A Methodology for Mending Dynamic Constraint Violations in Cyber Physical Systems By Generating Model Transformations

Abstract

Cyber-Physical Systems (CPSs) are defined as the combination of computational elements with physical components. Systems that require communication, computation, and control are by definition CPSs. The complexity of these systems often grows exponentially as they incorporate more elements into their design. As such, many approaches to designing CPSs revolve around the development of Domain Specific Modeling Languages (DSMLs). DSMLs drastically reduce the development time for CPSs by abstracting elements of the development process to a high level. DSMLs can be constrained in such a way that it is impossible to construct structurally invalid models of CPSs. This allows designers to think abstractly and ignore time consuming low level implementation details. However, these methods do not prevent designers from constructing systems that can be invalid in other, more dynamic, ways. That is, structural constraints on a DSML for a CPS do not prevent constraint violations where some analysis must be performed on the system to verify that the constraint has been satisfied. In the state-of-the-art, it is violations on these dynamic constraints that modelers must spend their time designing around. Dynamic constraints can be incorporated into the framework of a DSML by integrating the concepts of automatic feedback control into the DSML with model transformations. The methodology that describes this new approach to Domain Specific Modeling (DSM) is called Dynamic Constraint Feedback (DCF). At a glance: first a DSML is created for a CPS. Next, an interface is developed for two-way interaction between the DSML and external tools. Third, an expert block that can perform analysis on the models is created. The expert block is responsible for determining constraint violations and solutions. Lastly, model transformations are generated based on expert block output and applied to the existing models. This process repeats until a solution is either found or declared to be unreachable.