Safe Control Synthesis via Input Constrained Control Barrier Functions

TL;DR

This paper proposes Input Constrained Control Barrier Functions (ICCBFs) for designing safety-critical controllers in nonlinear systems with input limits, enabling real-time safe control synthesis.

Contribution

It introduces ICCBFs as a generalization of Higher Order Control Barrier Functions, applicable to systems with non-uniform relative degrees.

Findings

ICCBFs effectively identify safe state subsets.

Controllers based on ICCBFs can be computed via quadratic programs.

Simulation results demonstrate practical applicability in vehicle and spacecraft scenarios.

Abstract

This paper introduces the notion of an Input Constrained Control Barrier Function (ICCBF), as a method to synthesize safety-critical controllers for non-linear control affine systems with input constraints. The method identifies a subset of the safe set of states, and constructs a controller to render the subset forward invariant. The feedback controller is represented as the solution to a quadratic program, which can be solved efficiently for real-time implementation. Furthermore, we show that ICCBFs are a generalization of Higher Order Control Barrier Functions, and thus are applicable to systems of non-uniform relative degree. Simulation results are presented for the adaptive cruise control problem, and a spacecraft rendezvous problem.