On the relationship between control barrier functions and projected dynamical systems

TL;DR

This paper explores the connection between control barrier functions and projected dynamical systems, offering new insights for designing safe, stable controllers and enabling continuous implementations of projection-based methods.

Contribution

It establishes a theoretical link between CBF-controlled systems and PDSs, providing a new perspective for controller analysis and design.

Findings

CBF-controlled vector fields are perturbations of PDS set-valued maps

The approach aids in designing safe, stable controllers without undesired equilibria

Enables continuous implementation of projection-based controllers

Abstract

In this paper, we study the relationship between systems controlled via Control Barrier Function (CBF) approaches and a class of discontinuous dynamical systems, called Projected Dynamical Systems (PDSs). In particular, under appropriate assumptions, we show that the vector field of CBF-controlled systems is a Krasovskii-like perturbation of the set-valued map of a differential inclusion, that abstracts PDSs. This result provides a novel perspective to analyze and design CBF-based controllers. Specifically, we show how, in certain cases, it can be employed for designing CBF-based controllers that, while imposing safety, preserve asymptotic stability and do not introduce undesired equilibria or limit cycles. Finally, we briefly discuss about how it enables continuous implementations of certain projection-based controllers, that are gaining increasing popularity.