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Output-feedback networked control system and its stability

Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (engineering Science) 2008年第3期42卷 378-381页

作者： Liu, Song-Hui Wu, Jun Xu, Wei-Hua Chen, Sheng State Key Laboratory of Industrial Control Technology Institute of Advanced Process Control Zhejiang University Hangzhou 310027 China Department of Chemical Engineering Hangzhou Vocational Technology College Hangzhou 310018 China School of Electronics and Computer Science University of Southampton Southampton SO17 1BJ United Kingdom

A kind of output-feedback networked control system was addressed to overcome the defect of feedback lag introduced by the network usage in the networked control system. By introducing a plant model and a buffer into this system, when feedback was available, this system could compute the control output and update the plant model with the plant output, otherwise, compute the control output based on the plant model output instead of plant output. On the condition that the plant was SISO and the error between plant and model existed, the necessary and sufficient condition for closed-loop stability of this system was derived. Simulation indicates that the range of model error within which this system is stable is easy to be derived by using this necessary and sufficient condition.

关键词： Closed loop control systems

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In memoriam: Edmond S. Stan Gillespie

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IEEE ANTENNAS AND PROPAGATION MAGAZINE 2007年第4期49卷 120-121页

作者： Hess, Doren Francis, Mike Rengarajan, Sembiam Key Laboratory of Industrial Internet of Things & Networked Control Ministry of Education Chongqing University of Posts and Telecommunications Chongqing China Department of Computer Science and Engineering Konkuk University Seoul Korea

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Optimal controller Realisations with the Smallest Dynamic Range

Optimal Controller Realisations with the Smallest Dynamic Ra...

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IEEE Conference on Decision and control

作者： Jun Wu Sheng Chen Gang Li Jian Chu National Key Laboratory of Industrial Control Technology Institute of Advanced Process Control University of Zhejiang Hangzhou China School of Electronics and Computer Science University of Southampton UK School of Electrical and Electronic Engineering Nanyang Technological University Singapore

ISBN: (纸本)1424401704;9781424401703

An approach is proposed to design optimal finite word length (FWL) realisations of digital controllers implemented in fixed-point arithmetic. A minimax-based search procedure is first used to obtain an optimal controller realisation that optimises an FWL closed-loop stability measure. Since this FWL closed-loop stability measure is solely linked to the fractional part or precision of fixed-point format, the resulting realisation may not have the smallest dynamic range. A measure is derived to indicate the dynamic range of a realisation. Based on an orthogonal transformation of this dynamic range measure for the optimal precision controller realisation, a numerical optimisation method is developed to make the controller realisation having the smallest dynamic range without sacrificing FWL closed-loop stability robustness

关键词： Optimal control Dynamic range Robust stability Digital control Robust control USA Councils Fixed-point arithmetic Optimization methods Design optimization Laboratories

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Weighted support vector machine for classification with uneven training class sizes

Weighted support vector machine for classification with unev...

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International Conference on Machine Learning and Cybernetics, ICMLC 2005

作者： Huang, Yi-Min Du, Shu-Xin Zhejiang Gongshang University Computer and Information Engineering Academy National Key Lab of Industrial Control Technology Institute of Intelligent Systems and Decision Making

ISBN: (纸本)078039092X

In the standard support vector machines for classification, training sets with uneven class sizes results in classification biases towards the class with the large training size. That is to say, the larger the training sample size for one class is, the smaller its corresponding classification error rate is, while the smaller the sample size, the larger the classification error rate. The main causes lie in that the penalty of misclassification for each training sample is considered equally. Weighted support vector machines for classification are proposed in this paper where penalty of misclassification for each training sample is different. By setting the equal penalty for the training samples belonging to same class, and setting the ratio of penalties for different classes to the inverse ratio of the training class sizes, the obtained weighted support vector machines compensate for the undesirable effects caused by the uneven training class size, and the classification accuracy for the class with small training size is improved. Experimental simulations on breast cancer diagnosis show the effectiveness of the proposed methods. © 2005 IEEE.

关键词： Learning systems

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Weighted support vector machine for classification with uneven training class sizes

Weighted support vector machine for classification with unev...

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International Conference on Machine Learning and Cybernetics (ICMLC)

作者： Yi-Min Huang Shu-Xin Du Computer and Information Engineering Academy Zhejiang Gongshang University China National Key Laboratory of Industrial Control Technology Institute of Intelligent Systems and Decision Making

关键词： Support vector machines Support vector machine classification industrial training Error analysis Machine learning Object detection Fault diagnosis industrial control Intelligent systems Machine intelligence

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Optimal floating-point realizations of finite-precision digital controllers

Optimal floating-point realizations of finite-precision digi...

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IEEE Conference on Decision and control

作者： Jun Wu Sheng Chen J.F. Whidborne Jian Chu National Key Laboratory of Industrial Control Technology Institute of Advanced Process Control University of Zhejiang Hangzhou China Department of Electronics and Computer Science University of Southampton Southampton UK Department of Mechanical Engineering King''s College London UK

ISBN: (纸本)0780375165

The paper investigates the closed-loop stability issue of finite-precision realizations for digital controllers implemented in floating-point arithmetic. Unlike the existing methods which only address the effect of the mantissa bits in floating-point format to the sensitivity of closed-loop stability, the sensitivity of closed-loop stability is analyzed with respect to both the mantissa and exponent bits of floating-point format. A computationally tractable finite word length (FWL) closed-loop stability measure is defined, and the optimal controller realization problem is posed as searching for a floating-point realization that maximizes the proposed measure. A numerical optimization approach is adopted to solve for the resulting optimization problem. Simulation results show that the proposed design procedure yields computationally efficient controller realizations with enhanced FWL closed-loop stability performance.

关键词： Optimal control Digital control Stability Floating-point arithmetic Length measurement Design methodology Uncertainty Laboratories industrial control Process control

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Global optimal realizations of finite precision digital controllers

Global optimal realizations of finite precision digital cont...

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IEEE Conference on Decision and control

作者： Jun Wu Sheng Chen Gang Li Jian Chu National Key Laboratory of Industrial Control Technology University of Zhejiang Hangzhou China Department of Electronics and Computer Science University of Southampton Southampton UK School of Electrical and Electronic Engineering Nanyang Technological University Singapore

ISBN: (纸本)0780375165

The paper analyzes global solutions to the optimal digital controller realization problem based on maximizing a finite word length (FWL) closed-loop stability measure. For each closed-loop eigenvalue, a single-pole FWL stability function is first introduced, and a single-pole FWL stability measure is then defined as the maximum of the corresponding single-pole stability function over all the controller realizations. It is shown that the minimum of the single-pole stability measures for all the closed-loop eigenvalues is an upper bound of the optimal value for the optimal realization problem. An analytical method to compute a single-pole stability measure is developed, and an expression for all the realizations which achieve a given single-pole measure is derived. When a realization, which is a solution of the minimum single-pole measure, further satisfies the condition that the values of all its single-pole stability functions are not less than the minimum single-pole measure, the minimum single-pole measure is the optimal value of the optimal realization problem and this realization is the solution for the optimal realization problem. A computationally simple algorithm is presented.

关键词： Optimal control Digital control control systems Stability analysis Eigenvalues and eigenfunctions Uncertainty Laboratories industrial control industrial electronics computer science

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The optimal controller realization using the δ operator for sampled data systems with finite word length consideration

The optimal controller realization using the δ operator for...

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1999 European control Conference, ECC 1999

作者： Wu, J. Istepanian, R.H. Chu, J. Whidborne, J.F. Chen, S. Luk, B.L. National Key Laboratory of Industrial Control Technology Institute of Industrial Process Control Zhejiang University Hangzhou310027 China Department of Electrical and Computer Engineering Ryerson Polytechnic University TorontoONM5B 2K3 Canada Department of Mechanical Engineering King's College LondonWC2R 2LS United Kingdom Department of Electrical and Electronic Engineering University of Portsmouth PortsmouthPO1 3DJ United Kingdom

ISBN: (纸本)9783952417355

This paper present a new effective algorithm for the optimal realization of digital controller structures using the delta operator for sampled data systems subject to Finite-Word-Length (FWL) constraints. The problem is formulated as a non-linear programming to provide an easy and efficient optimization tool to solve such complex problem. Simulation results of the optimum realizations of digital controller structures are presented to illustrate the effectiveness of the proposed strategy. © 1999 EUCA.

关键词： Nonlinear programming

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Stability issues of finite precision controller structures using the delta operator for sampled data systems

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IFAC Proceedings Volumes 1999年第2期32卷 8681-8686页

作者： Jun Wu Robert Habib Istepanian Jian Chu James F. Whidborne Sheng Chen Jianbo Hu National Key Laboratory of Industrial Control Technology Institute of Industrial Process Control Zhejiang University Hangzhou 310027 P.R. China Fax: 86-571-7951206 Department of Electrical and Computer Engineering Ryerson Polytechnic University Toronto Ontario M5B 2K3 Canada Department of Mechanical Engineering King's College London London WC2R 2LS UK Department of Electrical and Electronic Engineering University of Portsmouth Portsmouth PO1 3DJ UK

This paper present a new effective algorithm for the optimal realization of sampled-data SISO two order controller structures using the delta operator subject to Finite-Word-Length (FWL) constraints. The problem is formulated as a non-linear programming problem with a maximum of four independent variables to provide an easy and efficient optimization tool to solve such complex problems. Simulation results of the optimum FWL realizations of digital SISO two order controller structure applied to an electrohydraulic actuator system are presented to illustrate the effectiveness of the proposed strategy.

关键词： control applications of computers stability robustness sampled data systems optimization problems linear systems

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Active Stabilization of Rotating Stall in Axial-Flow Gas Compressors

Active Stabilization of Rotating Stall in Axial-Flow Gas Com...

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IEEE Regional Conference on Aerospace control Systems

作者： H.O. Wang R.A. Adomaitist E.H. Abed Key Lab of Industrial Computer Control Engineering of Hebei Province Yanshan University슠 Qinhuangdao China

Active stabilization of stall instabilities in axial flow compressors is pursued using a combination of bifurcation analysis and nonlinear control. A low-order discretization model of a PDE compressor model is found to exhibit a stationary (pitchfork) bifurcation at the onset of stall. Using throttle opening as a control, analysis of the linearized system at stall shows that the critical mode (zero eigenvalue) is unaffected by linear feedback. Hence, nonlinear stabilization techniques are necessary. A quadratic feedback control law is proposed based on the lower-order model and is found to adequately serve the control purposes for both the lower order and higher order discretizations.

关键词： Compressors Bifurcation Fluid flow control system analysis control systems Feedback control Aerodynamics Stability Educational institutions Nonlinear control systems

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