Control Of Heterogeneous Multi-agent Systems Research Articles

Containment control of heterogeneous multi-agent systems

Containment control of multi-agent systems has attracted a lot of research attention lately and there is a significant room for generalizing the results by considering the agent models to be heterogeneous. Attaining containment control of heterogeneous multi-agent systems using a single gain matrix/controller is a challenging task and not always achievable. In this paper, we propose a strategy to attain containment control for linear second order heterogeneous multi-agent systems using a weighted sum of a derivative term, a proportional term and some integral terms. These weights, chosen using the root locus based method, for a given directed acyclic graph ensure that containment control is possible even when some of the agents have inherently unstable dynamics. The leaders are assumed to follow a given polynomial trajectory and the followers are contained within the convex hull of these leaders’ positions. A number of simulations are presented to vindicate the efficacy of the proposed method for controller design.

Containment control for heterogeneous multi-agent systems with time delay via an output regulation approach

Containment control for heterogeneous multi-agent systems with time delay via an output regulation approach

Distributed Adaptive Fault-Tolerant Formation Control for Heterogeneous Multiagent Systems With Communication Link Faults

In this paper, we investigate the distributed adaptive fault-tolerant formation control problem for a group of heterogeneous multiagent systems consisting of multiple follower unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) with parametric uncertainties and communication link faults. Based on the local states information of the vehicles, the adaptive fault-tolerant formation control protocol with varying control gains is developed for each follower UAV and UGV such that all followers track the dynamic trajectory of the virtual leader and obtain the expected formation configuration simultaneously under the influence of communication link faults and external disturbances. The distributed formation tracking convergence performance is discussed through Lyapunov theory. Finally, a simulation study based on the UAVs-UGVs collaborative systems is provided to show the effectiveness of the developed control strategy.

Distributed Continuous‐Time Containment Control of Heterogeneous Multiagent Systems with Nonconvex Control Input Constraints

This paper focuses on studying containment control problem with switching communication graphs of continuous‐time heterogeneous multiagent systems where the control inputs are constrained in a nonconvex set. A nonlinear projection algorithm is proposed to address the problem. We discuss the stability and containment control of the system with switching topologies and nonconvex control input constraints under three different conditions. It is shown that all agents converge to the convex hull of the given leaders ultimately while staying in the nonconvex set under the premise that at least one directed path from leaders to the agents exists in each bounded time interval. Finally, the validity of the results obtained in this paper is verified by simulation.

Fully distributed event-triggered pinning group consensus control for heterogeneous multi-agent systems with cooperative-competitive interaction strength

This paper mainly studies the group consensus problem of the heterogeneous multi-agent systems with cooperative and competitive interactions and their strength among the agents. And both event-triggered mechanism and pinning control method are considered based on the system’s topology with connected components. Besides, the novel fully distributed event-triggered conditions which only contain the local information for each agent are designed. Then, some sufficient conditions and the corresponding pinning control strategies are obtained via using algebraic graph theory and Lyapunov stability theorem, which can guarantee the system to reach multiple group consensus. In addition, Zeno-behavior for each agent is strictly excluded by utilizing time-correlation function. Finally, several simulations illustrate that our findings and the proposed methods are effective. Moreover, the results show that the convergence rate of the system will increase with the appropriate change of the cooperative or competitive interaction or their strength.

Observer-Based Consensus Control for Heterogeneous Multi-Agent Systems with Output Saturations

This paper studies the consensus problem for heterogeneous multi-agent systems with output saturations. We consider the agents to have different dynamics and assume that the agents are neutrally stable and that the communication graph is undirected. The goal of this paper is to achieve the consensus for leaderless and leader-following cases. To solve this problem, we propose the observer-based distributed consensus algorithms, which consists of three parts: the nonlinear observer, the reference generator, and the regulator. Then, we analyze the consensus based on the Lasalle’s Invariance Principle and the input-to-state stability. Finally, we provide numerical examples to demonstrate the validity of the proposed algorithms.

Fixed-Time Fault-Tolerant Formation Control for Heterogeneous Multi-Agent Systems With Parameter Uncertainties and Disturbances

This paper investigates the fixed-time time-varying formation control problems for heterogeneous multi-agent systems (MASs) composed of multiple Unmanned Ground Vehicles (UGVs) and multiple Unmanned Aerial Vehicles (UAVs) in the presence of actuator faults, parameter uncertainties, matched and mismatched disturbances. Besides achieving the desired formation configurations, each follower can also track the position trajectory produced by the virtual leader within fixed time simultaneously. The difference dynamic characteristics between the heterogeneous agents leads to unbalanced interaction of lumped uncertainties in the communication network, which increases the difficulty of collaborative control. To estimate the mismatched disturbances and lumped uncertainties, a fixed-time observer for each follower is designed, which can guarantee the estimation errors converge to the origin in fixed settling time. Subsequently, by utilizing the backstepping technique and the fixed-time stability theory, an observer-based distributed fixed-time formation controller for each follower in the $X$ - $Y$ axes and the observer-based decentralized fixed-time tracking controllers for follower-UAVs in the $Z$ axes are presented, which are shown to be fixed-time stable even under the influence of actuator faults and mismatched disturbances. Moreover, the fixed-time results can ensure the convergence time is independent of initial conditions. Finally, numerical simulations demonstrate the effectiveness of the proposed algorithms.

Fault-Tolerant Formation Tracking Control for Heterogeneous Multiagent Systems with Directed Topology

In this paper, the adaptive fault-tolerant formation tracking control problem for a set of heterogeneous unmanned aerial vehicle (UAV) and unmanned ground vehicle (UGV) systems with actuator loss of effectiveness faults is investigated. The cooperative fault-tolerant formation control strategy for UAV and UGV collaborative systems is classified into the altitude consensus control scheme for follower UAVs and the position cooperative formation control scheme for all followers. The altitude consensus control algorithm is designed by utilizing backstepping control technique to drive all UAVs to a desired predefined height. Then, based on synchronization formation error information, the position cooperative formation control algorithm is proposed for all followers to reach the expected position and perform the desired formation configuration. The adaptive fault estimation term is adopted in the designed fault-tolerant formation control algorithm to compensate for the actuator loss of effectiveness fault. Finally, a simulation example is proposed to reveal the validity of the designed cooperative formation tracking control scheme.

Group Leader-Following Consensus Control for Heterogeneous Multi-Agent Systems With Time Delays

In this paper, the problem of group leader-following consensus is discussed for high-order heterogeneous multi-agent systems(HMASs) with multiple leaders and time delays. The four situations are considered: autonomous leaders, active leaders with controllers, and accepting their own information with/without time delays. Different protocols are designed for different situations. Under the corresponding protocols, HMASs can achieve group leader-following consensus without the limitation of in-degree balance. And the networked predictive scheme(NPS) actively compensating for time delays is used to predict current information of agents. Besides, the results are extended to multiple groups case. Finally, the simulation results show that, based on the NPS, the state trajectory of each agent in the time-delay case is very close to that in no time-delay case.

Distributed model reference adaptive containment control of heterogeneous multi-agent systems with unknown uncertainties and directed topologies

In this paper, the containment control problem of heterogeneous uncertain high-order linear Multi-Agent Systems (MASs) is addressed and solved via a novel fully-Distributed Model Reference Adaptive Control (DMRAC) approach, where each follower computes its adaptive control action on the basis of local measurements, information shared with neighbors (within the communication range) and the matching errors w.r.t. its own reference model, without requiring any previous knowledge of the global directed communication topology structure. The approach inherits the robustness of the direct model reference adaptive control (MRAC) scheme and allows all agents converging towards the convex hull spanned by leaders while fulfilling at the same time local additional performance requirements at single-agent level, such as prescribed settling time, overshoot, etc. The asymptotic stability of the whole closed-loop network is analytically derived by exploiting the Lyapunov theory and the Barbalat lemma, hence proving that each follower converges to the convex hull spanned by the leaders, as well as the boundedness of the adaptive gains. Extensive numerical analysis for heterogeneous MAS composed of stable, unstable and oscillating agent dynamics are presented to validate the theoretical framework and to confirm the effectiveness of the proposed approach.

Distributed control of heterogeneous multi-agent systems with unknown control directions via event/self-triggered communication

This paper investigates the leader-following output consensus of heterogeneous multi-agent systems (MASs) with unknown and nonidentical control directions under switching topology. To save the communication resources, a distributed adaptive control protocol together with an event-triggered communication scheme is proposed to achieve the output consensus. A self-triggered communication strategy is further given to prevent the continuous monitoring of neighbors states. Moreover, we prove that the proposed event/self-triggered strategies are Zeno-free. The obtained results are successfully applied to design the output formation controller. Finally, the effectiveness of the proposed theoretical results is demonstrated by two numerical examples.

Distributed adaptive observer‐based output formation‐containment control for heterogeneous multi‐agent systems with unknown inputs

Here, the authors study the distributed time-varying output formation-containment control of heterogeneous multi-agent systems, where multiple targets have heterogeneous dynamics and unknown inputs. A distributed adaptive observer-based output formation-containment controller is proposed. Firstly, consensus-based adaptive finite impulse response filters are established to estimate the unknown inputs and states of the targets. Then, by constructing an augmented system with the centre of the targets' outputs as its output and using the observers, an output regulation-based formation-containment controller is developed to make agents encircle the targets with certain formation. Finally, a simulation example is given to illustrate the effectiveness of the proposed method.

Robust model predictive control of heterogeneous time-delay multi-agent systems with polytopic uncertainties and input amplitude constraints

This article studies the robust model predictive control of heterogeneous multi-agent systems with polytopic uncertainties and time delay. Moreover, some constraints on the amplitude of the control inputs are considered for each agent. The proposed distributed controllers are designed as state feedback. The goal is to design the feedback gains such that the multiagent system achieves consensus in the presence of time-delay and model uncertainties. For this purpose, an optimization problem is proposed, and by using the constrained robust model predictive control and the appropriate Lyapunov–Krasovskii functional, sufficient conditions are obtained to solve the optimization problem through solving the linear matrix inequalities. In this regard, a theorem is presented, and it is proved that the consensus errors converge to zero. Finally, the effectiveness of the proposed method is illustrated using numerical simulations.

Top-Down Synthesis of Multiagent Formation Control: An Eigenstructure Assignment Based Approach

We propose a top-down approach for formation control of heterogeneous multi-agent systems, based on the method of eigenstructure assignment. Given the problem of achieving scalable formations on the plane, our approach globally computes a state feedback control that assigns desired closed-loop eigenvalues/eigenvectors. We characterize the relation between the eigenvalues/eigenvectors and the resulting inter-agent communication topology, and design special (sparse) topologies such that the synthesized control may be implemented locally by the individual agents. Moreover, we present a hierarchical synthesis procedure that significantly improves computational efficiency. Finally, we extend the proposed approach to achieve rigid formation and circular motion, and illustrate these results by simulation examples.

Controllability of heterogeneous multiagent systems

SummaryThe existing results on controllability of multiagent systems (MASs) are mostly based on homogeneous nodes. This paper focuses on controllability of heterogeneous MASs, where the agents are modeled as two types. One type is that the agents have the same high‐order dynamics, and the interconnection topologies of the information flow in different orders are supposed to be different; the other type is that the agents have generic linear dynamics, and the dynamics are supposed to be heterogeneous. For the first type, the necessary and sufficient condition for controllability of heterogeneous‐topology system is derived via combination of Laplacian matrices. For the second type, the contribution also has two parts. The first part supposes that the agents have the same dimensional states and proves that controllability of this kind of MASs is equivalent to the controllability of each node and the whole interconnection topology, while the last parameter of the state feedback vector must not be 0. The second part supposes that the agents may have different dimensional states. For this kind of systems, the concept of β‐controllability is proposed. The necessary and sufficient condition for β‐controllability of heterogeneous‐dynamic systems is also derived and it is also proved that the feedback gain vectors have the effect to improve controllability. Different illustrative examples are provided to demonstrate the effectiveness of the theoretical results in this paper.

Scaled consensus control of heterogeneous multi-agent systems with switching topologies

In this contribution, we aim to examine the scaled consensus problem for heterogeneous multi-agent systems, which comprise two kinds of agents: the agents with first-order dynamics and the agents with second-order dynamics. The scaled consensus here means that the ratios between the states of the agents asymptotically approach specified constants instead of the same value. Firstly, appropriate distributed control protocols are designed for first-order and second-order networked agents, respectively. Particularly, the effects of switching communication networks and time-varying delays on model performance are investigated in this paper. Secondly, an augmented system approach based on algebraic graph theory and non-negative matrix theory is adopted to solve the proposed scaled consensus problem. Finally, a sufficient criterion is established to certify the scaled consensus performance of mixed agents. The correctness of the theoretical result is demonstrated through several simulation examples.

Robust output regulation for containment control of heterogeneous discrete-time nonlinear multi-agent systems

ABSTRACTIn existing researches on containment control of heterogeneous multi-agent systems (MASs), the solution is usually dependent on the solvability of regulator equations. However, the closed-form solution of many nonlinear regulator equations of systems is rarely obtained. Towards this end, in this paper the containment control problem of heterogeneous discrete-time nonlinear MASs subject to parameter uncertainties is considered, and the power series approach is adopted to solve complex regulator equations by decomposing them into a series of solvable linear equations. Then, a distributed robust control law based on internal model principle is presented by utilising the solution of the linear equations. Theoretical analysis shows that under certain assumptions asymptotic containment control is achieved for the heterogeneous discrete-time nonlinear MASs with sufficiently small parameter perturbations. Finally, a numerical simulation is implemented to verify the proposed control law.

Distributed impulsive control for heterogeneous multi-agent systems based on event-triggered scheme

In this paper, the distributed impulsive control for heterogeneous multi-agent systems based on event-triggered approach is investigated. According to whether the information transfer of the dynamic compensator is continuous or not, two different kinds of impulsive controllers are designed, respectively. Based on these two kinds of controllers, the corresponding distributed event-triggered conditions are provided, which make the impulsive instants of all agents do not need occur simultaneously. Moreover, the lower bound of impulsive intervals can also be guaranteed for all the event-triggered conditions, which means that the control schemes given in this paper can avoid the Zeno-behavior successfully. Eventually, a simulation example is proposed to support the effectiveness of the results obtained in this paper.

Distributed Event-triggered Consensus Control for Heterogeneous Multi-agent Systems under Fixed and Switching Topologies

This paper investigates the distributed consensus problem for heterogeneous multi-agent systems via event-triggered scheme. To alleviate the communication burden, a distributed event-triggered consensus algorithm using an open-loop estimate and neighboring information is proposed. In the proposed event-triggered scheme, the control input of each agent is dependent on the estimate and information at discrete instants. Firstly, the novel event-triggered consensus algorithm is proposed for fixed topology, which involves the discrete communication between neighboring agents. Then, for the switching topology, the triggering condition is proposed by virtue of a topology-dependent dwell time approach. Further, the corresponding consensus procedures are given. Finally, the effectiveness of the proposed scheme is illustrated by numerical results.

Secure consensus control for heterogeneous multi-agent systems with trusted nodes

This study focuses on the secure consensus problem for heterogeneous multi-agent systems composed of first- and second-order agents. First, we show that the network robustness can be significantly improved by setting a subset of nodes as trusted nodes. Then, we propose a secure consensus algorithm for heterogeneous systems with trusted nodes. The sufficient conditions for the convergence of the normal agents states to a common value under adversarial nodes are presented. Finally, certain numerical examples are provided to illustrate the effectiveness of the theoretical results.