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Motion Stability Analysis of Non-sinusoidal Oscillation of Mold Driven by Servomotor

Chinese Journal of Mechanical engineering 2015年第6期28卷 1269-1276页

作者： YAO Yunfeng LI Junxia FANG Yiming School of Materials Science and Engineering Hebei University of Science and Technology Key Laboratory of Material Near-net Forming Technology of Hebei Province Key Laboratory of Industrial Computer Control Engineering of Hebei Province Yanshan University National Engineering Research Center for Equipment and Technology of Cold Strip Rolling

The investments of the electro-hydraulic servo system of the mold non-sinusoidal oscillator are great, the modification ratio of the mechanical type is unable to be adjusted online, and some continuous casters suffer from server resonance during the casting. A mold non-sinusoidal oscillation mechanism driven by servomotor is proposed and the prototype is produced in the lab, the investment is low and the modification ratio is can be adjusted online, and the stability problem is studied. At first the dynamics model of the servomotor non-sinusoidal oscillation is established, and the kinematics differential function is deduced. Furthermore, based on the harmonic balance method, the eigenvalues of the system are solved; the criterion of the stability of the system is put forward. In addition, the eigenvalues and harmonic with different oscillating parameters are analyzed. Analytical results show that the real parts of the eigenvalues are positive, the system will be unstable, and the resonance will occur when the positive real parts of the eigenvalues are extremum. A foundation is established for solving the running smooth problem and next application of this mechanism.

关键词： continuous casting mold non-sinusoidal oscillation servomotor stability resonance

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Real-time vehicle tracking for traffic monitoring systems

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High Technology Letters 2016年第3期22卷 248-255页

作者：胡硕 Zhang Xuguang Wu Na Key Laboratory of Industrial Computer Control Engineering of Hebei Province Institute of Electrical EngineeringYanshan University Key Laboratory of Measurement Technology & Instrumentation of Hebei Province Institute of Electrical EngineeringYanshan University

A real-time vehicle tracking method is proposed for trattlC monitoring system at roau mte^cc- tions, and the vehicle tracking module consists of an initialization stage and a tracking stage. Li- cense plate location based on edge density and color analysis is used to detect the license plate re- gion for tracking initialization. In the tracking stage, covariance matching is employed to track the license plate. Genetic algorithm is used to reduce the computational cost. Real-time image tracking of multi-lane vehicles is achieved. In the experiment, test videos are recorded in advance by record- ers of actual E-police systems erage false detection rate and at several different city intersections. In the tracking module, the av- missed plates rate are 1.19%, and 1.72%, respectively.

关键词： traffic monitoring system covariance matching genetic algorithms vehicle tracking

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Hopf bifurcation control for a coupled nonlinear relative rotation system with time-delay feedbacks

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Chinese Physics B 2014年第10期23卷 299-305页

作者：刘爽李雪谈书贤李海滨 Key Laboratory of Industrial Computer Control Engineering of Hebei Province Yanshan University National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University

This paper investigates the Hopf bifurcations resulting from time delay in a coupled relative-rotation system with time- delay feedbacks. Firstly, considering external excitation, the dynamical equation of relative rotation nonlinear dynamical system with primary resonance and 1：1 internal resonance under time-delay feedbacks is deduced. Secondly, the averaging equation is obtained by the multiple scales method. The periodic solution in a closed form is presented by a perturbation approach. At last, numerical simulations confirm that time-delay theoretical analyses have influence on the Hopf bifurcation point and the stability of periodic solution.

关键词： relative rotation coupled nonlinear system bifurcation time delay

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Grazing bifurcation analysis of a relative rotation system with backlash non-smooth characteristic

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Chinese Physics B 2015年第7期24卷 279-287页

作者：刘爽王兆龙赵双双李海滨李建雄 Key Laboratory of Industrial Computer Control Engineering of Hebei Province Yanshan University National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University

Grazing bifurcation of a relative rotation system with backlash non-smooth characteristic is studied along with the change of the external excitation in this paper. Considering the oil film, backlash, time-varying stiffness and time-varying error, the dynamical equation of a relative rotation system with a backlash non-smooth characteristic is deduced by applying the elastic hydrodynamic lubrication（EHL） and the Grubin theories. In the process of relative rotation, the occurrence of backlash will lead to the change of dynamic behaviors of the system, and the system will transform from the meshing state to the impact state. Thus, the zero-time discontinuous mapping（ZDM） and the Poincare mapping are deduced to analyze the local dynamic characteristics of the system before as well as after the moment that the backlash appears（i.e.,the grazing state）. Meanwhile, the grazing bifurcation mechanism is analyzed theoretically by applying the impact and Floquet theories. Numerical simulations are also given, which confirm the analytical results.

关键词： relative rotation system backlash grazing bifurcation zero-time discontinuous mapping

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Stability and Hopf bifurcation of a nonlinear electromechanical coupling system with time delay feedback

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Chinese Physics B 2015年第1期24卷 345-353页

作者：刘爽赵双双王兆龙李海滨 Key Laboratory of Industrial Computer Control Engineering of Hebei Province Yanshan University National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University

The stability and the Hopf bifurcation of a nonlinear electromechanical coupling system with time delay feedback are studied. By considering the energy in the air-gap field of the AC motor, the dynamical equation of the electromechanical coupling transmission system is deduced and a time delay feedback is introduced to control the dynamic behaviors of the system. The characteristic roots and the stable regions of time delay are determined by the direct method, and the relationship between the feedback gain and the length summation of stable regions is analyzed. Choosing the time delay as a bifurcation parameter, we find that the Hopf bifurcation occurs when the time delay passes through a critical value.A formula for determining the direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions is given by using the normal form method and the center manifold theorem. Numerical simulations are also performed, which confirm the analytical results.

关键词： electromechanical coupling time delay Hopf bifurcation stability

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Bifurcation and chaos analysis of a nonlinear electromechanical coupling relative rotation system

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Chinese Physics B 2014年第9期23卷 271-277页

作者：刘爽赵双双孙宝平张文明 Key Laboratory of Industrial Computer Control Engineering of Hebei Province Yanshan University National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University

Hopf bifurcation and chaos of a nonlinear electromechanical coupling relative rotation system are studied in this paper. Considering the energy in air-gap field of AC motor, the dynamical equation of nonlinear electromechanical coupling relative rotation system is deduced by using the dissipation Lagrange equation. Choosing the electromagnetic stiffness as a bifurcation parameter, the necessary and sufficient conditions of Hopf bifurcation are given, and the bifurcation characteristics are studied. The mechanism and conditions of system parameters for chaotic motions are investigated rigorously based on the Silnikov method, and the homoclinic orbit is found by using the undetermined coefficient method. Therefore, Smale horseshoe chaos occurs when electromagnetic stiffness changes. Numerical simulations are also given, which confirm the analytical results.

关键词： relative rotation electromechanical coupling Hopf bifurcation chaos

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Nonlinear parametrically excited vibration and active control of gear pair system with time-varying characteristic

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Chinese Physics B 2015年第10期24卷 303-311页

作者：刘爽王进进刘金杰李雅倩 Key Laboratory of Industrial Computer Control Engineering of Hebei Province Yanshan University National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University

In the present work, we investigate the nonlinear parametrically excited vibration and active control of a gear pair system involving backlash, time-varying meshing stiffness and static transmission error. Firstly, a gear pair model is established in a strongly nonlinear form, and its nonlinear vibration characteristics are systematically investigated through different approaches. Several complicated phenomena such as period doubling bifurcation, anti period doubling bifurcation and chaos can be observed under the internal parametric excitation. Then, an active compensation controller is designed to suppress the vibration, including the chaos. Finally, the effectiveness of the proposed controller is verified numerically.

关键词： nonlinear parametrically excited vibration time-varying meshing stiffness static transmission er-ror chaos

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Flatness intelligent control via improved least squares support vector regression algorithm

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Journal of Central South University 2013年第3期20卷 688-695页

作者：张秀玲张少宇赵文保徐腾 Key Laboratory of Industrial Computer Control Engineering of Hebei Province (Yanshan University) National Engineering Research Centre for Equipment and Technology of Cold Strip Rolling

To overcome the disadvantage that the standard least squares support vector regression(LS-SVR) algorithm is not suitable to multiple-input multiple-output(MIMO) system modelling directly,an improved LS-SVR algorithm which was defined as multi-output least squares support vector regression(MLSSVR) was put forward by adding samples' absolute errors in objective function and applied to flatness intelligent *** solve the poor-precision problem of the control scheme based on effective matrix in flatness control,the predictive control was introduced into the control system and the effective matrix-predictive flatness control method was proposed by combining the merits of the two *** experiment was conducted on 900HC reversible cold *** performance of effective matrix method and the effective matrix-predictive control method were compared,and the results demonstrate the validity of the effective matrix-predictive control method.

关键词： least squares support vector regression multi-output least squares support vector regression flatness effective matrix predictive control

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Prediction of chaotic time series based on interval type-2 T-S fuzzy system

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Journal of Computational Information Systems 2014年第13期10卷 5403-5412页

作者： Wang, Shu'en Dou, Jinmei Liu, Yan Liu, Fucai Key Lab of Industrial Computer Control Engineering of Hebei Province Yanshan University Qinhuangdao China

Fuzzy model based chaotic time series prediction has been extensively studied. However, traditional type-1 fuzzy system, whose membership functions are type-1 fuzzy set, has its limitation in handling uncertainties. Type-2 fuzzy system, whose membership functions are type-2 fuzzy set, has more adaptable parameters and design degree of freedom, making it more powerful in dealing with nonlinear and uncertain problems. In this paper, the interval type-2 fuzzy system, whose fuzzy space is divided by mesh diagonal method and consequent parameters are adapted by the forgetting factor recursive least square method while previous parameters remain unchanged, is applied to modeling and prediction of chaotic time series. Finally, the proposed scheme is tested by prediction of Mackey-Glass chaotic time series in case of noise free and noise condition, the simulation results show that the proposed scheme has a higher prediction accuracy and is powerful in handling uncertainties. © 2014 by Binary Information Press

关键词： Forecasting

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Distributed containment control with dynamic leaders based on binocular vision

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Journal of Information and Computational Science 2015年第4期12卷 1319-1327页

作者： Shao, Nuan Li, Huiguang Liu, Le Li, Guoyou Key Lab of Industrial Computer Control Engineering of Hebei Province Yanshan University Qinhuangdao China

In this paper, we study the distributed containment control problem for multi-robot system with dynamic leaders in the presence of parametric uncertainties. The binocular vision system is used as the sensing device to provide real-time status information for the followers, so firstly, a new binocular visual model for dynamic target is established. Then RBF neural networks are employed to approximate the unknown nonlinear functions in the system model of followers, and the approximated values are introduced into the designed sliding mode controllers to make compensation. Finally, simulation results are presented to show the validity of the proposed control strategy. ©, 2015, Binary Information Press

关键词： Multipurpose robots

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