Event triggered control of two time scale system
01 Jan 2017-Vol. 2017, pp 309-314
TL;DR: It is proved that the closed loop system asymptotically converges to an adjustable region around the equilibrium point and a minimum bound on inter-execution time is also guaranteed.
Abstract: This paper describes the framework for event triggered control of a plant possessing two time scales. The periodic sampling requirement is relaxed and states are sampled based on a triggering rule. The dynamic trigger function where event triggering threshold varies with time has been used. Triggering function parameters are different for slow and fast states and events are detected independently in the two subsystems. This also allows the sensors for slow and fast states to be geographically distributed in the network. Further singular perturbation technique is used to decouple the system into fast and slow subsystems and stability of the overall system is investigated. It is proved that the closed loop system asymptotically converges to an adjustable region around the equilibrium point and a minimum bound on inter-execution time is also guaranteed. Asymptotic stability may also be obtained if the parameters of trigger function are adequately selected. Simulation results manifest the efficacy of the proposed approach and verify the theoretical analysis.
Citations
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01 Jan 2002
TL;DR: In this article, it is shown that Lebesgue sampling gives better performance for some simple systems than traditional Riemann sampling, which is an analog of integration theory and is called event-based sampling.
Abstract: The normal approach to digital control is to sample periodically in time. Using an analog of integration theory we can call this Riemann sampling. Lebesgue sampling or event based sampling is an alternative to Riemann sampling. It means that signals are sampled only when measurements pass certain limits. In this paper it is shown that Lebesgue sampling gives better performance for some simple systems.
33 citations
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TL;DR: The theory of singular perturbation is used to decouple the system into slow and fast subsystems, and stability of the system is established and the proposed control strategy guarantees convergence of system states to an adjustable region around origin excluding the Zeno behavior.
Abstract: This brief proposes an event-triggered composite control of a two time scale system. A periodic sampling requirement is relaxed and both slow and fast states of the system decide independently when transmitting their current measurements based on a time-dependent triggering rule. The distinct feature of this scheme is that it does not require synchronized measurement updates of its slow and fast dynamics. Further, the theory of singular perturbation is used to decouple the system into slow and fast subsystems, and stability of the system is established. The proposed control strategy guarantees convergence of system states to an adjustable region around origin excluding the Zeno behavior. Simulation results manifest the effectiveness of the proposed approach.
18 citations
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TL;DR: This work proposes an event-trigger theory which leverages the physical property of discrete two-time scale system to reduce the requirement of network bandwidth.
Abstract: There are several physical systems which exhibit two-time scale property. When these systems are controlled through networks, uniform sampling causes an extra burden on the network bandwidth. Furthermore, uniform sampling of slow and fast variables leads to over-sampling of slow variables. This work proposes an event-trigger theory which leverages the physical property of discrete two-time scale system to reduce the requirement of network bandwidth. Events in slow and fast variables occur as per their respective dynamics and based on the occurrence of a respective event, only slow or fast variables are communicated through a network. Thus the communication of the state is carried out based on an event of the respective set of variables. Simulation studies are presented to validate the theoretical developments.
1 citations
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TL;DR: The singular perturbation technique is used to analyse the stability of the event-triggered control closed-loop system with a dual-stage event-triggering condition and the relations between the parameters in the events can be selected in a range independent of the matrices in the model.
Abstract: In this paper, the model-based event-triggered control is addressed for a class of linear systems with two time scales. The singular perturbation technique is used to analyse the stability of the e...
1 citations
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TL;DR: The stability properties of overall closed loop system is studied and it is found that for sufficiently small value of singular perturbation parameter, system attains practical stability and by adequately selecting trigger function parameters, asymptotic stability is also achieved.
Abstract: In this paper, we consider the event triggered control of the singularly perturbed linear system, where the communication between sensor and the controller/actuator is through a digital communication network and the transmission is based on some state dependent criterion. The models of slow and fast subsystems of the plant are added at the controller and are used for the estimation of states between the transmission times. Whenever the difference between estimated and actual states exceeds a certain threshold, controller is updated with the actual states of the plant provided by the sensor. This effectively reduces the communication frequency. The stability properties of overall closed loop system is studied and it is found that for sufficiently small value of singular perturbation parameter, system attains practical stability and by adequately selecting trigger function parameters, asymptotic stability is also achieved. A numerical example is shown to illustrate the results of the paper.
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References
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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.
2,850 citations
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Book•
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TL;DR: This SIAM Classics edition of the 1986 book, the original text is reprinted in its entirety (along with a new preface), providing once again the theoretical foundation for representative control applications.
Abstract: From the Publisher:
Singular perturbations and time-scale techniques were introduced to control engineering in the late 1960s and have since become common tools for the modeling, analysis, and design of control systems. In this SIAM Classics edition of the 1986 book, the original text is reprinted in its entirety (along with a new preface), providing once again the theoretical foundation for representative control applications.
This book continues to be essential in many ways. It lays down the foundation of singular perturbation theory for linear and nonlinear systems, it presents the methodology in a pedagogical way that is not available anywhere else, and it illustrates the theory with many solved examples, including various physical examples and applications. So while new developments may go beyond the topics covered in this book, they are still based on the methodology described here, which continues to be their common starting point.
Audience
Control engineers and graduate students who seek an introduction to singular perturbation methods in control will find this text useful. The book also provides research workers with sketches of problems in the areas of robust, adaptive, stochastic, and nonlinear control. No previous knowledge of singular perturbation techniques is assumed.
About the Authors
Petar Kokotovic is Director of the Center for Control Engineering and Computation at the University of California, Santa Barbara. Hassan K. Khalil is Professor of Electrical and Computer Engineering at Michigan State University. John O'Reilly is Professor of Electronics and Electrical Engineering at the University of Glasgow, Scotland.
2,328 citations
"Event triggered control of two time..." refers methods in this paper
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TL;DR: In this paper, it is shown that Lebesgue sampling gives better performance for some simple systems than traditional Riemann sampling, which is an analog of integration theory and is called event-based sampling.
Abstract: The normal approach to digital control is to sample periodically in time. Using an analog of integration theory we can call this Riemann sampling. Lebesgue sampling or event based sampling is an alternative to Riemann sampling. It means that signals are sampled only when measurements pass certain limits. In this paper it is shown that Lebesgue sampling gives better performance for some simple systems.
925 citations
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TL;DR: A novel control strategy for multi-agent coordination with event-based broadcasting is presented, in which each agent decides itself when to transmit its current state to its neighbors and the local control laws are based on these sampled state measurements.
Abstract: A novel control strategy for multi-agent coordination with event-based broadcasting is presented. In particular, each agent decides itself when to transmit its current state to its neighbors and the local control laws are based on these sampled state measurements. Three scenarios are analyzed: Networks of single-integrator agents with and without communication delays, and networks of double-integrator agents. The novel event-based scheduling strategy bounds each agent's measurement error by a time-dependent threshold. For each scenario it is shown that the proposed control strategy guarantees either asymptotic convergence to average consensus or convergence to a ball centered at the average consensus. Moreover, it is shown that the inter-event intervals are lower-bounded by a positive constant. Numerical simulations show the effectiveness of the novel event-based control strategy and how it compares to time-scheduled control.
894 citations
"Event triggered control of two time..." refers methods in this paper
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TL;DR: An upper bound of the difference between both loops is derived, which shows that the approximation of the continuous state-feedback loop by the event-based control loop can be made arbitrarily tight by appropriately choosing the threshold parameter of the event generator.
Abstract: This paper proposes a new method for event-based state-feedback control in which a control input generator mimics a continuous feedback between two consecutive event times. The performance of the event-based control system is evaluated by comparing this loop with the continuous state-feedback loop. An upper bound of the difference between both loops is derived, which shows that the approximation of the continuous state-feedback loop by the event-based control loop can be made arbitrarily tight by appropriately choosing the threshold parameter of the event generator.
885 citations
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