Francesco Bullo

  1. Cyber-Physical Attacks in Power Networks: Models, Fundamental Limitations and Monitor Design.

    Authors: Francesco Bullo, Fabio Pasqualetti, Florian Dörfler
    Subjects: Optimization and Control
    Abstract

    Future power networks will be characterized by safe and reliable
    functionality against physical malfunctions and cyber attacks. This paper
    proposes a unified framework and advanced monitoring procedures to detect and
    identify network components malfunction or measurements corruption caused by an
    omniscient adversary. We model a power system under cyber-physical attack as a
    linear time-invariant descriptor system with unknown inputs. Our attack model
    generalizes the prototypical stealth, (dynamic) false-data injection and replay
    attacks.

  2. Distributed Estimation and False Data Detection with Application to Power Networks.

    Authors: Francesco Bullo, Ruggero Carli, Fabio Pasqualetti
    Subjects: Optimization and Control
    Abstract

    This work presents a distributed method for control centers in a power
    network to estimate the operating condition of the power plant, and to
    ultimately determine the occurrence of threatening situations. State estimation
    has been recognized to be a fundamental task for network control centers to
    ensure correct and safe functionalities of power grids. We consider (static)
    state estimation problems, in which the state vector consists of the voltage
    magnitude and angle at all network buses.

  3. Kron Reduction of Graphs with Applications to Electrical Networks.

    Authors: Francesco Bullo, Florian Dorfler
    Subjects: Combinatorics
    Abstract

    Consider a weighted and undirected graph, possibly with self-loops, and its
    corresponding Laplacian matrix, possibly augmented with additional diagonal
    elements corresponding to the self-loops. The Kron reduction of this graph is
    again a graph whose Laplacian matrix is obtained by the Schur complement of the
    original Laplacian matrix with respect to a subset of nodes.

  4. Visibility maintenance via controlled invariance for leader-follower Dubins-like vehicles.

    Authors: Francesco Bullo, Fabio Morbidi, Domenico Prattichizzo
    Subjects: Multiagent Systems
    Abstract

    The paper studies the visibility maintenance problem (VMP) for a
    leader-follower pair of Dubins-like vehicles with input constraints, and
    proposes an original solution based on the notion of controlled invariance. The
    nonlinear model describing the relative dynamics of the vehicles is interpreted
    as linear uncertain system, with the leader robot acting as an external
    disturbance. The VMP is then reformulated as a linear constrained regulation
    problem with additive disturbances (DLCRP).

  5. Discrete Partitioning and Coverage Control for Gossiping Robots.

    Authors: Francesco Bullo, Paolo Frasca, Ruggero Carli, Joseph W. Durham
    Subjects: Robotics
    Abstract

    We propose distributed algorithms to automatically deploy a group of mobile
    robots to partition and provide coverage of a non-convex environment. To handle
    arbitrary non-convex environments, we represent them as connected graphs. Our
    partitioning and coverage algorithm requires only short-range, unreliable
    pairwise "gossip" communication among the agents. The algorithm has two
    components: (1) a motion protocol to ensure that each robot communicates with
    its neighbors at least sporadically, and (2) a pairwise partitioning rule to
    update territory ownership whenever two robots communicate.

  6. Multi-Agent Deployment for Visibility Coverage in Polygonal Environments with Holes.

    Authors: Francesco Bullo, Karl J. Obermeyer, Anurag Ganguli
    Subjects: Robotics
    Abstract

    This article presents a distributed algorithm for a group of robotic agents
    with omnidirectional vision to deploy into nonconvex polygonal environments
    with holes. Agents begin deployment from a common point, possess no prior
    knowledge of the environment, and operate only under line-of-sight sensing and
    communication. The objective of the deployment is for the agents to achieve
    full visibility coverage of the environment while maintaining line-of-sight
    connectivity with each other.

  7. Accuracy and Decision Time for a Class of Sequential Decision Aggregation Rule.

    Authors: Francesco Bullo, Sandra H. Dandach, Ruggero Carli
    Subjects: Applications
    Abstract

    This work focuses on decentralized decision making in a population of
    individuals each implementing the sequential probability ratio test. The
    individual decisions are combined into a decentralized decision via an
    aggregation rule chosen from a family of aggregation rules, denoted as q out of
    N rule. We study how the population size affects the performance of the
    decentralized decision making, i.e., the decision accuracy and time. In a group
    applying the q out of N, a global decision is reached as soon as q out of the N
    decision makers agree on an answer.

  8. Distributed Abstract Optimization via Constraints Consensus: Theory and Applications.

    Authors: Francesco Bullo, Giuseppe Notarstefano
    Subjects: and Cluster Computing, Distributed, Parallel
    Abstract

    Distributed abstract programs are a novel class of distributed optimization
    problems where (i) the number of variables is much smaller than the number of
    constraints and (ii) each constraint is associated to a network node. Abstract
    optimization programs are a generalization of linear programs that captures
    numerous geometric optimization problems.

  9. Transient Stability Analysis in Power Networks and Synchronization of Non-uniform Kuramoto Oscillators.

    Authors: Francesco Bullo, Florian Dorfler
    Subjects: Optimization and Control
    Abstract

    In the current discussion about the future smart power grid one of the major
    problems is that of transient stability, which is the power system's ability to
    maintain synchronism in the presence of transient disturbances. This paper
    proposes a novel network-based approach to this problem resulting in concise
    and purely algebraic conditions that relate transient stability of a power
    network to the underlying network parameters and state.

  10. Randomized Sensor Selection in Sequential Hypothesis Testing.

    Authors: Vaibhav Srivastava, Kurt Plarre, Francesco Bullo
    Subjects: Information Theory
    Abstract

    We consider the problem of sensor selection for time-optimal detection of a
    hypothesis. We consider a group of sensors transmitting their observations to a
    fusion center. The fusion center considers the output of only one randomly
    chosen sensor at the time, and performs a sequential hypothesis test. We
    consider the class of sequential tests which are easy to implement,
    asymptotically optimal, and computationally amenable. For three distinct
    performance metrics, we show that, for a generic set of sensors and binary
    hypothesis, the fusion center needs to consider at most two sensors.

  11. Randomized Sensor Selection in Sequential Hypothesis Testing.

    Authors: Vaibhav Srivastava, Kurt Plarre, Francesco Bullo
    Subjects: Information Theory
    Abstract

    We consider the problem of sensor selection for time-optimal detection of a
    hypothesis. We consider a group of sensors transmitting their observations to a
    fusion center. The fusion center considers the output of only one randomly
    chosen sensor at the time, and performs a sequential hypothesis test. We
    consider the class of sequential tests which are easy to implement,
    asymptotically optimal, and computationally amenable. For three distinct
    performance metrics, we show that, for a generic set of sensors and binary
    hypothesis, the fusion center needs to consider at most two sensors.

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