Contract-based design of control protocols for safety-critical cyber-physical systems

We introduce a platform-based design methodology that addresses the complexity and heterogeneity of cyber-physical systems by using assume-guarantee contracts to formalize the design process and enable realization of control protocols in a hierarchical and compositional manner. Given the architecture of the physical plant to be controlled, the design is carried out as a sequence of refinement steps from an initial specification to a final implementation, including synthesis from requirements and mapping of higher-level functional and nonfunctional models into a set of candidate solutions built out of a library of components at the lower level. Initial top-level requirements are captured as contracts and expressed using linear temporal logic (LTL) and signal temporal logic (STL) formulas to enable requirement analysis and early detection of inconsistencies. Requirements are then refined into a controller architecture by combining reactive synthesis steps from LTL specifications with simulation-based design space exploration steps. We demonstrate our approach on the design of embedded controllers for aircraft electric power distribution.