Control Barrier Functions and Input-to-State Safety with Application to Automated Vehicles

TL;DR

This paper introduces a constructive control synthesis method using Control Barrier Functions (CBF) and Input-to-State Safety (ISSf) to ensure safety and performance in automated vehicles, validated through simulation and real-world experiments.

Contribution

It develops a practical CBF design methodology for safety-critical control, incorporating robustness via ISSf, and demonstrates its application on a connected automated truck system.

Findings

Robust safety guarantees are maintained despite actuation disturbances.

The proposed approach achieves safety without sacrificing performance.

Experimental validation confirms effectiveness on an automotive system.

Abstract

Balancing safety and performance is one of the predominant challenges in modern control system design. Moreover, it is crucial to robustly ensure safety without inducing unnecessary conservativeness that degrades performance. In this work we present a constructive approach for safety-critical control synthesis via Control Barrier Functions (CBF). By filtering a hand-designed controller via a CBF, we are able to attain performant behavior while providing rigorous guarantees of safety. In the face of disturbances, robust safety and performance are simultaneously achieved through the notion of Input-to-State Safety (ISSf). We take a tutorial approach by developing the CBF-design methodology in parallel with an inverted pendulum example, making the challenges and sensitivities in the design process concrete. To establish the capability of the proposed approach, we consider the practical setting of safety-critical design via CBFs for a connected automated vehicle (CAV) in the form of a class-8 truck without a trailer. Through experimentation we see the impact of unmodeled disturbances in the truck's actuation system on the safety guarantees provided by CBFs. We characterize these disturbances and using ISSf, produce a robust controller that achieves safety without conceding performance. We evaluate our design both in simulation, and for the first time on an automotive system, experimentally.