Publications

This chapter investigates the output feedback control problem for NCSsNetworked Control Systems (NCSs) under a stochastic schedulingScheduling protocol. An IID schedulingScheduling protocol is first introduced to orchestrate the signal transmission via a bandwidth-limited communication network. Taking into account IID scheduling protocol, network-induced delays, and packet dropouts, a stochastic impulsive delayed model is established for the studied system. Sufficient conditions for guaranteeing the stability of the studied system in mean-square sense are derived.

This paper deals with delay‐dependent H ∞ control for discrete‐time systems with time‐varying delay. A new finite sum inequality is first established to derive a delay‐dependent condition, under which the resulting closed‐loop system via a state feedback is asymptotically stable with a prescribed H ∞ noise attenuation level. Then, an iterative algorithm involving convex optimization is proposed to obtain a suboptimal H ∞ controller. Finally, two numerical examples are given to show the effectiveness of the proposed method. Copyright © 2007 John Wiley & Sons, Ltd.

This paper investigates network-based output tracking control for a T-S fuzzy system that can not be stabilized by a nondelayed fuzzy static output feedback controller, but can be stabilized by a delayed fuzzy static output feedback controller. By intentionally introducing a communication network that produces proper network-induced delays in the feedback control loop, a stable and satisfactory tracking control can be ensured for the T-S fuzzy system. Due to the presence of network-induced delays, the fuzzy system and the fuzzy tracking controller operate in an asynchronous way. Taking the asynchronous operation and network-induced delays into consideration, the network-based tracking control system is modeled as an asynchronous T-S fuzzy system with an interval time-varying delay. A new delaydependent criterion for L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -gain tracking performance is derived by using the deviation bounds of asynchronous normalized membership functions and a complete Lyapunov-Krasovskii functional. Applying a particle swarm optimization technique with the feasibility of the derived criterion, a novel design algorithm is presented to determine the minimum L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -gain tracking performance and control gains simultaneously. The effectiveness of the proposed method is illustrated by performing network-based output tracking control of a Duffing-Van der Pol's oscillator.

This paper is concerned with passivity of a class of delayed neural networks. In order to derive less conservative passivity criteria, two Lyapunov-Krasovskii functionals (LKFs) with delay-dependent matrices are introduced by taking into consideration a second-order Bessel-Legendre inequality. In one LKF, the system state vector is coupled with those vectors inherited from the second-order Bessel-Legendre inequality through delay-dependent matrices, while no such coupling of them exists in the other LKF. These two LKFs are referred to as the coupled LKF and the noncoupled LKF, respectively. A number of delay-dependent passivity criteria are derived by employing a convex approach and a nonconvex approach to deal with the square of the time-varying delay appearing in the derivative of the LKF. Through numerical simulation, it is found that: 1) the coupled LKF is more beneficial than the noncoupled LKF for reducing the conservatism of the obtained passivity criteria and 2) the passivity criteria using the convex approach can deliver larger delay upper bounds than those using the nonconvex approach.

This paper investigates robust absolute stabilization problem for a class of uncertain neutral systems with sector-bounded nonlinearity. Based on Lyapunov-Krasovaskii stability theory and LMI approach, a delay-dependent design method of robust guaranteed cost controller is given such that closed-loop system absolutely stable and guarantee that the given quadratic cost function is no more than a positive upper bound. Moreover, a linearization algorithm is applied to solve an optimization problem and a suboptimal guaranteed cost can be derived. A numerical example is given to illustrate the proposed results

Two-sided diagonal scaling for transfer matrices is formulated. An efficient algorithm is proposed to compute globally optimal solutions using the iterated bi-section and linear matrix inequality (LMI) solver. It is shown that the two-sided scaling of filter bank (FB) frames can be implemented by the adjustment of channel gains and the periodic precoding of source signal, and that the frame-bound-ratio of FB frames can be effectively improved by such scaling. Explicit formulas are established for both uniform and nonuniform FB frames, including detail formulas for discrete Weyl-Heisenberg frames and tree-structured FBs (discrete wavelets). Different examples show the effectiveness of the obtained results.

This paper is concerned with the problem of distributed joint state and sensor fault estimation for autonomous ground vehicles subject to unknown-but-bounded (UBB) external disturbance and measurement noise. In order to improve the estimation reliability and performance in cases of poor data collection and potential communication interruption, a multi-sensor network configuration is presented to cooperatively measure the vehicular yaw rate, and further compute local state and fault estimates. Toward this aim, an augmented descriptor vehicle model is first established, where the unknown sensor fault is modeled as an auxiliary state of the system model. Then, a new distributed ellipsoidal set-membership estimation approach is developed so as to construct an optimized bounding ellipsoidal set which guarantees to contain the vehicle's true state and the sensor fault at each time step despite the existence of UBB disturbance and measurement noises. Furthermore, a convex optimization algorithm is put forward such that the gain matrix of each distributed estimator can be recursively obtained. Finally, simulation results are provided to validate the effectiveness of the proposed approach.

This paper deals with the H ∞ dynamic output feedback control problem of a seismic-excited building. The control aims to reduce the vibration of a building caused by an earthquake. Instead of system states, the system output measurements are used to design suitable H ∞ controllers. Depending on whether the system measurements are sampled or not, two kinds of dynamic output feedback control schemes are investigated. By the Lyapunov stability theory, some bounded real lemmas are formulated such that the closed-loop system is asymptotically stable and achieves a prescribed H ∞ disturbance attenuation level. The cone complementary algorithm is employed to design H ∞ controllers based on a solution to a nonlinear minimization problem subject to a set of linear matrix inequalities. Finally, a three-storey building model is given to show the effectiveness of the proposed method.

Welcome to the twelfth issue of 2023 in the IEEE/CAA Journal of Automatica Sinica (JAS).In the sixth issue of 2023, I systematically addressed the latest development of MetaVehicles, and sorted out some important contributions published in the IEEE/CAA JAS focusing on control, estimation, and optimization of automated vehicles with reliability, security, efficiency, and intelligence.When shifting the perspective to cyber-physical systems (CPSs), the styles or paradigms of control and filtering are going through major changes benefiting from the widespread applications of both cloud computing and digital twins.Particularly, the desired performance and management functions of CPSs under the virtual and real framework will be achieved via Metaverse technologies and strict system analysis involving behavior recognition of users, decision-making processes as well as parameter design and optimization.It is evident that the system's performance and cost are synthetic reflections of its behavior in both cyberspace and the real world [1].This kind of control paradigm can be referred to as MetaControl [2].It should be pointed out that MetaControl is built upon cyberspace and hence security threats are naturally inherited and inevitably enhanced due to the ever-increasing complexity and diversity of system functionalities while faults in the physical space are also a big concern.As such, new methods of control, filtering, and optimization should be creatively developed to satisfy the requirement of external security in cyberspace and internal safety in the physical space of CPSs.At IEEE/CAA JAS, we value and demonstrate the latest advancement in secure and safe MetaControl for cyber-physical systems.In this editorial, I collected eighteen articles published in IEEE/CAA JAS in the recent three years, relevant to this interesting topic.Specifically, I classify them into the following three groups. 1) Passively secure control and filteringIt should be pointed out that malicious attacks that occur in CPSs could appear differences in the form, strength, and stealthiness due to the tight integration of virtual cyberspace and real physical space in comparison with traditional control systems.Therefore, it is essential to provide innovative design concepts to generate control commands or reconstruct system states based on only measured, but potentially corrupted information.To tolerate unpredictable anomalies caused by

This paper studies an attack detection problem for a networked leader-following multi-agent system subject to unknown-but-bounded system noises and quantization effects, where an adversary launches malicious cyber attacks on agents' measurement outputs aiming to distrust the leader-following consensus. An effective distributed attack detection algorithm is firstly developed for each follower such that the attack can be identified at the time of its occurrence. The core of the algorithm lies in a set-membership filtering approach from which each designed filter can provide an ellipsoidal state prediction set and an ellipsoidal state estimation set. Whether a filter can detect the occurrence of such an attack is then determined by the existence of intersection between these two sets. Furthermore, a convex optimization algorithm is established to solve out anticipated consensus protocol and two-step set-membership filter by resorting to some recursive linear matrix inequalities. Finally, an illustrative example is given to show the effectiveness of the proposed main results.

In this paper, new sufficient conditions for the stability of time-delay interval systems are presented. Subsequently, design procedures are provided to synthesize robust static feedback controllers for dynamic time-delay interval systems.A pole region assignment design technique is applied to make the closed-loop system achieve the requirements in system performance and stability robustness. Examples given confirm the availability of the proposed design approaches.

This paper is concerned with the problem of two targets tracking over sensor networks. A heterogeneous sensor network framework in considered, in which two types of sensors are employed (denoted as x-type and y-type sensors, respectively). Sensors with x-type can only measure information from target x, while sensors with y-type can only measure information from target y. Sensors update their tracking estimations by using only local information collected from neighboring ones. The network topology is random and governed by a continuous-time Markov process, whose states represent possible modes of interaction topologies of sensors. To solve the two targets tracking problem, a novel distributed tracking protocol in the form of consensus-based estimators is delicately developed. Then, tracking performance analysis against the effects of random network topologies is carried out as well as a criterion for designing desired tracking protocol parameters is derived such that the two targets tracking can be achieved. A numerical example is given to demonstrate the effectiveness of the proposed theoretical results.

This paper deals with absolute stability for a class of nonlinear neutral systems using a discretized Lyapunov functional approach. A delay-dependent absolute stability criterion is obtained and formulated in the form of linear matrix inequalities (LMIs). The criterion is valid not only for systems with small delay, but also for systems with non-small delay. Neither model transformation nor bounding technique for cross terms, nor free weighting matrix method is involved through derivation of the stability criterion. Numerical examples show that for small delay case, the results obtained in this paper significantly improve the estimate of the stability limit over some existing result in the literature; for non-small delay case, the ideal results can also be achieved.

This paper is concerned with the cooperative target tracking of multiple autonomous surface vehicles (ASVs) under switching interaction topologies. For the target to be tracked, only its position can be measured/received by some of the ASVs, and its velocity is unavailable to all the ASVs. A distributed extended state observer taking into consideration switching topologies is designed to integrally estimate unknown target dynamics and neighboring ASVs' dynamics. Accordingly, a novel kinematic controller is designed, which takes full advantage of known information and avoids the approximation of some virtual control vectors. Moreover, a disturbance observer is presented to estimate unknown time-varying environmental disturbance. Furthermore, a distributed dynamic controller is designed to regulate the involved ASVs to cooperatively track the target. It enables each ASV to adjust its forces and moments according to the received information from its neighbors. The effectiveness of the derived results is demonstrated through cooperative target tracking performance analysis for a tracking system composed of five interacting ASVs.

SUMMARY This paper is concerned with quantitative analysis and synthesis for a networked control system under simultaneous consideration of non‐uniformly distributed packet dropouts, interval time‐varying sampling periods and network‐induced delays. A new packet dropout separation method is proposed to separate packet dropouts from the lump sum of network‐induced delays and packet dropouts. An interval time‐varying sampling period approach, which is more general than a switched sampling period approach, is presented to model the variation of the sampling period. Then a packet dropout decomposition‐based Lyapunov functional is constructed to drive some stability criteria. Based on these stability criteria, a state feedback controller is designed to asymptotically stabilize the networked system in the sense of mean‐square. Numerical examples are given to illustrate the effectiveness of the obtained results. Copyright © 2013 John Wiley &amp; Sons, Ltd.

The conformal flow of metrics [2] has been used to successfully establish a special case of the Penrose inequality, which yields a lower bound for the total mass of a spacetime in terms of horizon area. Here we show how to adapt the conformal flow of metrics, so that it may be applied to the Penrose inequality for general initial data sets of the Einstein equations. The Penrose conjecture without the assumption of time symmetry is then reduced to solving a system of PDE with desirable properties.

This chapter investigates the network-based modeling and event-triggered H ∞ reliable control for an offshore structure. First, a network-based model of the offshore structure subject to external wave force and actuator faults is presented. Second, an...