Guaranteeing timeliness in safety critical real-time systems

A method to guarantee the timeliness property of a set of real-time tasks is introduced. The approach is based on a model for real-time tasks and on the definition of the parallel composition of tasks, i.e. the synchronized product operator. The operator composes the state-transition diagrams of the casks in order to represent their interactions together with the associated set of timeliness constraints. For analyzing the schedulability of tasks executed in parallel, we then generate thanks to the use of the synchronized product a set of linear constraints that has to be solved. This work is done in the framework of the OASIS(1) project for the design of more reliable and safer nuclear plant control systems. Copyright (C) 1998 IFAC.