Controller synthesis for interconnected systems using parametric assume-guarantee contracts

In this paper we synthesize controllers for interconnected systems to enforce parametric assume-guarantee contracts (AGC), which encode behaviors of the systems in some parameter domains. In our approach to solve the design problem, we synthesize a controller for each component of the system so that it satisfies its own parametric AGC separately, and then define a mapping that generates the sequence of parameters for which the corresponding contracts are satisfied after interconnecting the components. Then if a small-gain like condition on the sequence of parameters hold, a parametric AGC is declared for the interconnected system. The classical small-gain theorem on bounded input bounded output (BIBO) stability is recovered by the obtained results showing the relation between the assume-guarantee reasoning and the small-gain approach. We also provide an example of a large-scale transportation system to illustrate our results.