Event-triggered Output Feedback Research Articles

Adaptive Event-triggered Output Feedback Control for a Class of Switched Stochastic Nonlinear Systems with Unknown Output Gain

Adaptive Event-triggered Output Feedback Control for a Class of Switched Stochastic Nonlinear Systems with Unknown Output Gain

Adaptive optimal output regulation of linear discrete-time systems based on event-triggered output-feedback

This paper presents novel event-triggered control approaches to solve the adaptive optimal output regulation problem for a class of linear discrete-time systems. Different from most existing research on output regulation problems, the developed adaptive optimal control approaches are based on (1) output-feedback instead of full-state or partial-state feedback, (2) adaptive dynamic programming (ADP) which provides approximate solutions of the optimal control problem without requiring the precise knowledge of the plant dynamics, and (3) an event-triggering mechanism that reduces the communication between the controller and the plant. It is shown that the system in closed-loop with the developed controllers is asymptotically stable at an equilibrium of interest, and the tracking errors asymptotically converge to zero. Moreover, the suboptimality of the closed-loop system is directly determined by the relative threshold, which is a ratio between the triggering threshold and the actual state. A numerical simulation example is employed to verify the effectiveness of the proposed methodologies.

Event-triggered output feedback containment control for a class of stochastic nonlinear multi-agent systems

An output feedback-based containment control strategy is proposed with an event-triggered mechanism for a class of stochastic nonlinear multi-agent systems (MASs). For unavailable internal states of individual agent, a state observer is constructed for their estimations. The dynamic surface control (DSC) technology is employed to improve traditional backstepping, where a first-order filter is introduced for derivation calculation of virtual control laws. For the purpose of reducing communication resources, a fixed threshold-based triggered strategy is presented to reduce data transmission bits over communication channels. It is proven that all signals in the closed-loop system are bounded in probability and the containment control is achieved. Finally, the effectiveness of the proposed control strategy is verified via two examples.

Dynamic Event-Triggered Output Feedback Control for a Class of High-Order Feedforward Nonlinear Time-Delay Systems

This brief addresses the event-triggered output feedback control issue for high-order feedforward nonlinear systems with time-varying delays. Different from the existing results, a novel event-triggering mechanism coupling with a dynamic gain is proposed. Finally, a novel event-triggered output feedback controller is designed to ensure the boundedness of the closed-loop system. Moreover, the Zeno behavior is avoided. Two examples are presented to verify the effectiveness of the proposed scheme.

Practical tracking of uncertain nonlinear systems via adaptive event-triggered output feedback

This paper investigates the problem of global practical tracking by adaptive event-triggered output feedback for a class of uncertain nonlinear systems with unknown time-varying control coefficients. The nonlinear systems under consideration allow more general growth restriction, e.g., unknown constant and output-polynomial function coupled to the unmeasurable states. Based on non-separation principle, an adaptive event-triggered output feedback controller is proposed by combining dynamic high-gain scaling approach with backstepping method. It is worth emphasizing that a novel updating law of the high-gain is introduced to overcome the system nonlinearities and the serious uncertainties mentioned above. The controller proposed guarantees that the states of the resulting closed-loop systems are globally bounded, while the tracking error converges to a prescribed arbitrarily small neighborhood of the origin after a finite time. Finally, a numerical example is given to illustrate the effectiveness of the proposed approach.

Global Event-Triggered Output Feedback Stabilization for a Class of Nonlinear Time-Delay Systems

This note considers the issue of global asymptotic stabilization for a class of nonlinear systems with unknown time-varying delays and control gain using a dynamic event-triggered (DET) output feedback scheme. In the context of unknown time-varying delays and control gain, nonsmooth control law and some extra redundant terms will be encountered in the design of DET controller, which would bring substantial challenges to the achievement of event-triggered stabilization. Specifically, two dynamic gains and a modified Lyapunov-Krasovskii functional are first presented, which makes the effects of time-varying delays and control gain be conquered. Then, a DET mechanism utilizing the dynamic gain is given to reduce the amounts of event transmissions and dynamically compensate the triggering error. By virtue of the designed strategy, a new DET output feedback controller is developed, which renders the closed-loop system globally asymptotically stable. Meanwhile, it is proved that the Zeno behavior does not happen. Finally, in order to demonstrate the feasibility of the proposed scheme, corresponding examples are provided.

Passivity-based event-triggered control for a class of switched nonlinear systems

A static output feedback based event-triggered control mechanism for a class of switched nonlinear systems with a passivity property is proposed in this paper. Each subsystem of such a switched system does not necessarily have passivity in the classical sense, while maintaining the passivity property only on the active time intervals. Moreover, passivity is based on multiple storage functions and the storage functions are allowed to increase at switching instants. The proposed event-triggered output feedback controller can not only maintain asymptotic stability but also exclude Zeno behavior under some conditions. Finally, a numerical example is presented to illustrate the effectiveness of the method.

Global Event-Triggered Output Feedback Stabilization of a Class of Nonlinear Systems

This article investigates the problem of global output feedback stabilization by using aperiodic-sampled-data control, i.e., event-triggered control, for a class of uncertain nonlinear systems under certain assumptions. By employing the technique of output feedback domination, an observer-based event-triggered output feedback control law is explicitly constructed to guarantee the globally asymptotic stabilization. To avoid the Zeno behavior, a combining mechanism with event-triggered and time-triggered is proposed to ensure that the two consecutive updated time for the sampled-data controller is larger than one positive constant. Finally, it is shown that the problem of global output feedback stabilization for a class of uncertain nonlinear systems is solved via the proposed event-triggered control law. Finally, some comparative simulation examples are given to show the efficiency of the introduced method.

Adaptive Output Feedback Control of Steer-by-Wire Systems With Event-Triggered Communication

This article addresses the event-triggered output feedback control problem for steer-by-wire (SbW) systems with uncertain nonlinearity and time-varying disturbance. First, a new framework of event-triggered control systems is proposed to eliminate the jumping phenomenon of event-based control input, in which the tradeoff between saving communication resources and attenuating jumping phenomenon can be relaxed. Then, an adaptive fuzzy logic system (FLS) is developed to approximate the uncertain nonlinearity, and an adaptive FLS-based state observer is developed to estimate the augmented SbW system state, such that the unnecessary sensors can be removed. In light of the sliding mode control technique and FLS-based state observer, an adaptive event-triggered control is proposed for SbW systems, such that controller-area-network communication resources can be saved. Much significantly, the effect of observation error and event-triggered error can be counteracted by the dynamic gain technique. Furthermore, theoretical analysis based on Lyapunov stability theory is provided to verify both the observer error of state and the tracking error of the SbW system can converge to a neighborhood of the origin in finite time. Finally, simulations and experiments are given to evaluate the effectiveness and superiority of proposed methods.

Event-triggered output feedback control for feedforward nonlinear systems with unknown measurement sensitivity

This paper investigates the event-triggered output feedback control problem for feedforward nonlinear systems with unknown measurement sensitivity. The nonlinear terms are assumed to be bounded by an unknown constant multiplied by fractional power of states and controller. We design an auxiliary system independent of the output signal to construct controller and propose a novel time-varying triggering mechanism. It is the first time to introduce the logarithmic function into the auxiliary system and state transformation to deal with event-triggered control problem. Under the designed event-triggered controller, the convergence of all states is obtained and the Zeno behavior is effectively avoided. Finally, two numerical examples are presented to demonstrate the effectiveness of the designed event-triggered controller.

Estimate-Based Dynamic Event-Triggered Output Feedback Control of Networked Nonlinear Uncertain Systems

This paper develops a new estimate-based dynamic event-triggered output feedback controller for networked control systems subject to nonlinear uncertainties. Specifically, based on the sampled-data, a discrete-time output feedback controller and a discrete-time dynamic event-triggering condition are proposed by the virtue of feedback domination technique. The proposed event-triggered control method is easy to implement in digital computers due to the form of discrete time. Under the proposed dynamic event-triggered control method, the selection regions of the sampling period and the scaling gain are explicitly given to guarantee the global practical/asymptotic stability of the closed-loop system. Finally, two examples are employed to verify the efficiency of the proposed dynamic event-triggered control approach.

Adaptive model-based dynamic event-triggered output feedback control of a robotic manipulator with disturbance

This paper focuses on the stable tracking control of the manipulator with constrained communication, unmeasurable velocity, and nonlinear uncertainties. An NN observer-depended output feedback scheme in the discrete-time domain is developed by virtue of the model-based dynamic event-triggered backstepping technique in the channel of sensor to controller. For generalizing the zero-order-holder (ZOH) implementation, a plant model is built to approximate the triggered states in the time flow, and according to which, the control law is fabricated. Based on model-based error events, we construct a dead-zone triggered condition with a dynamically adjustable threshold, making the threshold evolve with the system performance, to achieve flexible communication scheduling and avoid the accumulation of triggers in small tracking errors. The internal and external nonlinear uncertainties are online compensated by the neural network, and the aperiodic adaptive law is derived in the sense of control stability to save the computation. Finally, the conditions for semi-global ultimate uniform bounded (SGUUB) of all variables are given via impulse Lyapunov analysis, and a positive lower bound in the time interval between consecutive executions to guarantee the Zeno free behavior is obtained. Simulations are conducted on a three-link manipulator to illustrate the effectiveness of our method.

Fuzzy adaptive event-triggered output feedback control for nonlinear systems with tracking error constrained and unknown dead-zone

ABSTRACT In this paper, an adaptive fuzzy event-triggered output feedback control scheme is studied for a class of non-strict feedback systems with tracking error constrained and unknown dead-zone. Fuzzy logical systems (FLSs) are employed to solve the uncertainties of the controlled plant, and the immeasurable states are estimated by employing the fuzzy observer. In the designed observer, to compensate for the effect of unknown dead-zone by invoking the known designed event-triggered input signal, an adaptive parameter is designed. Furthermore, due to event-triggered control (ETC) places a great burden on the computing space, the dynamic surface control (DSC) technique is used to solve the problem of ‘explosion of complexity’ in each step, and the simplified barrier Lyapunov function (SBLF) is utilised to restrict the tracking error within the prescribed boundaries. Consequently, the designed parameter adaptive laws and event-triggered controller can ensure that all signals of the closed-loop system are semi-globally uniformly ultimately bounded (SGUUB). Ultimately, two numerical simulation examples are provided to illustrate the effectiveness of the proposed event-triggered control theory.

Event-Triggered Output Feedback Control of Switched Nonlinear Systems With Input Saturation.

This article is concerned with the event-triggered output feedback control problem for a class of switched nonlinear strict-feedback systems subject to asymmetric input saturation. The nonlinear terms are assumed to be bounded by a continuous function of the output multiplied by unmeasured states. The hyperbolic tangent function is employed to process the error caused by the event-triggered scheme, and an indicator function of the saturation degree is used to analyze the influence generated by the asymmetric input saturation. By adopting the common Lyapunov function method and the dynamic gain control design approach, a new design procedure based on a reduced-order observer is proposed to construct an output feedback controller. It is proved by the Lyapunov analysis that the proposed event-triggered control scheme can ensure that all the signals of the closed-loop system are globally bounded. Furthermore, the output can be converged to a bounded region around the origin, and this region can be tuned to be small by adjusting the design parameters. Different from typical existing results on the switched nonlinear strict-feedback systems, the celebrated backstepping method is not employed in this article. The continuous stirred tank reactor is finally used to demonstrate the effectiveness of the proposed control scheme.

Formula omitted]-gain analysis for dynamic event-triggered networked control systems with packet losses and quantization

The problem of event-triggered output feedback control for networked control systems (NCSs) with packet losses and quantization is addressed. A new dynamic quantization scheme is proposed to prevent saturation of the quantizer in the presence of external disturbances, and using the emulation-based approach, we show how to design the event-triggering conditions to guarantee the L2-gain performance of the overall system. To cope with the successive packet losses and the dynamic quantization, the NCS is embedded into a hybrid dynamical system, which is capable of describing these dynamics. Then, a novel Lyapunov function type is constructed to analyze the L2-gain performance with the quantization and packet dropout effects. Furthermore, owing to the proposed method, the Zeno phenomenon resulting from the transmission instants and updates of quantizer are prevented by introducing a minimum inter-event time. Finally, a numerical simulation is introduced to demonstrate the feasibility of the proposed design approach.

Dynamic event-triggered output feedback control for a class of nonlinear systems with time-varying delays

This note studies the problem of dynamic event-triggered output feedback control for a class of nonlinear systems under homogeneous growth condition with unknown growth rate and time delays. Firstly, in order to deal with unknown growth rate and time-varying state delays, a double-gain dynamic scheme is introduced and a suitable Lyapunov–Krasovskii functional is selected. Secondly, a dynamic event-triggered strategy is proposed by introducing the dynamic gain to the event-triggered condition, which makes the triggering threshold be tuned dynamically. Compared with some existing works related to event-triggered strategy, the proposed strategy is more flexible for saving communication resources. Subsequently, a new output feedback control law is developed in the context of event-triggered mechanism to guarantee the boundedness of system signals while the system states globally enter a compact set around the origin. Finally, two examples are given to show the feasibility and merit of the presented scheme.

Memory Event-triggered Output Feedback Synchronization Control for Complex Dynamic Network with Bounded Distributed Delays

In this paper, the method of memory event triggering output feedback is used to study the synchronization of complex dynamic network with bounded distributed delays when the target node is known or unknown. A memory event triggering scheme is proposed to reduce the transmission of data packets and shorten the transient process, and the network transmission delay is considered. The data packet signals released in recent times are stored at the sensor side and the controller side, which are used to generate event trigger function and design memory output feedback controller. By using Lyapunov stability theory, a sufficient condition for exponentially ultimately bounded of error dynamic system is given in the form of linear matrix inequalities (LMIs). Finally, an example proves the validity and feasibility of the theoretical results.

Minimum-Time and Minimum-Triggering Observability of Stochastic Boolean Networks

This article investigates the observability of Markovian jump Boolean networks (MJBNs) via algebraic state space representation approach. A necessary and sufficient criterion in the form of linear programming is derived for the asymptotic observability in distribution of MJBNs, and several conditions are obtained for the finite-time observability based on the properties of nilpotent matrices. Subsequently, in order to minimize the time consumption, a maximum principle is established to address the minimum-time observability problem. With regard to the event-triggered output feedback observability, an efficient procedure is developed to minimize the number of triggering events. Finally, three numerical examples are employed to demonstrate the effectiveness of theoretical results.

Fuzzy-Approximation-Based Event-Triggered Output Feedback Adaptive Control for Nonlinear Switched Large-Scale Systems With Actuator Faults

This article investigates the output feedback adaptive fuzzy event-triggered fault-tolerant control issue of nonlinear switched large-scale systems. First, a new state observer is established to estimate unmeasured states. Fuzzy logic systems are exploited to identify both unknown interconnections and uncertainties. Next, the Nussbaum gain technique is employed to tackle actuator failures and unknown control directions. A novel adaptive fuzzy fault-tolerant event-triggered controller is derived to guarantee the boundedness of closed-loop signals. Moreover, the Zeno phenomenon can be avoided. Finally, a practical simulation is given to illustrate the validity of the developed method.

Dynamic event-triggered output feedback control for stochastic nonlinear systems

Abstract In this paper, the event-triggered stabilization problem for stochastic nonlinear systems is addressed. A dynamic event-triggered transmission strategy is proposed for general stochastic nonlinear systems without the linear growth assumption and the proposed transmission strategy can be applied to the output-based dynamic controller. Zeno phenomenon is avoided in the transmission strategy. The resulted closed-loop system is modeled into a stochastic hybrid system. Uniformly globally asymptotic stability in probability is concluded by showing that the equilibrium set is uniformly globally stable in probability and arbitrarily small neighborhood of the equilibrium set is uniformly globally recurrent in probability.