Silent Testing for Safety Validation of Automated Driving in Field Operation

Abstract

The safety validation of automated vehicles is currently a major challenge, even though substantial achievements have been made. The credibility of the results of conventional approaches such as the real-world testing or the simulation-based testing is questioned despite enormous testing effort. Therefore, new approaches for safety assurance with a high degree of credibility, adaptability and applicability are thus pursued. Under this circumstance, the approach “Virtual Assessment of Automation in Field Operation” (VAAFO) for testing automated vehicles is motivated. The key idea of this approach is that an instance is in charge of driving a vehicle, while a virtual automated vehicle runs in parallel in a virtual world, receiving real sensor inputs but separated from the real actuators. The instance in charge in the real world can be either a human driver or an automated precursor or representative system. Thus, the virtual automated vehicle and the instance in charge make decisions simultaneously but independently. Based on this working principle, the driving function of an automated vehicle can be tested under real conditions without bringing any additional risks. The goal of the work is to develop and implement the approach and finally to determine its contribution to the safety validation of automated vehicles. During the development and implementation of the approach, four research questions are studied. How to guarantee a valid environmental representation for the virtual vehicle is the first research focus. Since the objects detected by sensors are related to the instance in charge, they cannot be directly used for the virtual vehicle in the case of state deviations between the instance in charge and the virtual vehicle. Therefore, the mapping of the environmental representation in the virtual world is investigated. To answer this research question, a coordinate transformation is performed, and the lifetime and the birth cycle of virtual vehicles as two key parameters are introduced. How to evaluate the safety of the virtual vehicle and identify critical scenarios is the second research focus. To address the second research question, triggers are derived and substantiated by a developed criticality index. The third research focus is the development of a suitable ring buffer and a modular framework for the approach. The determination of the coverage degree of the approach is the last research focus. In order to derive the application scope of the approach, simulations and real-world tests are performed. Finally, considering the coverage degree and the limits of applicability, the role of the VAAFO approach in the whole family of approaches for the safety validation of automated vehicles is determined. Lastly, further studies for the future are pointed out.