Output-based Event-triggered Control Research Articles

Exponential Stabilization of Nonlinear Impulsive Systems via Output-Based Event-Triggered Control

This article applies output-based event-triggered control (ETC) strategies to nonlinear systems involving impulses and investigates the problem for globally exponential stability (GES). The impulses are not directly related to events and two kinds of control schemes (static and dynamic ETC) are fully considered, respectively. Moreover, the stabilizing and destabilizing impulses can coexist (i.e., hybrid impulses). By employing properties of impulsive system theory and Lyapunov conditions, some theoretical conditions for GES and non-Zeno behavior are derived under static and dynamic event-triggered mechanism, respectively. And the results for stability are different but complementary to each other. Based on the linear matrix inequality, the design criteria of expected triggered mechanism and control gains are derived. Finally, two numerical examples containing simulations are given to demonstrate the effectiveness of the proposed control strategy.

Output-based event-triggered control for discrete-time systems with three types of performance analysis

<abstract><p>This paper considers an output-based event-triggered control approach for discrete-time systems and proposes three new types of performance measures under unknown disturbances. These measures are motivated by the fact that signals in practical systems are often associated with bounded energy or bounded magnitude, and they should be described in the $ \ell_{2} $ and $ \ell_\infty $ spaces, respectively. More precisely, three performance measures from $ \ell_{q} $ to $ \ell_{p} $, denoted by the $ \ell_{p/q} $ performances with $ (p, q) = (2, 2), \ (\infty, 2) $ and $ (\infty, \infty) $, are considered for event-triggered systems (ETSs) in which the corresponding event-trigger mechanism is defined as a function from the measured output of the plant to the input of the dynamic output-feedback controller with the triggering parameter $ \sigma (>0) $. Such a selection of the pair $ (p, q) $ represents the $ \ell_{p/q} $ performances to be bounded and well-defined, and the three measures are natural extensions of those in the conventional feedback control, such as the $ H_\infty $, generalized $ H_2 $ and $ \ell_1 $ norms. We first derive the corresponding closed-form representation with respect to the relevant ETSs in terms of a piecewise linear difference equation. The asymptotic stability condition for the ETSs is then derived through the linear matrix inequality approach by developing an adequate piecewise quadratic Lyapunov function. This stability criterion is further extended to compute the $ \ell_{p/q} $ performances. Finally, a numerical example is given to verify the effectiveness of the overall arguments in both the theoretical and practical aspects, especially for the trade-off relation between the communication costs and $ \ell_{p/q} $ performances.</p></abstract>

Output-based event-triggered tracking control for networked pneumatic muscle actuators system with packet disorders

Output-based event-triggered tracking control for networked pneumatic muscle actuators system with packet disorders

Distributed dynamic event-triggered communication and control for multi-agent consensus: A hybrid system approach

This paper investigates the output-based event-triggered communication and control for linear multi-agent consensus under a directed graph based on a co-design method. The communication among the agents, as well as the controller updates, are determined by some new event-triggering mechanisms, in order to reduce the use of the network resources. To simultaneously guarantee the significant properties including the asymptotic consensus, and strong Zeno-freeness (strictly positive inter-event times), a novel distributed dynamic event-triggered protocol is proposed. Unlike the most-existing emulation-based approaches in which the control gain is previously decided, a systematic co-design procedure is proposed to design the controller gain, the observer gain, and the event-triggering mechanisms altogether in terms of solving a linear matrix inequality optimization problem. Based on the resulting hybrid system framework, a hybrid model is established for the distributed closed-loop system and the asymptotic consensus is achieved. Finally, a numerical example is presented to verify our systematic design methodology.

Event-triggered output-based control of T-S fuzzy systems under quantisation, actuator saturation and cyber attacks

This paper studies output-based event-triggered security control of networked T-S fuzzy systems under signal quantisation, actuator saturation and deception attacks governed by a Bernoulli distribution. Firstly, using periodically sampled output of a T-S fuzzy system, a discrete event-triggered mechanism (ETM) is introduced to save network bandwidth, which excludes Zeno behaviour absolutely. Secondly, a closed-loop system model is built, which integrates parameters of the T-S fuzzy plant, the ETM, quantiser, actuator saturation, stochastic attacks, network-induced delays and fuzzy dynamic output feedback controller in a unified framework. Thirdly, sufficient conditions for asymptotic stability of the T-S fuzzy system are obtained, and further a fuzzy output-based security controller is designed. Finally, examples confirm effectiveness of the proposed methods.

Output-based event-triggered resilient control of uncertain NCSs under DoS attacks and quantisation

This paper studies output-based resilient control of uncertain networked control systems under denial-of-service (DoS) attacks, resilient event-triggered mechanism (ETM) and quantisation. Firstly, to save constrained system resources such as network bandwidth, using information of DoS attacks and sampled outputs of plant, an output-based resilient ETM is introduced. Secondly, a switched system model is built, which characterises effects of DoS attacks, the resilient ETM, plant uncertainty and quantisation in a unified framework. Thirdly, sufficient conditions for exponential stability are obtained with less conservativeness, which establish quantitative relationships among DoS attacks, the resilient ETM, plant uncertainty, quantisation, dynamic output feedback (DOF) controller and system stability. Further, co-design conditions are presented to compute parameters of the resilient ETM and DOF controller simultaneously. Finally, example illustrates effectiveness of the proposed method.

Output-Based Event-Triggered Predictive Control for Networked Control Systems

In this article, the output-based predictive control problem for networked control systems (NCSs) with communication delays is investigated by utilizing the event-triggered mechanism (ETM). First, the output-based ETM is introduced in order to save limited network resources effectively. Second, the system states are estimated from the received output measurements by the Luenberger observer. Third, the model-based networked predictive control (NPC) approach is developed to actively deal with the time delay and stabilize the system. Moreover, two different approaches including the augmented model and the piecewise linear model are adopted, and sufficient conditions that guarantee the closed-loop stability and performance are further provided, respectively. Finally, two simulation examples are given to demonstrate the effectiveness and applicability of the proposed methods for the addressed NCSs.

Cooperative global robust output regulation for a class of nonlinear multi-agent systems by distributed event-triggered control

This paper studies the event-triggered cooperative global robust output regulation problem for a class of nonlinear multi-agent systems via a distributed internal model design. We show that our problem can be solved practically in the sense that the ultimate bound of the tracking error can be made arbitrarily small by adjusting a design parameter in the proposed event-triggered mechanism. Our result offers a few new features. First, our control law is robust against both external disturbances and parameter uncertainties, which are allowed to belong to some arbitrarily large prescribed compact sets. Second, the nonlinear functions in our system do not need to satisfy the global Lipschitz condition. Thus our systems are general enough to include some benchmark nonlinear systems that cannot be handled by existing approaches. Finally, our control law is a specific distributed output-based event-triggered control law, which lends itself to a direct digital implementation.

Output-based event-triggered schemes on leader-following consensus of a class of multi-agent systems with Lipschitz-type dynamics

This paper addresses the problem of leader-follower consensus for a class of nonlinear multi-agent systems with Lipschitz-type dynamics and a directed communication topology. First, in order to reduce communication frequency among followers, an output-based event-triggered control strategy is proposed for leader-following consensus. Second, neural-network-based observers are designed to reconstruct those immeasurable information of follower agents. Third, instead of continuously monitoring follower agents’ measurements, a distributed self-triggered control strategy is put forward, which is based only on each agent’s local estimation and its previous triggered instants. Furthermore, it is proved theoretically that the consensus tracking errors are ultimately bounded and the Zeno behavior is definitely excluded. Finally, simulation results are given to show the effectiveness and advantage of the proposed results.

Event-Triggered Global Robust Output Regulation for a Class of Nonlinear Systems

This note studies the global robust output regulation problem for a class of nonlinear systems by an output-based event-triggered control law. First, we convert the problem into the event-triggered global robust stabilization problem of a well-defined augmented system based on the internal model approach. Then, we design an output-based event-triggered control law together with an output-based event-triggered mechanism to solve the stabilization problem, which in turn leads to the solution to the original problem by an output-based event-triggered control law. Finally, we illustrate our approach by an example.

Output-Based Event-Triggered Control with Performance Guarantees

We propose an output-based event-triggered control solution for linear discrete-time systems with a performance guarantee relative to periodic time-triggered control, while reducing the communication load. The performance is expressed as an average quadratic cost and the plant is disturbed by Gaussian process and measurement noises. We establish several connections with previous works in the literature discussing, in particular, the relation to absolute and relative threshold policies. The usefulness of the results is illustrated through a numerical example.

Global Robust Output Regulation for a Class of Nonlinear Systems via Event-Triggered Control

In this paper, we study the event-triggered global robust output regulation problem for a class of nonlinear systems in output feedback form with unity relative degree. We first convert the problem into the event-triggered global robust stabilization problem of a well defined augmented system by the internal model approach. Then, we solve the stabilization problem by an output-based event-triggered control law together with an output-based event-triggered mechanism. Finally, the theoretical result is applied to the Lorenz systems.

Output-Based Event-Triggered Control With Guaranteed ${\cal L}_{\infty}$-Gain and Improved and Decentralized Event-Triggering

Most event-triggered controllers available nowadays are based on static state-feedback controllers. As in many control applications full state measurements are not available for feedback, it is the objective of this paper to propose event-triggered dynamical output-based controllers. The fact that the controller is based on output feedback instead of state feedback does not allow for straightforward extensions of existing event-triggering mechanisms if a minimum time between two subsequent events has to be guaranteed. Furthermore, since sensor and actuator nodes can be physically distributed, centralized event-triggering mechanisms are often prohibitive and, therefore, we will propose a decentralized event-triggering mechanism. This event-triggering mechanism invokes transmission of the outputs in a node when the difference between the current values of the outputs in the node and their previously transmitted values becomes “large” compared to the current values and an additional threshold. For such event-triggering mechanisms, we will study closed-loop stability and L∞-performance and provide bounds on the minimum time between two subsequent events generated by each node, the so-called inter-event time of a node. This enables us to make tradeoffs between closed-loop performance on the one hand and communication load on the other hand, or even between the communication load of individual nodes. In addition, we will model the event-triggered control system using an impulsive model, which truly describes the behavior of the event-triggered control system. As a result, we will be able to guarantee stability and performance for event-triggered controllers with larger minimum inter-event times than the existing results in the literature. We illustrate the developed theory using three numerical examples.