Sensitivity of Automated Vehicle Operational Safety Assessment (OSA) Metrics to Measurement and Parameter Uncertainty

As the deployment of automated vehicles (AVs) on public roadways expands, there is growing interest in establishing metrics that can be used to evaluate vehicle operational safety. The set of Operational Safety Assessment (OSA) metrics, that include several safety envelope-type metrics, previously proposed by the Institute of Automated Mobility (IAM) are a step towards this goal. The safety envelope OSA metrics can be computed using kinematics derived from video data captured by infrastructure-based cameras and thus do not require on-board sensor data or vehicle-to-infrastructure (V2I) connectivity, though either of the latter data sources could enhance kinematic data accuracy. However, the calculation of some metrics includes certain vehicle-specific parameters that must be assumed or estimated if they are not known a priori or communicated directly by the vehicle. Uncertainty and errors in kinematic measurements and assumed parameters can influence the accuracy and ultimately the utility of the safety envelope metrics.

This paper investigates how sensitive the OSA safety envelope metrics are to errors and variations in measured and assumed variables, respectively. The metrics are introduced in the context of a car-following scenario, and data sources are discussed, though the sensitivity analyses are ultimately agnostic to the specific sensor modality employed. Results reveal that measurement and parameter uncertainty are especially important when vehicles are close to safety envelope thresholds or in congested driving conditions. The outcomes of this research can help to understand the effects of measurement uncertainty on OSA metrics calculations and inform the selection of suitable sensors and hardware for the accurate and reliable assessment of vehicle operational safety.