On Scenario Formalisms for Automated Driving
Christian Neurohr, Lukas Westhofen, Tjark Koopmann, Eike Möhlmann, Eckard Böde, Axel Hahn
TL;DR
This paper addresses ambiguities in how concrete, logical, and abstract scenarios are defined and used in automated driving by proposing a formal unification framework that models each qualification: concrete scenarios as piecewise-continuous trajectories on a scene space, logical scenarios as parameterized instantiations, and abstract scenarios as declarative constraints over world models. It compares the formalisms along expressiveness, specification effort, sampling, and monitoring, showing that abstract scenarios can be more expressive and compact but may incur heavier sampling costs or rely on decision procedures, while logical scenarios are typically easier to sample but less expressive. The work provides practical guidance for selecting a formalism based on the task (sampling, monitoring, requirement specification) and discusses future directions including proofs, empirical comparisons, and intellectual-property considerations for world-model components. Overall, it establishes a formal basis to reason about scenario qualifications and informs practitioner choices for scenario-based ADS development and verification.
Abstract
The concept of scenario and its many qualifications -- specifically logical and abstract scenarios -- have emerged as a foundational element in safeguarding automated driving systems. However, the original linguistic definitions of the different scenario qualifications were often applied ambiguously, leading to a divergence between scenario description languages proposed or standardized in practice and their terminological foundation. This resulted in confusion about the unique features as well as strengths and weaknesses of logical and abstract scenarios. To alleviate this, we give clear linguistic definitions for the scenario qualifications concrete, logical, and abstract scenario and propose generic, unifying formalisms using curves, mappings to sets of curves, and temporal logics, respectively. We demonstrate that these formalisms allow pinpointing strengths and weaknesses precisely by comparing expressiveness, specification complexity, sampling, and monitoring of logical and abstract scenarios. Our work hence enables the practitioner to comprehend the different scenario qualifications and identify a suitable formalism.