Fault-tolerant Containment Research Articles

Adaptive fault-tolerant containment control for heterogeneous uncertain nonlinear multi-agent systems under actuator faults

As modern control systems involve a growing number of actuators, the consequent number of faults occurrence, which may deteriorate the closed-loop system performance, is increasing. Focusing on the containment control problem of generic nonlinear high-order heterogeneous uncertain Multi-Agent Systems, this study proposes a novel distributed adaptive fault-tolerant Proportional-Integral-Derivative control protocol to improve the reliability and the resilience of the whole networked systems against actuator failures. The Lyapunov theory, combined with the Barbalat lemma, provides the design of suitable adaptive mechanisms that adjust the PID control actions to ensure the asymptotic convergence of the closed-loop containment errors for the overall network, hence implying the convergence of each agent state toward the convex region shaped by the multiple leaders, despite the occurrence of actuators faults. The fulfillment of the fault-tolerant containment objective is ensured by requiring a lower computational burden with respect to alternative solutions, hence resulting in more attractive for wider practical engineering applications. Numerical simulation results, also including a comparison analysis with a state-of-the-art controller, corroborate the efficiency and the advantages of the proposed distributed PID controller.

Distributed two-channel dynamic event-triggered adaptive finite-time fault-tolerant containment control for multi-leader UAV formations

This paper addresses the distributed adaptive finite-time containment control problem in multi-leader UAV formations with actuator failures, limited communication, and external disturbances. A two-channel dynamic event-triggered strategy based on adaptive and sliding mode control is proposed as a containment control scheme, which solves the contradiction between the need to include containment error in the continuous term of the sliding mode surface in the adaptive law and the discontinuity of the communication between neighboring subsystems (follower UAVs) by constructing intermediate variables. Unlike the traditional event triggering condition that can only be applied to asymptotically convergent systems, the dynamic triggering condition designed in this paper, based on auxiliary variables, hyperbolic tangent function, and adaptive techniques, realizes finite-time convergence during the adjustment of the system and sets a more reasonable lower limit for the triggering thresholds, thus further reducing the communication frequency and ensuring the finite-time convergence of the system. The stability of the closed-loop system can be proved by the Lyapunov theorem. Zeno behavior can be avoided. The simulation results verify the effectiveness of the developed control algorithm.

Event-driven intelligent fault-tolerant containment control for nonlinear multiagent systems with unknown disturbances

This paper investigates the event-driven intelligent fault-tolerant containment control problem for nonlinear multiagent systems affected by unknown disturbances, and conducts a comprehensive analysis of the dynamic stability of the system. Reduced-order modelling is employed for system modelling and identification, while radial basis function neural networks are utilised to estimate the nonlinear functions of the system model. An event-driven control scheme is designed based on the backstepping method and Lyapunov functional approach. In contrast to existing consensus control schemes, the proposed event-driven control schemes are specifically tailored to improve the energy efficiency and endurance of nonlinear multiagent systems operating in complex environments. Under the proposed control law, the output of each follower is converge to the convex hull spanned by the outputs of the leaders. The effectiveness of the proposed method is rigorously validated through numerical simulations. Furthermore, a practical example involving the design of a marine surface vehicle using advanced robotics technology is presented to further substantiate the efficacy of the proposed method.

Distributed adaptive event-triggered finite-time fault-tolerant containment control for multi-UAVs with input constraints and actuator failures

This article investigates the distributed adaptive finite-time containment control problem for multi-UAVs with input constraints, actuator failures, communication limitations, and external disturbances. First, a new smoothing function is used to smooth the asymmetric input constraint signals so that the input constraint and actuator fault control problem can be transformed into a variable gain control problem. Subsequently, a new Nussbaum function is proposed to solve the variable gain control problem. A new adaptive event-triggered strategy is designed to solve the communication limitation problem, and the trigger threshold has the characteristic of adaptive adjustment that can be dynamically decreased. In response to external disturbances, an adaptive law is designed to estimate and compensate for the boundaries of disturbances. It follows from the analysis based on Lyapunov theory that under the proposed controller, the followers will converge to the convex envelope formed by the leaders in a finite time, and Zeno-free is achieved. Simulation results are provided to verify the effectiveness of the developed adaptive event-triggered finite-time fault-tolerant containment control laws.

Semi-Global Bipartite Fault-Tolerant Containment Control for Heterogeneous Multiagent Systems With Antagonistic Communication Networks and Input Saturation.

Semi-global bipartite fault-tolerant containment control framework on antagonistic communication networks is proposed in this article for heterogeneous multiagent systems (MASs) under the influence of input saturation and actuator faults. An observer is constructed to estimate the leaders' states on signed digraph, where the communication networks are antagonistic. A fully distributed virtual control approach is developed to acquire the containment trajectory. Based on the observer, a semi-global containment control method is developed to compensate for the detrimental impacts of both input saturation and actuator faults. Besides, the dynamics and state-space dimensions of the agents can be different. The proposed framework overcomes two drawbacks of the conventional containment control: 1) the containment trajectory is obtained under general antagonistic communication networks, which is more general in engineering applications and 2) both actuator faults and input saturation are solved for heterogeneous agents, which relaxes the limitation of homogeneous dynamics. Finally, a simulation example is conducted to test and verify the feasibility of the proposed method framework.

Distributed Adaptive Fault-Tolerant Formation-Containment Control With Prescribed Performance for Heterogeneous Multiagent Systems.

This article proposes a distributed adaptive fault-tolerant formation-containment control with prescribed performance for heterogeneous multiagent systems (MASs) consisting of multiple unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) in the presence of actuator faults. First, utilizing the neighborhood formation error information, the distributed fault-tolerant formation control strategy is developed for the trajectory dynamics of each UAV to achieve the formation tracking, that is, all UAVs track the virtual leader and perform the prespecified formation configuration. Then, the adaptive fault-tolerant containment algorithm, independent of the positions of the leaders, is proposed to guarantee the UGVs converge to the convex hull formed by the leader UAVs. The adaptive estimation scheme is constructed to compensate for the unknown system parameters and actuator loss-of-effectiveness and bias faults. The formation-containment tracking performance is analyzed based on Lyapunov theory with the synchronization errors satisfying the prescribed performance. A simulation example based on UAVs-UGVs systems is adopted to verify the effectiveness of the proposed control strategy.

Distributed adaptive fault-tolerant containment control for multi-agent systems with nonautonomous leaders: A hierarchical event-triggered scheme

Distributed adaptive fault-tolerant containment control for multi-agent systems with nonautonomous leaders: A hierarchical event-triggered scheme

Distributed Fault-Tolerant Containment Control Protocols for the Discrete-Time Multiagent Systems via Reinforcement Learning Method.

This article investigates the model-free fault-tolerant containment control problem for multiagent systems (MASs) with time-varying actuator faults. Depending on the relative state information of neighbors, a distributed containment control method based on reinforcement learning (RL) is adopted to achieve containment control objective without prior knowledge on the system dynamics. First, based on the information of agent itself and its neighbors, a containment error system is established. Then, the optimal containment control problem is transformed into an optimal regulation problem for the containment error system. Furthermore, the RL-based policy iteration method is employed to deal with the corresponding optimal regulation problem, and the nominal controller is proposed for the original fault-free system. Based on the nominal controller, a fault-tolerant controller is further developed to compensate for the influence of actuator faults on MAS. Meanwhile, the uniform boundedness of the containment errors can be guaranteed by using the presented control scheme. Finally, numerical simulations are given to show the effectiveness and advantages of the proposed method.

Adaptive fixed-time consensus for stochastic multi-agent systems with uncertain actuator faults

In this paper, we study the adaptive fixed-time consensus control for stochastic multi-agent systems (SMASs) with uncertain actuator faults. Firstly, a fully distributed adaptive consensus protocol and an adaptive fault-tolerant consensus protocol are proposed, respectively, to ensure that the fixed-time consensus of SMASs with actuator faults can be reached. Secondly, an adaptive fault-tolerant containment consensus protocol is further proposed for the SMASs by leveraging the signum function, and this protocol can effectively solve the containment consensus in the unbalanced communication network. Finally, some simulation examples are given to verify the effectiveness of our consensus protocols.

Adaptive fuzzy fault-tolerant containment control for nonlinear multiagent systems based on modified distributed observer

This paper investigates the finite-time fault-tolerant containment control problem for stochastic nonlinear multiagent systems with intermittent actuator faults. A modified distributed observer is designed to estimate unmeasured states in systems. Compared with the existing result, the estimation precision of the modified observer is significantly enhanced in the presence of various uncertainties in the control channel. Moreover, this paper designs a compensation mechanism for intermittent faults to suppress the adverse effects caused by each fault. Then a finite-time fuzzy fault-tolerant containment control scheme is proposed to make all followers converge to the convex hull formed by leaders in a finite time. It is proved that all signals of closed-loop systems are semi-globally finite-time stable in probability based on the finite-time stochastic Lyapunov stability theory, and containment errors can converge to a small neighborhood of the origin. Finally, simulation studies are provided to illustrate the effectiveness of the proposed control scheme.

Cooperative Fault-Tolerant Containment Control for Nonlinear Multiagent Systems With Switching Directed Topologies Based on Hierarchical Mechanism

In this article, the cooperative fuzzy hierarchical fault-tolerant containment control (FTCC) method is proposed for nonlinear multiagent systems (MASs) over switching directed topologies. Based on the hierarchical mechanism, the problem of the cooperative FTCC for nonlinear MASs under switching directed topologies is decoupled into the cooperative containment control problem of the virtual reference system (upper layer) under switching directed topologies and the tracking control problem of the actual system (lower layer). Due to the existence of switching topologies, the state of the virtual reference system may jump, which further affects the transient performance of the lower tracking system; moreover, the actuator faults may also cause a sudden change in actual system. In order to mitigate the influence of switching topologies and actuator faults on the lower tracking system, the generalized restricted potential function is introduced to ensure the norm of the lower tracking error within the predefined performance function. Finally, a simulation example is introduced to illustrate the theoretical results obtained.

Distributed fault-tolerant containment control for a class of non-linear multi-agent systems via event-triggered mechanism

An issue of actuator faults in non-linear multi-agent systems with multiple leaders is addressed in this work. Through an event-triggered mechanism, a novel fault-tolerant containment control protocol is designed to eliminate the adverse effects of actuator faults on the systems, and the communication resources can be saved efficiently in the meantime. The self-regulation of the event-triggered mechanism is enhanced significantly by utilizing the adaptive updating strategies, and the proposed triggering thresholds are both time-dependent and state-dependent. A sufficient condition is derived to make the systems with aperiodic sampling stabilizable. Moreover, it is proved that Zeno behavior can be avoided in this article. A numerical simulation is also presented to exhaustively illustrate the effectiveness of the designed scheme.

Robust Adaptive Fault-tolerant Containment Control of Networked Heterogeneous Agent Systems with Multiple Active Leaders and Mismatched Affine Uncertainties

Robust Adaptive Fault-tolerant Containment Control of Networked Heterogeneous Agent Systems with Multiple Active Leaders and Mismatched Affine Uncertainties

Fuzzy fault-tolerant containment control for multi-agent systems with unknown nonlinear dynamics

This paper studies the containment control problem for a class of nonlinear multi-agent systems (MASs) with actuator faults (AFs) and external disturbance under switching communication topologies. To address this problem, a new fuzzy fault-tolerant containment control method is developed via utilizing adaptive mechanisms. Furthermore, a sufficient condition is obtained to guarantee the stability of the considered closed-loop system by the dwell time technique combined with Lyapunov stability theory. Unlike the traditional method to estimate the weight matrix, the fuzzy logic system is used to estimate the norm of weight vectors. Thus, the difficulty that the unknown nonlinear function cannot be compensated for when the actuator produces outage or stuck fault is solved. Compared with the existing controllers for nonlinear MASs, the proposed controller is more suitable for the considered problem under the influence of AFs that are detrimental to the operation of each agent system. Besides which, the closed-loop system is proven to be stable by using the developed controller, and all followers converge asymptotically to the convex hull formed by the leaders. Finally, an example based on a reduced-order aircraft model is presented to verify the effectiveness of the designed control scheme.

Distributed Fault-Tolerant Containment Control for Nonlinear Multi-Agent Systems Under Directed Network Topology via Hierarchical Approach

This paper investigates the distributed fault-tolerant containment control (FTCC) problem of nonlinear multi-agent systems (MASs) under a directed network topology. The proposed control framework which is independent on the global information about the communication topology consists of two layers. Different from most existing distributed fault-tolerant control (FTC) protocols where the fault in one agent may propagate over network, the developed control method can eliminate the phenomenon of fault propagation. Based on the hierarchical control strategy, the FTCC problem with a directed graph can be simplified to the distributed containment control of the upper layer and the fault-tolerant tracking control of the lower layer. Finally, simulation results are given to demonstrate the effectiveness of the proposed control protocol.

Fault-Tolerant Containment Control for IT2 Fuzzy Networked Multiagent Systems Against Denial-of-Service Attacks and Actuator Faults

This article investigates the fault-tolerant containment control issue for uncertain nonlinear networked multiagent systems (MASs) under denial-of-service (DoS) attacks and actuator faults by interval type-2 (IT2) Takagi–Sugeno (T–S) fuzzy model. The lower and upper membership functions (LUMFs) are first applied to networked MASs to capture parameter uncertainties. The malicious behavior of DoS attacks that cause the loss of information for MASs is considered. Whereafter, based on attack situations, i.e., whether the attack invades the communication channels successfully or not, the uncertain nonlinear networked MAS is remodeled as a switched version with four subsystems and analyzed via the average dwell-time approach. In view of long-term utilization or burn-in of components, the actuator faults are taken into account for considered MASs. Afterward, on the basis of the Lyapunov stability theory, a novel IT2 fuzzy dynamic containment control protocol is proposed such that the states of followers can converge to the convex hull governed by those of leaders in spite of DoS attacks and actuator faults. Finally, a demonstrative example is shown to illustrate the effectiveness and practicabilities of the proposed fuzzy containment control strategy.

Distributed Adaptive Fuzzy Fault-Tolerant Containment Control for Heterogeneous Nonlinear Multiagent Systems

This article is concerned with the problem of distributed adaptive fuzzy fault-tolerant containment control (FTCC) for a class of heterogeneous nonlinear multiagent systems with actuator faults and external disturbances. Two FTCC strategies are proposed for two different cases, i.e., leader’s input can be obtained by its neighboring follower agents and the input of the leader is not available by any followers, respectively. In the first case, a distributed observer-based adaptive FTCC protocol is presented to achieve the containment control objective. In the second case, a distributed adaptive FTCC method which is independent of global information about the communication topology and upper bounds of the leader’s input is developed using the local containment error. An auxiliary controller gain is proposed to solve the problem of partial loss of effectiveness faults, and the potential singularity brought by the auxiliary controller gain to the controller can be avoided by introducing a projection operator. It is shown that each follower converges asymptotically to a convex hull spanned by the leaders with external input. Finally, the developed method is demonstrated by simulation results.

Distributed Fault-Tolerant Containment Control for Linear Heterogeneous Multiagent Systems: A Hierarchical Design Approach.

In this article, the problem of distributed hierarchical fault-tolerant containment control for heterogeneous linear multiagent systems (MASs) is investigated. In most of the existing distributed methods for MASs with system failures, each agent broadcasts its state, or output, or the estimation of state to neighbors. Once an agent is subjected system failures, faults affect the dynamics of other agents over the network, that is, the influence of faults on the agent will propagate with the network. In order to overcome this drawback, a fault-tolerant hierarchical containment control protocol is developed, which includes two layers: 1) the upper layer and 2) the lower layer. The upper layer consists of a virtual system and a cooperative controller to achieve a virtual containment objective. The lower layer consists of an actual system and a fault-tolerant controller to track the upper layer virtual system. Compared with the existing results, the phenomenon of fault propagation can be avoided by introducing the hierarchical design approach, that is, the fault of agent i only affects the dynamics of itself, and does not affect the dynamics of other agents through the network. It is shown that each follower converges asymptotically to a convex hull spanned by leaders with external input. Finally, the developed method is demonstrated by simulation results.

Distributed finite-time fault-tolerant containment control for multiple ocean Bottom Flying node systems with error constraints

The Ocean Bottom Flying Node (OBFN) belongs to Autonomous Underwater Vehicle (AUV) designed for detecting seabed resources. When considering model uncertainties, external disturbances, and thruster faults, by applying the nonsingular fast terminal sliding-mode technique, a distributed finite-time fault-tolerant error constraint containment control method for multiple OBFN systems is proposed under directed communication topology. Besides, only a part of follower OBFNs can get the information of leader OBFNs. First, the error constraint strategy is considered to improve the system performance while the defined error variable of containment control was converted into a suitable form. Then, by choosing the appropriate nonsingular fast terminal sliding surface, the systems states can reach the sliding surface in finite time such that the follower OBFNs could converge to the convex hull formed by the leader OBFNs in finite time. Neural Network (NN) is employed to estimate and compensate the general disturbances consisting of model uncertainties, external disturbances, and thruster faults. An adaptive law is designed to compensate the upper bound of the estimation errors. The finite-time stability of the systems and the boundedness of containment errors are proved by utilizing graph theory, finite time theory, and Lyapunov technique. Numerical simulations under different types of thruster faults are given to show the effectiveness of the proposed methods.

Distributed Finite-Time Fault-Tolerant Containment Control for Multiple Unmanned Aerial Vehicles.

This paper investigates the distributed finite-time fault-tolerant containment control problem for multiple unmanned aerial vehicles (multi-UAVs) in the presence of actuator faults and input saturation. The distributed finite-time sliding-mode observer (SMO) is first developed to estimate the reference for each follower UAV. Then, based on the estimated knowledge, the distributed finite-time fault-tolerant controller is recursively designed to guide all follower UAVs into the convex hull spanned by the trajectories of leader UAVs with the help of a new set of error variables. Moreover, the unknown nonlinearities inherent in the multi-UAVs system, computational burden, and input saturation are simultaneously handled by utilizing neural network (NN), minimum parameter learning of NN (MPLNN), first-order sliding-mode differentiator (FOSMD) techniques, and a group of auxiliary systems. Furthermore, the graph theory and Lyapunov stability analysis methods are adopted to guarantee that all follower UAVs can converge to the convex hull spanned by the leader UAVs even in the event of actuator faults. Finally, extensive comparative simulations have been conducted to demonstrate the effectiveness of the proposed control scheme.