SQ-CBF: Signed Distance Functions for Numerically Stable Superquadric-Based Safety Filtering

Fuente: arXiv
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Main Authors: Zhao, Haocheng, Brunke, Lukas, Lagerquist, Oliver, Zhou, Siqi, Schoellig, Angela P.
Format: Preprint
Published: 2026
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author Zhao, Haocheng
Brunke, Lukas
Lagerquist, Oliver
Zhou, Siqi
Schoellig, Angela P.
author_facet Zhao, Haocheng
Brunke, Lukas
Lagerquist, Oliver
Zhou, Siqi
Schoellig, Angela P.
contents Ensuring safe robot operation in cluttered and dynamic environments remains a fundamental challenge. While control barrier functions provide an effective framework for real-time safety filtering, their performance critically depends on the underlying geometric representation, which is often simplified, leading to either overly conservative behavior or insufficient collision coverage. Superquadrics offer an expressive way to model complex shapes using a few primitives and are increasingly used for robot safety. To integrate this representation into collision avoidance, most existing approaches directly use their implicit functions as barrier candidates. However, we identify a critical but overlooked issue in this practice: the gradients of the implicit SQ function can become severely ill-conditioned, potentially rendering the optimization infeasible and undermining reliable real-time safety filtering. To address this issue, we formulate an SQ-based safety filtering framework that uses signed distance functions as barrier candidates. Since analytical SDFs are unavailable for general SQs, we compute distances using the efficient Gilbert-Johnson-Keerthi algorithm and obtain gradients via randomized smoothing. Extensive simulation and real-world experiments demonstrate consistent collision-free manipulation in cluttered and unstructured scenes, showing robustness to challenging geometries, sensing noise, and dynamic disturbances, while improving task efficiency in teleoperation tasks. These results highlight a pathway toward safety filters that remain precise and reliable under the geometric complexity of real-world environments.
format Preprint
id arxiv_https___arxiv_org_abs_2602_11049
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle SQ-CBF: Signed Distance Functions for Numerically Stable Superquadric-Based Safety Filtering
Zhao, Haocheng
Brunke, Lukas
Lagerquist, Oliver
Zhou, Siqi
Schoellig, Angela P.
Robotics
Ensuring safe robot operation in cluttered and dynamic environments remains a fundamental challenge. While control barrier functions provide an effective framework for real-time safety filtering, their performance critically depends on the underlying geometric representation, which is often simplified, leading to either overly conservative behavior or insufficient collision coverage. Superquadrics offer an expressive way to model complex shapes using a few primitives and are increasingly used for robot safety. To integrate this representation into collision avoidance, most existing approaches directly use their implicit functions as barrier candidates. However, we identify a critical but overlooked issue in this practice: the gradients of the implicit SQ function can become severely ill-conditioned, potentially rendering the optimization infeasible and undermining reliable real-time safety filtering. To address this issue, we formulate an SQ-based safety filtering framework that uses signed distance functions as barrier candidates. Since analytical SDFs are unavailable for general SQs, we compute distances using the efficient Gilbert-Johnson-Keerthi algorithm and obtain gradients via randomized smoothing. Extensive simulation and real-world experiments demonstrate consistent collision-free manipulation in cluttered and unstructured scenes, showing robustness to challenging geometries, sensing noise, and dynamic disturbances, while improving task efficiency in teleoperation tasks. These results highlight a pathway toward safety filters that remain precise and reliable under the geometric complexity of real-world environments.
title SQ-CBF: Signed Distance Functions for Numerically Stable Superquadric-Based Safety Filtering
topic Robotics
url https://arxiv.org/abs/2602.11049