• Title, Summary, Keyword: Sliding velocity

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Wear Properties of Epoxy Matrix Nanocomposites (에폭시 기지 나노복합재료의 마모 특성)

  • Kim, J.D.;Kim, H.J.;Koh, S.W.;Kim, Y.S.
    • Journal of Power System Engineering
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    • v.14 no.6
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    • pp.83-88
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    • 2010
  • The wear behavior of epoxy matrix composites filled with nano sized silica particles is discussed in this paper. Especially, the variation of the coefficient of friction and the wear resistance according to the change of apply load and sliding velocity were investigated for these materials. Wear tests of pin-on-disc mode were carried out and the wear test results exhibited as following ; The epoxy matrix composites showed lower coefficient of friction compared to the neat epoxy through the whole sliding distance. As increasing the sliding velocity the epoxy matrix composites indicated lower coefficient of friction, whereas the neat epoxy showed higher coefficient of friction as increasing the sliding velocity. The specific friction work of both materials were increased with apply load. In case of the epoxy matrix composites, the running in periods of friction were reduced as increase in apply load. The epoxy matrix composites were improved the wear resistance by adding the nano silica particles remarkably. It is expected that the load carrying capacity of the epoxy matrix composites will be improved by increase of Pv factor.

Monitoring System Design for Estimating Lateral Velocity and Sideslip Angle (감지시스템을 통한 차량의 횡 속도 및 슬립각 추정)

  • Han, Sang-Oh;Huh, Kun-Soo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.1
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    • pp.51-57
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    • 2011
  • Information of the lateral velocity and the sideslip angle in a vehicle is very useful in many active vehicle safety applications such as yaw stability control and rollover prevention. Because cost-effective sensors to measure the lateral velocity and the sideslip angle are not available, reliable algorithms to estimation them are necessary. In this paper, a sliding mode observer is designed to estimate the lateral velocity. The side slip angle is estimated using the recursive least square with the disturbance observer and the pseudo integral. The estimated parameters from the combined estimation method are updated recursively to minimize the discrepancy between the model and the physical plant, and any possible effects caused by disturbances. The performance of the proposed monitoring system is evaluated through simulations and experiments.

Fuzzy Moving Sliding Model Control for Robotic Manipulators (로봇 매니퓰레이터를 위한 퍼지 이동슬라이딩 모드 제어)

  • Chun, Kyung-Han;Park, Bong-Yeol
    • Journal of Institute of Control, Robotics and Systems
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    • v.7 no.7
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    • pp.597-604
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    • 2001
  • Recently, the study of the moving sliding mode in the variable structure control is in progress ac-tively. The conventional time-invariant sliding model control can\`t guarantee the sliding mode in the reaching phase, which is robust against the uncertainty. But with the time-varying method, the controller makes the states track the desired trajectories and keeps the sliding mode. Nevertheless, the piecewise continuous method of the past still has the reaching mode. Thus we propose the continuously moving sliding surface by the fuzzy algorithm. The proposed algorithm is made of the fuzzy rule considering both the error and the error velocity, and may apply to the entire phase plane without sacrificing sliding mode. Especially the proposed scheme can rotate tot he slope-decreasing direction, needless to say rotating to the slope-increasing direction. For showing that the proposed controller guarantees the sliding model and ensures the robustness, we apply the proposed method to the two-link robot manipulator simulation.

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Surface Temperature in Sliding Systems Using the FFT Finite Element Analysis (FFT-FEM을 이용한 윤활 기구에서 표면온도에 관한 연구)

  • 조종두;안수익
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.73-79
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    • 1999
  • Finite element equations by using fast Fourier transformation were formulated for studying temperatures resulting from frictional heating in sliding systems. The equations include the effect of velocity of moving components. The program developed by using FFT-FEM that combines Fourier transform techniques and the finite element method, was applied to the sliding bearing system. Numerical prediction obtained by FFT-FEM was in an excellent agreement of experimental temperature measurements.

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Surface Temperature in Sliding Systems Using the En Finite Element Analysis (FFT-FEM을 이용한 윤활 기구에서 표면온도에 관한 연구)

  • 조종두;안수익
    • Tribology and Lubricants
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    • v.16 no.3
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    • pp.218-222
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    • 2000
  • Finite element equations by using fast Fourier transformation were formulated for studying temperatures resulting from frictional heating in sliding systems. The equations include the effect of velocity of moving components. The program developed by using FFT-FEM that combines Fourier transform techniques and the finite element method, was applied to the sliding bearing system. Numerical prediction obtained by FFT-FEM was in an excellent agreement of experimental temperature measurements.

A Study on the Sliding Wear Characteristicsn of the Die Steel for the Cold Molding (냉간성형용 Die 강의 미끄럼 마멸특성에 관한 연구)

  • 전태옥;박흥식;류경곤
    • Tribology and Lubricants
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    • v.9 no.1
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    • pp.38-44
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    • 1993
  • The present study was undertaken to investigate the dry wear characteristics of die steel STD 11 for cold molding. The wear test was experimentally carried out under different conditions using a wear device, which was made in laboratory, and in which annular surfaces of wear testing specimens wear rubbed in dry sliding condition with varying the sliding speed, contact pressure, and sliding distance. The wear loss by variation of sliding speed was much in 0.3 m/sec and less in higher speed range above its sliding speed according to formation of the boundary lubrication film. The critical sliding speed with maximum value of the specific wear rate switched over to lower speed side according. as contact pressure increased. The critical sliding distance was increased with decrease in oxidation reaction velocity. The depth below subsurface showing maximum hardness (Hv) came out at the position, $60 \mu m$, of the maximum shear stress due to strain hardening.

Trajectory control of a manipulator by the decoupling sliding mode control (비 간섭 슬라이딩 모드 기법을 이용한 로봇 매니퓰레이터의 궤도제어)

  • Nam, Taek-Kun;Roh, Young-Oh;Ahn, Byung-Won
    • Proceedings of the KSME Conference
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    • pp.702-707
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    • 2004
  • In this paper, we proposed the decoupling VSS controllers for a trajectory control of a two degrees of freedom SCARA type manipulator. We decoupled the position and velocity of a manipulator tip by using a nonlinear error functions. The reference inputs of the controller can be decided directly from the desired position and velocity. Simulation result is provided to verity the effectiveness of the proposed control scheme.

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A Study on Tracking Control of an Industrial Overhead Crane Using Sliding Mode Controller (슬라이딩모드 제어기를 이용한 산업용 천정크레인의 추종제어에 관한 연구)

  • Park, Byung-Suk;Yoon, Ji-Sup;Kang, E-Sok
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.11
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    • pp.1022-1032
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    • 2000
  • We propose a sliding mode controller tracking the states of a time-varying reference model. The reference model generates the desired trajectories of the states, and the sliding mode controller regulates robustly the errors between the desired states and the measured states. We apply this controller to the overhead crane. Its reference model generates the trajectories of the damped-out swing angle and the swing angular velocity to suppress the swinging motion caused by the acceleration and the deceleration of crane transportation. Also, this model generates the desired trajectories of the position and velocity of the crane. The crane model is identified from the experimental data using an orthogonal function. Kalman filtering is applied to estimate the crane states. The designed controller is simulated on a computer and is tested through a 2-ton industrial overhead crane using the vector-controlled servo motor system. It is verified that, from the simulated and experimental results, the sliding mode controller tracking a time-varying reference model works well.

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An Improved Friction Model for Precise Tracking Control Systems (정밀 위치제어 시스템을 위한 개선된 마찰 모델)

  • Choe, J.J.;Han, S.I.;Kim, H.M.;Kim, J.S.
    • Proceedings of the KSME Conference
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    • pp.799-804
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    • 2003
  • Friction phenomenon can be described as two parts which are pre-sliding and sliding regions. In motion of the sliding region, friction forces depend on the velocity of the system and are known as Coulomb, stick-slip, stribeck effect and viscous friction. The pre-sliding region, which is before breakaway, depends on the position of the system. The motion of friction in the sliding region can be described as the LuGre model. But the pre-sliding motion of friction, which has hysteresis characteristics in general, is not known widely. Therefore, an improved friction model, which can describe the motion of friction in the pre-sliding region, is proposed in this paper. And simulation and experimental results show the effectiveness of the proposed friction model for precise tracking control systems.

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Sliding Surface Design by Eigenstructure Assignment and Sliding Mode Control of Matched Uncertain Systems (고유구조 지정에 의한 슬라이딩 평면 설계와 불확실한 시스템의 슬라이딩 모드 제어)

  • Lee, Tae-Bong;Yang, Hyun-Suk
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.8
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    • pp.812-817
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    • 2009
  • In this paper, a new method to design sliding surfaces using eigenstructure assignment is proposed. Most conventional methods for constructing the surfaces require special form like canonical or regular canonical form of system matrices. But the proposed method can be applied to arbitrary system matrices. Futhermore, the surface matrix, C can be decided for the matrix multiplication, CB to have a designated form. SVD is used to decide desirable eigenvectors explicitly. To verify the proposed algorithm, a sliding mode controller for a multivariable system with matched uncertainty is constructed. The controller is designed to guarantee minimum approach velocity to the sliding surface.