Modular assurance of an Autonomous Ferry using Contract-Based Design and Simulation-based Verification Principles

With the introduction of autonomous technology into our society, e.g. autonomous shipping, it is important to assess and assure the safety of autonomous systems in a real-world context. Simulation-based testing is a common approach to attempt to verify performance of autonomous systems, but assurance also requires formal evidence. This paper introduces the Assurance of Digital Assets (ADA) framework, a structured method for the assurance of digital assets, i.e. novel, complex, or intelligent systems enabled by digital technologies, using contract-based design. Results are shown for an autonomous ferry assurance case, focusing on collision avoidance during the ferry's transit. Further, we discuss the role of simulation-based testing in verifying compliance to contract specifications, to build the necessary evidence for an assurance case.