Author
Daniel J. Stilwell
Other affiliations: Mitre Corporation, University of Virginia, United States Naval Academy ...read more
Bio: Daniel J. Stilwell is an academic researcher from Virginia Tech. The author has contributed to research in topics: Remotely operated underwater vehicle & Network topology. The author has an hindex of 27, co-authored 139 publications receiving 3872 citations. Previous affiliations of Daniel J. Stilwell include Mitre Corporation & University of Virginia.
Papers published on a yearly basis
Papers
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TL;DR: Simultaneous tracking and formation control is addressed for a team of autonomous agents that evolve dynamically in a space containing a measurable vector field with dual goals of driving the average field measurement to a specified value and maintaining a desired formation about the average.
313 citations
TL;DR: Skufca and Bollt as mentioned in this paper showed that a time-varying network could propagate sufficient in time varying networks in a time varying network, which is similar to our work.
Abstract: In previous work [J D Skufca and E Bollt, Mathematical Biosciences and Engineering, 1 (2004), pp 347-359], empirical evidence indicated that a time-varying network could propagate sufficient in
311 citations
TL;DR: This work examines the consensus problem for a group of agents that communicate via a stochastic information network that is modeled as a weighted directed random graph that switches periodically.
Abstract: We examine the consensus problem for a group of agents that communicate via a stochastic information network. Communication among agents is modeled as a weighted directed random graph that switches periodically. The existence of any edge is probabilistic and independent from the existence of any other edge. We further allow each edge to be weighted differently. Sufficient conditions for asymptotic almost sure consensus are presented for the case of positive weights and for the case of arbitrary weights.
304 citations
TL;DR: In this paper, a decentralized control design methodology for regulating global functions of cooperating mobile systems is presented, which leads to a novel broadcast-only communication structure, where the feedback mechanism between vehicles is the measurement of the global variables and broadcast of their integrated values.
Abstract: We have presented a decentralized control design methodology for regulating global functions of cooperating mobile systems The application of relatively standard system-theoretic tools, leads to a novel broadcast-only communication structure The feedback mechanism between vehicles is the measurement of the global variables and broadcast of their integrated values More generally, the methods presented allow the designer to determine what explicit communication strategies are sufficient for a stabilizing decentralized control to exist Using a simplified model, we showed that it is indeed possible to regulate global variables of a platoon of autonomous underwater vehicles, in particular, the center of the platoon and the distribution of the vehicles about the center A relatively small amount of explicit communication is required between vehicles and that no vehicle must regulate its actual position Further, the approach presented is scalable to any number of cooperating vehicles without the need for additional communication, although there is a practical limit on the size of the platoon
298 citations
TL;DR: It is shown that a time-varying network could propagate sufficient in a discrete-time model to model the response of the immune system to disease.
Abstract: In previous work, empirical evidence indicated that a time-varying network could propagate sufficient information to allow synchronization of the sometimes coupled oscillators, despite an instantaneously disconnected topology. We prove here that if the network of oscillators synchronizes for the static time-average of the topology, then the network will synchronize with the time-varying topology if the time-average is achieved sufficiently fast. Fast switching, fast on the time-scale of the coupled oscillators, overcomes the descychnronizing decoherence suggested by disconnected instantaneous networks. This result agrees in spirit with that of where empirical evidence suggested that a moving averaged graph Laplacian could be used in the master-stability function analysis. A new fast switching stability criterion here-in gives sufficiency of a fast-switching network leading to synchronization. Although this sufficient condition appears to be very conservative, it provides new insights about the requirements for synchronization when the network topology is time-varying. In particular, it can be shown that networks of oscillators can synchronize even if at every point in time the frozen-time network topology is insufficiently connected to achieve synchronization.
291 citations
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TL;DR: The major concepts and results recently achieved in the study of the structure and dynamics of complex networks are reviewed, and the relevant applications of these ideas in many different disciplines are summarized, ranging from nonlinear science to biology, from statistical mechanics to medicine and engineering.
9,441 citations
TL;DR: In this article, a wide list of topics ranging from opinion and cultural and language dynamics to crowd behavior, hierarchy formation, human dynamics, and social spreading are reviewed and connections between these problems and other, more traditional, topics of statistical physics are highlighted.
Abstract: Statistical physics has proven to be a fruitful framework to describe phenomena outside the realm of traditional physics. Recent years have witnessed an attempt by physicists to study collective phenomena emerging from the interactions of individuals as elementary units in social structures. A wide list of topics are reviewed ranging from opinion and cultural and language dynamics to crowd behavior, hierarchy formation, human dynamics, and social spreading. The connections between these problems and other, more traditional, topics of statistical physics are highlighted. Comparison of model results with empirical data from social systems are also emphasized.
3,840 citations
TL;DR: This work offers a comprehensive review on both structural and dynamical organization of graphs made of diverse relationships (layers) between its constituents, and cover several relevant issues, from a full redefinition of the basic structural measures, to understanding how the multilayer nature of the network affects processes and dynamics.
2,669 citations
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TL;DR: This paper proposes gradient descent algorithms for a class of utility functions which encode optimal coverage and sensing policies which are adaptive, distributed, asynchronous, and verifiably correct.
Abstract: This paper presents control and coordination algorithms for groups of vehicles. The focus is on autonomous vehicle networks performing distributed sensing tasks where each vehicle plays the role of a mobile tunable sensor. The paper proposes gradient descent algorithms for a class of utility functions which encode optimal coverage and sensing policies. The resulting closed-loop behavior is adaptive, distributed, asynchronous, and verifiably correct.
2,198 citations
TL;DR: In this article, a distributed observer-type consensus protocol based on relative output measurements is proposed to solve the consensus problem of multi-agent systems with a time-invariant communication topology consisting of general linear node dynamics.
Abstract: This paper addresses the consensus problem of multiagent systems with a time-invariant communication topology consisting of general linear node dynamics. A distributed observer-type consensus protocol based on relative output measurements is proposed. A new framework is introduced to address in a unified way the consensus of multiagent systems and the synchronization of complex networks. Under this framework, the consensus of multiagent systems with a communication topology having a spanning tree can be cast into the stability of a set of matrices of the same low dimension. The notion of consensus region is then introduced and analyzed. It is shown that there exists an observer-type protocol solving the consensus problem and meanwhile yielding an unbounded consensus region if and only if each agent is both stabilizable and detectable. A multistep consensus protocol design procedure is further presented. The consensus with respect to a time-varying state and the robustness of the consensus protocol to external disturbances are finally discussed. The effectiveness of the theoretical results is demonstrated through numerical simulations, with an application to low-Earth-orbit satellite formation flying.
2,096 citations