Comparing the Perception of Critical Longitudinal Distances Between Dynamic Driving Simulation, Test Track and Vehicle in the Loop

The choice of an appropriate research environment is a fundamental issue for research on advanced driver assistance system controllability which precedes questions regarding the criticality of test scenarios and the deduction of pass-fail-criteria. The methodological trade-off between research on test tracks and driving simulation cannot be resolved easily. While test track research allows for the analysis of human interaction with real vehicle dynamics, the investigation of safety-critical situations requires considerable technological efforts and is sometimes not feasible. E.g., the complexity of real-life urban scenarios cannot be readily replicated on a test track. These restrictions do not apply to driving simulations, but limitations concerning visual and vestibular feedback raise the question of external validity. To the best of our knowledge, the perception of critical longitudinal car following distances, as measured by time headway, has been investigated on a limited scope and not under highly standardized conditions. We aim to extend the knowledge in this domain. In our study, three test environments were compared: a dynamic driving simulator, a test track vehicle, and the novel Vehicle-In-the-Loop (VIL), which is a hybrid between a test track vehicle and a driving simulator. As a result, relative validity for the perception of distance measures was established between the test environments. However, time headways were generally judged to be more critical in both simulator environments compared to the test track – a finding that should be considered when conducting future research.