Monitoring of Temporal Requirements with Stocharts Observation Patterns, Application to a Level Crossing Control System

Abstract

Works in the field of verification systems have shown the critical importance of time. The non-satisfaction of time may have important consequences for both security and performance points of view. For automated systems with level of security, the verification of time requirements is an essential part of the process validation system. In this paper, we are laying the foundations for a new and systematic approach for the verification of discrete event systems with time constraints. The contribution of this approach is threefold: first, unlike existing approaches, it allows for the verification of several requirements at once. Therefore, the approach is generic because we focus on developing mechanisms that take into account different types of requirements rather than the system to be verified. Finally, the implementation of the approach is almost as systematic because the verification tools we are developing are based on the instantiation of patterns. These patterns are designed on the basis of a classification of temporal requirements that we have established. The concepts of parallelism and hierarchy which characterize the Stocharts formalism compared to other state-transitions models help us build the foundations of our approach. An example of application to the control-command in the railway field is presented to illustrate the key concepts of our approach and its implementation.