• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.917-921
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• 1991

Hydraulic fitting impulse tester is equipment which produce impulse pressure waveform that specified foreign standard of SAE, JIS etc. Test conditions of SAE J1453 about waveform standard indicates frequency of 35-70 cycle/min, pressure of 560 bar, oil temperature of 93 .+-.3.deg. C etc. and required cycle is a million over. In additions, Test condition operated continuously equipment. This development item adopted new pattern method such as intensifier and rotary distributor is different from already established fitting impulse tester applied servo valve and high pressure direct directional control valve. Therefore, this development item which compares already established item is good reliability, low cost of manufacture and save of electric energy. especially, Domestic small and medium enterprise uses this tester because of economical cause. We develope appropriateness tester which conforms to demand of user.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.928-933
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• 1991

In this study, the authors developed a hydraulic motor performance test system which automatically accomplishes the procedure of basic performance test and represents the data obtained in the test as performance curves. The software is made as conversation style between a computer and a user, so even to novices it is very easy to use. The most important point of this study is to get desirable isoefficiency curves. As some defined number of data are obtained at actual test, additional data necessary for desirable isoefficiency curves are generated numerically by interpolation. Basis spline function is used to get more smooth representative performance curves.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.962-967
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• 1991

A counter balance valve is used as one part of hydraulic motor brake system. The function of this valve is to protect over-run or free falling of inertia load. But occasionally the brake system with counter balance valve makes some undesirable problems such as pressure surges or vibrations. In this study, for the purpose of easy estimation about dynamic characteristics of hydraulic system including counter balance valve, precise formulation describing fluid dynamics and valve dynamics under various boundary conditions were made. Dynamic characteristics were analysed by numerical integration using Runge-Kutta method, because the equations in this circuit with counter balance valve contain various nonlinear terms. Propriety of this analysis method is verified by experiment. For the purpose of obtaining fundamental data for preventing instability, this study experimented the effects of the spool taper, spring constant, cylindrical choke. And we developed double acting brake system integrated counter balance valve.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1116-1121
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• 1991

In this paper the feedback linearization of the valve-controlled nonlinear hydraulic velocity control system and the Implementation of the digital state feedback controller is studied. The C.inf. nonlinear transformation to the electro-hydraulic velocity control system, which transforms nonlinear system to linear equivalent one, is obtained. It is shown that this transformation Is global one. The digital controller to this linearized model is obtained by using the one-step ahead state estimator and implemented to real plant. The proposed method In this paper is easier to implement than other proposed methods and it is possible to control in real tine. The experiment and simulation study show that the implementation of the digital state feedback controller based on the feedback linearized model is successful.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.4
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• pp.346-352
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• 2010

This paper presents an intuitive interface scheme for controlling a hydraulic backhoe, which is a piece of excavating equipment consisting of a digging bucket on the end of a two-part articulated arm, and typically mounted and rotated on the back of a tractor or front loader. The passive levers/joysticks for actuator operations of a hydraulic backhoe are replaced into electric joysticks with a robotic controller, which will generate the end-effecter command trajectories of the backhoe through joystick rate control in cylindrical coordinate. The developed backhoe with the hydraulic control system showed the maxim position error of 3 cm with intuitive coordinate operations, which would be helpful for conveniently performing various excavating tasks with natural and effective ways.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.6
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• pp.509-517
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• 2001

To deal with non-linearities and time-varying characteristics of hydraulic systems, in this paper, the neuro-fuzzy controller has been introduced. This controller does not require and accurate mathematical model for the nonlinear factor. In order to solve general fuzzy inference problems, the input membership function and fuzzy reasoning rules are used for determining the controller parameters. These parameters are determined by using the learning algorithm. The control performance of the neuro-fuzzy controller is evaluated through a series of experiments for the various types of inputs while applying disturbances to the hydraulic system. The performance of this controller was compared with those of PID and PD controllers. From these results, We observe be said that the position tracking performance of neuro-fuzzy is better those of PID and PD controllers.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.915-921
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• 2004

In this paper, a variable structure controller(VSC) is used to control the position of the hydraulic servo system subjected to unknown disturbances. The system consists of two cylinders, which connected in series. One cylinder executes position control, the other executes force control to generate disturbances. In order to control each cylinder, interaction must be considered between two cylinders because two cylinders are connected in series. Therefore, the controller is designed regarding interaction between two cylinders as disturbances. Performance of the proposed controller was verified through experiments and compared to PID controller. The experiments showed that the proposed controller had a good performance and robustness.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.658-662
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• 1986

In the microcomputer-based velocity control for an electro-hydraulic servo system, the effects of control methods and control hardware on the performance of the system were investigated. Experiments were carried out with PID and deadbeat controllers using 8 or 16 bit microprocessor and 8 or 12 bit A/D and D/A converters. It is found that the transient response of the system is better with PID controller than with deadbeat controller. When the number of bits of the microprocessor and converters are small, it is also found that amplitude quantization due to limited wordlength gives significant effects on transient responses of the system. Analytically predicted step-responses are in good agreement with experimental ones.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.1
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• pp.22-29
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• 2004

This paper studies the coordinated trajectory control of an excavator as a kind of robotic manipulators driven by hydraulic actuators. Hydraulic robot system has many non-linearity in dynamics and kinematics, and strong coupling among joints(or hydraulic cylinders). This paper proposes a combined controller frame of the adaptive robust control(ARC) and the sliding mode control(SMC) for the trajectory tracking control of the excavator to preserve the advantages of the both methods while overcoming their drawbacks, namely, asymptotic stability of adaptive system for parametric uncertainties and guaranteed transient performance of sliding mode control for both parametric uncertainties and external disturbance. The suggested control technique is applied for the tracking of a straight-line motion of end-effector of manipulators, and through computer simulations, its trajectory tracking performances and the robustness to payload variation and uncertainties are illustrated.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.687-692
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• 1990

The purpose of this study is ID form the required force for measurements of the performances of the equipments or testpieces. For the generation of the required force, ft difference of pressures in each chamber of the hydraulic cylinder was controlled and Variable Structure Control theory was adopted to control it. Besides, observers -Luenberger Observer and nonlinear Variable Structure Observer - were designed to estimate the derivative of the load pressure which is necessary ID determine the sliding surface in VSC theory. As a consequence of the computer simulation, it was shown that VSC had better performance than classical control theory(P, PD control) and VSO performed better than the Luenberger Observer at the load pressure control.