Diagnosability of Fuzzy Discrete Event Systems

In order to more effectively cope with the real-world problems of vagueness, {\it fuzzy discrete event systems} (FDESs) were proposed recently, and the supervisory control theory of FDESs was developed. In view of the importance of failure diagnosis, in this paper, we present an approach of the failure diagnosis in the framework of FDESs. More specifically: (1) We formalize the definition of diagnosability for FDESs, in which the observable set and failure set of events are {\it fuzzy}, that is, each event has certain degree to be observable and unobservable, and, also, each event may possess different possibility of failure occurring. (2) Through the construction of observability-based diagnosers of FDESs, we investigate its some basic properties. In particular, we present a necessary and sufficient condition for diagnosability of FDESs. (3) Some examples serving to illuminate the applications of the diagnosability of FDESs are described. To conclude, some related issues are raised for further consideration.Comment: 14 pages; revisions have been mad

Graph Transformation for Domain-Specific Discrete Event Time Simulation

Proceedings of: Fifth International Conference on Graph Transformation (ICGT 2010). Enschede, The Netherlands, September 27–October 2, 2010.Graph transformation is being increasingly used to express the semantics of domain specific visual languages since its graphical nature makes rules intuitive. However, many application domains require an explicit handling of time in order to represent accurately the behaviour of the real system and to obtain useful simulation metrics. Inspired by the vast knowledge and experience accumulated by the discrete event simulation community, we propose a novel way of adding explicit time to graph transformation rules. In particular, we take the event scheduling discrete simulation world view and incorporate to the rules the ability of scheduling the occurrence of other rules in the future. Hence, our work combines standard, efficient techniques for discrete event simulation (based on the handling of a future event set) and the intuitive, visual nature of graph transformation. Moreover, we show how our formalism can be used to give semantics to other timed approaches.Work partially sponsored by the Spanish Ministry of Science and Innovation, under project “METEORIC” (TIN2008-02081) and mobility grants JC2009-00015 and PR2009-0019, as well as by the R&D programme of the Community of Madrid, project “e-Madrid” (S2009/TIC-1650).Publicad

Control Barrier Function-based Lateral Control of Autonomous Vehicle for Roundabout Crossing

A lateral control scheme is presented to control Autonomous Vehicles (AVs) utilizing the nonlinear dynamics of the vehicle, based on the concepts of Control Lyapunov Functions (CLFs) to enforce stability and High Order Control Barrier Functions (HOCBFs) to impose safety constraints for the vehicle. The control input is then calculated using Quadratic Programming (QP) optimization while limiting the control input due to vehicle limitations and passenger comfort at a roundabout crossing. Simulation results are presented to show the performance of the proposed lateral controllerQatar Foundation; Qatar National Research FundScopu

Smart Cities [Scanning the Issue]

This special issue brings together recent international research on one of the most challenging and multidisciplinary subjects of present and future engineering, architectural, medical, economic, information, and social sciences: the smart city paradigm