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Fault detection design of networked control systems

IET CONTROL THEORY AND APPLICATIONS 2011年第12期5卷 1439-1449页

作者： Li, W. Zhu, Z. Ding, S. X. China Univ Min & Technol Sch Mech Engn Xuzhou 221116 Peoples R China Univ Duisburg Essen Inst Automat Control & Complex Syst D-47057 Duisburg Germany

In this study, the fault detection design of networked control systems (NCSs) considering time varying transmission delays, packet dropouts and quantisation errors is proposed. The design of the residual generator is formulated in the H-infinity framework, where the transmission delays are described as polytopic uncertainties, quantisation errors are modelled as norm bounded uncertainties and packet dropouts are described as a binary Bernoulli process. The dynamics of residual generator is shown to be governed by a Markov jumping linear system with uncertainties, and then the residual generator is designed to be sensitive to system faults and robust against network-induced effects by applying a reference model strategy. A new residual evaluation scheme for NCSs is also proposed, where the absolute value of each residual signal is selected as the evaluation function and the threshold is computed by considering the mean value and variance of residual signals. In this way, the upper bound of the false alarm rate is ensured.

关键词： H∞ control time varying transmission delays fault diagnosis Markov processes evaluation function residual generator packet dropouts Optimal control H∞ framework fault detection design reference model strategy residual evaluation scheme norm bounded uncertainties quantisation errors polytopic uncertainties networked control systems binary Bernoulli process Markov jumping linear system

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Verifying digital filter error analysis using DFT techniques

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CONTROL ENGINEERING PRACTICE 2000年第1期8卷 39-47页

作者： Oliver, MA Forsythe, W Loughborough Univ Technol Dept Elect & Elect Engn Loughborough LE11 3TU Leics England

There are several different error forms generated simultaneously by digital filters. Owing to their inherent coexistence, verification against the theoretical values has always been difficult. A spectral technique is presented for separating the deterministic and the stochastic error components in the output signal of a digital filter, thus allowing evaluation of the individual constituents. (C) 2000 Elsevier Science Lid, rill rights reserved.

关键词： digital filters error analysis discrete Fourier transform quantisation errors analogue filter

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Robustly stabilising model predictive control design for networked control systems with an application to direct current motors

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IET CONTROL THEORY AND APPLICATIONS 2012年第7期6卷 943-952页

作者： Caruntu, C. -F. Lazar, C. Gheorghe Asachi Tech Univ Iasi Dept Automat Control & Appl Informat Iasi 700050 Romania

In networked control systems there are many network-induced imperfections and constraints: quantisation errors, packet dropouts, variable sampling periods, time-varying delays and communication constraints. The goal of this study is to provide a control design methodology that can assure the closed-loop performances of a network-controlled application, while compensating the time-varying delays introduced by the communication network. To this end, firstly, the error caused by the time-varying delays is modelled as a disturbance and a novel method of bounding the disturbances is proposed. Secondly, an one-step ahead predictive controller based on flexible control Lyapunov functions is designed, which explicitly takes into account the bounds of the disturbances caused by time-varying delays and guarantees also the input-to-state stability of the system. The methodology is then applied for a network-controlled direct current (DC) motor and the TrueTime simulations illustrate the effectiveness and robustness of the proposed delay modelling and control strategy.

关键词： DC direct current motors Control of electric power systems disturbance bounding predictive control time-varying systems Time-varying control systems Stability in control theory control system synthesis communication constraints packet dropouts Control system analysis and synthesis methods d.c. machines flexible control Lyapunov functions compensation closed loop systems networked control systems robust control Lyapunov methods delays robustly stabilising model predictive control design machine control input-to-state stability Optimal control time-varying delay compensation variable sampling periods closed-loop performances network-controlled direct current motor application Distributed parameter control systems DC motors quantisation errors TrueTime simulations

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Congestion control with AQM and dynamic quantisers

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IET CONTROL THEORY AND APPLICATIONS 2020年第20期14卷 3601-3609页

作者： Sadek, Belamfedel Alaoui El Houssaine, Tissir Noreddine, Chaibi Univ Sidi Mohamed Ben Abdellah LISAC Fac Sci Dhar El Mahraz BP 1796 Fes Morocco

This study is concerned with the design of active queue management (AQM) subjected to quantisation errors. First, the authors will show here that quantisation errors exist when AQM experiences transmission control protocol (TCP) during the congestion. Second, a TCP/AQM model that takes into account quantisation errors is proposed - the considered quantisers are dynamic and have a scale parameter. Based on this model, stabilisation will be analysed in which the controller and the scaling parameters are obtained using the Lyapunov-Krassovskii functional method. Finally, Matlab simulation results are displayed to show the effectiveness of the proposed method.

关键词： telecommunication congestion control control system synthesis Lyapunov methods transport protocols queueing theory stability telecommunication network management stochastic systems adaptive control uncertain systems telecommunication control congestion control dynamic quantisers active queue manager AQM quantisation errors scaling parameters transmission control protocol TCP

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Robust H_∞ output feedback control with partly quantised information

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IET CONTROL THEORY AND APPLICATIONS 2013年第4期7卷 523-536页

作者： Ge, Yang Wang, Jingcheng Li, Chuang Zhang, Langwen Shanghai Jiao Tong Univ Dept Automat Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ Minist Educ China Key Lab Syst Control & Informat Proc Shanghai 200240 Peoples R China

This study is concerned with the stability and stabilisability problems of networked control systems (NCSs) with partly quantised information. More precisely, the remote state variables transported from other sub-systems experience different network-induced time delays and quantisation errors, whereas the local state variables do not. This consideration is much more natural in NCSs because of the distributive nature of sensors and controllers, even systems. Network-induced time delays are introduced as a Markov chain and quantisation errors are represented as convex polytopic uncertainties. Based on the Lyapunov-Krasovskii functional approach, sufficient conditions for the existence of a quantised robust H-infinity output feedback controller for NCSs are presented. Such conditions are obtained in terms of bilinear matrix inequalities (BMIs). Furthermore, a cone complementarity algorithm is utilised to convert these BMIs into a convex optimisation problem. Finally, a simulation example is provided to demonstrate the efficiency of proposed theorems.

关键词： H∞ control Optimisation techniques convex programming convex optimisation partly quantised information network-induced time delays Stability in control theory robust Hâˆž output feedback control Markov chain robust H∞ output feedback control stability problems convex polytopic uncertainties BMI networked control systems robust control feedback NCS Algebra Lyapunov methods delays Lyapunovâ€“Krasovskii functional approach Optimal control linear matrix inequalities stabilisability problems Markov processes Lyapunov–Krasovskii functional approach Distributed parameter control systems quantisation errors Hâˆž control bilinear matrix inequalities

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Analysis by synthesis spatial audio coding

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IET SIGNAL PROCESSING 2014年第1期8卷 30-38页

作者： Elfitri, Ikhwana Shi, Xiyu Kondoz, Ahmet Univ Surrey Lab Multimedia Commun Res Guildford GU2 7XH Surrey England Andalas Univ Fac Engn Dept Elect Engn Padang Indonesia Mulsys Ltd Guildford Surrey England

This study presents a novel spatial audio coding (SAC) technique, called analysis by synthesis SAC (AbS-SAC), with a capability of minimising signal distortion introduced during the encoding processes. The reverse one-to-two (R-OTT), a module applied in the MPEG Surround to down-mix two channels as a single channel, is first configured as a closed-loop system. This closed-loop module offers a capability to reduce the quantisation errors of the spatial parameters, leading to an improved quality of the synthesised audio signals. Moreover, a sub-optimal AbS optimisation, based on the closed-loop R-OTT module, is proposed. This algorithm addresses a problem of practicality in implementing an optimal AbS optimisation while it is still capable of improving further the quality of the reconstructed audio signals. In terms of algorithm complexity, the proposed sub-optimal algorithm provides scalability. The results of objective and subjective tests are presented. It is shown that significant improvement of the objective performance, when compared to the conventional open-loop approach, is achieved. On the other hand, subjective test show that the proposed technique achieves higher subjective difference grade scores than the tested advanced audio coding multichannel.

关键词： synthesis spatial audio coding analysis minimisation encoding processes Optimisation techniques closed-loop system quantisation errors algorithm complexity signal reconstruction AbS optimisation SAC technique reverse one-to-two speech coding open-loop approach Speech and audio coding signal distortion audio signal reconstruction audio coding synthesised audio signals closed-loop module Speech processing techniques MPEG surround Audio equipment and systems spatial parameters closed-loop R-OTT module

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STABILITY ANALYSIS OF DIGITAL-FILTERS UNDER FINITE WORD-LENGTH EFFECTS

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IEE PROCEEDINGS-G CIRCUITS DEVICES AND SYSTEMS 1989年第4期136卷 167-172页

作者： CHEN, BS KUO, CT TATUNG INST TECHNOL DEPT ELECT ENGNTAIPEITAIWAN

An approach is introduced for analysing the effects of finite word length and testing the stability in digital filters. Based on the analysis of both the quantisation errors of filter coefficients and the computational roundoff errors of multiplications and additions, a sufficient stability condition is introduced to give an insight into the hardware/cost tradeoff for word-length design choices under the effects of finite word length. The Bellman-Gronwall lemma in discrete form is employed to tackle this problem. In addition, some numerical examples are presented to illustrate the results.

关键词： computational roundoff errors digital filters quantisation errors stability condition Bellman-Gronwall lemma state-space methods stability criteria filter coefficients Digital filters additions discrete form error analysis hardware/cost tradeoff finite word-length effects multiplications roundoff errors state-space structures

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Proficient operation of grid interfaced solar PV system for power quality improvement during adverse grid conditions

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IET GENERATION TRANSMISSION & DISTRIBUTION 2020年第25期14卷 6330-6337页

作者： Shukl, Pavitra Singh, Bhim Indian Inst Technol Delhi Dept Elect Engn New Delhi 110016 India

The penetration of solar energy into the distribution network is affected by the seasonal and day-to-day variability of the solar power generation. In underdeveloped and developing countries, the power quality (PQ) deterioration issues are primarily observed due to the presence of the weak utility grid. Therefore, smart grid operability is achieved through power exchange along with the improvement in PQ indices by the application of the biquad filter, thereby exhibiting multifunctional control capability. The biquad filter is less affected by quantization errors and involves no additional usage of sensors or control loops, which are the significant advantages observed in its implementation. The biquad filter utilization in this work, includes the estimation of fundamental load current along with mitigation of harmonics, improving PQ, reactive power compensation, and satisfactory performance during voltage unbalance, sag, distortion, swell, and unbalanced loading conditions, which are observed during weak grid conditions. The stochastic inputs of the solar PV array interfaced utility grid system are agitated due to the erratic availability of solar power, and are overcome through an adaptive perturb and observe technique, which uses a variable perturbation step size. Test cases considered here, validate the performance in accordance to the IEEE-519 standard.

关键词： smart power grids power generation control photovoltaic power systems power supply quality reactive power solar power biquadratic filters power harmonic filters solar cell arrays proficient operation grid interfaced solar PV system power quality improvement adverse grid conditions solar energy distribution network seasonal day-to-day variability solar power generation power quality deterioration weak utility grid smart grid operability power exchange PQ indices multifunctional control capability quantisation errors control loops biquad filter utilisation reactive power compensation unbalanced loading conditions weak grid conditions solar photovoltaic array variable perturbation step size grid voltage load currents fundamental load current harmonics mitigation adaptive perturb and observe technique IEEE-519 standard

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Enhanced split-architecture Δ-Σ ADC

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ELECTRONICS LETTERS 2006年第13期42卷 737-739页

作者： Lee, K. Temes, G. C. Oregon State Univ Kelley Engn Ctr Dept Elect Engn & Comp Sci Corvallis OR 97331 USA

A split Delta-Sigma ADC topology is proposed which provides enhanced noise shaping by cross-coupling the quantisation errors of the two halves of the structure. Unlike the multi-stage noise shaping architecture, the new structure is insensitive to mismatch errors and it does not reduce the stability of the loops. Simulations confirm the effectiveness of the proposed scheme.

关键词： enhanced split architecture mismatch errors analog-to-digital converter multistage noise shaping architecture quantisation (signal) ΣΔ ADC quantisation errors sigma-delta modulation A/D and D/A convertors

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EFFECTS OF FIELD-DEPENDENT MOBILITY ON TRANSFER EFFICIENCY IN MOS BBD ANALOG DELAY-LINES

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PROCEEDINGS OF THE INSTITUTION OF ELECTRICAL ENGINEERS-LONDON 1977年第2期124卷 109-113页

作者： HASLETT, JW KEJARIWAL, ML UNIV CALGARY FAC ENGN DEPT ELECT ENGN CALGARY T2N 1N4 ALBERTA CANADA

The effects of field-dependent mobility on transfer inefficiency due to intrinsic transfer limitations, dynamic-dram conductance and threshold-voltage modulation are calculated for an m.o.s. bucket-brigade delay line. The results show significant differences over previous theories at higher clock frequencies, where line performance is critical if quantisation errors are to be minimised in analogue applications.

关键词： Analogue circuits field dependent mobility effects monolithic integrated circuits Other analogue circuits transfer efficiency quantisation errors intrinsic transfer limitations bucket brigade delay line metal-insulator-semiconductor devices BBD metal oxide semiconductor analogue delay lines MOS threshold voltage modulation analogue computer circuits delay lines dynamic drain conductance

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