Achieving a desired collective centroid by a formation of agents moving in a controllable force field
28 Mar 2016-pp 182-187
TL;DR: In this article, an all-to-all coupled planar motion model is proposed to solve the problem of a formation of agents trying to achieve a desired stationary or moving collective centroid.
Abstract: In this paper, we study the problem of a formation of agents trying to achieve a desired stationary or moving collective centroid. The agents are assumed to be moving in a force field which is controlled externally. The stabilization of the collective centroid to a fixed desired location results in a balanced formation of the agents about that point. Similarly, the centroid of the system of agents may be required to move along a certain given trajectory. For this, the centroid of the formation must converge to the desired trajectory. To solve this problem, we propose an all-to-all coupled planar motion model that explicitly incorporates an additional control pertaining to the external force field. Simulation results are presented to support the theoretical findings.
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TL;DR: This paper proposes a combined controller to stabilize a formation shape and synchronize the heading of each agent simultaneously and considers several different formation design approaches based on different formation specifications under different interaction graphs.
Abstract: This paper discusses the problem of controlling formation shapes for a group of nonholonomic unicycle-type agents with constant speeds. The control input is designed to steer their orientations and the aim is to achieve a desired formation configuration for all the agents subject to constant-speed constraints. The circular motion center is adopted as a virtual position for each agent to define the desired formation shape. We consider several different formation design approaches based on different formation specifications under different interaction graphs. In particular, two different formation design approaches, namely, a displacement-based approach and a distance-based approach, are discussed in detail to coordinate constant-speed agents in achieving a desired formation shape with stable circular motions via limited interactions. The communication and measurement requirements for each approach are also discussed. Furthermore, we propose a combined controller to stabilize a formation shape and synchronize the heading of each agent simultaneously. The effectiveness of the proposed formation control schemes is validated by both numerical simulations and real experiments with actual unmanned fixed-wing aircraft.
61 citations
Cites background from "Achieving a desired collective cent..."
...Furthermore, some recent papers [18]–[20] have discussed the control problem of a group of unit-speed agents to achieve different collective tasks, e....
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01 Jan 2008
TL;DR: This paper considers the problem of controlling a group of agents under the constraint that every agent must be given the same control input, relevant for the control of mobile micro-robots that all receive the same power and control signals through an underlying substrate.
Abstract: This paper considers the problem of controlling a group of agents under the constraint that every agent must be given the same control input This problem is relevant for the control of mobile micro-robots that all receive the same power and control signals through an underlying substrate Despite this restriction, several examples in simulation demonstrate that it is possible to get a group of micro-robots to perform useful tasks All of these tasks are derived by thinking about the relationships between robots, rather than about their individual states
13 citations
Proceedings Article•
08 May 2020TL;DR: This paper develops a two-phase search algorithm, called SWARM-MAPF, whose first phase is inspired by swarm-based algorithms (in open regions) and whose second phase isinspired by multi-agent path-finding (MAPF) algorithms ( in congested regions).
Abstract: In this paper, we formalize and study the Moving Agents in Formation (MAiF) problem, that combines the tasks of finding short collision-free paths for multiple agents and keeping them in close adherence to a desired formation Previous work includes controller-based algorithms, swarm-based algorithms, and potential-field-based algorithms They usually focus on only one or the other of these tasks, solve the problem greedily without systematic search, and thus generate costly solutions or even fail to find solutions in congested environment In this paper, we develop a two-phase search algorithm, called SWARM-MAPF, whose first phase is inspired by swarm-based algorithms (in open regions) and whose second phase is inspired by multi-agent path-finding (MAPF) algorithms (in congested regions) In the first phase, SWARM-MAPF selects a leader among the agents and finds a path for it that is sufficiently far away from the obstacles so that the other agents can preserve the desired formation around it It also identifies the critical segments of the leader's path where the other agents cannot preserve the desired formation and the refinement of which has thus to be delegated to the second phase In the second phase, SWARM-MAPF refines these segments Theoretically, we prove that SWARM-MAPF is complete Empirically, we show that SWARM-MAPF scales well and is able to find close-to-optimal solutions
4 citations
Additional excerpts
...Examples include behavior-based [1], leader-follower [3], virtual-structure [12], potential-field [11], graph-based [4], and other swarm-based algorithms [9, 13, 21]....
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TL;DR: This paper analyses collective motion of multi-vehicle systems in balanced or splay formation when the vehicles are equipped with heterogeneous controller gains and proposes strategies to achieve such balanced and splay formations about a desired centroid location while allowing the vehicles to move either along straight line paths or on individual circular orbits.
Abstract: This paper analyses collective motion of multi-vehicle systems in balanced or splay formation when the vehicles are equipped with heterogeneous controller gains. Balancing refers to a situation in which the positional centroid of the vehicles is stationary. The splay formation is a special case of balancing in which the vehicles are spatially distributed with equal angular separation between them. The paper proposes strategies to achieve such balanced and splay formations about a desired centroid location while allowing the vehicles to move either along straight line paths or on individual circular orbits. Feedback control laws that can tolerate heterogeneity in the controller gains, which may be caused by imperfect implementation, are derived and analyzed. It is shown that drastic failures leading to controller gains becoming zero for almost half of the vehicles in the group can be tolerated and balanced formation can still be achieved. On the other hand, splay formation can still be achieved if the controller gain is zero for at most one vehicle. Simulation examples are given to illustrate the theoretical findings.
2 citations
01 Jan 2017
TL;DR: This paper proposes a heterogeneous gains based controller design methodology to stabilize a particular type of collective motion in a multi-agent system where the heading angles of the agents are in balanced formation and derives feedback control laws that operate with heterogeneous control gains.
Abstract: This paper proposes a heterogeneous gains based controller design methodology to stabilize a particular type of collective motion in a multi-agent system where the heading angles of the agents are in balanced formation. Balancing refers to the situation in which the movement of agents causes the position of their centroid to become stationary. Our interest, in this paper, is to achieve balanced formation about a desired location of the centroid while allowing the agents to move either along straight line paths or around individual circular orbits. For this purpose, we derive feedback control laws that operate with heterogeneous control gains, and are more practical compared to the homogeneous gains based controls existing in the literature. We also show that if the heterogeneous control gains are zero for almost half of the agents of the group, it is possible to achieve balanced formation at an additional advantage of reduced computational complexity of the proposed control law. Simulations are given to illustrate the theoretical findings.
1 citations
Cites background or result from "Achieving a desired collective cent..."
...In a similar context, the authors in [9] and [10] propose a steering control which operates with homogeneous control gains, and depends on both positions and heading angles of the agents [9] or only on the heading angles of the agents with an additional external force applied to them [10]....
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...Unlike [9] and [10], in the present work, the proposed feedback control uses heterogeneous control gains that ensures the robustness of the system against variations in the homogeneous control gains caused by physical implementation (by means of some electrical circuitry)....
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...However, unlike [9] and [10], in this paper, we generalize existing results and propose a more realistic steering control law which uses heterogeneous control gains....
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References
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Book•
26 Oct 2007TL;DR: Academic control systems researchers and their counterparts in government laboratories and robotics- and aerospace-related industries will find the ideas presented in Distributed Consensus in Multi-vehicle Cooperative Control of great interest.
Abstract: The coordinated use of autonomous vehicles has an abundance of potential applications from the domestic to the hazardously toxic. Frequently the communications necessary for the productive interplay of such vehicles may be subject to limitations in range, bandwidth, noise and other causes of unreliability. Information consensus guarantees that vehicles sharing information over a network topology have a consistent view of information critical to the coordination task. Assuming only neighbor-neighbor interaction between vehicles, Distributed Consensus in Multi-vehicle Cooperative Control develops distributed consensus strategies designed to ensure that the information states of all vehicles in a network converge to a common value. This approach strengthens the team, minimizing power consumption and the deleterious effects of range and other restrictions. The monograph is divided into six parts covering introductory, theoretical and experimental material and featuring: an overview of the use of consensus algorithms in cooperative control; consensus algorithms in single- and double-integrator dynamical systems; consensus algorithms for rigid-body attitude dynamics; rendezvous and axial alignment, formation control, deep-space formation flying, fire monitoring and surveillance. Notation drawn from graph and matrix theory and background material on linear and nonlinear system theory are enumerated in six appendices. The authors maintain a website at which can be found a sample simulation and experimental video material associated with experiments in several chapters of this book. Academic control systems researchers and their counterparts in government laboratories and robotics- and aerospace-related industries will find the ideas presented in Distributed Consensus in Multi-vehicle Cooperative Control of great interest. This text will also serve as a valuable support and reference for graduate courses in robotics, and linear and nonlinear control systems.
755 citations
TL;DR: A decentralized multiple-UAV approach to monitoring the perimeter of a fire using a six degree-of-freedom dynamic model for the UAV and a numerical propagationmodel for the forest fire is developed.
Abstract: The objective of this paper is to explore the feasibility of using multiple low-altitude, short endurance (LASE) unmanned air vehicles (UAVs) to cooperatively monitor and track the propagation of large forest fires. A real-time algorithm is described for tracking the perimeter of fires with an on-board infrared sensor. Using this algorithm, we develop a decentralized multiple-UAV approach to monitoring the perimeter of a fire. The UAVs are assumed to have limited communication and sensing range. The effectiveness of the approach is demonstrated in simulation using a six degree-of-freedom dynamic model for the UAV and a numerical propagation model for the forest fire. Salient features of the approach include the ability to monitor a changing fire perimeter, the ability to systematically add and remove UAVs from the team, and the ability to supply time-critical information to fire fighters.
529 citations
"Achieving a desired collective cent..." refers background in this paper
...The applications have encompassed tracking, environmental monitoring, surveillance, reconnaissance, search and data collection [1]-[6]....
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TL;DR: The results of the paper provide a low-order parametric family of stabilizable collectives that offer a set of primitives for the design of higher-level tasks at the group level.
Abstract: This paper proposes a design methodology to stabilize isolated relative equilibria in a model of all-to-all coupled identical particles moving in the plane at unit speed. Isolated relative equilibria correspond to either parallel motion of all particles with fixed relative spacing or to circular motion of all particles with fixed relative phases. The stabilizing feedbacks derive from Lyapunov functions that prove exponential stability and suggest almost global convergence properties. The results of the paper provide a low-order parametric family of stabilizable collectives that offer a set of primitives for the design of higher-level tasks at the group level
528 citations
"Achieving a desired collective cent..." refers background in this paper
...In recent literature [7]-[11], two natural collective formations, synchronization and balancing, have been widely studied....
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...Previous works in this area deal with the stabilization of these formations when the agents are coupled through homogeneous [7] and heterogeneous [9] controller gains....
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...(14) Here,〈z1,z2〉= Re{z̄1z2} [7], represents the inner product of complex numbers z1,z2 ∈C, where z̄1 denotes the complex conjugate of z1....
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...Proof: In (5), by choosing control law u0 = ṙre f = f (D)û, one can compute ṙc− ṙre f = 1N N ∑ k=1 eiθk (11) which implies, r̈c− r̈re f = 1N N ∑ k=1 ieiθk θ̇k (12) Let the error between the velocity of the collective centroid, ṙc, and reference velocity, ṙre f , be ev = ṙc− ṙre f (13) Consider a candidate Lyapunov function U(θ ) = N 2 |ev|2 = N2 ∣∣ṙc− ṙre f ∣∣2 = N 2 〈 ṙc− ṙre f , ṙc− ṙre f 〉 (14) Here,〈z1,z2〉= Re{z̄1z2} [7], represents the inner product of complex numbers z1,z2 ∈C, where z̄1 denotes the complex conjugate of z1....
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...As in [7], [11], collective dynamics of N autonomous agents, moving in a planar space, each assumed to be a selfpropelled Newtonian particle with unit mass and unit speed, is considered in this paper and represented as...
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TL;DR: A design methodology to stabilize relative equilibria in a model of identical, steered particles moving in the plane at unit speed to show how previous results assuming all-to-all communication can be extended to a general communication framework.
Abstract: This paper proposes a design methodology to stabilize relative equilibria in a model of identical, steered particles moving in the plane at unit speed. Relative equilibria either correspond to parallel motion of all particles with fixed relative spacing or to circular motion of all particles around the same circle. Particles exchange relative information according to a communication graph that can be undirected or directed and time-invariant or time-varying. The emphasis of this paper is to show how previous results assuming all-to-all communication can be extended to a general communication framework.
465 citations
TL;DR: It is shown that the observed movement of the nanocars is a new type of fullerene-based wheel-like rolling motion, not stick-slip or sliding translation, due to evidence including directional preference in both direct and indirect manipulation and studies of related molecular structures.
Abstract: With the hope of directing future bottom-up fabrication through bulk external stimuli (such as electric fields) on nanometer-sized transporters, we sought to study controlled molecular motion on surfaces through the rational design of surface-capable molecular structures called nanocars. Here we show that the observed movement of the nanocars is a new type of fullerene-based wheel-like rolling motion, not stick−slip or sliding translation, due to evidence including directional preference in both direct and indirect manipulation and studies of related molecular structures.
425 citations
"Achieving a desired collective cent..." refers background in this paper
...[30] present directional control of thermally driven single-molecule nanocars, and Chiang et al....
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