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Implementation of remote monitoring system for prediction of tool wear and failure using ART2

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Journal of Central South University 2011年第1期18卷 177-183页

作者： NOH Min-Seok HONG Dae Sun School of mechatronics Changwon National University

Remote monitoring of tools for prediction of tool wear in cutting processes was considered, and a method of implementation of a remote-monitoring system previously developed was proposed. Sensor signals were received and tool wear was predicted in the local system using an ART2 algorithm, while the monitoring result was transferred to the remote system via intemet. The monitoring system was installed at an on-site machine tool for monitoring three kinds of tools cutting titanium alloys, and the tool wear was evaluated on the basis of vigilances, similarities between vibration signals received and the normal patterns previously trained. A number of experiments were carried out to evaluate the performance of the proposed system, and the results show that the wears of finishing-cut tools are successfully detected when the moving average vigilance becomes lower than the critical vigilance, thus the appropriate tool replacement time is notified before the breakage.

关键词： tool wear remote monitoring system ART2 neural network machine tool tool replacement time

Torsional vibration analysis of lathe spindle system with unbalanced workpiece

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Journal of Central South University 2011年第1期18卷 171-176页

作者：郭瑞 JANG Sung-Hyun CHOI Young-Hyu School of mechatronics Changwon National University

For the purpose of analyzing the torsional vibration caused by the gravitational unbalance torque arisen in a spindle system when it is machining heavy work piece,a 10-DOF lumped parameter model was made for the machine tool spindle system with geared *** using the elementary method and Runge-Kutta method in Matlab,the eigenvalue problem was solved and the pure torsional vibration responses were obtained and *** results show that the spindle system cannot operate in the desired constant rotating speed as far as the gravitational unbalance torque is engaged,so it may cause bad effect on machining *** the torsional vibration increases infinitely near the resonant frequencies,so the spindle system cannot operate normally during these spindle speed ranges.

关键词： unbalanced work piece gravitational unbalance torque torsional vibration spindle system geared transmission

Segregation of voiced and unvoiced components from residual of speech signal

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Journal of Central South University 2012年第2期19卷 496-503页

作者： JO Cheol-woo KIM Jae-hee School of mechatronics Changwon National University

In conventional source-filter models, voiced and unvoiced components were considered independently. However, in practice it was difficult to separate the source into two parts. An actual source consists of a mixture of two sources and the ratio varies according to the content or the intention of speaker. It had been investigated to separate the voiced and unvoiced components for different source models. Source signals were modeled based on the residual signal measured from inverse filtering. Three different source models were assumed. The parameters of each model were optimized for the original speech signal using a genetic algorithm. The resulting parameters were compared in terms of the mel-cepstral distance to the original signal, the spectrogram and the spectral envelope from the synthesized signal. The optimization method achieves an improvement of 15% for the Klatt model, but there is little improvement in the modified residual case.

关键词： voice source model synthesis optimization genetic algorithm

A genetic algorithm based lookup table approach for optimal stepping sequence of open-loop stepper motor systems

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控制理论与应用（英文版） 2013年第1期11卷 35-41页

作者： Suleiman BANIHANI Khalid AL-WIDYAN Ahmad AL-JARRAH Mohammad ABABNEH mechatronics Engineering Department The Hashemite University

Stepper motor driven systems are widely used in industrial applications. They are mainly used for their low cost open-loop high performance. However, as dynamic systems need to be increasingly faster and their motion more precise, it is important to have an open-loop system which is accurate and reliable. In this paper, we present a novel technique in which a genetic algorithm （GA） based lookup table approach is used to find the optimal stepping sequence of an open-loop stepper motor system. The optimal sequence objective is to minimize residual vibration and to accurately follow trajectory. A genetic algorithm is used to find the best stepping sequence which minimizes the error and improves the system performance. Numerical simulation has showed the effectiveness of our approach to improve the system performance for both position and velocity. The optimized system reduced the residual vibration and was able to follow the trajectory with minimal error.

关键词： Stepper motor Open-loop Genetic algorithm Optimal Stepping sequence Control

Optimal design of FRMSM to decrease detent force

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Journal of Central South University 2011年第2期18卷 458-464页

作者： JANG Ki-Bong PYO Se-Ho AN Ho-Jin KIM Gyu-Tak School of mechatronics Changwon National University

An optimal configuration of the flux-reversal linear synchronous motor (FRLSM) with the optimal number of attachment permanent magnets (PMs) was presented. The optimal model of 2 000 N was designed to reduce the detent force by redesigning the air-gap structure and skewing. The design parameters,mover PMs and stator core,were selected for optimal design by DOE. The thrust and the detent force of the designed optimal models were compared by finite element analysis (FEA). As a result,the thrust of the optimal model is slightly decreased by 1.97% compared with the basic model,and the detent force of the optimal model is greatly decreased by 88.47% compared with the basic model.

关键词： flux-reversal linear synchronous motor detent force thrust design of experiment skew and overhang

Fluid flow and heat transfer characteristics of spiral coiled tube: Effects of Reynolds number and curvature ratio

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Journal of Central South University 2012年第2期19卷 471-476页

作者： YOO Geun-jong CHOI Hoon-ki DONG Wa-ryong School of mechatronics Changwon National University

Numerical analysis was performed to investigate flow and heat transfer characteristics in spiral coiled tube heat exchanger. Radius of curvature of the spiral coiled tube was gradually increased as total rotating angle reached 12n. As the varying radius of curvature became a dominant flow parameter, three-dimensional flow analysis was performed to this flow together with different Reynolds numbers while constant wall heat flux condition was set in thermal field. From the analysis, centrifugal force due to curvature effect is found to have significant role in behavior of pressure drop and heat transfer. The centrifugal force enhances pressure drop and heat transfer to have generally higher values in the spiral coiled tube than those in the straight tube. Even then, friction factor and Nusselt number are found to follow the proportionality with square root of the Dean number. Individual effect of flow parameters of Reynolds number and curvature ratio was investigated and effect of Reynolds number is found to be stronger than that of curvature effect.

关键词： spiral coiled tube heat exchanger Reynolds number curvature ratio secondary flow friction factor Nusselt number

Fourier and wavelet transformations application to fault detection of induction motor with stator current

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Journal of Central South University 2010年第1期17卷 93-101页

作者： LEE Sang-hyuk 王一奇 SONG Jung-il School of mechatronics Changwon National University

Fault detection of an induction motor was carried out using the information of the stator current. After synchronizing the actual data, Fourier and wavelet transformations were adopted in order to obtain the sideband or detail value characteristics under healthy and various faulty operating conditions. The most reliable phase current among the three phase currents was selected using an approach that employs the fuzzy entropy measure. Data were trained with a neural network system, and the fault detection algorithm was verified using the unknown data. Results of the proposed approach based on Fourier and wavelet transformations indicate that the faults can be properly classified into six categories. The training error is 5.3×10-7, and the average test error is 0.103.

关键词： Fourier transformation wavelet transformation induction motor fault detection

Continuity control method of cutter posture vector for efficient five-axis machining

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Journal of Central South University 2011年第6期18卷 1969-1975页

作者： HWANG Jong-dae KIM Sang-myung JUNG Hyun-chul JUNG Yoon-gyo School of mechatronics Changwon National University

During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to improve the efficiency of five-axis machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. By using an MC-space algorithm for interference avoidance, an MB-spline algorithm for continuous control was intended to create a five-axis machining tool path with excellent surface quality and economic feasibility. A five-axis cutting experiment was performed to verify the effectiveness of the continuity control. The result shows that the surface shape with continuous method is greatly improved, and the surface roughness is generally favorable. Consequently, the effectiveness of the suggested method is verified by identifying the improvement of efficiency of five-axis machining of an impeller in aspects of surface quality and machining time.

关键词： five-axis control machining configuration-space B-spline continuity control method impeller interference

Geometry effect on mechanical properties of woven fabric composites

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Journal of Central South University 2011年第6期18卷 1985-1993页

作者： KIM Myungsoo SONG Jung-Il School of mechatronics Changwon National University

The effects of geometry on mechanical properties in woven fabric composites were explored. Two types of composites, including one-layered and two-layered composites, were designed and studied. For one-layered composites, inter-strand gap effects on the mechanical properties were studied, while three cases of geometries with inter-strand gaps in two-layered composites were evaluated. A woven fiber micromechanics analytical model called MESOTEX was employed for theoretical simulation. The predicted results show that the inter-strand gap and simple variation of the strand positions in a repeating unit cell significantly affect the mechanical properties of woven fabric composites.

关键词： woven fabric composites inter-strand gap mechanical properties micromechanics modeling