Clustering Traffic Scenarios Using Mental Models as Little as Possible

Test scenario generation for testing automated and autonomous driving systems requires knowledge about the recurring traffic cases, known as scenario types. The most common approach in industry is to have experts create lists of scenario types. This poses the risk both that certain types are overlooked; and that the mental model that underlies the manual process is inadequate. We propose to extract scenario types from real driving data by clustering recorded scenario instances, which are composed of timeseries. Existing works in the domain of traffic data either cannot cope with multivariate timeseries; are limited to one or two vehicles per scenario instance; or they use handcrafted features that are based on the mental model of the data scientist. The latter suffers from similar shortcomings as manual scenario type derivation. Our approach clusters scenario instances relying as little as possible on a mental model. As such, we consider the approach an important complement to manual scenario type derivation. It may yield scenario types overlooked by the experts, and it may provide a different segmentation of a whole set of scenarios instances into scenario types, thus overall increasing confidence in the handcrafted scenario types. We present the application of the approach to a real driving dataset.