Formation Problem For Multi-agent Systems Research Articles

Robust Formation Control for Nonlinear Heterogeneous Multiagent Systems Based on Adaptive Event-Triggered Strategy

In this article, a distributed adaptive event-triggered formation control strategy is proposed for unified nonlinear heterogeneous multiagent systems under uncertainties and disturbances to achieve time-varying formations. To reduce the frequency of data transmission, a distributed dual adaptive observer with an event-triggered strategy is developed to estimate the states of a reference exosystem. Without incurring prior global information about a communication graph, a novel robust formation controller, with dynamic distributed compensators for uncertainties and disturbances, is designed based on an observer result and a nonlinear internal control principle. Finally, both simulation and experiment are conducted for tracking and patrolling formation to verify the effectiveness of the proposed formation control strategy and its robustness. Note to Practitioners—This article addresses the collaborative formation problem of multiagent systems that has potential applications in transportation and disaster relief. The design of robust and energy-saving coordination strategies is challenging in heterogeneous multivehicle systems. The proposed distributed method is suitable for large-scale uncertain heterogeneous systems, and the use of the dual adaptive event-triggered strategy reduces the data transmission rate.

Formation control of first-order multi-agents with region constraint

ABSTRACT Formation problem of multi-agents systems has been investigated studied by more and more scientists. This paper studies the formation problem of the first-order multi-agent systems with region constraint. Not only formation control but also the constraint area is considered. The state of each agent is constrained by a common convex set. A formation control protocol is proposed based on the local information of neighbourhood and region constraint. If the communication topology is connected, and the target framework is rigid, all agents would enter the target area while reaching the desired formation. The convergence of the formation control to the final formation is guaranteed as proven by Lyapunov framework. Compared with the leader follower controller, the controller does not depend on the leader and has good robustness. In addition, the controller can quickly and accurately control all agents to all agents to enter the constrained area. Finally, the results are illustrated by numerical simulations.

Decentralized event‐triggered circle formation control for multiagent systems via synchronous periodic event detection

SummaryThis paper investigates circle formation problem of multiagent systems over a kind of strongly connected and weight‐unbalanced directed graphs. To solve the concerned problem, decentralized periodic event‐triggered algorithms subject to or not to time delays are proposed, which have the advantages of decreasing the overall burden of the network in terms of finite communication and control input updates. In such algorithms, each agent independently evaluates whether the locally sampled information of itself should be broadcasted to or not to its neighbors. Furthermore, another advantage of our proposed algorithms is to automatically exclude Zeno behavior, which should be seriously considered in a variety of event‐based network systems. Sufficient conditions on circle formation control are derived under which the states of all agents can be ensured to converge to some desired equilibrium point. Simulation results are given to validate the effectiveness of the proposed methods.

Distributed event-triggered circle formation control for multi-agent systems with limited communication bandwidth

This paper investigates event-triggered circle formation problem of multi-agent systems (MASs) with limited communication bandwidth over such network setup among agents, in which each agent can only perceive the angular distance from itself to the nearest neighbor in counterclockwise direction as well as the counterpart in the clockwise direction be acquired through communication. To solve the concerned problem, a distributed algorithm relied on the combination between the quantized communication technology and event-triggered control (ETC) has been proposed. We show that, under the proposed law, all the designed quantizers do not appear saturated, and that the resulting network executions can ensure the states of all agents to converge to some desired equilibrium point. Numerical simulation results are provided to validate the effectiveness of the proposed algorithm.

A Stochastic Sampling Mechanism for Time-Varying Formation of Multiagent Systems With Multiple Leaders and Communication Delays.

The time-varying formation problem for multiagent systems (MASs) with stochastic sampling and multiple leaders is studied in this paper, in which communication delays are taken into account. All the agents are divided into the set of the follower group and the set of the leader group. Under the proposed stochastic sampling mechanism for time-varying formation of the MASs with communication delays, the followers are driven to achieve time-varying formation where the center of the formation is the convex combination of the states of the leaders. In the theoretical analysis, sufficient conditions for the MASs achieving time-varying formation in mean square under stochastic sampling with multiple leaders and communication delays are derived. Moreover, some corollaries are also given in this paper. Finally, the theoretical analysis is verified by a given simulation example.

Consensus for formation control of multi-agent systems

Summary This study considers the formation problem for multi-agent systems, which are described by the second-order dynamics on nonlinear manifolds SE(2) and SE(3). In particular, the model of each agent contains information about its attitude. Using a consensus strategy, a control law is developed to guarantee that any desired formation can be achieved asymptotically under the conditions of complete or tree-shaped communication topologies. Numerical simulations are presented to verify the theoretical results. Copyright © 2014 John Wiley & Sons, Ltd.

Tracking Algorithms for Multiagent Systems

This paper is devoted to the consensus tracking issue on multiagent systems. Instead of enabling the networked agents to reach an agreement asymptotically as the time tends to infinity, the consensus tracking between agents is considered to be derived on a finite time interval as accurately as possible. We thus propose a learning algorithm with a gain operator to be determined. If the gain operator is designed in the form of a polynomial expression, a necessary and sufficient condition is obtained for the networked agents to accomplish the consensus tracking objective, regardless of the relative degree of the system model of agents. Moreover, the H∞ analysis approach is introduced to help establish conditions in terms of linear matrix inequalities (LMIs) such that the resulting processes of the presented learning algorithm can be guaranteed to monotonically converge in an iterative manner. The established LMI conditions can also enable the iterative learning processes to converge with an exponentially fast speed. In addition, we extend the learning algorithm to address the relative formation problem for multiagent systems. Numerical simulations are performed to demonstrate the effectiveness of learning algorithms in achieving both consensus tracking and relative formation objectives for the networked agents.

Finite-time optimal formation control of multi-agent systems on the Lie group SE(3)

This paper investigates the finite-time optimal formation problem of multi-agent systems on the Lie group SE(3), for the situation when the formation time and/or the cost function need to be considered. Under the condition that the formation time is given according to the task requirement, a finite-time optimal formation controller is proposed for the two-agent case to guarantee that the desired formation is achieved at the given time and the corresponding cost function is optimal. For the systems with multiple agents, the obtained finite-time optimal formation control law has second-order approximation accuracy. Finally, some numerical simulations are provided to illustrate the effectiveness of the theoretical results.

A synthesis approach of distributed model predictive control for homogeneous multi-agent system with collision avoidance

For the tracking and formation problem of multi-agent systems with collision avoidance, a synchronous distributed model predictive control (DMPC) algorithm is proposed. We consider the deterministic, linear, time-invariant, and homogeneous dynamics for all agents. In the synchronous DMPC, all the agents solve their optimisation problems synchronously, taking advantage of their neighbours’ assumed predictive information, to obtain the current optimal inputs. Considering the uncertain deviation existing between the assumed and actual predictive information of each agent, we contribute to design a deviation-dependent collision avoidance constraint, which is imposed in the individual optimisation problem to guarantee the safety of each agent. We constrain the uncertain deviation by designing a time-varying compatibility constraint in the two-norm form, which is imposed in the individual optimisation problem to play an important role in both the collision avoidance and exponential stability. By applying the proposed algorithm, the guarantees for the recursive feasibility, exponential stability and collision avoidance are all proved. A simulation example is provided to illustrate the practicability and effectiveness of this approach.

Formation control of multi‐agent systems with stochastic switching topology and time‐varying communication delays

In this study, the authors formulate and study the distributed formation problem of multi-agent systems (MASs) with randomly switching topologies and time-varying delays. The non-linear dynamics of each agent at different time intervals corresponds to different switching mode, and the switching design reflects the changing of travelling path in practical systems. The communication topology of the system switches among finite modes that are governed by a finite-state Markov process. On the basis of artificial potential functions, a formation controller is designed in a general form. Sufficient conditions for stochastic formation stability of the MAS are obtained in terms of a Lyapunov functional and linear matrix inequalities. Some heuristic rules to design a formation controller for the MAS are then presented. Finally, specific potential functions are discussed and corresponding simulation results are provided to demonstrate the effectiveness of the proposed approach.