Road to safe autonomy with data and formal reasoning

TL;DR

This paper reviews data-driven safety analysis tools for autonomous vehicles, combining model-based reachability with sensitivity analysis, demonstrated through emergency braking scenarios to verify safety and assess risk levels.

Contribution

It introduces a hybrid approach integrating reachability and sensitivity analysis for safety verification of autonomous vehicle systems, with practical case studies.

Findings

Effective safety verification of emergency braking scenarios

Quantified safety envelopes across various parameters

Combined reachability with statistical risk assessment

Abstract

We present an overview of recently developed data-driven tools for safety analysis of autonomous vehicles and advanced driver assist systems. The core algorithms combine model-based, hybrid system reachability analysis with sensitivity analysis of components with unknown or inaccessible models. We illustrate the applicability of this approach with a new case study of emergency braking systems in scenarios with two or three vehicles. This problem is representative of the most common type of rear-end crashes, which is relevant for safety analysis of automatic emergency braking (AEB) and forward collision avoidance systems. We show that our verification tool can effectively prove the safety of certain scenarios (specified by several parameters like braking profiles, initial velocities, uncertainties in position and reaction times), and also compute the severity of accidents for unsafe scenarios. Through hundreds of verification experiments, we quantified the safety envelope of the system across relevant parameters. These results show that the approach is promising for design, debugging and certification. We also show how the reachability analysis can be combined with statistical information about the parameters, to assess the risk level of the control system, which in turn is essential, for example, for determining Automotive Safety Integrity Levels (ASIL) for the ISO26262 standard.