• Title, Summary, Keyword: Fluid Power Cylinder

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A study on the force control of a servo actuator with built-in MR Valve (MR 밸브 내장형 서보 액추에이터의 힘 제어에 관한 연구)

  • Ahn K.K.;Song J.Y.;Kim J.S.;Ahn Y.K.;Park J.H.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.3 no.1
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    • pp.1-6
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    • 2006
  • A servo actuator with a valve using MR (Magneto-Rheological) fluid is proposed for fluid control systems. The MR fluid is well known as a functional fluid whose apparent viscosity is controlled by the applied magnetic field strength. The pressure in the MR cylinder can be controlled by the applied magnetic field strength. Good points of the MR cylinder are more simple, compact and reliable structure than a conventional oil hydraulic cylinder. The experimental results show that the MR cylinder could be used as a servo actuator.

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The Error Analysis of Leak Measurement for Pneumatic Cylinder Using Isothermal Chamber

  • Jang, Ji-Seong;Ji, Sang-Won;Kagawa, Toshiharu
    • Transactions of The Korea Fluid Power Systems Society
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    • v.5 no.1
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    • pp.6-12
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    • 2008
  • ISO pneumatic cylinder reliability test requires air leakage measurement. Air cylinder has many parts and the leakage shall be measured before, during and after endurance test, and, the leakage should smaller than the specified value. The existing measurement method needs complex operation and the calibration of leak detector, and, has to separate the testing cylinder from endurance test device, which causes the change of contact condition of seal in the cylinder. Therefore, it is hard to evaluate the air leakage during endurance test, and guarantee the reliability of the conventional measurement method. In this paper, a new method for air leakage measurement using isothermal chamber, which does not requires calibration or temperature compensation, and, can measure air leakage accurately with quite simple operations, is proposed. As a result, reliability of air leakage measurement can be improved because the proposed method does not have to separate the testing cylinder from the endurance test device for air leakage measurement. The effectiveness of the proposed method is proved by error analysis of leak measurement from experimental result.

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A Study on the Modeling of a Position Control System with a Pneumatic Cylinder Considering Transfer Characteristics of a Transmission Line (전달 관로의 전달특성을 고려한 공기압 실린더 구동장치의 모델링에 관한 연구)

  • Kang B.S.;Jang J.S.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.1 no.2
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    • pp.20-25
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    • 2004
  • In this study, a position control characteristics of pneumatic cylinder with transmission line is analyzed. Dynamic characteristics of transmission line using compressible fluid is changed by the flowing stiles of the fluid the diameter and the length of the line. But, the effect of the change of dynamic characteristics of transmission line by the flowing states on the position control characteristics can be neglected because of the friction force of the pneumatic cylinder. So, We assume that the position control characteristics is affected by the diameter and length of the transmission line. The experimental results according to the change of parameter of the transmission line show that the relation between the parameter of the transmission line and the position control characteristics of pneumatic cylinder driving system with the transmission line.

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A study on the novel linear actuator using MR fluid

  • Song, Joo-Young;Ahn, Kyoung-Kwan;Ahn, Young-Kong
    • 제어로봇시스템학회:학술대회논문집
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    • pp.296-300
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    • 2004
  • A new MR cylinder with built-in valves using MR fluid (MR valve) is proposed for fluid power control systems. The MR or Magneto-Rheololgical fluid is a newly developed functional fluid whose obvious viscosity is controlled by the applied magnetic field intensity. The MR cylinder is composed of cylinder with small clearance and piston with electromagnet. The differential pressure is controlled by the applied magnetic field intensity. It has the characteristics of simple, compact and reliable structure. The size of MR cylinder and piston has ${\varphi}$60mm${\times}$259mm and ${\varphi}$58mm${\times}$136.5mm in face size respectively and 0.8mm in gap length. Through experiments on the static characteristics, it is found that the differential pressure is controlled by the applied magnetic field intensity under little influence of the flow rate, which corresponds to a pressure control valve. Effectiveness of the MR cylinder is demonstrated through the position control of one link MR manipulator.

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Control Characteristics of Fluid Power Cylinder Moving Up and Down (상하운동하는 유압실린더의 제어특성)

  • Yum, Man-Oh;Yoon, Il-Ro;Lee, Seok-Young
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.8
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    • pp.1152-1158
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    • 2004
  • In this study a MRAC(model reference adaptive control) for fluid power elevator model system was designed. The MRAC was compared with PI control in case of applying to the elevator model system with constant external load and changing external load. In this case external load was produced by a single fluid power cylinder combined with pressure control valve. In conclusion the MRAC control performance was better than PI control performance because overshoot and steady state error of the elevator model system controlled by the MRAC were not appeared for constant and changing external load.

Optimal Design of Hydraulic System Using the Complex Method (컴플렉스법에 의한 유압시스템의 최적 설계)

  • Lee S.R.;Lee Y.B.;Park J.H.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.1 no.4
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    • pp.1-8
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    • 2004
  • The optimum design parameters of several hydraulic systems are obtained using the complex method that is one kind of constrained direct search method. First, the parameters of lead-lag controller of the direct drive servovalve is designed using the complex method to satisfy the steady-state error requirement. Second, the optimum locating point of hydraulic cylinder Is determined to minimize the cylinder force in the operation range of rotational sluice gate. For the third application case, the optimum piston area of hydraulic cylinder is determined to minimize the man power to elevate the manually operated sluice gate.

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Fluid Film Characteristics between Cylinder Block and Valve Plates in Oil Hydraulic Piston Pumps (유압 피스톤 펌프의 실린더 블록과 밸브 플레이트 사이의 유막 특성)

  • Jung J.Y.;Song K.K.;Oh S.H.;Kim J.K.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.1 no.2
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    • pp.8-14
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    • 2004
  • Abstract: In the oil hydraulic piston pumps the clearance between the valve plate and cylinder block plays an important role for volumetric and overall efficiency. Thus, adequate lubricational fluid film is needed for the interface. In this study, fluid film thickness is measured by a gap sensor and a slip ring under operational conditions to observe the behavior of the lubrication mechanism in detail. To investigate the effect according to the valve plate types in view of the fluid film, three different types were designed. Leakage flow rate and shaft torque were also measured to clarify the effect according to the valve plate types. A broad range of experiments were conducted to provide reasonable data on the effect of fluid film. In this experiments two main parameters were found, of which the one is the discharge pressure and the other is valve plate geometry. As a result, we found that the spherical valve plate could get more stable fluid film thickness, maintain good efficiency for high pressure range than the other types.

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Propose, Design and Control of a New Actuator Using MR Fluid (MR 유체를 이용한 새로운 액추에이터의 제안, 설계 및 제어)

  • Kim J.S.;Ahn K.K.;Kha N.B.;Ahn Y.K.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.111-112
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    • 2006
  • A new MR cylinder with built-in valves using Magneto - Rheological fluid (MR valve) is proposed for fluid power control systems. The MR fluid is a newly developed functional fluid whose obvious viscosity is controlled by the applied magnetic field intensity. This MR cylinder, which is composed of cylinder with small clearance and piston with electromagnet, has the characteristics of simple, compact and reliable structure. This paper presents a method to control the pressure of MR cylinder by using Generalized Predictive Control (GPC) algorithm. The differential pressure is controlled by applying magnetic field intensity to MR fluid. The use of GPC controller is to generate a control sequence by minimizing a cost function in such a way that the future system output is driven close to reference over finite prediction horizons. Experimental results from real time control using GPC method compared with conventional PID control method are also shown in this paper.

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Motion Control of Injection Moulding Cylinder with Electric-Hydrostatic Drives (전기-정유압 구동식 사출성형 실린더의 운동제어)

  • Cho, S.H.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.5 no.4
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    • pp.26-31
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    • 2008
  • This paper deals with the issue of position tracking control of a clamp-cylinder for injection moulding machine with electric-hydrostatic drives. A fixed displacement pump is utilized in combination with AC motor in order to directly control a clamp-cylinder. A clamp-cylinder may be required to operate under a variety of operating conditions. Therefore, robust control performance is important in position tracking control applications. In order to accommodate mismatches between the real plant and the model used for controller design, discrete-time sliding mode control is developed by combining a velocity feedforward loop. From tracking control experiments, it is shown that significant reduction in position tracking error is achieved through the use of sliding mode control.

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Study of The Cushion Characteristics in accordance with Shapes of Cushion Ring of Hydraulic Cylinder (유압실린더의 쿠션링 형상에 따른 쿠션 특성 연구)

  • Lee, Y.B.;Ko, J.M.;Park, J.H.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.5 no.2
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    • pp.14-19
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    • 2008
  • Hydraulic excavator consists of booms, arms, bucket, and cylinder. The cylinder make these structures moved and the cushion parts of cylinder in operation absorb the great impact which is stemmed from high velocity and pressure at cushion parts of cylinders. The cushion technology of cylinders has a great effect on the operator's comfortable as well as protecting equipment from damage by suppressing the inertia of the hydraulic excavator. In this study, three hydraulic cylinders have different shapes of a cushion ring, respectively. we studied optimal cushion pattern by analyzing the change of cushion pressure and time, according to supply pressure and velocity variations.

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