Rollback Support in Hyflow Modular Models

In this paper we develop an extension of the HYFLOW (Hybrid Flow System Specification) formalism, for providing rollback support to hybrid modular models. HYFLOW extension preserves formalism modularity enabling the co-simulation of hierarchical models. Rollback plays an important role in some numerical methods. Examples include predictor corrector integrators (PCIs), and zero detectors (ZDs). These methods require simulation time to move both forward and backward in order to compute better estimates for the numerical solutions. We present formalism semantics and a description of PCI and ZD methods.