Safety guarantee is a fundamental requirement for numerous dynamical systems. In this work, the safe stabilization problem in complex scenarios is considered. First, we introduce the notion of the local safe set, a convex and compact set disjoint from unsafe regions, to construct a finite sequence of such sets. Next, we leverage Zubov’s theorem to propose the Zubov barrier function (Zubov BF), which provides safety guarantees on local safe sets. Compared with the existing ones, the Zubov BF reduces the conservatism and complexity in safety analysis. The relations between the Zubov BF and existing ones are discussed to show the generality of Zubov BF. The Zubov control barrier function (Zubov CBF) is further extended for control synthesis. Sufficient and necessary conditions are provided to verify the existence of the derived controller. To achieve the safe stabilization objective, we provide a modified quadratic programming (QP) framework with feasibility guarantee and demonstrate the continuity of the derived controller in closed form. Finally, a numerical example from the overtaking problem of two autonomous vehicles and a practical experiment on the safe navigation for a quadrotor are provided to illustrate the derived results.

Recent research has shown that the Macroscopic Fundamental Diagram (MFD) is an effective way to manage traffic flow and mitigate congestion, which regulates bidirectional transfer flows at regional boundaries via perimeter control. In practice, perimeter control may fail to achieve desired control targets due to adverse conditions such as inclement weather or accidents, which may result in loss of actuator effectiveness faults. To address this challenge, this paper proposes two adaptive fault-tolerant perimeter control schemes to handle both time-invariant and time-varying actuator faults. To cope with time-invariant actuator faults, a data-driven fault-tolerant perimeter control approach is presented, which employs adaptive dynamic programming to approximate the solution of the Hamilton-Jacobi-Bellman equation. For dealing with time-varying faults, an adaptive fault-tolerant perimeter controller is designed by linearizing the MFD function and ensuring tracking of a given reference model. Theoretical analysis proves that the tracking error converges to zero asymptotically. Finally, simulation studies validate the effectiveness of the proposed schemes in improving traffic management under actuator fault conditions.

A robust fault-tolerant control method based on set-membership estimation and tube model predictive control (MPC) is proposed for the constrained linear systems subject to unknown disturbance and noise. Firstly, an augmented observer is used to estimate state and fault simultaneously. A fault-tolerant controller is proposed based on the state and fault estimation. And the estimation and feedback errors are bounded using set-membership estimation method. Then, the obtained error sets are used to design robust output feedback tube MPC strategy. In order to make the estimation error robust against disturbance and noise, the observer gain is designed based onL∞method. Finally, the effectiveness and real-time performance of the proposed method is verified by a hardware-in-the-loop (HIL) test, which shows its potential application value in aeroengine control systems.

This article investigates the event-triggered adaptive robust motion control for hydraulic actuators with parametric uncertainties and system nonlinearities. Under the continuous communication condition, the traditional adaptive robust motion controller is recursively presented. In order to reduce the unnecessary bandwidth consumption in the aero-engine networked control platform, an adaptive threshold triggered mechanism according to network resources is developed to synthesize the motion controller. Adjustable threshold parameters are involved to flexibly adjust the data transmission times depending on the network bandwidth occupation. It is proved that with the motion controller and the proposed adjustable threshold triggered mechanism, all the closed-loop system signals are globally bounded, and the hydraulic system output achieves asymptotic tracking to the reference trajectory by virtue of the adaptive technique, the Nussbaum-type and sign functions. Besides, the Zeno behavior is excluded, successfully. Finally, the proposed event-based control scheme is tested and discussed on the aero-engine hardware-in-the-loop (HIL) experiment platform with hydraulic actuators.

Adaptive robust control technique is investigated to devise trajectory tracking event-triggered controller for a class of uncertain nonlinear systems. Different from most existing results, this article divides the entire control input into two parts, including the model compensation input term and the robust term, which are separately dealt with by means of special triggered mechanisms. The advantage of separation is that the system reduces the magnitude of chattering amplitude within triggered inputs. To balance the information updating frequency and the magnitude of chattering amplitude, this article proposes the dynamic-threshold-triggered mechanism and provides a new Lyapunov function to guarantee the global boundedness of all the closed-loop signals as well as the convergence of the tracking error to an arbitrary small set around zero. This article also considers desired compensation adaptive robust event-triggered control strategy, thereby further saving bandwidth resources and smoothing the triggered inputs. The Zeno behavior is excluded for two triggering schemes. Finally, simulation and hardware-in-the-loop experiments are used to verify the effectiveness of the proposed strategies.

In this article, we investigate the synchronization problem of continuous-time linear systems with time-varying output couplings. Both bidirectional and unidirectional couplings are studied. In the former one, each pair of connected subsystems can both measure the outputs consisting of the relative information, whereas in the unidirectional case, it is not necessarily the case and a specific scenario when the output matrices have a common matrix factor is considered. The distributed synchronization protocols are designed and the convergence conditions of the resulting system are established making use of switched systems theory based on the detectability assumption and appropriate graph connectivity conditions. Finally, numerical examples are given to verify the derived results.

The roundabouts exist widely in urban road networks and reduce the number of traffic crashes by reducing vehicle conflicts. However, road restrictions at the entrances and exits increase the collision possibility between vehicles as they enter or leave the roundabouts. Focusing on the driving scenes in a roundabout, this article proposes a multivehicle coordinated lane change strategy for the mandatory lane change of vehicles. First, depending on the fluctuation of the vehicle acceleration, the driver's aggressive coefficient is defined. Second, according to the vehicle's driving state and its distance to the exit, a cost function is proposed and model predictive control is used to control the vehicle's motion. Moreover, the Stackelberg game is utilized to model the relationship between the lane change vehicle and its surrounding vehicles, and then to determine the timing of the changing lane. Finally, the simulation experiments verify whether the algorithm can improve the average speed of the vehicle and maintain the driving stability.

This paper is concerned with the consensus problem of general linear dynamic multiagent systems with stochastic sampling. In this paper, the sampling intervals randomly switch between two different values. The communication topology between agents is fixed and directed. Full- and reduced-order observers are designed based on neighbor agents' relative output information. The algorithms to construct such observers are also provided. By using the estimated states of the agents, the observer-based consensus protocol with stochastic sampling are presented. Sufficient conditions to ensure consensus in mean square are derived by using Lyapunov stability theory. Finally, simulations are given to examine the effectiveness of the proposed methods.

This paper is concerned with the sampled-data-based consensus problem of heterogeneous multiagent systems under directed graph topology with communication failure. The heterogeneous multiagent system consists of first-order and second-order integrators. Consensus of the heterogeneous multiagent system may not be guaranteed if the communication failure always happens. However, if the frequency and the length of the communication failure satisfy certain conditions, consensus of the considered system can be reached. In particular, we introduce the concepts of communication failure frequency and communication failure length. Then, with the help of the switching technique and the Lyapunov stability theory, sufficient conditions are derived in terms of linear matrix inequalities, which guarantees that the heterogeneous multiagent system not only achieves consensus but also maintains a desired L2-gain performance. A simulation example is given to show the effectiveness of the proposed method in this paper.

In this paper, an adaptive fuzzy hierarchical sliding-mode control method for a class of multiinput multioutput unknown nonlinear time-delay systems with input saturation is proposed. The studied system is first transformed into an equivalent system. Subsequently, based on sliding-mode control technology and the concept of hierarchical design, a set of adaptive fuzzy hierarchical sliding-mode controllers are designed for the new defined system by using fuzzy systems to approximate uncertain functions and compensate input saturation. Choosing an appropriate Lyapunov-Krasovskii function, it is theoretically proved that all the signals in the closed-loop system together with the proposed sliding surfaces are uniformly ultimately bounded under our designed adaptive fuzzy controllers. Simulation results demonstrate the effectiveness of the proposed design techniques for the systems under consideration.

This paper discloses the similarities between the condition for realizing cluster synchronization and that for uncontrollability in diffusively coupled multi-agent networks, both of which are built upon the characteristics of the networks' topologies. We first generalize the notions of equitable partitions and almost equitable partitions to make them applicable to directed, weighted graphs. Consequently, we are enabled to characterize the controllable subspace of a given diffusively coupled multi-agent system using graph theoretic ideas. After comparing the condition to realize cluster synchronization and the condition for the network to be controllable, we conclude that those diffusively coupled multi-agent networks that are not controllable usually realize cluster synchronization asymptotically. Simulation results are provided to illustrate the theoretical results.