Results 1  10
of
46
Consensus Problems in Networks of Agents with Switching Topology and TimeDelays
, 2003
"... In this paper, we discuss consensus problems for a network of dynamic agents with fixed and switching topologies. We analyze three cases: i) networks with switching topology and no timedelays, ii) networks with fixed topology and communication timedelays, and iii) maxconsensus problems (or leader ..."
Abstract

Cited by 1112 (21 self)
 Add to MetaCart
(Show Context)
In this paper, we discuss consensus problems for a network of dynamic agents with fixed and switching topologies. We analyze three cases: i) networks with switching topology and no timedelays, ii) networks with fixed topology and communication timedelays, and iii) maxconsensus problems (or leader determination) for groups of discretetime agents. In each case, we introduce a linear/nonlinear consensus protocol and provide convergence analysis for the proposed distributed algorithm. Moreover, we establish a connection between the Fiedler eigenvalue of the information flow in a network (i.e. algebraic connectivity of the network) and the negotiation speed (or performance) of the corresponding agreement protocol. It turns out that balanced digraphs play an important role in addressing averageconsensus problems. We introduce disagreement functions that play the role of Lyapunov functions in convergence analysis of consensus protocols. A distinctive feature of this work is to address consensus problems for networks with directed information flow. We provide analytical tools that rely on algebraic graph theory, matrix theory, and control theory. Simulations are provided that demonstrate the effectiveness of our theoretical results.
Flocking for MultiAgent Dynamic Systems: Algorithms and Theory
, 2006
"... In this paper, we present a theoretical framework for design and analysis of distributed flocking algorithms. Two cases of flocking in freespace and presence of multiple obstacles are considered. We present three flocking algorithms: two for freeflocking and one for constrained flocking. A compre ..."
Abstract

Cited by 436 (2 self)
 Add to MetaCart
(Show Context)
In this paper, we present a theoretical framework for design and analysis of distributed flocking algorithms. Two cases of flocking in freespace and presence of multiple obstacles are considered. We present three flocking algorithms: two for freeflocking and one for constrained flocking. A comprehensive analysis of the first two algorithms is provided. We demonstrate the first algorithm embodies all three rules of Reynolds. This is a formal approach to extraction of interaction rules that lead to the emergence of collective behavior. We show that the first algorithm generically leads to regular fragmentation, whereas the second and third algorithms both lead to flocking. A systematic method is provided for construction of cost functions (or collective potentials) for flocking. These collective potentials penalize deviation from a class of latticeshape objects called αlattices. We use a multispecies framework for construction of collective potentials that consist of flockmembers, or αagents, and virtual agents associated with αagents called β and γagents. We show that migration of flocks can be performed using a peertopeer network of agents, i.e. “flocks need no leaders.” A “universal” definition of flocking for particle systems with similarities to Lyapunov stability is given. Several simulation results are provided that demonstrate performing 2D and 3D flocking, split/rejoin maneuver, and squeezing maneuver for hundreds of agents using the proposed algorithms.
Consensus protocols for networks of dynamic agents,”
 in Proceedings of the American Control Conference,
, 2003
"... Abstract In this paper, we introduce linear and nonlinear consensus protocols for networks of dynamic agents that allow the agents to agree in a distributed and cooperative fashion. We consider the cases of networks with communication timedelays and channels that have filtering effects. We find a ..."
Abstract

Cited by 114 (6 self)
 Add to MetaCart
(Show Context)
Abstract In this paper, we introduce linear and nonlinear consensus protocols for networks of dynamic agents that allow the agents to agree in a distributed and cooperative fashion. We consider the cases of networks with communication timedelays and channels that have filtering effects. We find a tight upper bound on the maximum fixed timedelay that can be tolerated in the network. It turns out that the connectivity of the network is the key in reaching a consensus. The case of agreement with bounded inputs is considered by analyzing the convergence of a class of nonlinear protocols. A Lyapunov function is introduced that quantifies the total disagreement among the nodes of a network. Simulation results are provided for agreement in networks with communication timedelays and constrained inputs.
Control and Communication Challenges in Networked Realtime Systems
, 2007
"... A current survey of the emerging field of networked control systems is provided. The aim is to introduce the fundamental issues involved in designing successful networked control systems, to provide a snapshot assessment of the current state of research in the field, to suggest useful future researc ..."
Abstract

Cited by 62 (4 self)
 Add to MetaCart
A current survey of the emerging field of networked control systems is provided. The aim is to introduce the fundamental issues involved in designing successful networked control systems, to provide a snapshot assessment of the current state of research in the field, to suggest useful future research directions, and to provide a broad perspective on recent fundamental results. Reflecting the goals of the Special Issue itself, this paper surveys relevant work from the areas of systems and control, signal processing, detection and estimation, data fusion, and distributed systems. We discuss appropriate network architectures, topics such as coding for
Agreement Problems in Networks with Directed Graphs and Switching Topology
, 2003
"... In this paper, we provide tools for convergence and performance analysis of an agreement protocol for a network of integrator agents with directed information ow. Moreover, we analyze algorithmic robustness of this consensus protocol for the case of a network with mobile nodes and switching topol ..."
Abstract

Cited by 59 (1 self)
 Add to MetaCart
In this paper, we provide tools for convergence and performance analysis of an agreement protocol for a network of integrator agents with directed information ow. Moreover, we analyze algorithmic robustness of this consensus protocol for the case of a network with mobile nodes and switching topology. We establish a connection between the Fiedler eigenvalue of the graph Laplacian and the performance of this agreement protocol. We demostrate that a class of directed graphs, called balanced graphs, have a crucial role in solving averageconsensus problems. Based on the properties of balanced graphs, a group disagreement function (i.e. Lyapunov function) is proposed for convergence analysis of this agreement protocol for networks with directed graphs. This group disagreement function is later used for convergence analysis for the agreement problem in networks with switching topology. We provide simulation results that are consistent with our theoretical results and demonstrate the eectiveness of the proposed analytical tools.
Flocking of multiagents with a virtual leader
 IEEE Transactions on Automatic Control
, 2009
"... Abstract—All agents being informed and the virtual leader traveling at a constant velocity are the two critical assumptions seen in the recent literature on flocking in multiagent systems. Under these assumptions, OlfatiSaber in a recent IEEE TRANSACTIONS ON AUTOMATIC CONTROL paper proposed a flo ..."
Abstract

Cited by 33 (1 self)
 Add to MetaCart
(Show Context)
Abstract—All agents being informed and the virtual leader traveling at a constant velocity are the two critical assumptions seen in the recent literature on flocking in multiagent systems. Under these assumptions, OlfatiSaber in a recent IEEE TRANSACTIONS ON AUTOMATIC CONTROL paper proposed a flocking algorithm which by incorporating a navigational feedback enables a group of agents to track a virtual leader. This paper revisits the problem of multiagent flocking in the absence of the above two assumptions. We first show that, even when only a fraction of agents are informed, the OlfatiSaber flocking algorithm still enables all the informed agents to move with the desired constant velocity, and an uninformed agent to also move with the same desired velocity if it can be influenced by the informed agents from time to time during the evolution. Numerical simulation demonstrates that a very small group of the informed agents can cause most of the agents to move with the desired velocity and the larger the informed group is the bigger portion of agents will move with the desired velocity. In the situation where the virtual leader travels with a varying velocity, we propose modification to the OlfatiSaber algorithm and show that the resulting algorithm enables the asymptotic tracking of the virtual leader. That is, the position and velocity of the center of mass of all agents will converge exponentially to those of the virtual leader. The convergent rate is also given. Index Terms—Distributed control, flocking, informed agents, nonlinear systems, virtual leader. I.
Cooperative filters and control for cooperative exploration
 IEEE Trans. Automatic Control
, 2010
"... Abstract—Autonomous mobile sensor networks are employed to measure largescale environmental fields. Yet an optimal strategy for mission design addressing both the cooperative motion control and the cooperative sensing is still an open problem. We develop strategies for multiple sensor platforms to ..."
Abstract

Cited by 31 (2 self)
 Add to MetaCart
(Show Context)
Abstract—Autonomous mobile sensor networks are employed to measure largescale environmental fields. Yet an optimal strategy for mission design addressing both the cooperative motion control and the cooperative sensing is still an open problem. We develop strategies for multiple sensor platforms to explore a noisy scalar field in the plane. Our method consists of three parts. First, we design provably convergent cooperative Kalman filters that apply to general cooperative exploration missions. Second, we present a novel method to determine the shape of the platform formation to minimize error in the estimates and design a cooperative formation control law to asymptotically achieve the optimal formation shape. Third, we use the cooperative filter estimates in a provably convergent motion control law that drives the center of the platform formation to move along level curves of the field. This control law can be replaced by control laws enabling other cooperative exploration motion, such as gradient climbing, without changing the cooperative filters and the cooperative formation control laws. Performance is demonstrated on simulated underwater platforms in simulated ocean fields. Index Terms—Adaptive Kalman filtering, cooperative control, cooperative filtering, mobile sensing networks. I.
Flocking with Obstacle Avoidance: Cooperation with Limited Communication in Mobile Networks
, 2003
"... In this paper, we provide a dynamic graph theoretic framework for ocking in presence of multiple obstacles. In particular, we give formal de nitions of nets and ocks as spatially induced graphs and de ne ocking. We introduce the notion of framenets and describe a procedure for automatic constructi ..."
Abstract

Cited by 27 (2 self)
 Add to MetaCart
In this paper, we provide a dynamic graph theoretic framework for ocking in presence of multiple obstacles. In particular, we give formal de nitions of nets and ocks as spatially induced graphs and de ne ocking. We introduce the notion of framenets and describe a procedure for automatic construction of an energy function for groups of agents. The task of ocking is achieved via dissipation of this energy according to a protocol that only requires the use of local information. We show that all three rules of Reynolds are hidden in this single protocol. Three types of agents called , , and agents are used to create ocking. Simulation results are provided that demonstrate ocking by 100 dynamic agents.
Coordinated patterns of unit speed particles on a closed curve
 Syst. Control Lett
, 2007
"... We present methods to stabilize a class of motion patterns for unit speed particles in the plane. From their initial positions within a compact set in the plane, all particles converge to travel along a closed curve. The relative distance between each pair of particles along the curve is measured us ..."
Abstract

Cited by 25 (8 self)
 Add to MetaCart
We present methods to stabilize a class of motion patterns for unit speed particles in the plane. From their initial positions within a compact set in the plane, all particles converge to travel along a closed curve. The relative distance between each pair of particles along the curve is measured using the relative arclength between the particles. These distances are controlled to converge to constant values.
Connectivity and set tracking of multiagent systems guided by multiple moving leaders
 IEEE Trans. Automatic Control
"... ar ..."
(Show Context)