• Title, Summary, Keyword: linear system

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A Study on the Feed Rate Optimization of a Linear Motored Feed Drive System for Minimum Vibrations (Linear Motor 이송계의 진동 최소화를 위한 이송속도 최적화)

  • 최영휴;홍진현;최응영;김태형;최원선
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.321-325
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    • 2004
  • Linear motor feed drive systems have been broadly used in machine tools or precision automatic feed systems. Recently, modem machine tools require high speed and high precision feed drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was optimum designed, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slides system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a linear motor, for its minimum vibrations. Firstly, a 4-degree-of-freedom lumped parameter model is proposed for the vibration analysis of a linear motor driven machine tool feed drive system. Next, a feed rate optimization of the feed slide is carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile with jerk continuity. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.

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Standardization Specification Research for Linear Induction Motor Type Light Rail Vehicle (선형유도모터형 경량전철 표준사양 연구)

  • Hong, Jai-Sung;Ryu, Sang-Whan;Lee, Ahn-Ho;Hwang, Hyeon-Chyeol
    • Proceedings of the KSR Conference
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    • pp.40-44
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    • 2007
  • Light rail vehicle is optimized vehicle system for complex urban circumstance. LRT systems have many merits such as improve accuracy, speediness and safety. There are many LRT systems such as monorail, tram, automated guideway transit, linear induction motor propulsion and so on. These systems have operated in Japan and other advanced countries. In Korea, local government has many projects to apply the advanced LRT system. But there are no standardized specification, performance test specification, construction specification for monorail system, linear induction motor propulsion system, tram in Korea up to now. So, we need to establish of standardized to economical construction and safety. The linear induction motor system has been usually applied in Japan subway and ART(Advanced Rapid Transit) of Canada. In Korea, the linear induction motor system has been adopted for Yongin LRT and currently under construction. This paper covers the contents and technical base for main items of rolling stock, performance standard, carbody structure, bogie, electronic unit and brake equipment in order to implement linear induction motor LRT system according to local conditions.

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The use of the semi-empirical method to establish a damping model for tire-soil system

  • Cuong, Do Minh;Ngoc, Nguyen Thi;Ran, Ma;Sihong, Zhu
    • Coupled systems mechanics
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    • v.7 no.4
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    • pp.395-406
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    • 2018
  • This paper proposes a linear damping model of tire-soil system using semi-empirical method. A test rig was designed and developed to measure the vertical equivalent linear damping ratio of tire only and tire-soil system using Free-Vibration Logarithmic Decay Method. The test was performed with two kinds of tractor tires using a combination of five inflation pressure levels, two soil depths and four soil moisture contents in the paddy soil. The results revealed that the linear damping ratio of tires increased with decreasing tire inflation pressure; the linear damping ratio of tire-soil system also increased with decreasing tire inflation pressure and increased with the increasing soil depth (observed at 80 and 120 mm). It also increased with a relative increase of soil moisture contents (observed at 37.9%, 48.8%, 66.7% and 77.4%). The results also indicated that the damping ratio of tire-soil system was higher than that of tire only. A linear damping model of tire-soil system is proposed as a damping model in parallel which is established based on experimental results and vibration theory. This model will have a great significance in study of tractor vibration.

Development of Elevator Door System with Linear Induction Motor (리니어모터를 적용한 엘리베이터 도어시스템 개발)

  • Kim, Youn-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.8
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    • pp.3617-3625
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    • 2011
  • This paper introduces new concept elevator door system with linear induction motor(LIM) featuring simple structured and direct drive mechanism, which makes up for the weak points of the conventional complex structured door system. The optimal configuration of linear door system and the design results of linear LIM will be proposed in this paper and the validation of LIM design results will be investigated through the test. In this study, high performance of drive controller applied vector control and optimum drive pattern also are suggested. In addition, this paper describes details of designing and manufacturing process of linear door system and investigates the performance by analysis and test. The analytical and experimental results of this paper are considered as the productive data for the development of new elevator door system.

A Study on Intelligent Decentralized Active Suspension Control System with Descriptor LMI Design Method

  • Park, Jung-Hyen
    • Journal of information and communication convergence engineering
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    • v.6 no.2
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    • pp.198-203
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    • 2008
  • An Intelligent optimal control system design algorithm in active suspension equipment adopting linear matrix inequalities control system design theory with representing by descriptor system form is presented. The validity of the linear matrix inequalities intelligent decentralized control system design with representing by descriptor system form in active suspension system through the numerical examples is also investigated.

A Study on the Cooling Parameter Decision of Linear Motor System by Finite Volume Method (유한체적법을 이용한 리니어모터 시스템의 냉각조건 선정에 관한 연구)

  • Hwang Y.K.;Eun I.E.;Lee C.M.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.449-450
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    • 2006
  • Development of a feed drive system with high speed, positioning accuracy and thrust has been an important issue in modern automation systems and machine tools. Linear motors can be used as an efficient system to achieve such technical demands. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speeds and greater acceleration can be achieved without backlash or excessive friction. However, an important disadvantage of linear motor system is its high power loss and heating up of motor and neighboring machine components on operation. For the application of the linear motors to precision machine tools an effective cooling method and thermal optimizing measures are required. In this paper presents an investigation into a thermal behavior of linear motor cooling plate. FVM employed to analyze the thermal behavior of the linear motor cooling plate, using the ANSYS-CFX.

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Analysis and Experiments of the Linear Electrical Generator in Wave Energy Farm utilizing Resonance Power Buoy System

  • Park, Sang-Shin;Park, Se Myung;Jung, Jongkyo;Kim, Jin Ho
    • Journal of Magnetics
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    • v.18 no.3
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    • pp.250-254
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    • 2013
  • In this research, the linear electrical generator in wave energy farm utilizing resonance power buoy system is studied. The mechanical resonance characteristics of the buoy and the wave are analyzed to maximize the kinetic energy in a relatively small wave energy area where WRPS is operated. In this research, we chose an analog model of the linear electrical generator of which size is one-hundredth of an actual size of it in WPRS (Wave energy farm utilizing Resonance Power buoy System) prior to verifying the characteristics of actual model of linear electrical generator in WRPS. In addition, the finite element analysis is conducted using commercial electromagnetic analysis software named MAXWELL to examine the electric characteristic of linear generator. Finally, for the verification of dynamic and electric characteristics of linear generator, the prototype was manufactured and the experiments to measure the displacement and the output electric power were performed.

Performance Evaluation of a Crank-driven Compressor and Linear Compressor for a Household Refrigerator

  • Park, Minchan;Jung, Yoongho;Lee, Jaeyeol;Lee, Jaekeun;Ahn, Youngchull
    • Journal of Power System Engineering
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    • v.21 no.5
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    • pp.5-12
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    • 2017
  • With the difficulties in increasing the efficiency of conventional crank-driven compressors due to mechanical loss, compressor manufacturers have investigated new kinds of compressor such as a free piston compressor mechanism. This study investigates the energy efficiency of two different types of compressor for a household refrigerator. One is the conventional crank-driven compressor, and the other one is a linear compressor. The energy efficiencies of these compressors are evaluated. Experimental results show that the linear compressor has 10% lower power consumption than the brushless direct-current (BLDC) reciprocating compressor. The linear compressor demonstrates excellent energy efficiency by reducing the friction loss. Furthermore, a motor efficiency exceeding 90% is achieved by using a linear oscillating mechanism with a moving magnet. Additionally, the compressor stroke to piston diameter ratio of the oscillating piston in the linear compressor can be adjusted in order to modulate the cooling capacity of the compressor for improved system efficiency.

A Simultaneous Perturbation Stochastic Approximation (SPSA)-Based Model Approximation and its Application for Power System Stabilizers

  • Ko, Hee-Sang;Lee, Kwang-Y.;Kim, Ho-Chan
    • International Journal of Control, Automation, and Systems
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    • v.6 no.4
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    • pp.506-514
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    • 2008
  • This paper presents an intelligent model; named as free model, approach for a closed-loop system identification using input and output data and its application to design a power system stabilizer (PSS). The free model concept is introduced as an alternative intelligent system technique to design a controller for such dynamic system, which is complex, difficult to know, or unknown, with input and output data only, and it does not require the detail knowledge of mathematical model for the system. In the free model, the data used has incremental forms using backward difference operators. The parameters of the free model can be obtained by simultaneous perturbation stochastic approximation (SPSA) method. A linear transformation is introduced to convert the free model into a linear model so that a conventional linear controller design method can be applied. In this paper, the feasibility of the proposed method is demonstrated in a one-machine infinite bus power system. The linear quadratic regulator (LQR) method is applied to the free model to design a PSS for the system, and compared with the conventional PSS. The proposed SPSA-based LQR controller is robust in different loading conditions and system failures such as the outage of a major transmission line or a three phase to ground fault which causes the change of the system structure.