[
    {
        "id": "authors:j6jkn-nj815",
        "collection": "authors",
        "collection_id": "j6jkn-nj815",
        "cite_using_url": "https://authors.library.caltech.edu/records/j6jkn-nj815",
        "type": "article",
        "title": "Combinatorial Control Barrier Functions: Nested Boolean and p-choose-r Compositions of Safety Constraints",
        "author": [
            {
                "family_name": "Ong",
                "given_name": "Pio",
                "orcid": "0000-0002-9665-1320",
                "clpid": "Ong-Pio"
            },
            {
                "family_name": "Lee",
                "given_name": "Haejoon",
                "orcid": "0009-0001-1330-5087"
            },
            {
                "family_name": "Molnar",
                "given_name": "Tamas G.",
                "orcid": "0000-0002-9379-7121"
            },
            {
                "family_name": "Panagou",
                "given_name": "Dimitra",
                "orcid": "0000-0002-4547-167X"
            },
            {
                "family_name": "Ames",
                "given_name": "Aaron D.",
                "orcid": "0000-0003-0848-3177",
                "clpid": "Ames-A-D"
            }
        ],
        "abstract": "<p>This letter investigates the problem of composing multiple control barrier functions (CBFs)&mdash;and matrix control barrier functions (MCBFs)&mdash;through logical and combinatorial operations. Standard CBF formulations naturally enable conjunctive (AND) combinations, but disjunctive (OR) and more general logical structures introduce nonsmoothness and possibly a combinatorial blow-up in the number of logical combinations. We introduce the framework of combinatorial CBFs that addresses p-choose-r safety specifications and their nested composition. The proposed framework ensures safety for the exact safe set in a scalable way, using the original number of primitive constraints. We establish theoretical guarantees on safety under these compositions, and we demonstrate their use on a patrolling problem in a multi-agent system.</p>",
        "doi": "10.1109/lcsys.2025.3640191",
        "issn": "2705 - 2710",
        "publisher": "IEEE",
        "publication": "IEEE Control Systems Letters",
        "publication_date": "2025-12-03",
        "volume": "9",
        "pages": "1-1"
    },
    {
        "id": "authors:63dth-90524",
        "collection": "authors",
        "collection_id": "63dth-90524",
        "cite_using_url": "https://authors.library.caltech.edu/records/63dth-90524",
        "type": "article",
        "title": "Characterizing Smooth Safety Filters via the Implicit Function Theorem",
        "author": [
            {
                "family_name": "Cohen",
                "given_name": "Max H.",
                "orcid": "0000-0001-6957-9645",
                "clpid": "Cohen-Max-H"
            },
            {
                "family_name": "Ong",
                "given_name": "Pio",
                "orcid": "0000-0002-9665-1320",
                "clpid": "Ong-Pio"
            },
            {
                "family_name": "Bahati",
                "given_name": "Gilbert",
                "clpid": "Bahati-Gilbert"
            },
            {
                "family_name": "Ames",
                "given_name": "Aaron D.",
                "orcid": "0000-0003-0848-3177",
                "clpid": "Ames-A-D"
            }
        ],
        "abstract": "<div class=\"abstract-text row g-0\">\n<div class=\"col-12\">\n<div class=\"u-mb-1\">\n<div>Optimization-based safety filters, such as control barrier function (CBF) based quadratic programs (QPs), have demonstrated success in controlling autonomous systems to achieve complex goals. These CBF-QPs can be shown to be continuous, but are generally not smooth, let alone continuously differentiable. In this letter, we present a general characterization of smooth safety filters &ndash; smooth controllers that guarantee safety in a minimally invasive fashion &ndash; based on the Implicit Function Theorem. This characterization leads to families of smooth universal formulas for safety-critical controllers that quantify the conservatism of the resulting safety filter, the utility of which is demonstrated through illustrative examples.</div>\n</div>\n</div>\n</div>",
        "doi": "10.1109/lcsys.2023.3341345",
        "issn": "2475-1456",
        "publisher": "IEEE",
        "publication": "IEEE Control Systems Letters",
        "publication_date": "2023-12-11",
        "volume": "7",
        "pages": "3890-3895"
    },
    {
        "id": "authors:6k18b-jpa21",
        "collection": "authors",
        "collection_id": "6k18b-jpa21",
        "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200706-084348576",
        "type": "article",
        "title": "Safety-Critical Event Triggered Control via Input-to-State Safe Barrier Functions",
        "author": [
            {
                "family_name": "Taylor",
                "given_name": "Andrew J.",
                "orcid": "0000-0002-5990-590X",
                "clpid": "Taylor-Andrew-J"
            },
            {
                "family_name": "Ong",
                "given_name": "Pio",
                "orcid": "0000-0002-9665-1320",
                "clpid": "Ong-Pio"
            },
            {
                "family_name": "Cort\u00e9s",
                "given_name": "Jorge",
                "orcid": "0000-0001-9582-5184",
                "clpid": "Cort\u00e9s-J"
            },
            {
                "family_name": "Ames",
                "given_name": "Aaron D.",
                "orcid": "0000-0003-0848-3177",
                "clpid": "Ames-A-D"
            }
        ],
        "abstract": "The efficient utilization of available resources while simultaneously achieving control objectives is a primary motivation in the event-triggered control paradigm. In many modern control applications, one such objective is enforcing the safety of a system. The goal of this paper is to carry out this vision by combining event-triggered and safety-critical control design. We discuss how a direct transcription, in the context of safety, of event-triggered methods for stabilization may result in designs that are not implementable on real hardware due to the lack of a minimum interevent time. We provide an example showing this phenomena and, building on the insight gained, propose an event-triggered control approach via Input-to-State Safe Barrier Functions that achieves safety while ensuring that interevent times are uniformly lower bounded.",
        "doi": "10.1109/lcsys.2020.3005101",
        "issn": "2475-1456",
        "publisher": "IEEE",
        "publication": "IEEE Control Systems Letters",
        "publication_date": "2021-07",
        "series_number": "3",
        "volume": "5",
        "issue": "3",
        "pages": "749-754"
    }
]