Rafael Wisniewski

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This paper presents stability and control analysis of a satellite on a near polar orbit subject to the gravity torque. The satellite is actuated by a set of mutually perpendicular coils. The concept is that interaction between the Earth's magnetic "eld and a magnetic "eld generated by the coils results in a mechanical torque used for attitude corrections.(More)
This paper presents the MATLAB simulation framework, DiSC, for verifying voltage control approaches in power distribution systems. It consists of real consumption data, stochastic models of renewable resources, flexible assets, electrical grid, and models of the underlying communication channels. The simulation framework makes it possible to validate(More)
This paper proposes a compositional method for verifying the safety of a dynamical system, given as an interconnection of subsystems. The safety verification is conducted by the use of the barrier certificate method; hence, the contribution of this paper is to show how to obtain compositional conditions for safety verification. We show how to formulate the(More)
Large scale wind turbines are lightly damped mechanical structures driven by wind that is constantly fluctuating. In this paper, we address the design of a model-based receding horizon control scheme to reduce the structural loads in the transmission system and the tower, as well as provide constant (or at least smooth) power generation. Our controller(More)
In this article, a general method for model/controller order reduction of switched linear dynamical systems is presented. The proposed technique is based on the generalised gramian framework for model reduction. It is shown that different classical reduction methods can be developed into a generalised gramian framework. Balanced reduction within a specified(More)
Modern wind turbine controllers use wind speed information to improve power production and reduce loads on the turbine components. The turbine top wind speed measurement is unfortunately imprecise and not a good representative of the rotor effective wind speed. Consequently, many different modelbased algorithms have been proposed that are able to estimate(More)
This paper presents a method for abstracting continuous dynamical systems by timed automata. The abstraction is based on partitioning the state space of a dynamical system using positive invariant sets, which form cells that represent locations of a timed automaton. The abstraction is intended to enable formal verification of temporal properties of(More)
This paper considers the control problem of a class of uncertain switched systems defined on polyhedral sets known as piecewise linear systems where, instead of the conventional Carathéodory solutions, Filippov solutions are studied. In other words, in contrast to the previous studies, solutions with infinite switching in finite time along the facets and on(More)