Proxy Control Barrier Functions: Integrating Barrier-Based and Lyapunov-Based Safety-Critical Control Design

TL;DR

This paper presents a new Proxy Control Barrier Function (PCBF) approach that combines barrier and Lyapunov methods for safety-critical control of systems with unknown dynamics, using a modular design and disturbance observer.

Contribution

It introduces a novel PCBF scheme that integrates barrier and Lyapunov controllers with a disturbance observer, simplifying CBF construction for complex systems.

Findings

Ensures system safety through integrated control design.

Broadens applicability of CBF methods to systems with unknown dynamics.

Validated effectiveness via numerical simulations.

Abstract

This work introduces a novel Proxy Control Barrier Function (PCBF) scheme that integrates barrier-based and Lyapunov-based safety-critical control strategies for strict-feedback systems with potentially unknown dynamics. The proposed method employs a modular design procedure, decomposing the original system into a proxy subsystem and a virtual tracking subsystem that are controlled by the control barrier function (CBF)-based and Lyapunov-based controllers, respectively. By integrating these separately designed controllers, the overall system's safety is ensured. Moreover, a new filter-based disturbance observer is utilized to design a PCBF-based safe controller for strict-feedback systems subject to mismatched disturbances. This approach broadens the class of systems to which CBF-based methods can be applied and significantly simplifies CBF construction by requiring only the model of the proxy subsystem. The effectiveness of the proposed method is demonstrated through numerical simulations.