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Improving the accuracy of analog encoders via Kalman filtering

CONTROL ENGINEERING PRACTICE 2006年第4期14卷 337-350页

作者： Zimmerman, Y Oshman, Y Brandes, A Technion Israel Inst Technol Dept Aerosp Engn IL-32000 Haifa Israel Technion Israel Inst Technol Dept Mech Engn IL-32000 Haifa Israel Univ Roma La Sapienza Dept Comp Sci & Syst I-00184 Rome Italy

A new decoding method is presented for analog encoders enabling major improvements in both accuracy and resolution. A simulation study and experiments with real, industrial-grade, equipment demonstrate the performance improvement of the proposed method, revealing that the new method can generate position estimates with accuracy about three times better than that of standard methods. Moreover, in some special cases, the resulting position accuracy can reach sub-nanometer levels, thus enabling further size reduction in the semiconductor industry. The proposed algorithm also yields velocity estimates better by about two orders of magnitude than those obtained with standard methods. (c) 2005 Elsevier Ltd. All rights reserved.

关键词： encoders Kalman filters estimation algorithms monlinear filters accuracy measurement noise

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A Kalman-filtering derivation of simultaneous input and state estimation

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AUTOMATICA 2019年 108卷 108478-000页

作者： Bitmead, Robert R. Hovd, Morten Abooshahab, Mohammad Ali Univ Calif San Diego Dept Mech & Aerosp Engn 9500 Gilman DrMS-0411 La Jolla CA 92093 USA Norwegian Univ Sci & Technol Dept Engn Cybernet N-7491 Trondheim Norway

Simultaneous input and state estimation algorithms are studied as particular limits of Kalman filtering problems. This admits interpretation of the algorithm properties and critical analysis of their claims to being partly model-free and to providing unbiased estimates. A disturbance model, white noise of unbounded variance, is provided and the bias feature is shown to be a geometric projection property rather than probabilistic in nature. As a consequence of this analysis, the algorithm is connected, in the stationary case, to Algebraic Riccati equation computations for the gains, estimate covariances and filter frequency response. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： State estimation Input estimation Kalman filters estimation algorithms

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Elimination of drift-like errors in intelligent cyclic A/D converters

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MEASUREMENT 2012年第2期45卷 170-174页

作者： Jedrzejewski, Konrad Warsaw Univ Technol Fac Elect & Informat Technol Inst Elect Syst PL-00665 Warsaw Poland

The paper presents a new method of elimination of influence of drift-like errors in so called intelligent cyclic AID converters, in particular, errors caused by drifts (droops) of voltage at the output of sample-and-hold blocks. The method is based on application of the extended multi-dimensional algorithm, which estimates simultaneously values of the input sample and drift rate. Implementation of the extended algorithm in the intelligent cyclic AID converters requires only insignificant changes in the digital part of the converter and does not increase their production costs. The motivations to these investigations resulted from practical realizations of the intelligent cyclic A/D converter in CMOS technology and difficulties in design of a precise sample-and-hold circuit. The results of selected simulation experiments related to analysis of influence of a droop rate on the final performance of the intelligent cyclic A/D converters employing the standard (one-dimensional) and extended algorithms are discussed and compared in the paper. The results of experiments show that application of the proposed solution enables efficient functioning of the converters even in the presence of relatively large drifts. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Cyclic A/D converters Drift cancellation estimation algorithms

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Development of a Complex Parent-Metabolite Joint Population Pharmacokinetic Model

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AAPS JOURNAL 2011年第3期13卷 390-404页

作者： Bertrand, Julie Laffont, Celine M. Mentre, France Chenel, Marylore Comets, Emmanuelle Univ Paris Diderot INSERM UMR 738 F-75018 Paris France ENVT Physiol & Toxicol Expt INRA UMR181 Toulouse France Inst Rech Int Servier F-92415 Courbevoie France

This study aimed to develop a joint population pharmacokinetic model for an antipsychotic agent in development (S33138) and its active metabolite (S35424) produced by reversible metabolism. Because such a model leads to identifiability problems and numerical difficulties, the model building was performed using the FOCE-I and the Stochastic Approximation Expectation Maximization (SAEM) estimation algorithms in NONMEM and MONOLIX, respectively. Four different structural models were compared based on Bayesian information criteria. Models were first written as ordinary differential equations systems and then in closed form (CF) to facilitate further analyses. The impact of polymorphisms on genes coding for the CYP2C19 and CYP2D6 enzymes, respectively involved in the parent drug and the metabolite elimination were investigated using permutation Wald test. The parent drug and metabolite plasma concentrations of 101 patients were analyzed on two occasions after 4 and 8 weeks of treatment at 1, 3, 6, and 24 h following daily oral administration. All configurations led to a two compartment model with back-transformation of the metabolite into the parent drug and a first-pass effect. The elimination clearance of the metabolite through other processes than back-transformation was decreased by 35% [9-53%] in CYP2D6 poor metabolizer. Permutation tests were performed to ensure the robustness of the analysis, using SAEM and CF. In conclusion, we developed a complex joint pharmacokinetic model adequately predicting the impact of CYP2D6 polymorphisms on the parent drug and its metabolite concentrations through the back-transformation mechanism.

关键词： back-transformation mechanism estimation algorithms first-pass metabolism genetic covariate nonlinear mixed effects modeling

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Semi-parametric models of long- and short-term survival: an application to the analysis of breast cancer survival in Utah by age and stage

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STATISTICS IN MEDICINE 2002年第6期21卷 895-920页

作者： Tsodikov, A Univ Utah Huntsman Canc Inst Div Biostat Salt Lake City UT 84112 USA

A flexible class of semi-parametric survival models is proposed that takes account of long- and short-term covariate effects in cancer survival. The diversity of responses described by the models include non-proportional and crossing survival curves as well as a fraction of long-term survivors. Restricted non-parametric maximum likelihood estimation procedures (RNPMLE) are developed to provide point estimates, confidence intervals and tests for the models. Numerical algorithms to fit semi-parametric survival models are emphasized. The methods are applied to analyse post-treatment survival of breast cancer patients diagnosed in Utah by age and stage. Copyright (C) 2002 John Wiley Sons, Ltd.

关键词： semi-parametric models estimation algorithms age and survival breast cancer

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Stochastic volatility systems

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International Journal of Modelling & Simulation 1997年第2期17卷 137-137页

作者： Capobianco, E. Department of Statistics University of Padua 35122 Padova Via VIII Febbraio 2 Italy Stanford University PDP Research Group Stanford CA United States University of Padua Italy

Stochastic volatility models are a well-known framework for the analysis of financial time series data, together with the other important class of ARCH-type models. The main difference between them, at least from a statistical point of view, relies on the possibility of obtaining exact inference, in particular with regard to the estimation issue. Whereas for ARCH-type models the standard results apply, in the sense that maximum likelihood estimates for the parameters of interest can be computed, for stochastic volatility models there are more complications and usually only approximate results can be obtained, unless two particular estimation strategies are employed: exact non-Gaussian filtering methods or simulation techniques. This paper stresses the importance of "only" approximate and therefore suboptimal estimation methods for special models whose complexity makes it difficult to find exact solutions. The setup where the analysis is conducted is the state-space formulation and this suggests enclosing the cases here considered in a class of so-called stochastic volatility systems.

关键词： Stochastic volatility systems linear nonlinear and nongaussian state space formulations bilinear stochastic processes estimation algorithms

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estimation of Grid Frequency in Disturbed Converter-Based Power Systems by PLL State Variable Feedback

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IFAC-PapersOnLine 2020年第2期53卷 13371-13377页

作者： Nico Goldschmidt Horst Schulte University of Applied Sciences (HTW) Berlin Department of Engineering I Control Engineering Group Wilhelminenhofstr. 75A 12459 Berlin Germany

Fast real-time estimation of the grid frequency is essential for stable operation of renewable converter-based sources in future power systems. Therefore this paper presents a new phase-locked loop for the estimation of time-dependent frequencies in unbalanced power systems with harmonics. The proposed frequency estimation method consists of two signal processing steps: In the first step, a least mean square estimator reconstructs the fundamental sinusoidal signal from the measured three-phase grid voltage and splits it into positive, negative and zero sequence components. In the second step, the resulting first harmonic three-phase positive sequence is converted into the synchronous reference frame in the form of a phase-locked loop using a state feedback controller scheme to reconstruct the current grid frequency. Here the controller output is equivalent to the signal to be reconstructed. The feedback controller design is based on linear matrix inequalities where the requirements are explicitly considered. The capability of proposed state feedback phase-locked loop is demonstrated by full scaled electro magnetic transient simulations.

关键词： estimation algorithms Phase-locked loop Power system control Renewable energy systems Convex optimisation

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Multigrid Design in Point-Mass Approach to Nonlinear State estimation

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IFAC Proceedings Volumes 2003年第16期36卷 1693-1698页

作者： Miroslav Šimandl Jakub Královec Department of Cybernetics and Center for Research of Cybernetic Systems University of West Bohemia Univerzitní 8. 306 14 Pilsen. Czech Republic

Numerical solution of the Bayesian recursive relations in state estimation by the point-mass approach is treated. The stress is laid on the new grid design for multimodal probahility density functions of state. A bank of grids is used for representation of the state space to cover different modes of the density. Splitting and merging techniques are designed for managing the bank of grids.

关键词： stochastic systems state estimation nonlinear filters probability density function estimation algorithms

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Spacecraft Attitude and Body Rate estimation with Four Star Sensor Heads: Concepts and Ground and On-Orbit Verification Results

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IFAC Proceedings Volumes 2010年第15期43卷 490-495页

作者： Katsumasa Miyatake Shoji Yoshikawa Haruhiko Shimoji Hiroyuki Kawano Takeshi Suzuki Yoshinori Kunii Kazumori Hama Noriaki Oka Advanced Technology R&D Center Mitsubishi Electric Corporation Amagasaki Japan (Tel: 6-6497-7155) Kamakura Works Mitsubishi Electric Corporation Kamakura Japan Institute for Unmanned Space Experiment Free Flyer Tokyo Japan

Abstract We have developed a star sensor system with four heads as a prototype of a future small and low-priced satellite attitude controller. To reduce size and cost of the controller, we integrate attitude sensors into star sensors with medium resolution and medium sensitivity and adopt Commercial Off-The-Shelf (COTS) electrical parts for key parts such as CPU and CCD. Newly developed computer architecture is introduced for high reliability with COTS parts under the harsh space environment. In this paper, we will focus on the new star identification algorithm dedicated for the proposed four-head star sensor system and evaluate it with ground test and on-orbit check-out data.

关键词： Artificial satellites attitude estimation algorithms test data adequacy.

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Nonlinear estimation of a Parsimonious Wiener Model for the Neuromuscular Blockade in Closed-loop Anesthesia

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IFAC Proceedings Volumes 2014年第3期47卷 9258-9264页

作者： Olov Rosén Margarida M. Silva Alexander Medvedev Department of Information Technology Uppsala University SE-751 05 Uppsala Sweden Departamento de Matemática Faculdade de Ciências da Universidade do Porto Rua do Campo Alegre 4169-007 Porto Portugal and Center for Research and Development in Mathematics and Applications (CIDMA) Campus Universitário de Santiago 3810-193 Aveiro Portugal

The recursive identification of a parsimonious nonlinear Wiener model for the neuromuscular blockade in closed-loop anesthesia is considered. The performance of two popular nonlinear estimation techniques, namely the extended Kalman filter (EKF) and the particle filter (PF), is evaluated on synthetic and clinical data. The parameter estimates obtained with the PF, that does not rely on model linearization, exhibit less bias and shorter settling time than the ones produced by the EKF. This behavior persists when the parameter tracking capabilities of both estimation algorithms are assessed for the model in hand. Taking advantage of the model parameters that were recursively estimated from clinical data, it is demonstrated that the main source of intra-patient variability lies in the nonlinear pharmacodynamic part of the model. The distance to a bifurcation phenomenon leading to nonlinear oscillations of the Wiener model under PID feedback is also evaluated.

关键词： Biomedical control Dynamical systems estimation algorithms Parameter estimation Nonlinear oscillations

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