Feasibility-Guaranteed Safety-Critical Control with Applications to Heterogeneous Platoons

TL;DR

This paper introduces a new control method that guarantees safety and feasibility for systems with tight control bounds, demonstrated on a heterogeneous vehicle platoon with adaptive cruise control.

Contribution

It proposes a novel feasibility constraint and a new type of Control Barrier Function to ensure QP feasibility under safety constraints in general cases.

Findings

Guarantees QP feasibility and safety in control systems.

Successfully applied to heterogeneous vehicle platoons.

Produces smooth control transitions without abrupt changes.

Abstract

This paper studies safety and feasibility guarantees for systems with tight control bounds. It has been shown that stabilizing an affine control system while optimizing a quadratic cost and satisfying state and control constraints can be mapped to a sequence of Quadratic Programs (QPs) using Control Barrier Functions (CBF) and Control Lyapunov Functions (CLF). One of the main challenges in this method is that the QP could easily become infeasible under safety constraints of high relative degree, especially under tight control bounds. Recent work focused on deriving sufficient conditions for guaranteeing feasibility. The existing results are case-dependent. In this paper, we consider the general case. We define a feasibility constraint and propose a new type of CBF to enforce it. Our method guarantees the feasibility of the above mentioned QPs, while satisfying safety requirements. We demonstrate the proposed method on an Adaptive Cruise Control (ACC) problem for a heterogeneous platoon with tight control bounds, and compare our method to existing CBF-CLF approaches. The results show that our proposed approach can generate gradually transitioned control (without abrupt changes) with guaranteed feasibility and safety.