• Title, Summary, Keyword: Sliding velocity

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A Comparison of Sliding Mode and Integral Sliding Mode Controls for Robot Manipulators (로봇 매니퓰레이터를 위한 슬라이딩 모드와 적분 슬라이딩 모드 제어의 비교)

  • Yoo, Dong-Sang
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.1
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    • pp.168-172
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    • 2009
  • We compare an integral sliding mode control with a typical sliding mode control for robot manipulators through two primitive tasks: set-point regulation and trajectory tracking control. To prove the asymptotic stability of two methods for robot manipulators, we introduce three important properties in the robot dynamics: skew-symmetry, positive-definiteness, and boundedness of robot parameter matrices and we present one unified control structure using a parametric velocity vector. From illustrative examples, we show that two methods effectively control for robot manipulators.

Fabrication and Characteristics of $Al_2O_{3p}$/AC8A Composites by Pressureless Infiltration Process (무가압함침법에 의한 $Al_2O_{3p}$/AC8A 복합재료의 제조 및 특성)

  • 김재동;고성위;정해용
    • Composites Research
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    • v.13 no.6
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    • pp.1-8
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    • 2000
  • The fabrication Process of $Al_2O_{3p}$/AC8A composites by pressureless infiltration technique and the effects of additive Mg content and volume fraction of particulate reinforcement on mechanical and wear properties were investigated. It was found that the bending strength decreased with increasing volume fraction of $Al_2O_{3p}$ particles. Whereas hardness increased with volume fraction of $Al_2O_{3p}$ particles. The decrement of strength in case of high volume fraction of $Al_2O_{3p}$ particles was attributed to high porosity level. In terms of additive Mg content, $Al_2O_{3p}$/AC8A composites containing around 5~7wt% of additive Mg indicated the highest strength, and hardness values increased with additive Mg contents. Wear resistance of AC8A alloy were improved by reinforcement of $Al_2O_{3p}$ particles especially at high sliding velocity. Wear property of $Al_2O_{3p}$/AC8A composites and AC8A alloy exhibited different aspects. $Al_2O_{3p}$/AC8A composites indicated more wear loss than AC8A alloy at slow velocity region. However a transition point of wear loss was found at middle velocity region which shows the minimum wear loss and wear loss at high velocity region exhibited almost same value as at slow velocity region, whereas wear loss of AC8A alloy almost linearly increased with sliding velocity. It was found that $Al_2O_{3p}$/AC8A composites containing $Al_2O_{3p}$ volume fraction of 20% exhibited abrasive wear surface regardless of sliding velocity and $Al_2O_{3p}$/AC8A composites containing $Al_2O_{3p}$ volume fraction of 40% showed slightly adhesive wear surface at low sliding velocity, and it progressed to severe wear as increasing the sliding velocity.

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Transverse Vibration Control of an Axially Moving String by Velocity Boundary Control (속도경계제어를 이용한 축방향 주행 현의 횡진동 제어)

  • Ryu, Du-Hyeon;Park, Yeong-Pil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.1
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    • pp.135-144
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    • 2001
  • In this study, the time varying boundary control using the right boundary transverse motion is suggested to stabilize the transverse vibration of an axially moving string on the basis of the energy flux between the moving string and the boundaries. The effectiveness of the active velocity boundary control is showed through the FDM simulation results. Sliding mode control is adopted in order to achieve velocity tracking control of the time varying right boundary to dissipate vibration energy of the string effectively. Optical sensor system for measuring the transverse vibration of an axially moving string is developed, and the angle of the incident wave to the right boundary, which is the input of the velocity boundary controller, is obtained. Experimental research is carried out to examine the validity and the performance of the transverse vibration control using the suggested velocity right boundary control scheme.

Pre-Sliding Friction Control Using the Sliding Mode Controller with Hysteresis Friction Compensator

  • Choi, Jeong Ju;Kim, Jong Shik;Han, Seong Ik
    • Journal of Mechanical Science and Technology
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    • v.18 no.10
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    • pp.1755-1762
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    • 2004
  • Friction phenomenon can be described as two parts, which are the pre-sliding and sliding regions. In the motion of the sliding region, the friction force depends on the velocity of the system and consists of the Coulomb, stick-slip, Streibeck effect and viscous frictions. The friction force in the pre-sliding region, which occurs before the breakaway, depends on the position of the system. In the case of the motion of the friction in the sliding region, the LuGre model describes well the friction phenomenon and is used widely to identify the friction model, but the motion of the friction in the pre-sliding such as hysteresis phenomenon cannot be expressed well. In this paper, a modified friction model for the motion of the friction in the pre-sliding region is suggested which can consider the hysteresis phenomenon as the Preisach model. In order to show the effectiveness of the proposed friction model, the sliding mode controller (SMC) with hysteresis friction compensator is synthesized for a ball-screw servo system.

Dynamic Analysis of Automobile Collisions with Friction (마찰력이 수반된 자동차 충돌의 동역학적 해석)

  • Han, I.H.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.2
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    • pp.1-11
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    • 1994
  • The most commonplace of collisions that directly affect people is that of vehicles. Safety studies have noted a correlation between vehicle occupant injury severity and velocity changes. Methods for estimating collision velocity changes are discussed here. This topic is part of what is referred to as accident reconstruction. Only planar collisions are considered. When a vehicle collides with another, impact dynamics with friction should be considered. This paper presents a general analysis methodology of impact. must dynamics incorporating friction. The presence of friction between sliding contacts during the impact makes the problem difficult since the events such as reverse sliding or sticking, which may occur at different times throughout the impact, must be determined. This paper uses the results of RICSAC experiments for verifying the developed methodology. The analysis and experimental results agree well.

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Design of Sliding Mode Controller for Induction Motor to Remove Chattering (채터링 제거를 위한 유도 전동기의 슬라이딩 모드 제어기 설계)

  • 김성읍;곽군평;안호균
    • The Transactions of the Korean Institute of Power Electronics
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    • v.3 no.3
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    • pp.240-245
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    • 1998
  • This paper presents an improved sliding mode controller design for induction motor. In place of the discontinuous control inputs, continuous inputs are proposed in order to remove the undesirable chattering phenomena, which represent major drawbacks of the sliding mode controller. The design strategy is illustrated with a microprocessor based implementation for the velocity control of an induction motor. An induction motor is operated under sling mode control such that the motor angular velocity follows a predetermined trajectory. The experimental results confirm the validity of the proposed method.

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

  • Nam Taek-Kun
    • Journal of Advanced Marine Engineering and Technology
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    • v.29 no.8
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    • pp.842-848
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    • 2005
  • The decoupling control using state feedback was once intensively studied during 1960's by many researchers. However, this control scheme was sensitive to the disturbance and Parameter variations. SMC(sliding mode control) is known as a robust control methodology to overcome such a disturbance. In this paper. the decoupling control by means of SM(sliding mode) for a trajectory control of a two-degrees-of- freedom manipulator was discussed. The position and velocity of manipulator tip were adopted to compose a nonlinear error functions. The reference inputs of the controller can be decided by switching function combined with the desired position and velocity. Simulation result is provided to verify the effectiveness of the proposed control scheme.

PMSM Sensorless Speed Control Using a High Speed Sliding Mode Observer (고속 슬라이딩모드 관측기를 이용한 PMSM 센서리스 속도제어)

  • Son, Ju-Beom;Kim, Hong-Ryel;Seo, Young-Soo;Lee, Jang-Myung
    • Journal of Institute of Control, Robotics and Systems
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    • v.16 no.3
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    • pp.256-263
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    • 2010
  • The paper proposes a sensorless speed control strategy for a PMSM (Permanent Magnet Synchronous Motor) based on a new SMO (Sliding Mode Observer), which substitutes a signum function with a sigmoid function. To apply robust sensorless control of PMSM against parameter fluctuations and disturbance, the high speed SMO is proposed, which estimates the rotor position and angular velocity from the back EMF. The low-pass filter and additional position compensation of the rotor are used to reduce the chattering problem commonly found in sliding mode observer with signum function, which becomes possible by applying the sigmoid function with the control of a switching function. Also the proposed sliding mode observer with the sigmoid function has better efficiency than the conventional sliding mode observer since it adjusts the observer gain by variable boundary layer and estimates the stator resistance. The stability of the proposed sliding mode observer is verified by the Lyapunov second method in determining the observer gain. The validity of the proposed high speed PMSM sensorless velocity control has been demonstrated by real experiments.

The Low Current Starting Simulation of a Single Phase Induction Motor Using Sliding Mode Control (슬라이딩 모드 제어를 이용한 단상 유도전동기의 저 전류 기동 시뮬레이션)

  • Kim, Hyo-Ki;Lee, Byung-Ha
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.8
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    • pp.44-53
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    • 2007
  • In this paper, the Sliding Mode Controller is applied to reduce the starting current of the single phase induction motor. The input voltage to the single phase induction motor is controlled so that the starting current of the motor may be maintained within the rating value and the velocity is also controlled, by adjusting the switching function of the Sliding Mode Controller. The switching of sliding control made appropriately with regard to velocity error signal and acceleration signal. It is shown that the starting characteristics of the single phase induction motor(SPIM) can be greatly enhanced through the sliding control of single phase induction motor.

A Study on Wear Properties of Plasma Sprayed $Cr_3C_2$-NiCr Coating at High Temperature (크롬탄화물 용사피막의 고온마모 특성연구)

  • 김의현;권숙인
    • Journal of Welding and Joining
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    • v.11 no.4
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    • pp.91-102
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    • 1993
  • The plasma sprayed $Cr_3C_2$-NiCr coatings are widely used as wear-resistant and corrosion-resistant materials. The mechanical and wear properties of the plasma sprayed $Cr_3C_2$-NiCr coating on steel plate were examined in this study. The pore in the coatings could be classified into two types, the one is the intrinsic pore originated from the spraying powder, the other is the extrinsic pore formed during spraying. During the tensile adhesion test, the fracture occured at the interface of top coating and bond coating. It is though that the compressive residual stress increases with the increase of the top coating thickness. From the wear test, it was found that the wear rate increased with the increase of the sliding velocity regardless of the temperature. It is thought that the fracture toughness reduces with the increase of the sliding velocity at $30^{\circ}C$ and that the adhesion amount increases with the increase of the sliding velocity at $400^{\circ}C$ It is concluded that the wear mechanism at $30^{\circ}C$ is the fracture and pull-out of the carbide particles due to the fatigue on sliding surface, while the wear mechanism at $400^{\circ}C$ is the adhesion of the smeared layer formed during wear process.

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