Formation Control Of Multi-agent Systems Research Articles

Induced attack on formation control of multiagent systems with prescribed reference trajectories

AbstractThe induced attack on the formation control of multiagent systems is investigated from the perspective of the attacker, where a new induced attack strategy is proposed to drive the whole formation of multiagent systems to the prescribed reference trajectory. Compared with denial‐of‐service attacks and deception attacks, a desired formation reference trajectory with the stable formation structure is reached by the induced attack instead of disrupting the whole formation. First, the induced attack signal is produced by designing an attack generation exosystem, whose dynamics can be described by the regulated attack matrix and can be adjusted to generate the prescribed reference trajectory. Then, based on the local state information, the formation vector, and the induced attack signal among partial agents, a new distributed induced attack formation protocol is proposed, which is composed of the nominal formation term and the induced attack term. Meanwhile, the induced attack design criterion is proposed by utilizing a robust scheme, where the robust performance bound can be configured by two performance regulating parameters and can be used to design the appropriate regulated attack matrix. Furthermore, by establishing the projection of the induced attack signal onto the formation agreement subspace, an explicit expression of the prescribed reference trajectory is determined, which depicts the movement trajectory of the entire formation of the multiagent system under the induced attack. Finally, a simulation is provided to vindicate the effectiveness of theoretical results.

Periodic event-triggered formation control of multi-agent systems via complex Laplacian

Abstract The event-triggered formation control of first-order continuous multi-agent systems is studied based on complex Laplacian in this paper. Periodic event-triggered control is designed in which continuous communication between agents is not required. For each agent, two different triggering conditions are discussed. The first one relies on the inter-neighboring communication at each verification time, while the second one only need the broadcast states of neighbors at their triggering instants. According to the Lyapunov stability theory and algebraic graph theory, consensus conditions on the verification period and parameters in the triggering conditions are also provided. It is demonstrated that the maximum verification period under two triggering conditions are two times larger than the existing results. And a certain amount of communication between neighbors can be further reduced in the second one. Finally, the simulation examples prove the validity of the results proposed.

Optimized bipartite formation control for multiagent systems with obstacle and collision avoidance

This paper considers an optimal bipartite formation control problem for high-order nonlinear multiagent systems (MASs) with the consideration of obstacle/collision avoidance. Contrary to existing literature, the control strategy designed in this paper can render the agents in a bipartite formation to complete the obstacle/collision avoidance tasks without requiring the obstacles to be located on the coordinate axis. To save resources, an identifier-critic-actor-based optimized formation control scheme is designed for MASs. An obstacle/collision avoidance approach based on dynamical systems (DS) is designed for high-order nonlinear MASs. Different from the existing related results, the proposed DS-based obstacle/collision avoidance approach can avoid the phenomenon that the control quantities approach infinity near obstacles or other agents, and eliminate the dependence on global information. Finally, a simulation example is given to validate the proposed control method.

Distributed NN-Based Formation Control of Multi-Agent Systems: A Reduced-Order Appointed-Time Observer Approach.

Although the formation control of multi-agent systems has been widely investigated from various aspects, the problem is still not well resolved, especially for the case of distributed output-feedback formation controller design without input information exchange among neighboring agents. Using relative output information, this paper presents a novel distributed reduced-order estimation of the formation error at a predefined time. Based on the proposed distributed observer, a neural-network-based formation controller is then designed for multi-agent systems with connected graphs. The results are verified by both theoretical demonstration and simulation example.

Adaptive robust bearing-based formation control for multi-agent systems

The problem of bearing-based formation control with disturbance rejection has been studied by quite a few papers under various assumptions on the disturbances such as constant disturbances, trigonometric polynomial disturbances or bounded uniformly continuous disturbances with known bounds. In this paper, we further study the same problem with the disturbances being bounded piecewise continuous time functions. We first consider the case where the bounds of the disturbances are known. We show that the problem can be solved by a distributed static state feedback control law. Then we further consider the case where the bounds of the disturbances are unknown. We manage to solve this problem by introducing the adaptive control technique to deal with the unknown bounds of the disturbances. Our results include all the existing results on the bearing-based formation control with disturbance rejection as special cases. Moreover, we present a sufficient condition on the initial values of the closed-loop system for each case that prevents the collision.

Data-based bipartite formation control for multi-agent systems with communication constraints.

This article investigates data-driven distributed bipartite formation issues for discrete-time multi-agent systems with communication constraints. We propose a quantized data-driven distributed bipartite formation control approach based on the plant's quantized and saturated information. Moreover, compared with existing results, we consider both the fixed and switching topologies of multi-agent systems with the cooperative-competitive interactions. We establish a time-varying linear data model for each agent by utilizing the dynamic linearization method. Then, using the incomplete input and output data of each agent and its neighbors, we construct the proposed quantized data-driven distributed bipartite formation control scheme without employing any dynamics information of multi-agent systems. We strictly prove the convergence of the proposed algorithm, where the proposed approach can ensure that the bipartite formation tracking errors converge to the origin, even though the communication topology of multi-agent systems is time-varying switching. Finally, simulation and hardware tests demonstrate the effectiveness of the proposed scheme.

Event and Learning-Based Resilient Formation Control for Multiagent Systems Under DoS Attacks

Event and Learning-Based Resilient Formation Control for Multiagent Systems Under DoS Attacks

Prescribed Time Fault-Tolerant Affine Formation Control for Multi-Agent Systems with Double-Integrator Dynamics

There is an increasing interest in the affine formation control of multi-agent systems, because it can change the centroid, orientation and scale of the formation by controlling only a few leaders. In this paper, the fault-tolerant affine formation control problem is addressed for double-integrator multi-agent systems with partial loss of efficiency and bias faults. Firstly, in order to track the leaders with dynamically changing accelerations, an acceleration observer with prescribed time convergence is proposed, which can estimate the ideal acceleration for each follower. Then, based on the acceleration observer, a fault-tolerant control algorithm is given. A new Lyapunov function candidate is constructed, based on which a sufficient condition to achieve the control objective is derived. Theoretical analysis shows that the formation tracking error can converge to zero within a prescribed time, and remain in a small neighborhood of zero after that time. Finally, numerical simulations are given to show the effectiveness of the proposed algorithm and compare it with existing results.

Formation control of multi-agent systems with actuator saturation via neural-based sliding mode estimators

In this paper, the formation control problem for second-order multi-agent systems with model uncertainties and actuator saturation is investigated. An estimator-based robust formation controller is developed to ensure boundedness of the system’s formation tracking error. To estimate uncertain factors without prior knowledge of their Lipschitz constants, two new estimator designs that combine the neural-based estimation process and the sliding mode technique are proposed. Finite-time stability is achieved by introducing a new terminal estimation surface. Regarding the formation controller design, we provide a new framework to study the combined effect of input saturation and input coupling. Both an adaptive compensator and an input regulation algorithm are employed to attenuate state fluctuation led by the reverse effect. Comparative simulations regarding a multi-robot system are conducted to demonstrate the effectiveness of the proposed estimators and the estimator-based controller.

An adaptive bearing rigid formation control of multi-agent systems with nonlinear dead-zone inputs

In this paper, an adaptive bearing rigid formation control strategy for a class of nonlinear system with unknown dead-zone inputs and external disturbance is proposed. Firstly, the I-Type fuzzy system is used to approximate the unknown nonlinear dynamics of the formation model, and the approximation errors and unknown external disturbance are eliminated by the parameter adaptive estimation. Furthermore, the adaptive dynamic estimation algorithm is utilized to estimate and compensate the unknown dead-zone parameters, effectively suppressing the impact of dead-zone on formation system performance. Finally, the stability of the formation system is proved based on LaSalle’s invariance principle, and the effectiveness of the algorithm is verified by simulation results.

Distributed Formation Control of Multi-Agent Systems: A Novel Fast-Optimal Balanced Differential Game Approach

This paper proposes an efficient fast-optimal balanced differential game (DG) approach to address the formation control problem in dynamic environments for networked multi-agent systems (MASs). Compared to existing receding horizon distributed differential game (RH-DDG) approaches, the proposed approach employs a two-layer game structure to balance optimality and real-time performance, with a focus on formation control, collision avoidance and obstacle avoidance. In the offline layer, the problem is converted into a distributed differential game (DDG) where each agent computes strategies using distributed information from locally neighboring agents. The strategy of each agent self-enforces a unique global Nash equilibrium (G-NE) with a strongly connected communication topology, providing an optimal reference trajectory for the online game. In the online layer, a receding horizon differential game with an event-trigger mechanism (RH-DGET) is presented to track the G-NE trajectory. Ego players are triggered to update online Nash strategies only when the event-triggering condition is satisfied, ensuring the real-time safety certificate. Rigorous proofs demonstrate that the online Nash strategies converge to the offline G-NE until the trigger ends, and a certain dwell time condition is given to prevent the Zeno behavior. Simulation results validate the effectiveness of the proposed approach.

Distributed robust adaptive formation control of multi-agent systems with heterogeneous uncertainties and directed graphs

This paper studies distributed time-varying formation control problems for a class of linear systems with heterogeneous uncertainties and directed graphs. Both the cases without and with an active leader having unknown control inputs are considered. Two new robust adaptive formation protocols are designed in a totally distributed fashion, both of which incorporate two parts: a fully distributed nominal controller relying on the neighbors’ relative state information and an adaptive compensating signal to restrain the influences of uncertainties. An original adaptive compensating strategy is proposed herein to deal with uncertainties related to not only system states but also control inputs. On the basis of adaptive mechanism, the controller design requires neither global information about communication topologies nor the upper bounds of uncertainties and the leader’s control inputs. Based on Lyapunov arguments, sufficient conditions to achieve the desired formation are derived in terms of Riccati equations. The proposed protocols guarantee that the formation errors can converge to zero. Finally, the theoretical results are demonstrated by numerical simulations.

Event-Triggered Bipartite Time-Varying Formation Control for Multiagent Systems With Unknown Inputs.

This article addresses the issues of the bipartite time-varying formation (BTVF) control for multiagent systems (MASs) on signed digraphs. All the designs are performed under the assumptions that the leader and followers suffer from external disturbances, the control input signal of the leader is unreachable to any follower, and the state variables of the followers are unmeasurable. To begin with, an unknown input observer (UIO) is designed for each follower using a traditional interval observer to obtain the state estimates. To realize the BTVF tracking, a distributed consensus error dynamic system is constructed. Furthermore, a distributed unknown input reconstruction method is developed to estimate the multiple disturbances in the consensus error system. Then, an event-triggered BTVF control protocol is proposed which allows two antagonistic time-varying formations to be formed, while excluding Zeno behavior. A simulation of a group of wheeled robots is used to demonstrate the performance of the proposed methods.

Fully distributed dynamic event-triggering formation control for multi-agent systems under DoS attacks: Theory and experiment

The fully distributed time-varying formation (TVF) control problem is investigated for multi-agent systems (MASs) subject to Denial-of-Service (DoS) attacks. An asynchronous dynamic event-triggering (DET) mechanism is introduced to alleviate agents’ communication burden suitably, and a fully distributed DET-TVF control protocol is designed. Sufficient conditions and theoretical analysis prove that this protocol can achieve the desired TVF configuration under DoS attacks, and Zeno behavior is excluded. Finally, experimental examples using six quadrotors demonstrate and fully showcase the efficacy of the proposed methods.

Finite-time ADRC formation control for uncertain nonaffine nonlinear multi-agent systems with prescribed performance and input saturation

AbstractThis paper explores finite-time formation control of multi-agent systems (MASs) with high-order nonaffine nonlinear dynamics and saturated input. Based on active disturbance rejection control theory, extended state observer is employed to identify unknown nonaffine nonlinear functions in MASs. The proposed control law consisting of backstepping control, tracking differentiator, and finite-time performance function is adopted for MASs to achieve the desired formation while reaching performance requirements. An auxiliary dynamic compensator is introduced to correct the control deviation caused by input saturation. Lyapunov stability theory is utilized to analyze the stability of the closed-loop system, which guarantees that the formation tracking error can asymptotically converge to an arbitrarily small neighborhood around zero in finite time. Finally, the simulation results show that compared to the adaptive, cooperative learning, and virtual structure methods, the proposed control algorithm has stronger tracking ability and faster setting time (1.8 s) under the influence of nonaffine nonlinear uncertainties. The integral square error for the formation control strategy in this paper is 0.16, which is much smaller than the abovementioned methods and is therefore provided to manifest the validity and feasibility of the proposed control strategy.

Security Time-Varying Formation Control for Multi-Agent Systems Under Denial-of-Service Attacks via Unknown Input Observer

The paper investigates the security time-varying formation control problem when the communication network of multi-agent systems (MASs) suffers from Denial-of-Service (DoS) attacks based on switched controller, state observers and unknown input reconstruction (UIR). To begin with, for the follower agents with unknown inputs, through an interval observer, the estimations of unknown input (UI) and system state can be obtained asymptotically and simultaneously by a Luenberger-like state observer (LLSO) combining with a UIR. After this, a distributed control protocol (DCP) on formation tracking is proposed based on the UIR and the state estimation, which can compensate the UI successfully. Moreover, the time space is divided into three parts utilizing the transmission interruption caused by DoS attacks, and the gain of the controller is designed corresponding to three different DoS attack duration, respectively. With the help of some concept in switched system, it is demonstrated that the given formation pattern can be reached under the proposed DCP. Finally, to verify the effectiveness of the proposed methods, a vehicle cruise control system used as the simulation example is given.

Distributed Cooperative Formation Control for Multi-agent System based on Virtual Centre Strategy

In this study, a distributed cooperative formation consistency control strategy is investigated for multi-agent system (MAS) to achieve formation consensus. Firstly, the virtual-centre-based reference formation is presented. Then a distributed cooperative formation control law based on virtual-centre is developed for MAS to achieve formation consensus. Finally, the new control scheme is applied to MAS consisting of 5 UAVs and the resulting closed-loop MAS is stable. The effectiveness of the new cooperative control behavior strategy is verified by simulations.

Event-Triggered Surrounding Formation Control of Multiagent Systems for Multiple Dynamic Targets

Event-Triggered Surrounding Formation Control of Multiagent Systems for Multiple Dynamic Targets

Distributed adaptive formation control of multi-agent systems with measurement noises

In this paper, we investigate the distributed adaptive formation control problem of leader-following multi-agent systems where the measurements are subject to noises. A distributed LMS-like algorithm is proposed to estimate the relative position between the followers and the leader. By employing the “certainty equivalence” principle, an adaptive motion controller is designed to achieve the desired formation under dynamically changing interaction topologies. The incompatibility in simultaneously satisfying the persistent excitation condition required by localization estimators and accomplishing the control tasks makes the theoretical analysis challenging. In order to deal with this issue, an excited noise signal is embedded into the control law. We give the upper bounds of both the estimation errors and formation error of the closed-loop multi-agent system under the distributed adaptive control law. Finally, the numerical simulations are provided to demonstrate the effectiveness of our theoretical results.

Dynamic Modelling and Numerical Simulation of Formation Control for Intelligent Multi-agent System with Target Geometric Configuration

Swarming motility arise very naturally in biological, physical, social sciences, etc. However, how to realize artificial intelligent self-organizing behavior is still an interesting and challenging task, especially for formation control of multiple agents with special geometric configuration. This work proposes a novel approach of formation control for a multi-agent system with target geometric configuration by combining dynamic model with graph realization. First, the global rigid graph is designed for the target formation pattern, then the interactive relationship and the expected distance between different intelligent agents are identified by the realization of graph. Secondly, the double-integrator dynamic model based on Newtonian mechanics is formulated for inherent driving force caused upon attenuation of potential energy, consistent of movement direction and speed. Thirdly, the stability of swarming motility is proved by Lyapunov’s second method, i.e., the movement of all agents will gradually stabilize to consistency of the movement direction and speed, and realize the target geometric configuration. Finally, numerical simulations of different geometric configurations are performed to verify the theoretical findings.