This article addresses the bipartite output consensus problem for descriptor discrete-time multiagent systems (MASs) subject to both process faults and parameter uncertainties. The study is framed within multiagent cyber–physical systems (CPSs), aiming to achieve secure and resilient consensus in adversarial environments characterized by directed signed topologies. To achieve simultaneous estimation of system states and fault signals under discrete-time descriptor dynamics, a new distributed estimator is designed by integrating the directed signed graph topology with a discrete-time generalized algebraic Riccati equation (ARE). Furthermore, a distributed observer is constructed for each follower to track the exosystem state, enabling the bipartite tracking of reference trajectories across two opposing subgroups. This design effectively accommodates exosystem matrices whose eigenvalues lie entirely outside the unit circle, thus relaxing the conventional neutral-stability requirement. Based on the$p$-copy internal model principle from robust output regulation theory, a distributed fault-tolerant output-feedback control law is synthesized. This controller guarantees bipartite output consensus over directed signed networks in the presence of concurrent process faults and model uncertainties. Finally, a numerical simulation validates the feasibility and effectiveness of the proposed approach.

In this paper, a resilient distributed model predictive control (DMPC) algorithm is proposed for the networked vehicle platoon system under denial-of-service (DoS) attacks. It is difficult to ensure the system-level stablibity and string stability of the networked vehicle platoon system simultiniously in the presence of DoS attacks. To this end, an optimization problem is established, which is related to the trajectories of the system. To minimize the cost function, the last-step shifting technique is employed and the assumed solution is determined by the local optimal solution. The last optimal solution without the occurrence of DoS attacks is used as the reference trajectory. This reference trajectory is then transmitted to the interconnected vehicles within the system. Demonstrating the stability of the closed-loop platoon system is achieved by using the Lyapunov function, which is designed by the sum of the cost function. String stability of the platoon system, the unique characteristic of platoon systems, is proven through rigorous mathematical derivation. Compared with existing results, the vehicle platoon system under DoS attacks can be converged both the internal and closed-loop stability. Finally, several simulation and experimental results are presented to verify the effectiveness of the proposed method.

In this paper, the distributed bipartite output formation control problem of heterogeneous discrete-time singular multi-agent systems (MASs) is studied under the cooperative-competition network. Different from the classical formation control issue, the leader (also called exosystem) is also described by more general discrete-time singular dynamics. Based on the cooperative output regulation theory, the bipartite output formation with two opposing subgroups is realized by reconstructing bipartite tracking error and singular exosystem. To obtain the bipartite state of exosystem, a new exosystem observer associated with discrete-time singular algebraic Riccati equation (ARE) and signed directed topological matrix is designed. The observer coupling gains are introduced to enable the global error system to be included in the stability region of the unit circle. Then under the singular regulator equations and the separation principle, two classes of distributed observed-based controllers via state and output feedbacks are respectively presented for bipartite formation scenarios where the states of followers are known and unknown. Moreover, by redefining the expected relative dynamic positions, the proposed control strategies can be extended to achieve time-varying bipartite output formation. Finally, simulation results are given to verify the feasibility and effectiveness of the proposed algorithms.

This article investigates resilient source seeking problem of second-order multirobot systems (MRSs) under mixed cyberattacks, which consist of misbehaving and Denial-of-Service (DoS) attacks. The misbehaving attacks can cover several types of malicious attacks, such as false data injection, stubborn, and Byzantine, while the network connectivity may be compromised by DoS attacks, potentially resulting in a time-varying and disconnected digraph. To this end, a resilient source seeking algorithm is proposed by designing an auxiliary point for each agent such that the coordination problem is transformed into a point tracking one. A reference velocity is calculated to guide benign robots toward the source, leveraging their historically optimal positions with the highest signal strength. This ensures the auxiliary points converge to the source, clustering benign robots nearby. When DoS attacks occur on some edges, the latest sampling data acquired before the attacks is used to hold the control signals for the robots. Then, sufficient conditions are established through rigorous stability analysis. In comparison to existing methods, the proposed approach extends the safe-kernel-based resilient consensus algorithms to a resilient source seeking algorithm for a general discrete-time second-order dynamics, while also can withstand a mixed cyberattack comprising both misbehaving and DoS attacks. Finally, simulation and experimental results are presented to validate the efficacy of the proposed algorithm.

Control design for nonstrict feedback nonlinear systems (NSFNS) with nonlower triangular structure may encounter algebraic loop problem, which is a significant, challenging, yet complicate issue to develop a controller with unknown control directions, especially in the presence of external disturbances and time-varying parameters. To solve these issues, unlike existing studies on prescribed-time stability under unknown control directions, a novel zero-error prescribed-time tracking control scheme is proposed for NSFNS based on the fuzzy logic approximation and adaptive technique. Moreover, a new switching event-triggered mechanism that focuses on triggering strategies and conditions to minimize resource wastage from continuous controller sampling is constructed. This approach effectively reduces the frequency of sampling and energy loss within the controller. In addition, the boundedness of the Lyapunov function is analyzed using invariant set theory. It demonstrates that the tracking error converges to zero within a user-defined time, which simultaneously ensures all signals of the closed-loop system be bounded and Zeno-free phenomenon. Finally, the efficacy of the proposed control algorithm is validated through numerical simulation results.

This article focuses on the safety flocking control problem of networked Lagrangian systems under event-triggered communication. To avoid collision and preserve connectivity, the concept of safety domain and safety vector is presented. Using these definitions, a novel potential function is designed to guarantee the interagent distance to be limited in an exact range during the flocking process. In addition, a fully distributed dynamic event-triggered scheme is proposed to schedule the communication sources. Both the controller and the event-triggered scheme operate without requiring any global information about the entire topology. Also, Zeno behavior is eradicated in the proposed event-triggered communication scheme. Finally, the effectiveness of the proposed method is shown by case studies.

In this article, the resilient coordination problem of networked Lagrangian systems with adversarial agents is considered. A novel algorithm called norm-based resilient decision algorithm is proposed to exclude the impact of adversarial agents. To ensure the coordination of networked Lagrangian systems, the maximum number of adversarial agents related to the robustness of the communication network is given. Under the proposed resilient consensus algorithm, secure coordination is guaranteed under adversarial agents. Then, the proposed resilient controller is extended to static formation scenarios. Finally, the effectiveness of the proposed method is demonstrated through case studies and experiments. Compared to the existing results, the proposed algorithm can reduce computing resources by designing auxiliary vectors and converting them into scalars to remove extreme values.

In this paper, the string stable platoon control problem of discrete-time networked vehicle systems is considered by using distributed model predictive control (MPC) based method. An optimization problem is established to minimize the cost function associated to the system trajectories. The last-step shifting method is applied to set the local optimal solution as the assumed solution and send it to the neighbor vehicles. By using the sum of the cost function as Lyapunov function, the stability of the closed-loop platoon system is studied. Comparing with existing results, the string stability, which is the unique characteristics of the platoon system, is guaranteed under the bidirectional-based structure as well as the predecessor-follower-based information flow structure. Finally, several simulations are presented to demonstrate the effectiveness of the proposed algorithms.

In this article, we consider the resilient consensus control problem of multiple Euler–Lagrange systems in the presence of external disturbances and denial-of-service (DoS) attacks, which have bounded duration and frequency. Unlike the most existing methods for linear multiagent systems, the strong nonlinearity, and unknown disturbances of multiple Euler–Lagrange systems make the resilient control problem under DoS attacks be more challenging and still not well explored. To this end, an adaptive control scheme is first proposed with a robust sliding mode-like term to handle the unknown bounded external disturbances. In addition, an auxiliary system is designed by using the sampled neighboring information to achieve resilience to DoS attacks. Sufficient conditions are presented by using Lyapunov and small-gain approaches. Finally, simulation results are given to verify the effectiveness of the proposed resilient consensus control approach.

Fast and smooth driving is a preferable consideration in platooning algorithm development for intelligent autonomous vehicular systems. It can improve traffic efficiency while guaranteeing passenger comfort. To this end, this work investigates the fast distributed platooning problem of connected vehicular systems. Taking the inaccurate velocity measurement into consideration, an extended state observer (ESO) based on a fractional order faster nonsingular terminal sliding mode (FNTSM) is proposed for velocity and disturbance estimation simultaneously. An FNTSM control algorithm based on the double power reaching law is developed to reach fast platooning while guaranteeing string stability of the connected vehicular systems regardless of zero or nonzero initial spacing error conditions. The salient features of the proposed platoon controller are that system convergence can be achieved in finite time and the time-varying external disturbances can be estimated accurately. Finally, simulation and experiment studies are conducted to demonstrate the effectiveness and efficiency of the proposed control algorithm.

This paper investigates the fixed-time control issue for the post-capture space tethered robot system in the presence of uncertainty and external disturbances. A new form of fixed-time nonsingular terminal sliding mode surface (FNTSMS) is constructed by introducing the power function to traditional terminal sliding mode surface (TSM), thus the system fast response and singularity circumvention are ensured gracefully. With the aid of FNTSMS, a new fixed-time control scheme is proposed for post-capture space tethered robot, which can achieve the high-precision tracking performance and fast response rate after the space targets are captured. Moreover, the proposed scheme is compared with the traditional boundary layer sliding mode control method. The simulation results verify the effectiveness of the proposed control scheme.

In this article, the predefined-time cooperative platoon control problem with constrained communication range for uncertain networked aerial vehicles is considered. The uncertain networked aerial vehicles are subjected to external disturbance and parameter uncertainties. A novel adaptive sliding-mode disturbance observer is first designed for single uncertain networked aerial vehicle with an radial basis function of neural network estimator to guarantee the control performance. By embedding a dynamic control gain associated with the predefined convergence time, the proposed disturbance observer is proved to be uniformly ultimate boundedness stable by the time transformation approach. Then the dynamic gain technology is combined with the prescribed performance control to design the platoon controllers for uncertain networked aerial vehicles. With the proposed disturbance observer and the distribute controller, the platoon can be achieved within the predefined time. The proposed approach can simultaneously guarantee the system stabile without any initial conditions and system parameters. Finally, some simulation experiments are given to verify the effectiveness of the proposed protocols.

In this paper, based on sampled-data control method, we address the stabilization problem for a general class of linear continuous-time fractional systems whose solution contains the Mittag-Leffler function that does not obey the basic exponentiation identity. By considering the infinite memory and hereditary characteristics of fractional-order calculus, we propose a sampled-data controller that guarantees the resulting closed-loop system to be asymptotically stable. Simulation examples are presented to demonstrate the effectiveness of the proposed controller and verify the established results.

To steer a team of multiple mobile agents to desired collective maneuvers so that the geometric pattern, translation, orientation, and scale of formation can be changed continuously, this article studies the formation maneuver control of single-integrator and double-integrator multiagent systems by a leader-follower strategy. Unlike most existing results requiring generic configurations or convex configurations, the proposed control algorithms can be applied to either nongeneric or nonconvex configurations. Distributed control algorithms are designed for the leaders and followers over directed graphs, respectively, where the formation's maneuver parameters, such as geometric pattern, translation, orientation, and scale of formation are decided by the first leader. It is worth noting that the closed-loop tracking errors converge to zero globally. Some numerical simulations are given to illustrate the theoretical results.

In this article, we study the distributed resilient cooperative control problem for directed networked Lagrangian systems under denial-of-service (DoS) attacks. The DoS attacks will block the communication channels between the agents. Compared with the existing methods for the linear networked systems, the considered nonlinear networked Lagrangian systems with asymmetric channels under DoS attacks are more challenging and still not well explored. In order to solve this problem, a novel resilient cooperative control scheme is proposed by using the sampling control approach. Sufficient conditions are first derived in the absence of DoS attacks according to a multidimensional small-gain scheme. Then, in the presence of DoS attacks, the proposed resilient scheme works in a switching manner. Inspired by multidimensional small-gain techniques, the Lyapunov approach is used to analyze the closed-loop system, which enables us to establish sufficient stability conditions for the control gains in terms of the duration and frequency of the DoS attacks.

In this article, we consider the resilience problem in the presence of communication faults encountered in distributed secondary voltage and frequency control of an islanded alternating current microgrid. Such faults include the partial failure of communication links and some classes of data manipulation attacks. This practical and important yet challenging issue has been taken into limited consideration by existing approaches, which commonly assume that the measurement or communication between the distributed generations (DGs) is ideal or satisfies some restrictive assumptions. To achieve communication resilience, a novel adaptive observer is first proposed for each individual DG to estimate the desired reference voltage and frequency under unknown communication faults. Then, to guarantee the stability of the closed-loop system, voltage and frequency restoration, and accurate power sharing regardless of unknown communication faults, sufficient conditions are derived. Some simulation results are presented to verify the effectiveness of the proposed secondary control approach.

In this article, we consider the formation tracking problem of nonholonomic multiagent systems only using relative bearing measurements between the agents. Such a practical and important yet challenging issue has been taken into limited consideration by existing approaches, which usually requires additional measurements such as relative positions. The contributions of this article are two-fold. First, a fully distributed reference velocity estimator is proposed. Under the proposed adaptive estimator, each agent can estimate the time-varying reference velocity asymptotically. Second, an input-to-state stable controller is designed according to the bearing rigid theory. Under the proposed controller, the formation with bearing-only constraints can be achieved. Finally, the proposed scheme is demonstrated and its effectiveness is verified by presenting some simulation and experimental tests.

A wide range of cyber–physical systems can be modeled as Euler–Lagrange dynamics, whose inherent nonlinearities bring additional difficulties in the design and analysis of controllers for such systems. The objective of this article is to solve the jamming-resilient synchronization control problem of networked Lagrangian systems subject to unknown external disturbances, with the quantized sampling data. Under a jamming attack, a normal communication channel will be blocked with unknown frequencies and intervals. To achieve jamming attack resilience, a robust adaptive controller is proposed. Then a novel auxiliary system is designed for each subsystem over a directed network. By using the quantized sampling data from each subsystem and its neighbors, the jamming attack can be handled by an embedded single-integral subsystem. Sufficient conditions that are independent of the attack parameters are derived to guarantee the global stability of the closed-loop system. Compared with existing jamming-resilient methods, the proposed approach is concise and resilient to any jamming attacks with bounded frequencies and durations.

In this article, we address the bearing-only formation control problem of 3-D networked robotic systems with parametric uncertainties. The contributions of this article are two-fold: 1) the bearing-rigid theory is extended to solve the nonlinear robotic systems with the Euler-Lagrange-like model and 2) a novel almost global stable distributed bearing-only formation control law is proposed for the nonlinear robotic systems. Specifically, the robotic systems subject to nonholonomic constraints and dynamics are first transformed into a Euler-Lagrange-like model. By exploring the bearing-rigid graph theory, a backstepping approach is used to design the distributed formation controller. Simulations for 3-D robotics are given to demonstrate the effectiveness of the proposed control law. Compared to the distance-rigid formation control approach, the bearing-rigid approach guarantees almost global stability while naturally excluding flip ambiguities.

In this paper, the leader-following consensus control problem is studied for fractional-order nonlinear multiagent systems in the presence of system uncertainties and unknown external disturbances. An adaptive distributed control scheme is proposed for each agent with a local controller that contains a filter and estimators for estimating the bounds of the fractional-order derivatives of desired trajectory. All the control signals resulted from the control scheme are smooth and they are still able to achieve asymptotic output consensus tracking while ensuring global boundedness of all the closed-loop signals. Simulation results are provided to illustrate the effectiveness of the proposed control protocol and verify the obtained results.

In this paper, we consider the optimal trajectory tracking control problem for a cyber-physical marine surface vessel system with unknown dynamics by using a reinforcement learning (RL) algorithm. The main contributions of the paper are threefold: (1) The dynamics of the marine vessel system considered in this paper is partially unknown. (2) The actor-critic-identifier (ACI) architecture based on fuzzy logical system (FLS) approximation is designed to handle the optimal tracking control problem; (3) The same Bellman error is chosen to update the actor and critic FLS weights at the same time. To be more specific, by using FLS approximating the unknown optimal value function, optimal policy, and partial unknown dynamic, a reinforcement learning algorithm is used to solve the optimal tracking problem of the marine surface vessel system. By designing a fuzzy identifier, the actor-critic weights are adaptively updated simultaneously. The rigorous proof is given to verify the correctness of the algorithm.

In this paper, the bearing-only formation control problem of multi-agent systems is addressed. The main contributions of the paper are twofold: (1) The local maximal clique graph instead of the global infinitesimal bearing rigidity graph is used to describe the formation configuration; (2) The proposed formation control law is globally stable. To be more specific, by considering the inter-agent communication topology satisfies the maximal clique graph condition, a cost function is designed based on the target formation. Next, the rotation bias of the final formation and the target formation are analyzed. Based on the negative gradient of the cost function, a globally stable distributed controller that only depends on the inter-bearing measurements is proposed and global convergence result and analysis are given. An illustrative example demonstrates the effectiveness and efficiency of the proposed control law.