Event-triggered Control For Semi-global Stabilisation Of Systems With Actuator Saturation

This paper investigates the problem of event-triggered control for semi-global stabilisation of null controllable systems subject to actuator saturation. First, for a continuous-time system, novel event-triggered low-gain control algorithms based on Riccati equations are proposed to achieve semi-global stabilisation. The algebraic Riccati equation with a low-gain parameter is utilised to design both the event-triggering condition and the linear controller; a minimum inter-event time based on the Riccati ordinary differential equation is set a priori to exclude the Zeno behaviour. In addition, the high-low-gain techniques are utilised to extend the semi-global results to event-based global stabilisation. Furthermore, for a discrete-time system, novel low-gain and high–low-gain control algorithms are proposed to achieve event-triggered stabilisation. Numerical examples are provided to illustrate the theoretical results.postprin

Global and Semi-global Regulated State Synchronization for Homogeneous Networks of Non-introspective Agents in Presence of Input Saturation– A Scale-free Protocol Design

This paper studies global and semi-global regulated state synchronization of homogeneous networks of nonintrospective agents in presence of input saturation based on additional information exchange where the reference trajectory is given by a so-called exosystem which is assumed to be globally reachable. Our protocol design methodology does not need any knowledge of the directed network topology and the spectrum of the associated Laplacian matrix. Moreover, the proposed protocol is scalable and achieves synchronization for any arbitrary number of agents

Event-based global stabilization of linear systems via a saturated linear controller

postprin

Liu, C., Xia, Z., & Patton, R. J. (2024). Distributed Fault-Tolerant Consensus Control of Vehicle Platoon Systems With DoS Attacks. IEEE Transactions on Vehicular Technology

Vehicle platoon systems are regarded as autonomous vehicles in the platooning pattern, in which vehicles drive in sequence and maintain the desired inter-vehicle spacing. This paper investigates the platoon control problem of vehicle platoon dynamics under cyber-physical threats through the distributed fault-tolerant consensus control protocol. Complicated sensor and actuator faults in the physical layer and aperiodic denial-of-service (DoS) attacks in the cyber layer are modeled, respectively. Decentralized fault-estimation unknown input observers and event-triggered distributed anti-DoS-attack fault-tolerant consensus controllers are devised in a co-designed framework, thus maintaining not only the tolerance and resilience of platoon consensus errors and estimation errors but also the secure vehicle avoidance spacing by virtue of attack frequency and average dwelling time indicators. Simulations and experiments validate the distributed control algorithm in the pernicious short-cycle and long-cycle DoS attack scenarios

Distributed Event-triggered Fault-tolerant Consensus Control of Multi-agent Systems under DoS Attacks

This study investigates the distributed fault-tolerant consensus issue of multi-agent systems subject to complicated abrupt and incipient time-varying actuator faults in physical hierarchy and aperiodic denial-of-service (DoS) attacks in networked hierarchy. Decentralized estimators are devised to estimate consecutive system states and actuator faults. A unified framework with an absolute local output-based closed-loop estimator in decentralized fault estimation design and a relative broadcasting state-based open-loop estimator in distributed event-triggered fault-tolerant consensus design is developed. Criteria of exponential consensus of the faulty multi-agent systems under DoS attacks are derived by virtue of average dwelling time and attack frequency technique. Simulations are outlined to confirm the efficacy of the proposed distributed fault-tolerant consensus control algorithm based on an event-triggered mechanism

On the Control of Microgrids Against Cyber-Attacks: A Review of Methods and Applications

Nowadays, the use of renewable generations, energy storage systems (ESSs) and microgrids (MGs) has been developed due to better controllability of distributed energy resources (DERs) as well as their cost-effective and emission-aware operation. The development of MGs as well as the use of hierarchical control has led to data transmission in the communication platform. As a result, the expansion of communication infrastructure has made MGs as cyber-physical systems (CPSs) vulnerable to cyber-attacks (CAs). Accordingly, prevention, detection and isolation of CAs during proper control of MGs is essential. In this paper, a comprehensive review on the control strategies of microgrids against CAs and its defense mechanisms has been done. The general structure of the paper is as follows: firstly, MGs operational conditions, i.e., the secure or insecure mode of the physical and cyber layers are investigated and the appropriate control to return to a safer mode are presented. Then, the common MGs communication system is described which is generally used for multi-agent systems (MASs). Also, classification of CAs in MGs has been reviewed. Afterwards, a comprehensive survey of available researches in the field of prevention, detection and isolation of CA and MG control against CA are summarized. Finally, future trends in this context are clarified