Wachenfeld, Walther Hans Karl (2017)
How Stochastic can Help to Introduce Automated Driving.
Technische Universität Darmstadt
Dissertation, Erstveröffentlichung

Kurzbeschreibung (Abstract)

Status Quo: Automated systems will replace the human operator at different tasks in everyday life. From today’s perspective, these new technologies offer predicted but also unknown benefits. However, as every other new technology, also automated systems will have drawbacks for some stakeholders in our society. As long as new technologies are within readiness levels of research, their impact is mostly negligible. The technology readiness level of automated driving in road traffic is pushed forward strongly by many researchers and developers all over the world. Consequently, the demand for safety assurance gets urgent. From today’s perspective, a concept that evaluates the safety of automated driving in an affordable and meaningful way is missing. However, this concept is necessary to enable the introduction of automated driving to public road traffic. Objectives: The objective of this thesis is to improve the understanding of the challenge for safety assurance on automated vehicles. Therefore a concept is aimed for, that estimates the safety impact for the stakeholders of automated driving. Estimations are always based on assumptions and suffer from uncertainty. For that reason the concept needs to consider and express the underlying assumptions and uncertainties. Methodology: The methodology for reaching the objectives is formed around the core assumption of the concept: The safety of an Object under Test can be described by the parameter of a probability distribution. This parameter connects the number of events that result from driving a distance with the safety performance of the OuT. Based on this core assumption a model for safety evaluation is developed iteratively. First of all the relevant stakeholders that are influenced by the technology are identified and analyzed. The second step identifies measurable requirements for the safety of automated vehicles from the stakeholder’s perspectives. Based on this preliminary work on the one hand a usage strategy is defined that controls the introduction of automated vehicles. On the other hand an examination strategy is developed to evaluate whether this strategy enables the automation to meet the requirements. In step four the usage strategy is examined for the Autobahn automation being one representative use case. The results, meaning testing effort and introduction possibilities, are compared and discussed. A refinement of stakeholders as well as requirements is performed. Such a refinement is necessary as only a more precise and subtle analysis will lead to a share between efforts and benefits of the introduction of automated vehicles that forms a basis for the discussion on the safety assurance challenge. Results: The results of the thesis can be grouped into four mayor insights. Firstly, the number of rare events like accidents can be handled as being a product of a random experiment that depends on a safety performance of a traffic participant and the number of driven kilometers. From today’s perspective a falsification of this approach was not found and thus builds a simple first approach. Secondly, the statistical proof of safety based on real-world driving is not economically feasible before mass application of the automated vehicle. Thirdly, refinement of the requirements is necessary and justifiable to reduce the safety requirements. Splitting up the requirements of society and vehicle users leads to reduced testing efforts and an uncertainty-based usage strategy. This uncertainty most likely will reduce during usage, thus also enabling a statistical statement on safety at one point in future. Lastly, a method consisting of evaluation criteria as well as an introduction simulation is developed to examine proposed usage strategies. Thereby the possible safety impacts of the usage are studied. Conclusion: As the safety of automated driving cannot be proven statistically before introduction, the introduction needs to be performed despite and under consideration of an estimated uncertainty. This does not mean that the introduced vehicles are less safe compared to their benchmark; however during introduction it will be uncertain. As long as the uncertainty stays above a threshold a usage strategy that is included into the safety assurance concept is necessary. Such a usage strategy would be cautious and based on regular observation of the events encountered by introduced vehicles. Several challenges have been identified for the developed introduction concept of automated vehicles. Based on these challenges further work should mainly address two topics: 1. The identification and collection of data that is necessary for concept application. 2. The answer of an unavoidable question: How much harm, caused by a human built machine, is acceptable for the exposed humans?

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