Vs Victor Dolk

Output-Based and Decentralized Dynamic Event-Triggered Control With Guaranteed

Networked control systems are often subject to limited communication resources. By only communicating output measurements when needed, event-triggered control is an adequate method to reduce the usage of communication resources while retaining desired closed-loop performance. In this work, a novel event-triggered control (ETC) strategy for a class of nonlinear feedback systems is proposed that can simultaneously guarantee a finite Lp-gain and a strictly positive lower bound on the inter-event times. The new ETC scheme can be synthesized in an output-based and/or decentralized form, takes the specific medium access protocols into account, and is robust to (variable) transmission delays by design. Interestingly, in contrast with the majority of existing event-generators that only use static conditions, the newly proposed event-triggering conditions are based on dynamic elements, which has several advantages including larger average inter-event times. The developed theory leads to families of event-triggered controllers that correspond to different tradeoffs between (minimum and average) inter-event times, maximum allowable delays and Lp-gains. A linear and a nonlinear numerical example will illustrate all the benefits of this new dynamic ETC scheme.

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In this paper, we propose a systematic design framework for output-based dynamic event-triggered control (ETC) systems under denial-of-service (DoS) attacks. These malicious DoS attacks are intended to interfere with the communication channel causing periods in time at which transmission of measurement data is impossible. We show that the proposed ETC scheme, if well designed, can tolerate a class of DoS signals characterized by frequency and duration properties without jeopardizing the stability, performance and Zeno-freeness of the ETC system. In fact, the design procedure of the ETC condition allows tradeoffs between performance, robustness to DoS attacks, and utilization of communication resources. The main results will be illustrated by means of a numerical example.

- Gain Performance and Zeno-Freeness

In this work, a novel dynamic event-triggered control (ETC) strategy for state-feedback systems is proposed that can simultaneously guarantee a finite ℒp-gain from disturbance to output and a strictly positive lower bound on the inter-event times (implying Zeno-freeness). The developed theory leads to tradeoff curves between (minimum and average) inter-event times and ℒp-gains that depend on the selected medium access protocol.

Event-Triggered Control Systems Under Denial-of-Service Attacks

Networked control systems (NCSs) offer many benefits in terms of increased flexibility and maintainability but might also suffer from inevitable imperfections such as packet dropouts and limited communications resources. In this paper, (static and dynamic) event-triggered control (ETC) strategies are proposed that aim at reducing the utilization of communication resources while guaranteeing desired stability and performance criteria and a strictly positive lower bound on the inter-event times despite the presence of packet losses. For the packet losses, we consider both configurations with an acknowledgement scheme (as, e.g., in the transmission control protocol (TCP)) and without an acknowledgement scheme (as, e.g., in the user diagram protocol (UDP)). The proposed design methodology will be illustrated by means of a numerical example which reveals tradeoffs between the maximum allowable number of successive packet dropouts, (minimum and average) inter-event times and Lp-gains of the closed-loop NCS.

Dynamic event-triggered control: Tradeoffs between transmission intervals and performance

In this paper, a dynamic ETC strategy for nonlinear state-feedback systems is proposed that results in guarantees for a finite ℒp-gain from disturbance input to performance output and a strictly positive lower bound on the inter-event times despite the presence of packet losses. The proposed dynamic ETC strategy has several advantages with respect to the commonly studied static ETC strategy including significantly larger average inter-event times. The proposed design methodology results in tradeoffs between the maximum allowable number of successive packet dropouts, (minimum and average) inter-event times and ℒp-gains, which will be illustrated by means of a numerical example.

Event-triggered control systems under packet losses

We present a framework for the analysis and design of dynamic and static event-triggered controllers with time regularization for linear systems. This framework leads to guarantees on global exponential stability, ℒ2-stability, and a positive minimum inter-event time, in addition to a reduction in the number of events compared to regular time-triggered controllers and other event-triggered controllers in literature. By using new analysis tools tailored to linear systems, we achieve a significant reduction in conservatism, in the sense that the novel framework yields new event-generator designs with much larger inter-event times and much tighter bounds on the ℒ2-gain and convergence rate of the event-triggered control system compared to previous results for more general nonlinear systems. We demonstrate the benefits of our new results via a numerical example, and show that the conservatism in the estimates of the ℒ2-gain is indeed small.

Dynamic event-triggered control under packet losses: The case with acknowledgements

In this paper, we propose a dynamic event-triggered control (ETC) strategy for output-based feedback systems in the presence of Denial-of-Service (DoS) attacks. These malicious DoS attacks aim to impede the communication of measurement data in order to endanger the functionality of the closed-loop system. We show that the proposed ETC scheme, if well designed, can tolerate a class of DoS signals characterized by frequency and duration properties without jeopardizing the stability, performance and Zeno-freeness of the ETC system.

Dynamic event-triggered control with time regularization for linear systems

Cooperative adaptive cruise control (CACC) is a promising technology that is proven to enable the formation of vehicle platoons with small inter-vehicle distances, while avoiding amplifications of disturbances along the vehicle string. As such, CACC systems can potentially improve road safety, traffic throughput and fuel consumption due to the reduction in aerodynamic drag. Dedicated short range communication (DSRC) is a key ingredient in CACC systems to overcome the limitations of onboard sensors. However, wireless communication also involves inevitable network-induced imperfections, such as a limited communication bandwidth and time-varying transmission delays. Moreover, excessive utilization of communication resources jeopardizes the reliability of the DSRC channel. The latter might restrict the minimum time gap that can be realized safely. As a consequence, to harvest all the benefits of CACC, it is important to limit the communication to only the information that is actually required to establish a (string-)stable platoon over the wireless network and to avoid unnecessary transmissions. For this reason, an event-triggered control scheme and communication strategy is developed that takes into account the aforementioned network-induced imperfections and that aims to reduce the utilization of communication resources, while maintaining the desired closed-loop performance properties. The resulting

Output-based event-triggered control systems under Denial-of-Service attacks

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Event-Triggered Control for String-Stable Vehicle Platooning

string-stable control strategy is experimentally validated by means of a platoon of three passenger vehicles.