Results 1  10
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10
Flocking in Fixed and Switching Networks
, 2003
"... The work of this paper is inspired by the flocking phenomenon observed in Reynolds (1987). We introduce a class of local control laws for a group of mobile agents that result in: (i) global alignment of their velocity vectors, (ii) convergence of their speeds to a common one, (iii) collision avoidan ..."
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Cited by 73 (7 self)
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The work of this paper is inspired by the flocking phenomenon observed in Reynolds (1987). We introduce a class of local control laws for a group of mobile agents that result in: (i) global alignment of their velocity vectors, (ii) convergence of their speeds to a common one, (iii) collision avoidance, and (iv) minimization of the agents artificial potential energy. These are made possible through local control action by exploiting the algebraic graph theoretic properties of the underlying interconnection graph. Algebraic connectivity a#ects the performance and robustness properties of the overall closed loop system. We show how the stability of the flocking motion of the group is directly associated with the connectivity properties of the interconnection network and is robust to arbitrary switching of the network topology.
On the Stability of the Kuramoto Model of Coupled Nonlinear Oscillators
 In Proceedings of the American Control Conference
, 2004
"... We provide a complete analysis of the Kuramoto model of coupled nonlinear oscillators with uncertain natural frequencies and arbitrary interconnection topology. Our work extends and supersedes existing, partial results for the case of an alltoall connected network. Using tools from spectral gra ..."
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Cited by 58 (8 self)
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We provide a complete analysis of the Kuramoto model of coupled nonlinear oscillators with uncertain natural frequencies and arbitrary interconnection topology. Our work extends and supersedes existing, partial results for the case of an alltoall connected network. Using tools from spectral graph theory and control theory, we prove that for couplings above a critical value all the oscillators synchronize, resulting in convergence of all phase di#erences to a constant value, both in the case of identical natural frequencies as well as uncertain ones. We further explain the behavior of the system as the number of oscillators grows to infinity.
Stable Flocking of Mobile Agents, Part II: Dynamic Topology
 In IEEE Conference on Decision and Control
, 2003
"... This is the second of a twopart paper, investigating the stability properties of a system of multiple mobile agents with double integrator dynamics. In this second part, we allow the topology of the control interconnections between the agents in the group to vary with time. Specifically, the contro ..."
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Cited by 49 (5 self)
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This is the second of a twopart paper, investigating the stability properties of a system of multiple mobile agents with double integrator dynamics. In this second part, we allow the topology of the control interconnections between the agents in the group to vary with time. Specifically, the control law of an agent depends on the state of a set of agents that are within a certain neighborhood around it. As the agents move around, this set changes giving rise to a dynamic control interconnection topology and a switching control law. This control law consists of a a combination of attractive/repulsive and alignment forces. The former ensure collision avoidance and cohesion of the group and the latter result to all agents attaining a common heading angle, exhibiting flocking motion. Despite the use of only local information and the time varying nature of agent interaction which affects the local controllers, flocking motion can still be established, as long as connectivity in the neighboring graph is maintained.
Stable flocking of multiple inertial agents on balanced graphs
 Computer Science, The University of Newcastle
, 2006
"... and the optimum value of max[P (0)] was max[P (0)] = 00:40844 < 0 which indicates that this system has no robustly unobservable states. For the optimal value of given above, a plot of max[P (t)] as a function of t is shown in Fig. 6. ..."
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Cited by 16 (3 self)
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and the optimum value of max[P (0)] was max[P (0)] = 00:40844 < 0 which indicates that this system has no robustly unobservable states. For the optimal value of given above, a plot of max[P (t)] as a function of t is shown in Fig. 6.
Agreement with NonUniform Information Delays
, 2006
"... We propose a novel agreement framework for multiple (possibly heterogeneous) agents evolving on a directed information graph with nonuniform delays. Our proposed framework can ensure agreement of a certain scalar quantity among the agents, as long as 1) for each agent, we can design a local contr ..."
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Cited by 7 (0 self)
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We propose a novel agreement framework for multiple (possibly heterogeneous) agents evolving on a directed information graph with nonuniform delays. Our proposed framework can ensure agreement of a certain scalar quantity among the agents, as long as 1) for each agent, we can design a local control s.t. its closedloop transfer function has unit gain at dc and gain strictly less than unity elsewhere; 2) the information graph has a globally reachable node (i.e. there exists a path from it to every other nodes); and 3) the information delays are finite constants. Rendezvous simulation is performed to verify the theory.
Stability of Flocking Motion
, 2003
"... This paper in vestigates the aggregated stability properties of of a system of multiple mobileagen ts described by simpledynleS55 systems. Theagen ts are steered through local coordin2Sfi5 con trol laws that arise as a combin7 tion of attractive/repulsivean align2F t forces. These forces ences colli ..."
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Cited by 6 (0 self)
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This paper in vestigates the aggregated stability properties of of a system of multiple mobileagen ts described by simpledynleS55 systems. Theagen ts are steered through local coordin2Sfi5 con trol laws that arise as a combin7 tion of attractive/repulsivean align2F t forces. These forces ences collision avoidan e a n cohesion of the groupan result to all agen ts attain[S a common headin anin exhibitin flockin motion Two cases are con197 ered: in the first, position in[]5 ation from all group members is available to each agen t; in the seconc each agen t has access to position i n ormation of on( the agen ts layin in ide its n ighborhood. It is then shown that regardless ofan y arbitrary chan[1 in thenS[9 bor set, the flockinmotion remain stable aslon as the graph that describes the n ighborin relation amon the agen ts in the group is always con9 cted. 1
VisionBased, Distributed Control Laws for Motion Coordination of Nonholonomic Robots
 ACCEPTED FOR PUBLICATION IN IEEE TRANSACTIONS ON ROBOTICS
"... We study the problem of distributed motion coordination among a group of planar nonholonomic agents. Inspired by social aggregation phenomena such as flocking and schooling in birds and fish, we develop visionbased control laws for parallel and circular formations using a consensus approach. The pr ..."
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Cited by 6 (1 self)
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We study the problem of distributed motion coordination among a group of planar nonholonomic agents. Inspired by social aggregation phenomena such as flocking and schooling in birds and fish, we develop visionbased control laws for parallel and circular formations using a consensus approach. The proposed control laws are distributed, in the sense that only information from neighboring agents are included. Furthermore, the control laws are coordinatefree and do not rely on measurement or communication of heading information among neighbors, but instead require measurements of bearing, optical flow and timetocollision, all of which can be measured using vision. Collision avoidance capabilities are added to the team members and the effectiveness of the control laws are demonstrated on a group of mobile robots.
1 On the Stability of the Kuramoto Model of Coupled Nonlinear Oscillators †
, 2005
"... We provide an analysis of the classic Kuramoto model of coupled nonlinear oscillators that goes beyond the existing results for alltoall networks of identical oscillators. Our work is applicable to oscillator networks of arbitrary interconnection topology with uncertain natural frequencies. Using ..."
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We provide an analysis of the classic Kuramoto model of coupled nonlinear oscillators that goes beyond the existing results for alltoall networks of identical oscillators. Our work is applicable to oscillator networks of arbitrary interconnection topology with uncertain natural frequencies. Using tools from spectral graph theory and control theory, we prove that for couplings above a critical value, the synchronized state is locally asymptotically stable, resulting in convergence of all phase differences to a constant value, both in the case of identical natural frequencies as well as uncertain ones. We further explain the behavior of the system as the number of oscillators grows to infinity. Over the past decade, considerable attention has been devoted to the problem of coordinated motion of multiple autonomous agents. A variety of disciplines (as diverse as ecology, the social sciences, statistical physics, computer graphics and, indeed, systems and control theory) are developing an understanding of how a group of moving objects (such as flocks of birds, schools of fish, crowds of people [11], [20], or collections of autonomous robots or unmanned
To appear in ACC 2010 PassivityBased Position Consensus of Multiple Mechanical Integrators with Communication Delay
"... Abstract — We present a consensus framework for multiple variablerate heterogeneous mechanical integrators (i.e. multidimensional integrators with mass, damping and spring matrices) on undirected graph with constant, yet, nonuniform communication delay. By connecting multiple mechanical integrator ..."
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Abstract — We present a consensus framework for multiple variablerate heterogeneous mechanical integrators (i.e. multidimensional integrators with mass, damping and spring matrices) on undirected graph with constant, yet, nonuniform communication delay. By connecting multiple mechanical integrators via (discretetime) spring connections over delayed links with some damping injection, our proposed framework not only achieves position consensus, but also enforces closedloop discretetime passivity. Moreover, it allows arbitrary control gains regardless of integration steps, if there is no delay. Simulation result is also given to support the theory. I.
Modeling and Optimization of Building Emergency Evacuation Considering Blocking Effects on Crowd Movement
"... AbstractIn building emergency evacuation, the perception of hazards can stress crowds, evoke their competitive behaviors, and trigger disorder and blocking as they pass through narrow passages (e.g., a small exit). This is a serious concern threatening evacuees ' survivability and egress efficiency ..."
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AbstractIn building emergency evacuation, the perception of hazards can stress crowds, evoke their competitive behaviors, and trigger disorder and blocking as they pass through narrow passages (e.g., a small exit). This is a serious concern threatening evacuees ' survivability and egress efficiency. How to optimize crowd guidance while considering such effects is an important problem. Based on advanced microscopic pedestrian models and simulations, this paper establishes a new macroscopic networkflow model where fire, smoke, and psychological factors can evoke a crowd's desire to escapethe desired flow rate. Disorder and blocking occur when the desired flow rate exceeds the passage capacity, resulting in a drastic decrease of crowd movement in a nonlinear and random fashion. To effectively guide crowds, a divideandconquer approach is developed based on groups to reduce computational complexity and to reflect psychological