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Prognostics and system Health Management Conference (PHM)

作者： Xiaoyun Gong Mengxuan Hao Chuan Li Wenliao Du Yixiang Huang Henan International Joint Laboratory of Complex Mechanical Equipment Intelligent Monitoring and Control Zhengzhou University of Light Industry Zhengzhou China Research Center for System Health Maintenance Chongqing Technology and Business University Chongqing China The State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai China

ISBN: (数字)9798350360585

ISBN: (纸本)9798350360592

While existing flow-based models have the potential for data enhancement and intelligent fault diagnosis of bearings, these methods are mainly based on the time domain to learn features. In general, time-domain and frequency-domain features are important for recognizing faults. Especially, the spectral features in the frequency domain can reveal highly distinct patterns associated with fault types. Therefore, learning spectral feature helps to obtain comprehensive fault information and achieve high fault diagnosis accuracy. In this work, a spectral flow model framework is developed to learn and generate realistic data from mechanical sensor signals. The performance of fault diagnosis under unbalanced data is improved by learning the information contained in the spectral features, which are utilized to generate insufficient fault data. Experimental results show that the present method can generate a large number of samples with higher similarity and better diversity on the bearing dataset. The generated samples may be used to expand the limited dataset and significantly improve the accuracy of the bearing fault diagnosis task.

关键词： Fault diagnosis Mechanical sensors Vibrations Training Accuracy Frequency-domain analysis Training data

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state Estimation of Finite-state Hidden Markov Models Subject to Stochastically Event-triggered Measurements

State Estimation of Finite-State Hidden Markov Models Subjec...

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IEEE Annual Conference on decision and control

作者： Wentao Chen Junzheng Wang Ling Shi Dawei Shi State Key Laboratory of Intelligent Control and Decision of Complex Systems School of Automation Beijing Institute of Technology Beijing 100081 P.R. China Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong

ISBN: (纸本)9781479978878

We consider the event-triggered state estimation of a finite-state hidden Markov model with a general stochastic event-triggering condition. Utilizing the change of probability measure approach and the event-triggered measurement information available to the estimator, analytical expressions for the conditional probability distributions of the states are obtained, based on which the minimum mean square error event-based state estimates are further calculated. We show that the results also cover the case of packet dropout, under a special parameterization of the event-triggering conditions. With the results on state estimation, a closed-form expression of the average sensor-to-estimator communication rate is also presented. The effectiveness of the proposed results is illustrated by a numerical example and comparative simulations.

关键词： state estimation Hidden Markov models Event trigger Probability distribution Mean square error numerical example

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T-S fuzzy observer for nonlinear magnetic levitation system with uncertain variable friction coefficient

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Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) 2011年第SUPPL. 1期42卷 114-118页

作者： Zhou, Li-Jie Guo, Shu-Li Gao, Zhe School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex system Intelligent Control and Decision Ministry of Education Beijing Institute of Technology Beijing 100081 China

An adaptive fuzzy observer for nonlinear magnetic levitation system with uncertain friction coefficient is proposed. First, a T-S fuzzy model of the nonlinear magnetic levitation system is proposed. An observer is given by LMI method and the Lyapunov method. Through adding an auxiliary variable, it relaxes the constraint of the design of observer. The proposed approach is a more relaxed condition than others. Simulation results show the effectiveness of this approach. The results show that the position of magnetic levitation system is estimated effectively with unknown friction coefficient. There is some reference value for a kind of nonlinear systems with unknown parameter.

关键词： Lyapunov methods

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An algorithm based on ODLLTSA and SVM classier for door plate number recognition

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Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) 2011年第SUPPL. 1期42卷 789-793页

作者： Ma, Li-Ling Ji, Li-Jun Wang, Jun-Zheng School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision of Ministry of Education Beijing Institute of Technology Beijing 100081 China

A new method is proposed, through combining the algorithm of orthogonal discriminant linear local tangent space alignment (ODLLTSA) and the support vector machine (SVM), to improve the accuracy of recognizing door plate numbers. The feature of door plate characters is first extracted by the ODLLTSA and then this extracted feature is used to train the SVM classifier. Finally, the new plate characters are classified by the trained SVM. Using the algorithm, a high recognition rate can be achieved. Experimental results show that this method is effective and robust in the real applications.

关键词： Support vector machines

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Robust controller Design for Networked control systems with Nonlinear Uncertainties

Robust Controller Design for Networked Control Systems with ...

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2009 American control Conference (ACC 2009)

作者： Junyan Yu Long Wang Mei Yu Jie Chen Yingmin Jia Intelligent Control Laboratory Center for Systems and Control College of Engineering and Key Laboratory of Machine Perception (Ministry of Education) Peking University Beijing 100871 P.R.China Department of Automation North China Electric Power University Zhuxinzhuang Dewai Beijing 102206 P.R.China Beijing Institute of Technology Key Laboratory of Complex System Intelligent Control and Decision Ministry of Education Beijing 100081 P.R.China Seventh Research Division Beihang University Beijing 100083 P.R. China

ISBN: (纸本)9781424445233

We address robust stabilization problem for networked control systems with nonlinear uncertainties and packet losses by modelling such systems as a class of uncertain switched systems. Based on theories on switched Lyapunov functions, we derive the robustly stabilizing conditions for state feedback stabilization and design packet-loss dependent controllers by solving some matrix inequalities. A numerical example and some simulations are worked out to demonstrate the effectiveness of the proposed design method.

关键词： Networked control systems robust controller design Packet loss control systems design approach Switched systems controller design state feedback Uncertainty nonlinearity

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Ballistic method based on improved particle swarm optimization algorithm

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Dongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Southeast University (Natural Science Edition) 2013年第SUPPL.I期43卷 215-218页

作者： Cui, Jing Deng, Fang Fang, Hao School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision of Ministry of Education Beijing Institute of Technology Beijing 100081 China

In order to improve real-time performance of the fire control system, a ballistic resolving method based on the improved particle swarm optimization (PSO) algorithm is proposed, which improves the response speed of the system and provides a convenient extension to parallel computing on multicore platforms. First, particles are generated and initialized around the pre-estimated aiming angle. Then each particle is evaluated by an objective function composed of the ballistic differential equation etc. Finally, the position and velocity of particle swarm are updated. In order to accelerate the convergence speed, the correction angle of the global best particle obtained by Zhou's iterative and correction formula is used to guide the update of particle swarm. Experimental results show that the calculation speed is twice that of the iterative and correction method, and the convergence speed of particle swarm is 1.5 times that of the conventional PSO algorithm. Moreover, the proposed method is fully compatible with parallel computing and can further shorten execution time on multicore platforms.

关键词： Ballistics

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Optical encoder fault diagnosis based on characteristics of data and fuzzy logic

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Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) 2011年第SUPPL. 1期42卷 876-882页

作者： Deng, Fang Chen, Jie School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision Ministry of Education Beijing Institute of Technology Beijing 100081 China

The fault diagnosis for a class of widely used digital parallel output optical encoder were focused. After definition of the optical encoder, the main features of the optical encoder's output data were analyzed. A fault diagnosis method which did not rely on the system model where optical encoder used was proposed. The changes of optical encoder's output data were analyzed. Then, the inherent characteristics were calculated. The fuzzy logic was utilized to determine the fault type and locate the fault location. Theoretical analysis and experimental results show that this method can diagnose and isolate optical encoder fault accurately without disassembly.

关键词： Fuzzy logic

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Distance- And velocity-based collision avoidance for time-varying formation control of second-order multi-agent systems

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IEEE Transactions on Circuits and systems II: Express Briefs 2021年第4期68卷 1253-1257页

作者： Pang, Zhong-Hua Zheng, Chang-Bing Sun, Jian Han, Qing-Long Liu, Guo-Ping Key Laboratory of Fieldbus Technology and Automation of Beijing North China University of Technology Beijing100144 China State Key Laboratory of Intelligent Control and Decision of Complex Systems School of Automation Beijing Institute of Technology Beijing100081 China School of Software and Electrical Engineering Swinburne University of Technology MelbourneVIC3122 Australia Department of Artificial Intelligence and Automation Wuhan University Wuhan430072 China

This brief addresses the time-varying formation control problem with collision avoidance for second-order multi-agent systems. By taking both distances and velocities between agents into account, a novel collision avoidance scheme is proposed on the basis of conventional distance-based artificial potential field methods. Compared with the latter, the proposed scheme can more accurately determine possible collision situations and thus significantly reduce possible collision areas, which consequently not only can reduce energy consumption, but also has as few adverse effects on formation maintenance as possible. Then a time-varying formation control protocol is designed so as to achieve zero steady-state position and velocity formation tracking errors without collision. Finally, theoretical analysis, numerical demonstration, as well as comparative simulation are provided to verify the effectiveness of the proposed method. © 2004-2012 IEEE.

关键词： Multi agent systems

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Direct identification for the continuous models of servo systems with friction nonlinearity

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Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology 2010年第SUPPL. 1期30卷 86-90页

作者： Gan, Ming-Gang Gong, Wei-Guang Zhang, Guo-Zhu Chen, Jie Cai, Tao School of Automation Beijing Institute of Technology Beijing 100081 China Education Ministry Key Laboratory of Complex System Intelligent Control and Decision Beijing Institute of Technology Beijing 100081 China

In order to describe precisely the dynamics and friction nonlinearity of servo systems, a novel direct identification method for nonlinear continuous model is proposed. The sampled input-output data and logic data corresponding to the velocity direction are chosen as the identification data. Through equivalent transformation, the unknown parameters are removed to the linear part of the model. Then the identification method based on state variable filter is utilized to determine the unknown parameters. Subsequently, the nonlinear continuous model of the servo system is obtained. The effectiveness of the proposed method is demonstrated by simulations and identification experiments on the two axis servo table. Both the simulations and experimental results show that, with the proposed method, the accurate nonlinear continuous model can be obtained even under sensor noises, which gives an accurate description of the system dynamics.

关键词： Servomechanisms

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Analysis of router algorithms of tactical UAV group Ad hoc network router

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Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology 2010年第SUPPL. 1期30卷 161-164页

作者： Chen, Wen-Jie Dou, Li-Hua Li, Yu-Jin School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision Ministry of Education Beijing Institute of Technology Beijing 100081 China

In this paper an Ad hoc networks are established for the communication among unmanned air vehicle (UAV) group corporation. It is brought out that reference point group mobility model (RPGM) could simulate the behavior of UAV group to analyze the efficiency of router algorithms as to the movement of UAV node. The result shows that the Ad hoc networks can solve the communication problem of UAV group, and also find out that the ADOV algorithm has data large throughout and more adaptive to the variation of topology, the DSR has a lighter routing load. The efficiency of router algorithm also changes as to the node speed. As a result the routing algorithm should be chosen according to the different tactical mission of UAV group, and the designs of corporation method should consider the changing of network efficiency as to node moving speed.

关键词： Unmanned aerial vehicles (UAV)

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