Contracts as specifications for dynamical systems in driving variable form

This paper introduces assume/guarantee contracts on continuous-time control systems, hereby extending contract theories for discrete systems to certain new model classes and specifications. Contracts are regarded as formal characterizations of control specifications, providing an alternative to specifications in terms of dissipativity properties or set-invariance. The framework has the potential to capture a richer class of specifications more suitable for complex engineering systems. The proposed contracts are supported by results that enable the verification of contract implementation and the comparison of contracts. These results are illustrated by an example of a vehicle following system.Comment: 8 pages, 2 figures; minor changes in the final version, as accepted for publication in the Proceedings of the 2019 European Control Conference, Naples, Ital

Behavioural assume-guarantee contracts for linear dynamical systems

Motivated by the growing requirements on theoperation of complex engineering systems, we present con-tracts as specifications for continuous-time linear dynamicalsystems with inputs and outputs. A contract is defined asa pair of assumptions and guarantees, both characterized ina behavioural framework. The assumptions encapsulate theavailable information about the dynamic behaviour of theenvironment in which the system is supposed to operate, whilethe guarantees express the desired dynamic behaviour of thesystem when interconnected with relevant environments. Inaddition to defining contracts, we characterize contract imple-mentation, and we find necessary conditions for the existence ofan implementation. We also characterize contract refinement,which is used to characterize contract conjunction in two specialcases. These concepts are then illustrated by an example of avehicle following system