Extending Grafcet for the specification of control of hybrid systems

Grafcet is a powerful graphical language dedicated to the specification of the behaviour of sequential logical systems. In industrial applications it is often used with systems which are not purely sequential but also include continuous parts. We propose extensions to Grafcet in order to allow the specification of hybrid systems. In this hybrid Grafcet, continuous behaviours specified by Laplace transfer functions or state equations can be associated with steps as "continuous actions" initialisations of the differential equations are specified by instantaneous actions and the value of continuous variables can be used in transitions-conditions. The consistency of the specification is checked by the calculus of the underlying hybrid automata with special emphasis on the problem of stability.