C. De Persis

n-bit stabilization of n-dimensional nonlinear systems in feedforward form

A methodology is presented which allows to design encoder, decoder and controller for stabilizing a nonlinear system in feedforward form using saturated encoded state feedback basically under standard assumption, namely local Lipschitz property of the vector field defining the system. n (respectively, n + 1) bits are used to encode the state information needed to the purpose of semiglobally (globally) stabilizing an n-dimensional system. Minimality of the data rate is discussed.

Parsimonious event-triggered distributed control: A Zeno free approach ✩

Consider the problem of stabilizing large-scale systems by distributed controllers, where the controllers exchange information via a shared limited communication medium. Event-triggered sampling schemes are proposed, in which each system decides when to transmit new information across the network based on the crossing of some error thresholds, which only depend on information locally available at individual subsystems. Stability of the interconnected large-scale system is inferred by applying a generalized small-gain theorem.

Brief paperParsimonious event-triggered distributed control: A Zeno free approach☆

Consider the problem of stabilizing large-scale systems by distributed controllers, where the controllers exchange information via a shared limited communication medium. Event-triggered sampling schemes are proposed, in which each system decides when to transmit new information across the network based on the crossing of some error thresholds, which only depend on information locally available at individual subsystems. Stability of the interconnected large-scale system is inferred by applying a generalized small-gain theorem.

Resilient Control under Denial-Of-Service

We investigate resilient control strategies for linear systems under Denial-of-Service (DoS) attacks. By DoS attacks we mean interruptions of communication on measurement (sensor-to-controller) and control (controller-to-actuator) channels carried out by an intelligent adversary. We characterize the duration of these interruptions under which stability of the closed-loop system is preserved. The resilient nature of the control descends from its ability to adapt the sampling rate to the occurrence of the DoS.

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

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.

An internal model approach to frequency regulation in inverter-based microgrids with time-varying voltages

This paper studies the problem of frequency regulation in inverter-based microgrids with time-varying voltages, described by a third-order model. Building upon our previous result on optimal frequency regulation in an ordinary power grid [1], we propose the design of internal-model-based controllers and analyze it within an incremental passivity framework. We believe that this framework is general enough to allow for more complex control scenarios in future extensions.

Networked control of nonlinear systems under Denial-of-Service

Abstract We investigate the analysis and design of a control strategy for nonlinear systems under Denial-of-Service attacks. Based on an ISS-Lyapunov function analysis, we provide a characterization of the maximal percentage of time that feedback information can be lost without resulting in instability of the system. Motivated by the presence of a digital channel we consider event-based controllers for which a minimal inter-sampling time is explicitly characterized.

Remote tracking via encoded information for nonlinear systems

The problem addressed in this paper is to control a plant so as to have its output tracking (a family of) reference commands generated at a remote location and transmitted through a communication channel of finite capacity. The uncertainty due to the presence of the communication channel is counteracted by a suitable choice of the parameters of the regulator.

On feedback stabilization of nonlinear systems under quantization

The aim of this note is to show how the results in D. Liberzon, Hybrid feedback stabilization of systems with quantized signals, Automatica, 39, 1543-1554, 2003, concerning asymptotic stabilization using quantized feedback, still hold under the assumption of asymptotic stabilizability only. As a consequence, we are able to examine as special interesting cases nonlinear systems which are e.g. globally asymptotically and locally exponentially stabilizable and stabilizable by dynamic observer-based feedback. The results are also discussed for discrete-time nonlinear systems.

A modular design of incremental Lyapunov functions for microgrid control with power sharing

In this paper we contribute a theoretical framework that sheds a new light on the problem of microgrid analysis and control. The starting point is an energy function comprising the kinetic energy associated with the elements that emulate the rotating machinery and terms taking into account the reactive power stored in the lines and dissipated on shunt elements. We then shape this energy function with the addition of an adjustable voltage-dependent term, and construct incremental storage functions satisfying suitable dissipation inequalities. Our choice of the voltage-dependent term depends on the voltage dynamics/controller under investigation. Several microgrids dynamics that have similarities or coincide with dynamics already considered in the literature are captured in our incremental energy analysis framework. The twist with respect to existing results is that our incremental storage functions allow for an analysis of the coupled microgrid obviating the need for simplifying linearization techniques and for the restrictive decoupling assumption in which the frequency dynamics is fully separated from the voltage one.