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W P M H Heemels - One of the best experts on this subject based on the ideXlab platform.
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output based and decentralized dynamic event triggered Control with guaranteed mathcal l _ p gain performance and zeno freeness
IEEE Transactions on Automatic Control, 2017Co-Authors: V S Dolk, D P Borgers, W P M H HeemelsAbstract: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 $\mathcal{L}_{p}$ - 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 $\mathcal{L}_{p}$ - gains. A linear and a nonlinear numerical example will illustrate all the benefits of this new dynamic ETC scheme.
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periodic event triggered Control for nonlinear systems
Conference on Decision and Control, 2013Co-Authors: Romain Postoyan, Paulo Tabuada, W P M H Heemels, Adolfo Anta, Dragan NesicAbstract:Event-Triggered Control (ETC) is a Control strategy that is especially suited for applications where communication resources are scarce. By updating and communicating sensor and actuator data only when needed for stability or performance purposes, ETC is capable of reducing the amount of communications, while still retaining a satisfactory closed-loop performance. In this paper, an ETC strategy is proposed by striking a balance between conventional periodic sampled-data Control and ETC, leading to so-called periodic Event-Triggered Control (PETC). In PETC, the event-triggering condition is verified periodically and at every sampling time it is decided whether or not to compute and to transmit new measurements and new Control signals. The periodic character of the triggering conditions leads to various implementation benefits, including a minimum inter-event time of (at least) the sampling interval of the event-triggering condition. The PETC strategies developed in this paper apply to both static state-feedback and dynamical output-based Controllers, as well as to both centralized and decentralized (periodic) event-triggering conditions. To analyze the stability and the L2-gain properties of the resulting PETC systems, three different approaches will be presented based on 1) impulsive systems, 2) piecewise linear systems, and 3) perturbed linear systems. Moreover, the advantages and disadvantages of each of the three approaches will be discussed and the developed theory will be illustrated using a numerical example.
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extension and evaluation of model based periodic event triggered Control
European Control Conference, 2013Co-Authors: J L C Verhaegh, T M P Gommans, W P M H HeemelsAbstract:Periodic Event-Triggered Control (PETC) is a Control strategy that combines ideas from conventional periodic sampled-data Control and Event-Triggered Control. By communicating periodically sampled sensor and Controller data only when needed to guarantee stability and performance properties, PETC is capable of reducing the number of transmissions significantly, while still retaining a satisfactory closed-loop behavior. In this paper, we provide an extension of an existing model-based PETC strategy for linear systems by including an (approximate) disturbance model. This extension can further enhance communication savings in the presence of disturbances. In addition, we evaluate the extended model-based PETC strategy by comparing this strategy to the standard model-based PETC and to a model-based periodic time-triggered Control (PTTC) strategy. In this PTTC strategy, data is transmitted at fixed sampling times. For the evaluation, we present techniques for stability and l2-gain performance analysis for both the PETC strategy and the PTTC strategy. Finally, the advantage of the (extended) PETC strategy over the PTTC strategy will be demonstrated by providing numerical examples.
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model based periodic event triggered Control for linear systems
Automatica, 2013Co-Authors: W P M H Heemels, M C F DonkersAbstract:Periodic Event-Triggered Control (PETC) is a Control strategy that combines ideas from conventional periodic sampled-data Control and Event-Triggered Control. By communicating periodically sampled sensor and Controller data only when needed to guarantee stability or performance properties, PETC is capable of reducing the number of transmissions significantly, while still retaining a satisfactory closed-loop behavior. In this paper, we will study observer-based Controllers for linear systems and propose advanced event-triggering mechanisms (ETMs) that will reduce communication in both the sensor-to-Controller channels and the Controller-to-actuator channels. By exploiting model-based computations, the new classes of ETMs will outperform existing ETMs in the literature. To model and analyze the proposed classes of ETMs, we present two frameworks based on perturbed linear and piecewise linear systems, leading to conditions for global exponential stability and @?"2-gain performance of the resulting closed-loop systems in terms of linear matrix inequalities. The proposed analysis frameworks can be used to make tradeoffs between the network utilization on the one hand and the performance in terms of @?"2-gains on the other. In addition, we will show that the closed-loop performance realized by an observer-based Controller, implemented in a conventional periodic time-triggered fashion, can be recovered arbitrarily closely by a PETC implementation. This provides a justification for emulation-based design. Next to centralized model-based ETMs, we will also provide a decentralized setup suitable for large-scale systems, where sensors and actuators are physically distributed over a wide area. The improvements realized by the proposed model-based ETMs will be demonstrated using numerical examples.
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dynamic programming formulation of periodic event triggered Control performance guarantees and co design
Conference on Decision and Control, 2012Co-Authors: Duarte Antunes, W P M H Heemels, Paulo TabuadaAbstract:While potential benefits of choosing the transmissions times in a networked Control system based on state or event information have been advocated in the literature, few general methods are available that guarantee closed-loop improvements over traditional periodic transmission strategies. In this paper, we propose Event-Triggered Controllers that guarantee better quadratic discounted cost performance than periodic Control strategies using the same average transmission rate. Moreover, we show that the performance of a method in the line of previous Lyapunov based approaches is within a multiplicative factor of periodic Control performance, while using less transmissions. Our approach is based on a dynamic programming formulation for the co-design problem of choosing both transmission decisions and Control inputs in the context of periodic Event-Triggered Control for linear systems. A numerical example illustrates the advantages of the proposed method over traditional periodic Control.
Manuel Mazo - One of the best experts on this subject based on the ideXlab platform.
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abstracting the sampling behaviour of stochastic linear periodic event triggered Control systems
arXiv e-prints, 2021Co-Authors: Giannis Delimpaltadakis, Luca Laurenti, Manuel MazoAbstract:Recently, there have been efforts towards understanding the sampling behaviour of Event-Triggered Control (ETC), for obtaining metrics on its sampling performance and predicting its sampling patterns. Finite-state abstractions, capturing the sampling behaviour of ETC systems, have proven promising in this respect. So far, such abstractions have been constructed for non-stochastic systems. Here, inspired by this framework, we abstract the sampling behaviour of stochastic narrow-sense linear periodic ETC (PETC) systems via Interval Markov Chains (IMCs). Particularly, we define functions over sequences of state-measurements and interevent times that can be expressed as discounted cumulative sums of rewards, and compute bounds on their expected values by constructing appropriate IMCs and equipping them with suitable rewards. Finally, we argue that our results are extendable to more general forms of functions, thus providing a generic framework to define and study various ETC sampling indicators.
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formal traffic characterization of lti event triggered Control systems
IEEE Transactions on Control of Network Systems, 2018Co-Authors: Arman Sharifi Kolarijani, Manuel MazoAbstract:Unnecessary communication and computation in the periodic execution of Control tasks lead to overprovisioning in hardware design (or underexploitation in hardware utilization) in Control applications, in particular, in networked Control systems. To address these issues, researchers have proposed a new class of strategies, named event-driven strategies. Despite their beneficiary effects, matters such as task scheduling and appropriate dimensioning of communication components have become more complicated with respect to traditional periodic strategies. In this paper, we present a formal approach to derive an abstracted system that captures the sampling behavior of a family of Event-Triggered strategies for the case of LTI systems. This structure approximately simulates the sampling behavior of the aperiodic Control system. Furthermore, the resulting abstract system is equivalent to a timed safety automaton. In the construction of the abstraction, the state space is confined to a finite number of convex regions, each of which represents a mode in the quotient system. An LMI-based technique is deployed to derive a sampling time interval associated with each region. Finally, reachability analysis is leveraged to find the transitions of the abstract system.
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decentralized event triggered Control over wireless sensor actuator networks
IEEE Transactions on Automatic Control, 2011Co-Authors: Manuel Mazo, Paulo TabuadaAbstract:Event-Triggered Control has been recently proposed as an alternative to the more traditional periodic execution of Control tasks. In a typical Event-Triggered implementation, the Control signals are kept constant until the violation of a condition on the state of the plant triggers the recomputation of the Control signals. The possibility of reducing the number of recomputations, and thus of transmissions, while guaranteeing desired levels of Control performance, makes Event-Triggered Control very appealing in the context of sensor/actuator networks. In particular, by reducing the network traffic we also reduce the energy expenditures of battery powered wireless sensor nodes. In this paper we present a decentralized Event-Triggered implementation, over sensor/actuator networks, of centralized nonlinear Controllers.
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decentralized event triggered Control over wireless sensor actuator networks
arXiv: Optimization and Control, 2010Co-Authors: Manuel Mazo, Paulo TabuadaAbstract:In recent years we have witnessed a move of the major industrial automation providers into the wireless domain. While most of these companies already offer wireless products for measurement and monitoring purposes, the ultimate goal is to be able to close feedback loops over wireless networks interconnecting sensors, computation devices, and actuators. In this paper we present a decentralized Event-Triggered implementation, over sensor/actuator networks, of centralized nonlinear Controllers. Event-Triggered Control has been recently proposed as an alternative to the more traditional periodic execution of Control tasks. In a typical Event-Triggered implementation, the Control signals are kept constant until the violation of a condition on the state of the plant triggers the re-computation of the Control signals. The possibility of reducing the number of re-computations, and thus of transmissions, while guaranteeing desired levels of performance makes Event-Triggered Control very appealing in the context of sensor/actuator networks. In these systems the communication network is a shared resource and Event-Triggered implementations of Control laws offer a flexible way to reduce network utilization. Moreover reducing the number of times that a feedback Control law is executed implies a reduction in transmissions and thus a reduction in energy expenditures of battery powered wireless sensor nodes.
Panos J. Antsaklis - One of the best experts on this subject based on the ideXlab platform.
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learning based event triggered Control for synchronization of passive multi agent systems under attack
IEEE Transactions on Automatic Control, 2019Co-Authors: Arash Rahnama, Panos J. AntsaklisAbstract:In this paper, we study the synchronization of a group of output passive agents that communicate with each other according to an underlying communication graph. A distributed Event-Triggered Control framework that guarantees synchronization and reduces the required communication rate is introduced. A general Byzantine attack on a multi-agent system is defined and its negative effects on synchronization are characterized. The Byzantine agents are able to intelligently falsify their data and manipulate the underlying communication graph by altering their Control feedback weights. Next, a decentralized decision making and detection framework is introduced and its steady-state and transient performances are analyzed. Further, a method of identifying Byzantine neighbors and a learning-based procedure for estimating the attack parameters are introduced. Lastly, learning-based Control frameworks to mitigate the effects of the attack are proposed.
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model based event triggered Control for systems with quantization and time varying network delays
IEEE Transactions on Automatic Control, 2013Co-Authors: Eloy Garcia, Panos J. AntsaklisAbstract:This paper combines two important Control techniques for reducing communication traffic in Control networks, namely, model-based networked Control systems (MB-NCS) and Event-Triggered Control. The resulting framework is used for stabilization of uncertain dynamical systems and is extended to systems subject to quantization and time-varying network delays. The use of a model of the plant in the Controller node not only generalizes the zero-order-hold (ZOH) implementation in traditional Event-Triggered Control schemes but it also provides stability thresholds that are robust to model uncertainties. The effects of quantized measurements are especially important in the selection of stabilizing thresholds. We are able to design error events based on the quantized variables that yield asymptotic stability compared to similar results in Event-Triggered Control that consider nonquantized measurements which, in general, are not possible to use in digital computations. With respect to MB-NCS, the stability conditions presented here do not need explicit knowledge of the plant parameters as in previous work but are given only in terms of the parameters of the nominal model and some bounds in the model uncertainties. We consider the joint adverse effects of quantization and time delays and emphasize the expected tradeoff between the selection of quantization parameters and the admissible network induced delays.
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model based event triggered Control with time varying network delays
Conference on Decision and Control, 2011Co-Authors: Eloy Garcia, Panos J. AntsaklisAbstract:In this paper two approaches for reducing communication traffic in a Control network, namely, Model-Based Networked Control Systems (MB-NCS) and Event-Triggered Control, are unified under a single framework. The use of a model of the plant in the Controller node not only generalizes the Zero-Order-Hold (ZOH) implementation in traditional Event-Triggered Control schemes but it also provides stability thresholds that are robust to model uncertainties. With respect to MB-NCS, the stability conditions presented here do not need explicit knowledge of the plant parameters as in previous work but are given only in terms of the parameters of the nominal model and some bounds in the model uncertainties. The resulting framework is capable of increasing the update time intervals compared with the individual approaches considered in this paper.
Paulo Tabuada - One of the best experts on this subject based on the ideXlab platform.
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periodic event triggered Control for nonlinear systems
Conference on Decision and Control, 2013Co-Authors: Romain Postoyan, Paulo Tabuada, W P M H Heemels, Adolfo Anta, Dragan NesicAbstract:Event-Triggered Control (ETC) is a Control strategy that is especially suited for applications where communication resources are scarce. By updating and communicating sensor and actuator data only when needed for stability or performance purposes, ETC is capable of reducing the amount of communications, while still retaining a satisfactory closed-loop performance. In this paper, an ETC strategy is proposed by striking a balance between conventional periodic sampled-data Control and ETC, leading to so-called periodic Event-Triggered Control (PETC). In PETC, the event-triggering condition is verified periodically and at every sampling time it is decided whether or not to compute and to transmit new measurements and new Control signals. The periodic character of the triggering conditions leads to various implementation benefits, including a minimum inter-event time of (at least) the sampling interval of the event-triggering condition. The PETC strategies developed in this paper apply to both static state-feedback and dynamical output-based Controllers, as well as to both centralized and decentralized (periodic) event-triggering conditions. To analyze the stability and the L2-gain properties of the resulting PETC systems, three different approaches will be presented based on 1) impulsive systems, 2) piecewise linear systems, and 3) perturbed linear systems. Moreover, the advantages and disadvantages of each of the three approaches will be discussed and the developed theory will be illustrated using a numerical example.
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dynamic programming formulation of periodic event triggered Control performance guarantees and co design
Conference on Decision and Control, 2012Co-Authors: Duarte Antunes, W P M H Heemels, Paulo TabuadaAbstract:While potential benefits of choosing the transmissions times in a networked Control system based on state or event information have been advocated in the literature, few general methods are available that guarantee closed-loop improvements over traditional periodic transmission strategies. In this paper, we propose Event-Triggered Controllers that guarantee better quadratic discounted cost performance than periodic Control strategies using the same average transmission rate. Moreover, we show that the performance of a method in the line of previous Lyapunov based approaches is within a multiplicative factor of periodic Control performance, while using less transmissions. Our approach is based on a dynamic programming formulation for the co-design problem of choosing both transmission decisions and Control inputs in the context of periodic Event-Triggered Control for linear systems. A numerical example illustrates the advantages of the proposed method over traditional periodic Control.
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decentralized event triggered Control over wireless sensor actuator networks
IEEE Transactions on Automatic Control, 2011Co-Authors: Manuel Mazo, Paulo TabuadaAbstract:Event-Triggered Control has been recently proposed as an alternative to the more traditional periodic execution of Control tasks. In a typical Event-Triggered implementation, the Control signals are kept constant until the violation of a condition on the state of the plant triggers the recomputation of the Control signals. The possibility of reducing the number of recomputations, and thus of transmissions, while guaranteeing desired levels of Control performance, makes Event-Triggered Control very appealing in the context of sensor/actuator networks. In particular, by reducing the network traffic we also reduce the energy expenditures of battery powered wireless sensor nodes. In this paper we present a decentralized Event-Triggered implementation, over sensor/actuator networks, of centralized nonlinear Controllers.
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decentralized event triggered Control over wireless sensor actuator networks
arXiv: Optimization and Control, 2010Co-Authors: Manuel Mazo, Paulo TabuadaAbstract:In recent years we have witnessed a move of the major industrial automation providers into the wireless domain. While most of these companies already offer wireless products for measurement and monitoring purposes, the ultimate goal is to be able to close feedback loops over wireless networks interconnecting sensors, computation devices, and actuators. In this paper we present a decentralized Event-Triggered implementation, over sensor/actuator networks, of centralized nonlinear Controllers. Event-Triggered Control has been recently proposed as an alternative to the more traditional periodic execution of Control tasks. In a typical Event-Triggered implementation, the Control signals are kept constant until the violation of a condition on the state of the plant triggers the re-computation of the Control signals. The possibility of reducing the number of re-computations, and thus of transmissions, while guaranteeing desired levels of performance makes Event-Triggered Control very appealing in the context of sensor/actuator networks. In these systems the communication network is a shared resource and Event-Triggered implementations of Control laws offer a flexible way to reduce network utilization. Moreover reducing the number of times that a feedback Control law is executed implies a reduction in transmissions and thus a reduction in energy expenditures of battery powered wireless sensor nodes.
Gang Feng - One of the best experts on this subject based on the ideXlab platform.
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output consensus of heterogeneous linear multi agent systems with adaptive event triggered Control
IEEE Transactions on Automatic Control, 2019Co-Authors: Yangyang Qian, Lu Liu, Gang FengAbstract:This paper investigates the output consensus problem for heterogeneous linear multi-agent systems via Event-Triggered Control. By introducing a dynamic compensator for each agent, a fully distributed Event-Triggered Control strategy with an adaptive event-triggering mechanism is proposed. It is shown that under the proposed Control strategy, all agents asymptotically achieve output consensus with intermittent communication in a fully distributed manner. Moreover, with the proposed event-triggering mechanism, Zeno behavior is strictly excluded for each agent. Compared with existing mechanisms, the proposed event-triggering mechanism is independent of any global information and avoids the continuous monitoring issue. Finally, a numerical example is provided to illustrate the effectiveness of the proposed Event-Triggered Control strategy.
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observer based output feedback event triggered Control for consensus of multi agent systems
IEEE Transactions on Industrial Electronics, 2014Co-Authors: Gang Feng, Qijun ChenAbstract:This paper studies the consensus problem of linear multi-agent systems via observer-based Event-Triggered Control. Two novel observer-based Event-Triggered Control schemes, one centralized and the other distributed, are developed. It is shown that under the proposed Control protocols, consensus can be reached if the underlying communication graph of the MAS is connected. An example is finally presented to illustrate the effectiveness of the proposed Control methods.
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technical communique distributed event triggered Control of multi agent systems with combinational measurements
Automatica, 2013Co-Authors: Yuan Fan, Gang Feng, Yong Wang, Cheng SongAbstract:This paper studies the distributed rendezvous problem of multi-agent systems with novel Event-Triggered Controllers. We have proposed a combinational measurement approach to event design and developed the basic Event-Triggered Control algorithm. As a result, Control of agents is only triggered at their own event time, which reduces the amount of communication and lowers the frequency of Controller updates in practice. Furthermore, based on the convergence analysis of the basic algorithm, we have proposed a new iterative Event-Triggered algorithm where continuous measurement of the neighbor states is avoided. It is noted that the amount of communication among agents has been significantly reduced without obvious negative effects on the Control performances. The effectiveness of the proposed strategies is illustrated by numerical examples in 3D spaces.