• Title, Summary, Keyword: Sliding velocity

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Wear Behaviors of Ceramics TIN, TIC and TICN with Arc Ion Plating

  • Oh, Seong-Mo;Rhee, Bong-Goo;Jeong, Bong-Soo
    • Journal of Mechanical Science and Technology
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    • v.17 no.12
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    • pp.1904-1911
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    • 2003
  • In order to determine the wear properties of AIP (Arc Ion Plating) deposition, wear process was evaluated by using a Falex test machine. Also, in order to determine the effects of coating material on the wear process, TiC, TiN, and TiCN coatings of thickness about 5 $\mu\textrm{m}$∼6 $\mu\textrm{m}$ coated by Arc ion plating deposition method were tested. The wear property was determined under a dry sliding condition as a function of the applied load, sliding distance, sliding velocity and temperature. The results show that when wear of the coating-layer occurred, specific wear amount increased with the wear rate. At initial state, the wear rate rapidly increased, but it gradually reduced as the velocity increased. Also, when raising the temperature, the wear rate increased in the order of TiCN, TiN and TiC due to the frictional heat.

Robust Control for Rotational Inverted Pendulums Using Output Feedback Sliding Mode Controller and Disturbance Observer

  • Park, Jeong-Ju;Kim, Jong-Shik
    • Journal of Mechanical Science and Technology
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    • v.17 no.10
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    • pp.1466-1474
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    • 2003
  • This paper presents a system modeling, controller design and implementation for a rotational inverted pendulum system (RIPS), which is an under-actuated system and has the problem of unattainable velocity state. Two control strategies are applied to the RIPS. One is a sliding mode control method using the parameterization of both the hyperplane and the compensator for output feedback. The other is the disturbance observer which estimates disturbance and some modeling errors of RIPS with less computational effort. Some simulations and various kinds of experiments are performed in order to verify that the proposed controller has the ability to control RIPS whose velocity is assumed to be unavailable. The results of the simulations and experiments show that the proposed control system has superior performance for disturbance rejection and regulation at certain initial conditions as well as the robustness to model uncertainties.

An Experimental Study of Valve Seat Material Galling Characteristics in Waterworks

  • Park, Sung-Jun;Kim, Young-Tae;Lee, Sang-Jo
    • International Journal of Precision Engineering and Manufacturing
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    • v.8 no.1
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    • pp.46-51
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    • 2007
  • Environmental contamination creates shortages of potable water. In such situations, the leakage of water due to breakage or aging of rubber valve seats is a serious problem. Rubber is apt to break when it is placed between two materials that contact each other. One way to avoid water leakage due to rubber damage and breakdown is to replace the rubber with metal, which is currently taking place in water distribution systems. In tribology, a severe form of wear is characterized by local macroscopic material transfer or removal, or by problems with sliding protrusions when two solid surfaces experience relative sliding under load. One of the major problems when metal slides is the occurrence of galling. Experimentally, various conditions influence incipient galling, such as hardness, surface roughness, temperature, load, velocity, and the external environment. This study sought to verify the galling tendencies of metal according to its hardness, surface roughness, load, and sliding velocity, and determine the quantitative effect of each factor on the galling tendencies.

Coupled temperature-displacement modeling to study the thermo-elastic instability in disc brakes

  • Ramkumar, E.;Mayuram, M.M.
    • Coupled systems mechanics
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    • v.1 no.2
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    • pp.165-182
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    • 2012
  • Macroscopic hot spots formed due to the large thermal gradients at the surface of the disc brake rotor, make the rotor to fail or wear out early. Thermo-elastic deformation results in contact concentration, leading to the non uniform distribution of temperature making the disc susceptible to hot spot formation. The formation of one hot spot event will predispose the system to future hot spotting at the same location. This leads to the complete thermo-elastic instability in the disc brakes; multitude parameters are responsible for the thermo elastic instability. The predominant factor is the sliding velocity and above a certain sliding velocity the instability of the brake system occurs and hot spots is formed in the surface of the disc brake. Commercial finite element package ABAQUS(R) is used to find the temperature distribution and the result is validated using Rowson's analytical model. A coupled analysis methodology is evolved for the automotive disc brake from the transient thermo-elastic contact analysis. Temperature variation is studied under different sliding speeds within the operation range.

Properties of the Gold and Palladium-Nickel Alloy Plated Layers on Electrical Contact Materials (접점상에 입힌 Au 및 Pd-Ni 합금도금층의 특성)

  • 백철승;장현구;김회정
    • Journal of the Korean institute of surface engineering
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    • v.25 no.3
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    • pp.107-116
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    • 1992
  • The optimum thickness of Pd-Ni plated layers used as an electrical contact film was investigated by evaluating mechanical, thermal and environmental characteristics. The variations of morphologies and chemical compositions were studied by using SEM, EDS and ESCA. As a result of wear test, the wear resistance behavior of the gold plated layers was not changed with the sliding velocity changes. The palladium-nickel plated layer showed better wear resistance than the gold plated layer at low sliding velocity, but it showed poor wear resistance at high sliding velocity. Under the thermal condition of $400^{\circ}C$ in air, the gold thickness of $2\mu\textrm{m}$ without underplate on phosphorous bronze formed copper oxide on the surface layer by rapid diffusion of copper whereas the gold thickness of $0.8\mu\textrm{m}$ deposited on nickel and palladium-nickel underplate was stable at $400^{\circ}C$. Under the sulfur dioxide environments, the gold thickness of $0.3\mu\textrm{m}$ deposited on the nickel thickness of$ 3\mu\textrm{m}$ and the palladium-nickel thickness of $2\mu\textrm{m}$ underplate was more corrosion-resistant than the gold thickness of $2\mu\textrm{m}$ without underplate on phosphorous bronze. Under the nitric acid vapor environment, corrosion resistance of the gold film was superior to an equivalent thickness of the palladium-nickel film.

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Dynamic Speed Control of a Unicycle Robot (외바퀴 로봇의 동적 속도 제어)

  • Han, In-Woo;Hwang, Jong-Myung;Han, Seong-Ik;Lee, Jangmyung
    • Journal of Institute of Control, Robotics and Systems
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    • v.19 no.1
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    • pp.1-9
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    • 2013
  • This paper presents a new control algorithm for dynamic control of a unicycle robot. The unicycle robot motion consists of a pitch that is controlled by an in-wheel motor and a roll that is controlled by a reaction wheel pendulum. The unicycle robot doesn't have any actuator for a yaw axis control, which makes the derivation of the dynamics relatively simple. The Euler-Lagrange equation is applied to derive the dynamic equations of the unicycle robot to implement the dynamic speed control of the unicycle robot. To achieve the real time speed control of the unicycle robot, the sliding mode control and LQ regulator are utilized to guarantee the stability while maintaining the desired speed tracking performance. In the roll controller, the sigmoid-function based sliding mode controller has been adopted to minimize the chattering by the switching function. The LQR controller has been implemented for the pitch control to drive the unicycle robot to follow the desired velocity trajectory in real time using the state variables of pitch angle, angular velocity, angle and angular velocity of the wheel. The control performance of the two control systems form a single dynamic model has been demonstrated by the real experiments.

VSC with three-segment nonlinear sliding mode for robot manipulator (로봇 매니퓰레이터를 위한 삼분 비선형 슬라이딩 모드를 가지는 가변구조 제어)

  • 최성훈;전경한;최봉열
    • 제어로봇시스템학회:학술대회논문집
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    • pp.69-72
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    • 1996
  • In this paper robust tracking control scheme using the new three-segment nonlinear sliding mode technique for nonlinear rigid robotic manipulator is developed. Sliding mode consists of three segments, the promotional acceleration segment, the constant velocity segment and the deceleration segment using terminal sliding mode. Strong robustness and fast error convergence can be obtained for rigid robotic manipulators with large uncertain dynamics by using the new three-segment nonlinear sliding mode technique together with a few useful structural properties of rigid robotic manipulator. The efficiency of the proposed method for the tracking has been demonstrated by simulations for two-link robot manipulator.

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Effect of Sliding Distance and Temperature on Material Non-uniformity in Oxide CMP (Oxide CMP에서 Sliding Distance와 온도가 재료제거와 연마 불균일도에 주는 영향)

  • Kim, Young-Jin;Park, Boum-Young;Cho, Han-Chul;Jeong, Hae-Do
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.555-556
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    • 2007
  • Through the single head kinematics, sliding distance is a movement of a pad within wafer. The sliding distance is very important to frictional heat, material removal, and so on. A Temperature distribution is similar to sliding distance. But is not same. Because of complex process factor in CMP. A platen velocity is a dominant factor in a temperature and material removal. WIWNU is low in head faster condition.

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Design of Full-Order Observer-based Sliding Mode Controller for Power System Stabilizer : Part I (전력계통안정기를 위한 전-차수 관측기에 기준한 슬라이딩 모드 제어기 설계 : Part I)

  • Lee, Sang-Seung;Park, Jong-Keun
    • Proceedings of the KIEE Conference
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    • pp.1156-1158
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    • 1997
  • This paper presents the proposed full-order observer-based sliding mode power system stabilizer(FOOSMPSS) for finding unmeasurable state variables(torque angle, quadratic-axis transient voltage, exciter output voltage, voltage regulator output voltage and output voltage) by measuring angular velocity. The simulation results is shown by the comparison of the FOOPSS with the proposed FOOSMPSS.

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A longitudinal controller of an automated vehicle (자동화 차량의 전후 동역학 제어기)

  • 김주환;양현석
    • 제어로봇시스템학회:학술대회논문집
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    • pp.349-352
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    • 1997
  • In this paper, we propose a new longitudinal controller of automated vehicles. The controller is designed based on a sliding control method, which is known to be robust to disturbances and modelling errors. Contrary to currently available sliding controller, a switching controller gain method is suggested. It is shown throughout simulations that the proposed controller reduces the amount of overshoot, which may derive smoother velocity tracking in a platoon.

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