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

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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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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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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A Novel Method for Flatness Pattern Recognition via Least Squares Support Vector Regression

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Journal of Iron and Steel Research International 2012年第3期19卷 25-30页

作者： ZHANG Xiu-ling, ZHANG Shao-yu, TAN Guang-zhong, ZHAO Wen-bao (key laboratory of industrial computer control engineering of hebei Province, National engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004, hebei, China) Key Laboratory of Industrial Computer Control Engineering of Hebei Province National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University Qinhuangdao 066004 Hebei China

To adapt to the new requirement of the developing flatness control theory and technology, cubic patterns were introduced on the basis of the traditional linear, quadratic and quartic flatness basic patterns. Linear, quadratic, cubic and quartic Legendre orthogonal polynomials were adopted to express the flatness basic patterns. In order to over- come the defects live in the existent recognition methods based on fuzzy, neural network and support vector regres- sion （SVR） theory, a novel flatness pattern recognition method based on least squares support vector regression （LS-SVR） was proposed. On this basis, for the purpose of determining the hyper-parameters of LS-SVR effectively and enhan- cing the recognition accuracy and generalization performance of the model, particle swarm optimization algorithm with leave-one-out （LOO） error as fitness function was adopted. To overcome the disadvantage of high computational complexity of naive cross-validation algorithm, a novel fast cross-validation algorithm was introduced to calculate the LOO error of LDSVR. Results of experiments on flatness data calculated by theory and a 900HC cold-rolling mill practically measured flatness signals demonstrate that the proposed approach can distinguish the types and define the magnitudes of the flatness defects effectively with high accuracy, high speed and strong generalization ability.

关键词： flatness pattern recognition least squares support vector regression cross-validation

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

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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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Finite-time neural network adaptive control of under-actuated robots 4

Finite-time neural network adaptive control of under-actuate...

引用

2014 4th International Conference on Mechanical engineering, Industry and Manufacturing engineering, MEIME 2014

作者： Wu, Zhong Qiang Liu, Li Ling Zhao, Li Ru Key lab of industrial computer control engineering of Hebei province Yanshan University China

ISBN: (纸本)9783038353256

The finite-time neural network adaptive control of under-actuated robot is investigated, and a kind of multistep control strategy is used. First the transformation of dynamics model is made, and the passive joints are driven to desire positions by the coupling among joints, then the passive joints are locked. When the passive joints are locked to other operating point, the system becomes the one with structure uncertain. Combining the theory of finite-time control with neural network adaptive control, a finite-time neural network adaptive controller is got which can make the position tracking of joint rapidly. The simulation shows the effectiveness of the controller. © (2014) Trans Tech Publications, Switzerland.

关键词： Robots

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Compound control for speed and tension multivariable coupling system of reversible cold strip mill

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Journal of Central South University 2015年第2期22卷 529-538页

作者：方一鸣刘乐李建雄常茹 Key Laboratory of Industrial Computer Control Engineering of Hebei Province(Institute of Electrical Engineering Yanshan University) National Engineering Research Center for Equipment and Technology of Cold Strip Rolling(Yanshan University)

To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.

关键词： reversible cold strip mill speed and tension system decoupling invariance principle compound control extended state observer global sliding mode control

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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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