Cyclic Pursuit Strategy Research Articles

Communication-Delay-Dependent Rendezvous With Possible Negative Controller Gain in Cyclic Pursuit

In this article, we address the multiagent rendezvous problem for a group of single-integrator agents in the presence of a constant arbitrarily large bounded homogeneous communication delay. The agents are required to meet at a tunable desired point, which is unknown to all agents. To achieve this objective, we choose the cyclic pursuit strategy, which requires the minimum number of communication links. It is shown that the rendezvous can be achieved with at most one zero or negative gain in the presence of delay. A negative controller gain implies an antagonistic interaction of the agent with its neighbor, whereby it moves away from the neighbor. We find the bound on the negative gain such that rendezvous among all agents is possible. The margin on the negative gain decreases due to the presence of delay. An analytical expression has been obtained for the reachable rendezvous points in terms of an initial configuration of the agents, controller gains, and the delay. For fixed controller gains and increasing delay, the rendezvous point lies along the line joining the weighted centroid and the centroid of the initial configuration with the asymptotic nature toward the centroid when all gains are positive, while away from it when one gain is negative. For finite controller gains, the reachable set remains unchanged even in the presence of any finite delay. Numerical examples illustrate the presented results.

Exploring the Rendezvous of Agents in Cyclic Pursuit with Possible Negative Controller Gain and Homogeneous Input Delay

In this paper, the effect of homogeneous input delay on rendezvous of a group of agents under cyclic pursuit strategy is investigated. Presence of negative controller gain(s) aids in expanding the reachable set. It is found that at most one negative controller gain is possible for all the agents to converge under delayed condition. In contrast to accommodating any positive controller gains in the no-delay case, the controller gains in delayed case are restricted by the delay. A modification on the gains is proposed in order to tolerate arbitrarily large bounded delay. The weighted centroid of all agents does not change as time evolves and all agents finally converge to their weighted centroid. Simulation results are provided to substantiate the obtained delay-dependent conditions.

A generalized hierarchical nearly cyclic pursuit for the leader-following consensus problem in multi-agent systems

In this paper, we solve the leader-following consensus problem using a hierarchical nearly cyclic pursuit (HNCP) strategy for multi-agent systems. We extend the nearly cyclic pursuit strategy and the two-layer HNCP to the generalized L-layer HNCP that enables the agents to rendezvous at a point dictated by a beacon. We prove that the convergence rate of the generalized L-layer HNCP for the leader-following consensus problem is faster than that of the nearly cyclic pursuit. Simulation results demonstrate the effectiveness of the proposed method.

Scalable multi-agent formation with bearing only measurement: Consensus based approach

Target centric deviated cyclic pursuit is a variant of the deviated cyclic pursuit strategy designed to track a target. Deviated cyclic pursuit has more flexibility as compared to the classical cyclic pursuit laws. In this work, we obtain a scalable formation of the UAVs around the target. The formation is scaled in a decentralized manner by changing a parameter of any of the vehicles. The strategy uses only bearing angle information of the target and the neighbours. We carried out the analysis assuming simple kinematic model for each vehicle. At equilibrium, the vehicles get into a rigid polygonal formation which rotates around the target. The size of the polygon is scalable. We analysed the local stability of equilibrium formations. Simulation results are presented to demonstrate effectiveness of the proposed strategy. The strategy is applied to miniature areal vehicles (MAV) represented by 6-DOF dynamics in a hardware in-loop simulator, which includes all on-board electronics of the MAVs.

A variant of cyclic pursuit for target tracking applications: theory and implementation

This paper presents a variant of the cyclic pursuit strategy that can be used for target tracking applications. Cyclic pursuit has been extensively used in multi-agent systems for a variety of applications. In order to monitor a target point or to track a slowly moving vehicle, we propose to use a group of non-holonomic vehicles. At equilibrium, the vehicles form a rigid polygonal around the target while encircling it. Necessary conditions for the existence of equilibrium and the stability of equilibrium formations are analysed considering unicycle model of the vehicles. The strategy is then applied to miniature aerial vehicles (MAV) represented by 6-DOF dynamical model. Finally the results are verified in a hardware in-loop simulator in real time, which included all on-board electronics of the MAVs.

A Study of Balanced Circular Formation under Deviated Cyclic Pursuit Strategy

This paper deals with the study of balanced circular formation for n unicycles agents. It has been presented in the literature that there exists more than one balanced circular formation when the agents are following cyclic pursuit strategy. We modify cyclic pursuit strategy by introducing a parameter called deviation angle with the hope to get unique equilibrium formation. The modified strategy is called deviated cyclic pursuit. Monte Carlo simulations has been carried out to find the range of deviation angle where a unique equilibrium formation exists.

Cooperative Control for Satellite Formation Reconfiguration via Cyclic Pursuit Strategy

This paper investigates a methodology for group coordination and cooperative control of satellites with the aim to achieve formation reconfiguration such as radius enlargement and phase angle adjustment. The proposed approach separates the control law into two distinct stages: planar movement control and orthogonal displacement suppression. The in plane approach is based on a cyclic pursuit strategy, where satellite i pursues satellite i +1. For phase angle adjustment, a control law that makes use of beacons guidance is synthesized to maintain the circling centre stationary. In the orthogonal direction, a linear feed back control on displacement and velocity is used. Simulation of two missions with low thrust are provided, which high light the over all effectiveness of the proposed approach.

Cooperative control of multi-agent dynamical systems in target-enclosing operations using cyclic pursuit strategy

This article is concerned with formation stability analysis of distributed cooperative control for target-enclosing operations by multiple homogeneous dynamic agents. To this end, we first present an on-line path generator design method based on a cyclic pursuit scheme. Then, we provide Lyapunov and asymptotic stability conditions which should hold for the above path generation laws. These conditions are derived based on a simple stability analysis method for linear systems with a generalised frequency variable. The formation control scheme combined with a cyclic pursuit based distributed on-line path generator satisfying the derived stability conditions guarantees the required global convergence property with theoretical rigour. Furthermore, in order to show its distinctive features clearly, we present how to analyse a global formation stability for multi-agent systems, where each agent is modelled as a class of second-order systems and is locally stabilised by a proportional-derivative (PD) controller. Some simulation examples illustrate the distinctive features of the proposed method and the achievement of a desired pursuit pattern.

Distributed Formation Control for Target-enclosing Operations based on a Cyclic Pursuit Strategy

This paper studies a design methodology of a distributed cooperative controller for target-enclosing operations by multiple dynamic agents. To this end, we first present an on-line path generator design method based on a cyclic pursuit scheme. Then, we provide the stability condition which the developed path generator should satisfy. This condition is derived based on a simple stability analysis method for large-scale linear systems with generalized frequency variable. The formation control scheme combined with a cyclic pursuit based distributed on-line path generator satisfying the derived stability condition guarantees the required global convergence property with theoretical rigor. Simulation examples illustrate its distinctive features and the achievement of a desired pursuit pattern.

Cooperative control for target-capturing task based on a cyclic pursuit strategy

This paper studies a methodology for group coordination and cooperative control of n agents to achieve a target-capturing task in 3D space. The proposed approach is based on a cyclic pursuit strategy, where agent i simply pursues agent i + 1 modulo n. The distinctive features of the proposed method are as follows. First, no communication mechanism between agents is necessary and thus it is inherently a distributed control strategy. Also, it is a simple robust memoryless control scheme which has self-stability property. Finally, it guarantees a global convergence of all agents to the desired formation. Further, it is also guaranteed that no collision occurs. Simulation examples are given to illustrate the efficacy of the proposed method and the achievement of a desired pursuit pattern in 3D space.