. Furthermore we use the normalized coprime factorization to give another way of balancing the unstable nonlinear system. We give the relation between these two methods of balancing, which is similar to the relation in the linear case.

Adaptive switching gain for a discrete-time sliding mode controller

Sliding mode control is a well-known technique capable of making the closed loop system robust with respect to certain kinds of parameter variations and unmodelled dynamics. The sliding mode control law consists of a continuous component which is based on the model knowledge and discontinuous component which is based on the model uncertainty. This paper extends two known adaption laws for the switching gain for continuous-time sliding mode controllers to the multiple input case. Because these adaption laws have some fundamental problems in discrete-time, we introduce a new adaption law specifically designed for discrete-time sliding mode controllers.

A Web-based study support environment for systems and control courses

We describe the development and the current implementation of a Web-based study support environment that is used for teaching systems and control courses at Delft University of Technology, The Netherlands. The aim of this Web-based study support environment is to increase the study effectiveness in systems and control courses. First we describe the new course format that has been introduced to successfully implement the Web-based study support environment. We also give a brief overview of the study support environment itself and discuss our experiences with the environment, which is currently being used for the third consecutive year. We also compare our experiences and the results in using this study support system with those of the preceding years, in which the system was not yet used.

Geometric discretization of fluid dynamics

Based on the Stokes-Dirac structures proposed in, an extension of these descriptions is presented, for the Euler equations in the case of a one-dimensional manifold with boundary in order to include the entropy as a dynamic variable. Furthermore, a discretization procedure is proposed showing several nice properties. The effectiveness of the procedure for simulation purposes is shown with a simple model of an ideal pipeline.

Outer-(J/sub 1/, J/sub 2/)-lossless factorizations of linear discrete time-varying systems

In this paper the outer-J-lossless factorization for linear discrete time-varying systems is treated. Lossless operators and its corresponding J-lossless chain-scattering operators are studied. Then the factorization is treated by first taking out the anticausal part, and then considering the outer-J-lossless factorization of the causal part.