Validating Behavioral Requirements, Conditions, and Rules of Autonomous Systems with Scenario-Based Testing

Assuring the safety of autonomous vehicles is more and more approached by using scenario-based testing. Relevant driving situations are utilized here to fuel the argument that an autonomous vehicle behaves correctly. Many recent works focus on the specification, variation, generation, and execution of individual scenarios. However, it is still an open question if operational design domains, which describe the environmental conditions under which the system under test has to function, can be assessed with scenario-based testing. In this paper, we present open challenges and resulting research questions in the field of assuring the safety of autonomous vehicles. We have developed a toolchain that enables us to conduct scenario-based testing experiments based on scenario classification with temporal logic and driving data obtained from the CARLA simulator. We discuss the toolchain and present first results using analysis metrics like class coverage or distribution

No driver, No Regulation? --Online Legal Driving Behavior Monitoring for Self-driving Vehicles

Defined traffic laws must be respected by all vehicles. However, it is essential to know which behaviors violate the current laws, especially when a responsibility issue is involved in an accident. This brings challenges of digitizing human-driver-oriented traffic laws and monitoring vehicles' behaviors continuously. To address these challenges, this paper aims to digitize traffic law comprehensively and provide an application for online monitoring of legal driving behavior for autonomous vehicles. This paper introduces a layered trigger domain-based traffic law digitization architecture with digitization-classified discussions and detailed atomic propositions for online monitoring. The principal laws on a highway and at an intersection are taken as examples, and the corresponding logic and atomic propositions are introduced in detail. Finally, the digitized traffic laws are verified on the Chinese highway and intersection datasets, and defined thresholds are further discussed according to the driving behaviors in the considered dataset. This study can help manufacturers and the government in defining specifications and laws and can also be used as a useful reference in traffic laws compliance decision-making. Source code is available on https://github.com/SOTIF-AVLab/DOTL.Comment: 22 pages, 11 figure

Towards a Congruent Interpretation of Traffic Rules for Automated Driving - Experiences and Challenges

The homologation of automated driving systems for public roads requires a rigorous safety case. Regulations of the United Nations demand to demonstrate the compliance of the developed system with local traffic rules. Hence, evidences for this have to be delivered by means of formal proofs, online monitoring, and other verification techniques in the safety case. In order for such methods to be applicable traffic rules have to be made machine-interpretable. However, that pursuit is highly challenging. This work reports on our practical experiences regarding the formalization of a non-trivial part of the German road traffic act. We identify a central issue when formalizing traffic rules within a development process, coined as the congruence problem, which is concerned with the semantic equality of the legal and system interpretation of traffic rules. As our main contribution, we delineate potential challenges arising from the congruence problem, hence impeding a congruent yet formal interpretation of traffic rules. Finally, we aim to initiate discussions by highlighting steps to partially address these challenges

Capability-Based Routes for Autonomous Vehicles

The pursuit of vehicle automation is an ongoing trend in the automotive industry. Particularly challenging is the goal of introducing driverless autonomous vehicles (AVs) into road traffic. To realize this vision, a targeted development of autonomous driving functions is essential. However, a targeted development process is only possible if the driving functions are tailored as appropriately and completely as possible to the operational design domain (ODD). Regardless of use case, all AVs have one thing in common: driving at least one route from A to B - whether simple or complex. For operational purposes, it is therefore necessary to ensure that the driving requirements (DRs) of the potential routes within the ODD do not exceed the driving capabilities (DCs) of the AVs. Currently, there is no approach that accomplishes the identification of exceeded capabilities. This work presents a method for route-based specification of DRs and DCs for AVs. It addresses the core research question of how to identify routes with DRs that do not exceed the DCs of AVs. An initial analysis reveals the dependencies between route and DRs. Thereby, the scenery defined in the ODD is found to be a fundamental basis for the specification of behavioral requirements as part of the DRs. In combination with the applicable traffic rules, the scenery elements define the behavioral limits for AVs. These limits are specifically extracted and classified as behavioral demands from the scenery using an analysis of these combinations. To enable a route-based specification of DRs, the behavioral demands are modeled as behavior spaces and transformed into a generic map representation - the Behavior-Semantic Scenery Description (BSSD). Based on the BSSD, a method is developed that generates behavioral requirements based on the route-constrained concatenation of behavior spaces. As a result, in addition to the method itself, the associated behavioral requirements are available as a basis for the route-based specification of DRs and DCs. Constraints for the specification are defined by the developed concept for the matching of DRs and DCs. It is shown that the DRs are strongly dependent on the geometry and property of the scenery elements, so that equal behavioral requirements do not necessarily imply equal DRs. These dependencies are used for the specification enabling the definition of matching criteria for a selection of DRs and corresponding DCs. To realize the matching, a capability-based route search is developed and implemented. The route search incorporates all elaborated results of the work enabling the whole approach to be evaluated by applying it to a real road network. The evaluation shows that the identification of feasible routes for AVs based on the scenery is possible and which hurdles based on identified deficits still have to be overcome

Methodology for Specifying and Testing Traffic Rule Compliance for Automated Driving

The introduction of highly-automated driving functions promises to increase safety and comfort, but the safety validation remains an unsolved challenge. Here, the requirement is that the introduction does not reduce safety on public roads. This dissertation addresses one major aspect of road safety: traffic rule compliance. Even an automated vehicle must comply with existing traffic rules. The developed method enables automated testing of traffic rule compliance of automated driving functions. In the first part of the thesis, the state of the art for describing and formalizing behavioral rules is analyzed. A special challenge is posed by the different traffic rules depending on the traffic region. With existing approaches, a separate description and formalization of the behavior rules is necessary for each traffic region or even for individual traffic areas. This shows the necessity to develop new approaches for the abstraction and transferability of the behavioral rules in order to reduce the effort of testing and ensuring traffic rule compliance. The rule compliance criteria are to be integrated into the behavior specification within the functional specification. The objective of this thesis is to develop a method to formalize the limits of traffic rule compliance, based on which fail criteria for system testing are defined and applied. For this purpose, existing traffic rules are analyzed as a basis to identify which behavior constraints are imposed by the static traffic environment. Based on this, a semantic description that is transferable between traffic domains and that links the boundaries of traffic rule compliance to the static traffic environment is developed. The method involves deriving behavioral attributes from which the semantic behavior description is constructed. These behavioral attributes construct the behavior space that describes the boundaries of legally allowed behavior. Furthermore, methods for automated derivation of behavioral attributes from high definition maps are developed, thus extracting the behavioral requirement from an operational design domain. It is investigated which functionalities an automated vehicle has to provide to comply with the behavioral attributes. The attributes are then formalized to obtain quantifiable failure criteria of traffic rule compliance that can be used in automated testing. Finally, building on the state of the art, a test strategy for validating traffic rule conformance is presented. The explicit availability of the behavioral limits results in an advantage in the influence analysis of possible parameters for these tests. Finally, the developed method is applied to existing map material and to test drives with an automated vehicle prototype in order to investigate the practical applicability of the approach as well as the resulting gain in knowledge about traffic rule compliance testing. The developed approach allows to derive the behavioral specification with respect to traffic rule conformance as an essential part of the functional specification independent of the application domain. It is proven that the approach is able to test the traffic rule conformance of an automated vehicle in different test scenarios within an application domain. By applying the developed methodology, it was possible to identify defects in the investigated test vehicle with respect to rule understanding and compliance

Evaluation of Highway Geometrics Related to Large Trucks

One objective of this study was to determine the extent of highway safety and geometric problems associated with larger trucks using Kentucky\u27s highways. The accident analysis involved both a general analysis of all truck accidents statewide as well as the identification of specific high-accident locations. A second objective was to identify criteria which can be used in identifying roadway sections that cannot safely accommodate large trucks. The accident analysis given can be used to investigate locations which have a high number of truck accidents. The general accident statistics related to trucks can be used in the investigation of the high-accident locations to identify factors which may be contributing to the accident problem. The summary of information obtained from the review of literature can be used as a guide when determining the appropriate criteria to use in formalizing truck access criteria. For example, several references gave recommendations concerning lane width and horizontal curvature appropriate for highways that allowed large truck traffic

Sustainability of Informal Shuttle Transport in the City of Harare

This study sought to investigate the sustainability of informal shuttle transport in the city of Harare. Traditionally, the provision of public transport is considered to be government's responsibility. Due to lack of economic growth, rapid rise in urban population, and declining standards of living, government-provided public transport is often inadequate; it is the privately operated public transport modes that cater to the mobility needs of the population. Informal shuttle transport refers to small illegal vehicles that play part of taxes ferrying passengers within the city. These small vehicles do not follow most road traffic regulations but are always there when city people need transport and are a faster mode of urban transport. This informal shuttle passenger transport sector, however, is not sufficiently acknowledged due to a number of reasons including lack of proper passenger transport regulation, lack of road safety, highly polluting and a cause of traffic congestion. This paper unpacks challenges posed with informal public transport particularly those providing shuttle services within the central business district (CBD) of Harare. The paper then examines and recommends various strategies that can make such operators contribute to achieving sustainable urban transport system. Data was collected through unstructured interviews from key stakeholders in both private and public sector basically examining the relationship between the increase in informal shuttle transport and transport sustainability. Stakeholders agreed on the need to improve transport in Harare and proffered solutions which included mass transit, crafting of a policy framework to formalise informal shuttle transport operators, need for infrastructure improvements, institutional capacity and good governance among others. Key words: informal shuttle transport, congestion, sustainability, central business district, Harare, economic growth DOI: 10.7176/JESD/11-8-14 Publication date: April 30th 2020