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Unbalance identification Algorithm for Countershaft System of 2-DOF Precision Centrifuge

IFAC-PapersOnLine 2015年第28期48卷 273-278页

作者： Huo, Xin Han, Minghao Zheng, Shuangpeng He, Fenghua Chen, Weishan Control and Simulation Center School of Astronautics Harbin Institute of Technology Harbin150080 China School of Mechatronics Engineering Harbin Institute of Technology Harbin150080 China

Unbalance existing in the mechanical systems is one of the most common causes which lead to unexpected vibration, nonsmooth motions, uncertain dynamics and even instability. In this paper, the problem of unbalance identification is investigated for the countershaft system of a 2-DOF arm-typed precision centrifuge. In order to identify the phase and amplitude of the unbalance, a specific procedure is developed and a novel identification algorithm is proposed which utilizes two axis-layout displacement transducers installed associated to the mainshaft system to measure its tilt angle. The effectiveness of the proposed algorithm is illustrated by some numerical simulation experiments in ADAMS environment. © 2015

关键词： Centrifuges Transducers Vibrations (mechanical) ADAMS Countershaft system Displacement transducer identification algorithms Mechanical systems Numerical simulation experiment Precision centrifuge Uncertain dynamics

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Experiment design for improved frequency domain subspace system identification of continuous-time systems

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IFAC-PapersOnLine 2015年第28期48卷 886-891页

作者： Vakilzadeh, Majid Khorsand Yaghoubi, Vahid McKelvey, Tomas Abrahamsson, Thomas Ljung, Lennart Department of applied mechanics Chalmers University of Technology SE-41296 Gvteborg Sweden Department of signals and systems Chalmers University of Technology SE-41296 Gvteborg Sweden Department of Electrical Engineering Linkvping University S-58183 Linkvping Sweden

A widely used approach for identification of linear, time-invariant, MIMO (multi-input/multi output) systems from continuous-time frequency response data is to solve it in discrete-time domain using subspace based identification algorithm incorporated with a bilinear transformation. However, the bilinear transformation maps the distribution of the frequency lines from continuous-time domain to discrete-time domain in a non-linear fashion which may make identification algorithm to be ill-conditioned. In this paper we propose a solution to get around this problem by designing a dedicated frequency sampling strategy. Promising results are obtained when the algorithm is applied to synthetic data from a 6DOF mass-spring model. © 2015

关键词： Continuous time systems Frequency response identification (control systems) Linear transformations Mathematical transformations Metadata Nonlinear control systems Religious buildings Bias reduction Bilinear transformation Frequency sampling identification algorithms Multi input/multi outputs Sub space methods Subspace system identification Subspace based identification

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ADAPTIVE KALMAN FILTER FOR CONTROL OF SYSTEMS WITH UNKNOWN DISTURBANCES

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IEE PROCEEDINGS-D CONTROL THEORY AND APPLICATIONS 1981年第6期128卷 263-267页

作者： GRIMBLE, MJ Department of Electrical Engineering University of Strathclyde Glasgow UK

A canonical industrial filtering situation is considered whereby state estimates are required for feedback control purposes and parameter estimates are required because of an unknown and varying output disturbance. It is shown that the order of the extended Kalman filter may be reduced considerably by careful modelling. The disturbance is modelled using a modification to a technique proposed by Panuska. This modification allows parameters which can be assumed known tobe removed from the state equations. This latter method may also be applied to simplifying the identification algorithms used in self-tuning systems.

关键词： output disturbance Simulation, modelling and identification extended Kalman filter state estimation parameter estimates identification algorithms state estimates feedback Information theory Kalman filters self-tuning systems canonical industrial filtering parameter estimation Control system analysis and synthesis methods modelling feedback control filtering and prediction theory

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Real time identification of discrete event systems using Petri nets

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AUTOMATICA 2008年第5期44卷 1209-1219页

作者： Dotoli, Mariagrazia Fanti, Maria Pia Mangini, Agostino Marcello Dipartimento Elettrotecn & Elettron Politecn Bari I-70125 Bari Italy

The paper defines the identification problem for Discrete Event Systems (DES) as the problem of inferring a Petri Net (PN) model using the observation of the events and the available output vectors, that correspond to the markings of the measurable places. Two cases are studied considering different levels of the system knowledge. In the first case the place and transition sets are assumed known. Hence, an integer linear programming problem is defined in order to determine a PN modelling the DES. In the second case the transition and place sets are assumed unknown and only an upper bound of the number of places is given. Hence, the identification problem is solved by an identification algorithm that observes in real time the occurred events and the corresponding output vectors. The integer linear programming problem is defined at each observation so that the PN can be recursively identified. Some results and examples characterize the identified PN systems and show the flexibility and simplicity of the proposed technique. Moreover, an application to the synthesis of supervisory control of PN systems via monitor places is proposed. (c) 2008 Elsevier Ltd. All rights reserved.

关键词： discrete event systems Petri nets identification algorithms integer programming

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Valve friction and nonlinear process model closed-loop identification

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JOURNAL OF PROCESS CONTROL 2011年第4期21卷 667-677页

作者： Romano, Rodrigo Alvite Garcia, Claudio Univ Sao Paulo Polytech Sch Dept Telecommun & Control Engn BR-05508900 Sao Paulo Brazil

Among several process variability sources, valve friction and inadequate controller tuning are supposed to be two of the most prevalent. Friction quantification methods can be applied to the development of model-based compensators or to diagnose valves that need repair, whereas accurate process models can be used in controller retuning. This paper extends existing methods that jointly estimate the friction and process parameters, so that a nonlinear structure is adopted to represent the process model. The developed estimation algorithm is tested with three different data sources: a simulated first order plus dead time process, a hybrid setup (composed of a real valve and a simulated pH neutralization process) and from three industrial datasets corresponding to real control loops. The results demonstrate that the friction is accurately quantified, as well as "good" process models are estimated in several situations. Furthermore, when a nonlinear process model is considered, the proposed extension presents significant advantages: (i) greater accuracy for friction quantification and (ii) reasonable estimates of the nonlinear steady-state characteristics of the process. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： Control valves Nonlinear models identification algorithms Stiction

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Two nonlinear optimization methods for black box identification compared

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AUTOMATICA 2010年第10期46卷 1675-1681页

作者： Van Mulders, Anne Schoukens, Johan Volckaert, Marnix Diehl, Moritz Vrije Univ Brussel Dept ELEC B-1050 Brussels Belgium Katholieke Univ Leuven Dept MECH B-3001 Louvain Belgium Katholieke Univ Leuven Dept ESAT B-3001 Louvain Belgium

In this paper, two nonlinear optimization methods for the identification of nonlinear systems are compared. Both methods estimate the parameters of e.g. a polynomial nonlinear state-space model by means of a nonlinear least-squares optimization of the same cost function. While the first method does not estimate the states explicitly, the second method estimates both states and parameters adding an extra constraint equation. Both methods are introduced and their similarities and differences are discussed utilizing simulation data. The unconstrained method appears to be faster and more memory efficient, but the constrained method has a significant advantage as well: it is robust for unstable systems of which bounded input-output data can be measured (e.g. a system captured in a stabilizing feedback loop). Both methods have successfully been applied on real-life measurement data. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： identification algorithms Parameter estimation Nonlinear systems Nonlinear models State-space models Constraints

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identification of influential spreaders based on classified neighbors in real-world complex networks

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APPLIED MATHEMATICS AND COMPUTATION 2018年 320卷 512-523页

作者： Li, Chao Wang, Li Sun, Shiwen Xia, Chengyi Tianjin Univ Technol Tianjin Key Lab Intelligence Comp & Novel Softwar Tianjin 300384 Peoples R China Tianjin Univ Technol Minist Educ Key Lab Comp Vis & Syst Tianjin 300384 Peoples R China

Identifying the influential spreaders in complex network is a very important topic, which is conducive to deeply understanding the role of nodes in the information diffusion and epidemic spreading among a population. To this end, in this paper, we propose a novel classified neighbors algorithm to quantify the nodal spreading capability and further to differentiate the influence of various nodes. Here, we believe that the contribution of different neighbors to their focal node is different, and then classify the neighbors of the focal node according to the removal order of the neighbor in the process of k-shell decomposition. By assigning different weights for each class of neighbors and summing up the neighbors' contributions, the spreading capacity of the focal node can be accurately characterized. Through extensive simulation experiments over 9 real-world networks, the weight distribution of different types of neighbors has been optimized, and the results strongly indicate that the current algorithm has the higher ranking accuracy and differentiation extent when compared to other algorithms, such as degree centrality, k-shell decomposition method and mixed degree decomposition approach. Current results can help to greatly reduce the cost of sales promotion, considerably suppress the rumor dissemination and effectively control the outbreak of epidemics within many real-world systems. (C) 2017 Elsevier Inc. All rights reserved.

关键词： Influential spreaders identification algorithms Classified neighbors Complex networks

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Recursive subspace identification of linear and non-linear Wiener state-space models

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AUTOMATICA 2000年第11期36卷 1639-1650页

作者： Lovera, M Gustafsson, T Verhaegen, M Politecn Milan Dipartimento Elettron & Informaz I-20133 Milan Italy Chalmers Univ Technol Dept Signals & Syst S-41296 Gothenburg Sweden Univ Twente Fac Appl Phys Syst & Control Engn Div NL-7500 AE Enschede Netherlands

The problem of MIMO recursive identification is analyzed within the framework of subspace model identification (SMI) and the use of recent signal processing algorithms for the recursive update of the singular value decomposition (SVD) is proposed. To accommodate for arbitrary correlation of the disturbances, an instrumental variable (IV) approach is followed. In particular, recursive formulations for the subspace identification algorithms of the multivariable output-error state space (MOESP) class are given. A recursive algorithm for the identification of non-linear models of the Wiener type is also obtained. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： identification algorithms subspace methods recursive estimation state-space models

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Adaptive input shaping for single-link flexible manipulators using an algebraic identification

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CONTROL ENGINEERING PRACTICE 2012年第2期20卷 138-147页

作者： Pereira, Emiliano Trapero, Juan R. Diaz, Ivan M. Feliu, Vicente Univ Alcala de Henares Escuela Politecn Super Madrid 28805 Spain Univ Castilla La Mancha Fac Ciencias Quim E-13071 Ciudad Real Spain Univ Castilla La Mancha Escuela Tecn Super Ingn Ind E-13071 Ciudad Real Spain

This work proposes an adaptive control scheme applied to single link-flexible manipulators, which combines a feedback controller of the joint angle with an adaptive input shaper updated by an algebraic non-asymptotic identification. The feedback controller is designed to guarantee trajectory tracking of the joint angle, simplifying thus the input shaper, which can be designed for the arm dynamics only. The input shaper is updated by an algebraic identification of the natural frequency corresponding to the first vibration mode of the arm. In addition, the influence of the assumptions adopted to derive the algebraic identification on the performance of the estimation is studied. Finally, the proposed adaptive control strategy is implemented in practice. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： identification algorithms Adaptive control Open-loop control systems Flexible arms Trajectories and Monte Carlo simulation

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Recursive prediction error identification and scaling of non-linear state space models using a restricted black box parameterization

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AUTOMATICA 2006年第1期42卷 159-168页

作者： Wigren, T Uppsala Univ Dept Informat Technol Div Syst & Control SE-75107 Uppsala Sweden

A recursive prediction error algorithm for identification of systems described by non-linear ordinary differential equation (ODE) models is presented. The model is an ODE model, parameterized with coefficients of a multi-variable polynomial that describes one component of the right-hand side function of the ODE. This avoids over-parameterization problems. The selected model can also handle systems with more complicated right-hand side structure, by identification of a local input-output equivalent system in the coordinate system of the selected state variables. A novel technique based on scaling of the sampling period is proposed. The technique can improve the conditioning of the identification problem, thereby enhancing the chances of convergence to the correct minimum of the criterion. The algorithm is applied to live data from a system consisting of two cascaded tanks, with promising results. A MATLAB software package, which implements the proposed algorithm and a set of support scripts, can be freely downloaded from http://***/research/reports/. (c) 2005 Elsevier Ltd. All rights reserved.

关键词： identification algorithms non-linear systems prediction error methods recursive sampling state-space models

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