Simulation-based Verification of Autonomous Navigation Systems by Stepwise Scenario Extraction based on Risk Assessment

Abstract

　The safety assurance of autonomous vessels is a major issue for their implementation, and it is necessary to prove their equivalent safety compared to the existing vessels. Two “model-based approaches” are important to identify and quantify the risks of such complex systems: systemic risk analysis using descriptive models, and system simulation using numerical models. This paper proposes a method for defining test scenarios from risk assessment in the design phase of the autonomous vessel and shows the flow of simulation-based verification and validation (V&V) using model-based simulation. Specifically, we extended the System-Theoretic Process Analysis (STPA) and extracted specific risk-based critical scenarios. Then we picked up a specific scenario for the short-range voyage planning function and presented a simulation-based verification flow using a ship avoidance maneuvering simulator. The results of this study are expected to be utilized in discussions regarding the verification and certification process of autonomous systems and the functional requirements of the simulators for verification.