Projects

A Modelling and Simulation Based Approach to Dependable System Design

Abstract. Complex real-time system design needs to address dependability requirements, such as safety, reliability, and security. We introduce a modelling and simulation based approach which allows for the analysis and prediction of dependability constraints. Dependability can be improved by making use of fault tolerance techniques. The de-facto example in the real-time system literature of a pump control system in a mining environment is used to demonstrate our model-based approach. In particular, the system is modelled using the Discrete EVent system Specification (DEVS) formalism, and then extended to incorporate fault tolerance mechanisms. The modularity of the DEVS formalism facilitates this extension. The simulation demonstrates that the employed fault tolerance techniques are effective. That is, the system performs satisfactorily despite the presence of faults. This approach also makes it possible to make an informed choice between different fault tolerance techniques. Performance metrics are used to measure the reliability and safety of the system, and to evaluate the dependability achieved by the design. In our model-based development process, modelling, simulation and eventual deployment of the system are seamlessly integrated.^[*]

Mapping Traffic and Time Petri Net models onto TINA in AToM³

Abstract. This project describes an approach for analyzing any system whose behaviour explicitly depends on temporal parameters. These time-dependent systems may be modelled in the Time Petri Net formalism (TPN), and analyzed using such tools as TIme petri Net Analyser (TINA). The syntax of the TPN is meta-modelled in the Entity-Relationship Diagrams formalism (ER) and a visual modelling environment is produced using the Computer Automated Multi-Paradigm Modelling tool AToM³. Models constructed in this environment may be transformed into a textual representation imported by TINA for analysis purposes. Time Traffic (TT), a timed visual formalism for vehicle traffic networks, is introduced as an example of time-dependent system to be mapped onto TPN for subsequent analysis in TINA. A meta-model in ER and a visual modelling environment are also developed for this time-constrained system, and graph rewriting is used to transform TT models into TPN graphical, or further textual, models. Using TINA, a reachability graph can be constructed and analysis may be performed for the timed-system.^[*]

^[*]Technical papers are available. Email me for more information.