Event-Triggered Adaptive Control for a Class of Uncertain Nonlinear Systems
TL;DR: It is shown that the proposed control schemes guarantee that all the closed-loop signals are globally bounded and the tracking/stabilization error exponentially converges towards a compact set which is adjustable.
Abstract: In this technical note, the problem of event-trigger based adaptive control for a class of uncertain nonlinear systems is considered. The nonlinearities of the system are not required to be globally Lipschitz. Since the system contains unknown parameters, it is a difficult task to check the assumption of the input-to-state stability (ISS) with respect to the measurement errors, which is required in most existing literature. To solve this problem, we design both the adaptive controller and the triggering event at the same time such that the ISS assumption is no longer needed. In addition to presenting new design methodologies based on the fixed threshold strategy and relative threshold strategy, we also propose a new strategy named the switching threshold strategy. It is shown that the proposed control schemes guarantee that all the closed-loop signals are globally bounded and the tracking/stabilization error exponentially converges towards a compact set which is adjustable.
Citations
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TL;DR: A new finite-time stability criterion is proposed and a novel adaptive neural output-feedback control strategy is raised by backstepping technique, and under the presented control scheme, the finite- time quantized feedback control problem is coped with without limiting assumption for nonlinear functions.
Abstract: This paper addresses the finite-time tracking issue for nonlinear quantized systems with unmeasurable states. Compared with the existing researches, the finite-time quantized feedback control is considered for the first time. By proposing a new finite-time stability criterion and designing a state observer, a novel adaptive neural output-feedback control strategy is raised by backstepping technique. Under the presented control scheme, the finite-time quantized feedback control problem is coped with without limiting assumption for nonlinear functions.
366 citations
TL;DR: It is shown that all the signals are bounded, and the consensus tracking errors are located in a small neighborhood of the origin based on the Lyapunov stability theory and backstepping approach and is proved by simulation results.
Abstract: This paper considers the event-triggered tracking control problem of nonlinear multiagent systems with unknown disturbances. The event-triggering mechanism is considered in the controller update, which decreases the amount of communication and reduces the frequency of the controller update in practice. By designing a disturbance observer, the unknown external disturbances are estimated. Moreover, a part of adaptive parameters are only dependent on the number of followers, which weakens the computational burden. It is shown that all the signals are bounded, and the consensus tracking errors are located in a small neighborhood of the origin based on the Lyapunov stability theory and backstepping approach. Finally, the effectiveness of the approach proposed in this paper is proved by simulation results.
257 citations
Additional excerpts
...Motivated by [39], one has d dt | i(t)| = d dt ( i(t) × i(t)) (1)2 = sign( i(t))̇i(t) ≤ |ω̇i(t)|....
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TL;DR: It is proved through Lyapunov analyses that the proposed control protocol ensures that all the signals of the closed-loop system are globally bounded and the system output tracking error can exponentially converge to a residual which can be made arbitrarily small.
250 citations
TL;DR: This paper proposes a new way to encode and decode the event-triggered control signals to further decrease the communication rate and proves that the boundedness of all the signals is ensured and the output signal can be regulated to a compact set around zero, which is adjustable.
Abstract: In this paper, we investigate the problem of output feedback control for a class of uncertain nonlinear systems with event-triggered input. The considered system contains not only unknown system parameters, but also general nonlinear functions that are not required to be globally Lipschitz, in contrast to most of the existing results in the area. Besides providing two different event-triggered strategies without input-to-state stable assumption with respect to the measurement errors, we propose a new way to encode and decode the event-triggered control signals to further decrease the communication rate. With our newly proposed encoding–decoding mechanism, each time when the triggering event is violated, only 1-bit signal, either 1 or 0, is rendered to transmit through the communication channel between the controller and actuator. Clearly, this signal transmission mechanism is more effective and consumes less channel bandwidth. Through Lyapunov analyses, it is proved that the boundedness of all the signals is ensured and the output signal can be regulated to a compact set around zero, which is adjustable.
220 citations
Cites background from "Event-Triggered Adaptive Control fo..."
...In [21], the problem of event-triggered control for uncertain strict-feedback nonlinear systems is addressed and a new switching threshold strategy is proposed....
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TL;DR: By combining the Lyapunov stability theory and the backstepping technique, the proposed adaptive control approach ensures that all the signals in the closed-loop system are bounded, and the tracking error can be regulated to a compact set around zero in finite time.
Abstract: This paper investigates the adaptive event-triggered control problem for aclass of nonlinear systems subject to periodic disturbances. To reduce thecommunication burden, a reliable relative threshold strategy is proposed.Fourier series expansion and radial basis function neural network arecombined into a function approximator to model suitable time-varyingdisturbed function of known periods in strict-feedback systems. By combiningthe Lyapunov stability theory and the backstepping technique, the proposedadaptive control approach ensures that all the signals in the closed-loopsystem are bounded, and the tracking error can be regulated to a compact setaround zero in finite time. Finally, simulation resultsare presented to verify the effectiveness of the theoretical results.
215 citations
References
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05 Mar 2007
TL;DR: This work reviews several recent results on estimation, analysis, and controller synthesis for NCSs, and addresses channel limitations in terms of packet-rates, sampling, network delay, and packet dropouts.
Abstract: Networked control systems (NCSs) are spatially distributed systems for which the communication between sensors, actuators, and controllers is supported by a shared communication network. We review several recent results on estimation, analysis, and controller synthesis for NCSs. The results surveyed address channel limitations in terms of packet-rates, sampling, network delay, and packet dropouts. The results are presented in a tutorial fashion, comparing alternative methodologies
3,748 citations
"Event-Triggered Adaptive Control fo..." refers background in this paper
...Nowadays, network control gains more and more attention since it can improve control efficiency as well as reduce reconfiguration and maintenance cost [1]–[3]....
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TL;DR: This note investigates a simple event-triggered scheduler based on the paradigm that a real-time scheduler could be regarded as a feedback controller that decides which task is executed at any given instant and shows how it leads to guaranteed performance thus relaxing the more traditional periodic execution requirements.
Abstract: In this note, we revisit the problem of scheduling stabilizing control tasks on embedded processors. We start from the paradigm that a real-time scheduler could be regarded as a feedback controller that decides which task is executed at any given instant. This controller has for objective guaranteeing that (control unrelated) software tasks meet their deadlines and that stabilizing control tasks asymptotically stabilize the plant. We investigate a simple event-triggered scheduler based on this feedback paradigm and show how it leads to guaranteed performance thus relaxing the more traditional periodic execution requirements.
3,695 citations
"Event-Triggered Adaptive Control fo..." refers background in this paper
...While the framework of the first two, namely the fixed threshold strategy and the relative threshold strategy, are discussed in [16] and [7], respectively, the third one, here named switching threshold strategy, is introduced in this technical note for the first time....
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...In [7], a static rule for the system state is proposed, while in [13] and [14], an additional internal dynamic variable is given based on which a dynamic controller trigger event is designed....
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01 Dec 2012
TL;DR: An introduction to event- and self-triggered control systems where sensing and actuation is performed when needed and how these control strategies can be implemented using existing wireless communication technology is shown.
Abstract: Recent developments in computer and communication technologies have led to a new type of large-scale resource-constrained wireless embedded control systems. It is desirable in these systems to limit the sensor and control computation and/or communication to instances when the system needs attention. However, classical sampled-data control is based on performing sensing and actuation periodically rather than when the system needs attention. This paper provides an introduction to event- and self-triggered control systems where sensing and actuation is performed when needed. Event-triggered control is reactive and generates sensor sampling and control actuation when, for instance, the plant state deviates more than a certain threshold from a desired value. Self-triggered control, on the other hand, is proactive and computes the next sampling or actuation instance ahead of time. The basics of these control strategies are introduced together with a discussion on the differences between state feedback and output feedback for event-triggered control. It is also shown how event- and self-triggered control can be implemented using existing wireless communication technology. Some applications to wireless control in process industry are discussed as well.
1,642 citations
01 Jan 1999
TL;DR: A simple event-based PID controller is presented and it is shown that it is possible to obtain large reductions in CPU utilization with only minor control performance degradation.
Abstract: A simple event-based PID controller is presented. It is shown that it is possible to obtain large reductions in CPU utilization with only minor control performance degradation. Simulations on a double-tank process are presented.
865 citations
TL;DR: In this article, a simple event-based PID controller is presented, and it is shown that it is possible to obtain large reductions in CPU utilization with only minor control performance degradation.
796 citations