Johannes Reinschke

A Robust Control Framework for Linear, Time-Invariant, Spatially Distributed Systems

A robust control framework for linear, time-invariant (LTI), spatially distributed systems is outlined in this paper. We adopt an input-output approach which takes account of the spatially distributed nature of the input and output signals for such systems. The approach is a generalization of

Designing robustly stabilising controllers for LTI spatially distributed systems using coprime factor synthesis

H^\infty

Voltage and power flow oscillations induced by PV inverters connected to a weak power distribution grid

\xspace control in the sense that the 2-norm (in both time and space) is used to quantify the size of signals. It is shown that a frequency-domain representation, in the form of a graph symbol, exists for every LTI, spatially distributed system under very mild assumptions. The graph symbol gives rise to left and right coprime representations if the system is also stabilizable. We investigate fundamental issues of feedback control such as feedback stability and robust stability to plant and/or controller uncertainty quantified in the gap-metric. This includes a generalization of the Sefton--Ober gap formula to the infinite-dimensional operator case. A design example in which an electrostatically destabilized membrane is feedback-stabilized concludes the paper.

Method for determining the position and orientation of an endoscopy capsule guided through an examination object by using a navigating magnetic field generated by means of a navigation device

This paper considers the design of feedback controllers for linear, time-invariant, spatially distributed systems in an approach which generalises the H^~-framework and in particular the H^~ loop-shaping method. To this end, we introduce a class of spatially distributed system models called finite dimensional, distributed, linear, time-invariant systems. Sensors and actuators are considered to be part of the controller, rather than part of the plant, and thus the controller we wish to design is itself a spatially distributed system. Optimising over placements and shapes of the sensor and actuator spatial distribution functions is an integrated part of the controller design procedure. As an illustrative design example, we present the feedback stabilisation of an electrostatically destabilised, electrically conducting membrane.

Computer-aided method for determining desired values for controlling elements of profile and surface evenness

In this paper, we present simulation results for a basic setup in which a photovoltaic inverter and a load are connected to a weak power distribution grid. We use both DIgSILENT PowerFactory, with a standard PV model including a reactive power controller for voltage support, and MATLAB/Simulink as simulation software. We identify conditions under which load changes result in voltage oscillations or even instability. Potential ramifications for PhotoVoltaic (PV) inverter grid codes are briefly discussed.