Performance of Model-Based Networked Control Systems with discrete-time plants (original) (raw)
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2008
The aim of this technical report is to provide a thorough compendium of our results in stability of model-based networked control systems with intermittent feedback. The first set of sections deal with continuous time results, while the latter sections focus on discrete time. We apply the concept of Intermittent Feedback to a class of net-worked control systems known as Model-Based Networked Control Systems (MB-NCS). Model-Based Networked Control Systems use an explicit model of the plant in order to reduce the network traffic while attempting to prevent excessive performance degradation, while Intermittent Feedback consists of the loop remaining closed for some fixed interval, then open for another interval. We begin by introducing the basic architecture for model-based control with intermittent feedback, then address the case with output feedback (through the use of a state observer), providing a full description of the state response of the system, as well as a necessary and suff...
Networked Control Systems: A Model-Based Approach
Handbook of Networked and Embedded Control Systems, 2005
In this article a class of networked control systems called Model-Based Networked Control Systems (MB-NCS) is considered. This control architecture uses an explicit model of the plant in order to reduce the network traffic while attempting to prevent excessive performance degradation. MB-NCS can successfully address several important control issues in an intuitive and transparent way. In this article the main results of this MB approach are described with examples. Specifically, conditions for the stability of state and output feedback continuous and discrete systems are derived under different scenarios that include delay compensation, constant and time varying update times, non-linear plants and quantization of the feedback signals. In addition, a performance measure for MB-NCS with noise inputs is introduced.
MODEL-BASED NETWORKED CONTROL SYSTEMS - STABILITY
2002
In this report the control of continuous linear plants where the state sensor is connected to a linear controller/actuator via a network is addressed. The work focuses on reducing the network usage using knowledge of the plant dynamics. Specifically, the controller uses an explicit model of the plant that approximates the plant dynamics and makes possible stabilization of the plant even under slow network conditions. Necessary and sufficient conditions for stability are derived for the presented setup in terms of the update time h and the parameters of the plant and of its model. The deterioration of behavior when either h or the modeling error increase is explicitly shown.
State and output feedback control in model-based networked control systems
2002
In this paper the control of a continuous linear plant where the sensor is connected to a linear controller/actuator via a network is addressed. Both state and output feedback are considered. The work focuses on reducing the network usage using knowledge of the plant dynamics. Necessary and sufficient conditions for stability are derived in terms of the update time h, the network delay, and the parameters of the plant and of its model. The deterioration of behavior when either h, the delay τ, or the modeling error increase is explicitly shown and examples are used to illustrate the results. 0-7803-7516-5/02/$17.00 ©2002 IEEE
International Journal of Control, 2010
The aim of this paper is to provide a set of results in stability of model-based networked control systems with intermittent feedback, which we intend will serve as a nexus between the study of systems with instantaneous feedback and with continuous feedback. We apply the concept of Intermittent Feedback to a class of networked control systems known as Model-Based Networked Control Systems (MB-NCS). Model-Based Networked Control Systems use an explicit model of the plant in order to reduce the network traffic while attempting to prevent excessive performance degradation, while Intermittent Feedback consists of the loop remaining closed for some fixed interval, then open for another interval. We begin by introducing the basic architecture for model-based control, then discuss the concept of intermittent feedback, its applications in various fields, and its role as a link between instantaneous and continuous feedback. We then provide our results for the model-based architecture with intermittent feedback. We also address the case with output feedback (through the use of a state observer), providing a full description of the state response of the system, as well as a necessary and sufficient condition for stability in each case. Extensions of our results to cases with nonlinear plants are also presented. Next, we investigate the situation where the update times τ and h are time-varying, first addressing the case where they have upper and lower bounds, then moving on to the case where their distributions are i.i.d or driven by a Markov chain. Finally, we study the case of model-based control with intermittent feedback for discrete-time plants, again providing stability conditions for the basic architecture, the state observer case, and the case with time-varying parameters.
On the model-based approach to nonlinear networked control systems
Automatica, 2008
The problem of model-based stabilization of a nonlinear system based on its approximate discrete-time model is addressed, under the assumption that both the feedforward and the feedback paths are subject to network-induced constraints. These constraints include irregularity of the transfer intervals, timevarying communication delays, and the possibility of packet losses. A communication protocol that copes with these constraints is proposed. A "Stability+performance recovery" result for the nonlinear modelbased networked control system (NCS) is formulated and proven.Simulation results presented confirm that the proposed method improves the maximum allowable transfer interval.
Performance Evaluation for Model-Based Networked Control Systems
Lecture Notes in Control and Information Sciences, 2006
The performance of ac lass of Model-Based Networked Control System (MB-NCS) is consideredinthis paper.AMB-NCSuses an explicit model of the plant to reduce the network bandwidth requirements. In particular, an Output Feedback MB-NCSi ss tudied. Afterr eviewingt he stabilityr esults for this system ands ome lifting techniquesb asics,t wo performance measures related to thet raditionalH 2 performance measure for LTIs ystems are computed. The firstH 2l ikep erformance measurementi sc alledt he ExtendedH 2n orm of the system and is based on the norm of the impulseresponse of theMB-NCSattime zero.The second performance measure is calledt he Generalized H2 norm and it basicallyr eplaces thet raditional trace norm by the Hilbert-Schmidt norm that is morea ppropriate for infinite dimensionalo perators.T he Generalized H2 norm alsor epresents thea veragen orm of the impulser esponse of theM B-NCSf or impulsei nputs applieda td ifferentt imes. Examples show howb oth normsc onverge to thet raditionalH 2n orm for continuous H2 systems. Finally, with theh elp of an alternate way of representing lifted parameters, the relationship between theo ptimal samplera nd hold of as ampled data systema nd the structureo ft he Output FeedbackM B-NCSi ss hown. 1I ntroduction An etworked control system(NCS) is ac ontrol system in which ad ata network is useda sf eedbackm edia. NCS is an importanta rea see for example [bib03] and [NE00c, YTS02,WYB99a]. Industrial control systems are increasingly using networks as media to interconnectt he differentc omponents. The use of networked control systems poses,t hough, somec hallenges.O ne of the main problems to be addressedw hen considering an etworked control systemi st he size of bandwidth requiredb ye achs ubsystem.S incee achc ontrol subsystemm ust share the same mediumthe reductionofthe individual band
Stability of model-based networked control systems with time-varying transmission times
IEEE Transactions on Automatic Control, 2004
In model-based networked control systems (MB-NCSs), an explicit model of the plant is used to produce an estimate of the plant state behavior between transmission times. In this paper, the stability of MB-NCSs is studied when the controller/actuator is updated with the sensor information at nonconstant time intervals. Networked control systems with transmission times that are varying either within a time interval or are driven by a stochastic process with identically independently distributed and Markov-chain driven transmission times are studied. Sufficient conditions for Lyapunov stability are derived. For stochastically modeled transmission times almost sure stability and mean-square sufficient conditions for stability are introduced.
Model-based control of continuous-time systems with limited intermittent feedback
21st Mediterranean Conference on Control and Automation, 2013
This paper presents a practical alternative for the implementation of Model-Based Networked Control Systems (MB-NCS) with intermittent feedback. Our approach does not require continuous communication over a limited bandwidth channel during the closed-loop time intervals; instead, we propose a communication format that implements a fast rate for updating the state of the model. During the closed-loop interval the sensor transmits measurements at a fast rate but without assuming continuous communication. We consider uncertain continuous-time systems and study the state feedback and output feedback cases. For both cases, we provide necessary and sufficient conditions for stability as a function of the update periods.
On the model-based control of networked systems
Automatica, 2003
In this paper the control of linear plants, where the sensor is connected to a linear controller/actuator via a network is addressed. Both, state and output feedback, are considered and results are derived for both continuous and discrete plants. A key idea is that knowledge of the plant dynamics is used to reduce the usage of the network. Necessary and sufficient conditions for stability are derived as simple eigenvalue tests of a well-structured test matrix, constructed in terms of the update time h, and the parameters of the plant and of its model. These tests are extended to include network delay as well.