A framework for definition of logical scenarios for safety assurance of automated driving

Abstract

Objective: In order to introduce automated vehicles on public roads, it is necessary to ensure that these vehicles are safe to operate in traffic. One challenge is to prove that all physically possible variations of situations can be handled safely within the operational design domain of the vehicle. A promising approach to handling the set of possible situations is to identify a manageable number of logical scenarios, which provide an abstraction for object properties and behavior within the situations. These can then be transferred into concrete scenarios defining all parameters necessary to reproduce the situation in different test environments. Methods: This article proposes a framework for defining safety-relevant scenarios based on the potential collision between the subject vehicle and a challenging object, which forces the subject vehicle to depart from its planned course of action to avoid a collision. This allows defining only safety-relevant scenarios, which can directly be related to accident classification. The first criterion for defining a scenario is the area of the subject vehicle with which the object would collide. As a second criterion, 8 different positions around the subject vehicle are considered. To account for other relevant objects in the scenario, factors that influence the challenge for the subject vehicle can be added to the scenario. These are grouped as action constraints, dynamic occlusions, and causal chains. Results: By applying the proposed systematics, a catalog of base scenarios for a vehicle traveling on controlled-access highways has been generated, which can directly be linked to parameters in accident classification. The catalog serves as a basis for scenario classification within the PEGASUS project. Conclusions: Defining a limited number of safety-relevant scenarios helps to realize a systematic safety assurance process for automated vehicles. Scenarios are defined based on the point of the potential collision of a challenging object with the subject vehicle and its initial position. This approach allows defining scenarios for different environments and different driving states of the subject vehicle using the same mechanisms. A next step is the generation of logical scenarios for other driving states of the subject vehicle and for other traffic environments. ARTICLE HISTORY

Survey on Scenario-Based Safety Assessment of Automated Vehicles

“…The definition of logical scenarios based on a potential collision direction between the ego-vehicle and another vehicle is the subject of [67]. This methodology is developed especially for highway scenarios and can also include boundary conditions, such as an action restriction for the ego-vehicle due to other road users.…”

6-Layer Model for a Structured Description and Categorization of Urban Traffic and Environment

“…In all subsequent work ( [17]- [20]) Layer 3 is separated from the previous Layer 2 and describes solely tem-This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ This article has been accepted for publication in a future issue of this journal, but has not been fully edited.…”

“…However, [18] introduces a sixth layer for digital information. This sixth layer is later renamed 'Data and Communication' in [20], featuring the same definition as in the previous work. As [18] focuses on the highway use case, structural objects along the road, such as buildings, are not mentioned explicitly.…”

“…How the 6LM, as described in [18], can be used to develop a framework for scenario definition is shown in [20]. The work performed in [20] utilizes Layer 4 of the 6LM to define logical scenarios [15], [21] for controlled-access highways.…”

“…How the 6LM, as described in [18], can be used to develop a framework for scenario definition is shown in [20]. The work performed in [20] utilizes Layer 4 of the 6LM to define logical scenarios [15], [21] for controlled-access highways. Similarly, in [22] the layer model is used to develop a description language for functional scenarios and [23] uses the parameters on the individual layers to develop a structured concept to determine system-specific relevant testing scenarios.…”