Risk-Based Safety Envelopes for Autonomous Vehicles Under Perception Uncertainty

Ensuring the safety of autonomous vehicles remains challenging given the uncertainty in sensing other road users. Moreover, separate safety specifications for perception and planning components impede assessing the overall system safety. This work provides a probabilistic approach to calculate safety envelopes under perception uncertainty. The probabilistic envelope definition is based on a risk threshold. It limits the cumulative probability that the actual safety envelope in a fully observable environment is physically more extensive than the applied envelope and is solved using iterative worst-case analysis of envelopes. Our approach extends non-probabilistic envelopes - in this work, the responsibility-sensitive safety (RSS) framework - to handle uncertainties. To evaluate the probabilistic envelope approach, we compare it in a simulated highway merging scenario against several baseline safety architectures. Our evaluation shows that our model allows adjusting safety and performance based on a chosen risk level and the level of sensing uncertainty. We conclude with an outline of how to formally argue safety under perception uncertainty using our formulation of envelope violation risk.