294 research outputs found
A Graph-Transformation Modelling Framework for Supervisory Control
Formal design methodologies have the potential to accelerate the development and increase the
reliability of supervisory controllers designed within industry. One promising design framework
which has been shown to do so is known as supervisory control synthesis (SCS).
In SCS, instead of manually designing the supervisory controller itself, one designs models of
the uncontrolled system and its control requirements. These models are then provided as input to
a special synthesis algorithm which uses them to automatically generate a model of the supervisory
controller. This outputted model is guaranteed to be correct as long as the models of the uncontrolled
system and its control requirements are valid. This accelerates development by removing
the need to verify and rectify the model of the supervisory controller. Instead, only the models of
the uncontrolled system and its requirements must be validated.
To address problems of scale, SCS can be applied in modular fashion, and implemented in
hierarchical and decentralized architectures.
Despite the large body of research con rming the bene ts of integrating SCS within the development
process of supervisory controllers, it has still not yet found widespread application within
industry. In the author's opinion, this is partly attributed to the non-user-friendly nature of the
automaton-based modelling framework used create the models of the uncontrolled system (and
control requirements in even-based SCS). It is believed that in order for SCS to become more accessible
to a wider range of non experts, modelling within SCS must be made more intuitive and
user-friendly.
To improve the usability of SCS, this work illustrates how a graph transformation-based modelling
approach can be employed to generate the automaton models required for supervisory control
synthesis. Furthermore, it is demonstrated how models of the speci cation can be intuitively represented
within our proposed modelling framework for both event- and state-based supervisory
control synthesis. Lastly, this thesis assesses the relative advantages brought about by the proposed
graph transformation-based modelling framework over the conventional automaton based modelling
approach
Stochastic hybrid system : modelling and verification
Hybrid systems now form a classical computational paradigm unifying discrete and continuous system aspects. The modelling, analysis and verification of these systems are very difficult.
One way to reduce the complexity of hybrid system models is to consider randomization. The need for stochastic models has actually multiple motivations. Usually, when building models complete information is not available and we have to consider stochastic versions. Moreover, non-determinism and uncertainty are inherent to complex systems. The stochastic approach can be thought of as a way of quantifying non-determinism (by assigning a probability to each
possible execution branch) and managing uncertainty. This is built upon to the - now classical - approach in algorithmics that provides polynomial complexity algorithms via randomization.
In this thesis we investigate the stochastic hybrid systems, focused on modelling and analysis.
We propose a powerful unifying paradigm that combines analytical and formal methods. Its
applications vary from air traffic control to communication networks and healthcare systems.
The stochastic hybrid system paradigm has an explosive development. This is because of its
very powerful expressivity and the great variety of possible applications. Each hybrid system model can be randomized in different ways, giving rise to many classes of stochastic hybrid systems.
Moreover, randomization can change profoundly the mathematical properties of discrete and continuous aspects and also can influence their interaction. Beyond the profound foundational and semantics issues, there is the possibility to combine and cross-fertilize techniques from analytic mathematics (like optimization, control, adaptivity, stability, existence and uniqueness of trajectories, sensitivity analysis) and formal methods (like bisimulation, specification, reachability
analysis, model checking). These constitute the major motivations of our research. We
investigate new models of stochastic hybrid systems and their associated problems. The main difference from the existing approaches is that we do not follow one way (based only on continuous or discrete mathematics), but their cross-fertilization. For stochastic hybrid systems we introduce concepts that have been defined only for discrete transition systems. Then, techniques
that have been used in discrete automata now come in a new analytical fashion. This is partly explained by the fact that popular verification methods (like theorem proving) can hardly work even on probabilistic extensions of discrete systems. When the continuous dimension is added, the idea to use continuous mathematics methods for verification purposes comes in a natural
way.
The concrete contribution of this thesis has four major milestones:
1. A new and a very general model for stochastic hybrid systems;
2. Stochastic reachability for stochastic hybrid systems is introduced together with an approximating method to compute reach set probabilities;
3. Bisimulation for stochastic hybrid systems is introduced and relationship with reachability analysis is investigated.
4. Considering the communication issue, we extend the modelling paradigm
Synchronous modeling of avionics applications using the SIGNAL language
International audienceIn this paper, we discuss a synchronous, component-based approach to the modeling of avionics applications. The specification of the components relies on the avionics standard ARINC 653 and the synchronous language SIGNAL is considered as modeling formalism. The POLYCHRONY tool-set allows for a seamless design process based on the SIGNAL model, which provides possibilities of high level specifications, verification and analysis of the specifications at very early stages of the design, and finally automatic code generation through formal transformations of these specifications. This suits the basic stringent requirements that should be met by any design environment for embedded applications in general, and avionics applications in particular
Encrypted control for networked systems -- An illustrative introduction and current challenges
Cloud computing and distributed computing are becoming ubiquitous in many
modern control systems such as smart grids, building automation, robot swarms
or intelligent transportation systems. Compared to "isolated" control systems,
the advantages of cloud-based and distributed control systems are, in
particular, resource pooling and outsourcing, rapid scalability, and high
performance. However, these capabilities do not come without risks. In fact,
the involved communication and processing of sensitive data via public networks
and on third-party platforms promote, among other cyberthreats, eavesdropping
and manipulation of data. Encrypted control addresses this security gap and
provides confidentiality of the processed data in the entire control loop. This
paper presents a tutorial-style introduction to this young but emerging field
in the framework of secure control for networked dynamical systems.Comment: The paper is a preprint of an accepted paper in the IEEE Control
Systems Magazin
Foundations of Software Science and Computation Structures
This open access book constitutes the proceedings of the 23rd International Conference on Foundations of Software Science and Computational Structures, FOSSACS 2020, which took place in Dublin, Ireland, in April 2020, and was held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2020. The 31 regular papers presented in this volume were carefully reviewed and selected from 98 submissions. The papers cover topics such as categorical models and logics; language theory, automata, and games; modal, spatial, and temporal logics; type theory and proof theory; concurrency theory and process calculi; rewriting theory; semantics of programming languages; program analysis, correctness, transformation, and verification; logics of programming; software specification and refinement; models of concurrent, reactive, stochastic, distributed, hybrid, and mobile systems; emerging models of computation; logical aspects of computational complexity; models of software security; and logical foundations of data bases.
Paradoxes of interactivity: perspectives for media theory, human-computer interaction, and artistic investigations
Current findings from anthropology, genetics, prehistory, cognitive and neuroscience indicate that human nature is grounded in a co-evolution of tool use, symbolic communication, social interaction and cultural transmission. Digital information technology has recently entered as a new tool in this co-evolution, and will probably have the strongest impact on shaping the human mind in the near future. A common effort from the humanities, the sciences, art and technology is necessary to understand this ongoing co- evolutionary process. Interactivity is a key for understanding the new relationships formed by humans with social robots as well as interactive environments and wearables underlying this process. Of special importance for understanding interactivity are human-computer and human-robot interaction, as well as media theory and New Media Art. "Paradoxes of Interactivity" brings together reflections on "interactivity" from different theoretical perspectives, the interplay of science and art, and recent technological developments for artistic applications, especially in the realm of sound
Paradoxes of Interactivity
Current findings from anthropology, genetics, prehistory, cognitive and neuroscience indicate that human nature is grounded in a co-evolution of tool use, symbolic communication, social interaction and cultural transmission. Digital information technology has recently entered as a new tool in this co-evolution, and will probably have the strongest impact on shaping the human mind in the near future. A common effort from the humanities, the sciences, art and technology is necessary to understand this ongoing co- evolutionary process. Interactivity is a key for understanding the new relationships formed by humans with social robots as well as interactive environments and wearables underlying this process. Of special importance for understanding interactivity are human-computer and human-robot interaction, as well as media theory and New Media Art. »Paradoxes of Interactivity« brings together reflections on »interactivity« from different theoretical perspectives, the interplay of science and art, and recent technological developments for artistic applications, especially in the realm of sound
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