Stability Margins of CBF-QP Safety Filters: Analysis and Synthesis

Fuente: arXiv
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Hauptverfasser: Mousavi, Shima Sadat, Mestres, Pol, Ames, Aaron D.
Format: Preprint
Veröffentlicht: 2026
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author Mousavi, Shima Sadat
Mestres, Pol
Ames, Aaron D.
author_facet Mousavi, Shima Sadat
Mestres, Pol
Ames, Aaron D.
contents Control barrier function (CBF)-QP safety filters enforce safety by minimally modifying a nominal controller. While prior work has mainly addressed robustness of safety under uncertainty, robustness of the resulting closed-loop \emph{stability} is much less understood. This issue is important because once the safety filter becomes active, it modifies the nominal dynamics and can reduce stability margins or even destabilize the system, despite preserving safety. For linear systems with a single affine safety constraint, we show that the active-mode dynamics admit an exact scalar loop representation, leading to a classical robust-control interpretation in terms of gain, phase, and delay margins. This viewpoint yields exact stability-margin characterizations and tractable linear matrix inequality (LMI)-based certificates and synthesis conditions for controllers with certified robustness guarantees. Numerical examples illustrate the proposed analysis and the enlargement of certified stability margins for safety-filtered systems.
format Preprint
id arxiv_https___arxiv_org_abs_2604_04234
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Stability Margins of CBF-QP Safety Filters: Analysis and Synthesis
Mousavi, Shima Sadat
Mestres, Pol
Ames, Aaron D.
Systems and Control
Optimization and Control
Control barrier function (CBF)-QP safety filters enforce safety by minimally modifying a nominal controller. While prior work has mainly addressed robustness of safety under uncertainty, robustness of the resulting closed-loop \emph{stability} is much less understood. This issue is important because once the safety filter becomes active, it modifies the nominal dynamics and can reduce stability margins or even destabilize the system, despite preserving safety. For linear systems with a single affine safety constraint, we show that the active-mode dynamics admit an exact scalar loop representation, leading to a classical robust-control interpretation in terms of gain, phase, and delay margins. This viewpoint yields exact stability-margin characterizations and tractable linear matrix inequality (LMI)-based certificates and synthesis conditions for controllers with certified robustness guarantees. Numerical examples illustrate the proposed analysis and the enlargement of certified stability margins for safety-filtered systems.
title Stability Margins of CBF-QP Safety Filters: Analysis and Synthesis
topic Systems and Control
Optimization and Control
url https://arxiv.org/abs/2604.04234