Scientific publications

The majority of research in control engineering considers periodic or time-triggered control systems with equidistant sample intervals. However, practical cases abound in which it is of interest to considerevent-driven control systems, where the sampling is event-triggered. Although there are various benefits of using event-driven control like reducing resource usage (e.

In component-based development, the correctness of a system depends on the correctness of the individual components and on their interactions. Model-based testing is a way of checking the correctness of a component by means of executing test cases that are systematically generated from a model of the component.

Development of computerized embedded control systems is difficult because it brings together systems theory, electrical engineering and computer science. The engineering and analysis approaches advocated by these disciplines are fundamentally different which complicates reasoning about e.g. performance at the system level.

The verification of cryptographic protocol specifications is an active research topic and has received much attention from the formal verification community. By contrast, the black-box testing of actual implementations of protocols, which is, arguably, as important as verification for ensuring the correct functioning of protocols in the “real” world, is little studied.

A system functions as part of a broader enterprise. For the design of a system understanding is required of its purpose within the enterprise, as well as of its internal functioning. Models are a means to create and capture understanding. Many different models are needed during the design of a system, from broad enterprise models down to detailed implementation models of components or functions.

In this paper, the stability of a Networked Control System (NCS) with time-varying delays is analyzed. A discretetime state-space model is used to analyze the dynamics of the NCS. The delay is introduced by the network itself and is assumed to be upperbounded by a fraction of the sample-time. A typical motion control example is presented in which the timevariation of the delay results in an unstable system, although for each fixed delay the system is stable.

Since testing is inherently incomplete, test selection is of vital importance. Coverage measures evaluate the quality of a test suite and help the tester select test cases with maximal impact at minimum cost. Existing coverage criteria for test suites are usually defined in terms of syntactic characteristics of the implementation under test or its specification.

In the past decades, many formal frameworks (e.g. timed automata and temporal logics) and techniques (e.g. model checking and theorem proving) have been proposed to model a real-time system and to analyze real-time properties of the model. However, due to the existence of ineliminable timing differences between the model and its realization, real-time properties verified in the model often cannot be preserved in itsrealization.