• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.455-459
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• 1994

One relay control implementation to the servo control systepm is contrlved mainly for the high power electric or electro hydraulic type drive system. Proposed SERME control is relay emulated software scheme accounting a reay producing maximum torque in both direction in the insufficient bandwidth control system. Possibillty is proposed mathematically prlor to emperical work out.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.221-230
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• 1988

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 word-length 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.8 no.7
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• pp.584-588
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• 2002

The real-time characteristic of the adaptive leaning control algorithms is validated based on the applied results of the hydraulic servo system that has very strong a non-linearity. The evolutionary strategy automatically adjusts the search regions with natural competition among many individuals. The error that is generated from the dynamic system is applied to the mutation equation. Competitive individuals are reduced with automatic adjustments of the search region in accordance with the error. In this paper, the individual parents and offspring can be reduced in order to apply evolutionary algorithms in real-time. The feasibility of the newly proposed algorithm was demonstrated through the real-time test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.614-617
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• 1995

The unbalance heavy-load elevation driving systems are composed of rotating link-mechanism and hydraulic cylinder which actuates elevation and compensates the static unbalance moment of supporting mechanism. Control and compensation of gun driving is very difficult because these mechanism imply highly nonlinearities due to hydraulic fluid characteristics and mechanical rotation of link-mechanism. In this study, through the analysis of manufactured link-mechanism, the optimal link-mechanism design of the elevating system is suggested. Also to estimate the control performance of the unbalance heavy-load elevation servo-control driving system, modeling and simulation of the system are carried out. To prove the reliability of performance estimation program,simulation results are compared with the experimental results. Both results are similar, therefore this program will be helpful to study the control performance improvement of the system.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.54-59
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• 1994

In this study, a high-speed servo valve with no outer leakage is developed, which is used to drive flexible hydraulic actuators (FHA) for extreme environments. In the valve, multilayered PZT devices are used to drive a spool directly and quickly. A bellows is also used to prevent outer leak from the clearance between the spool and the sleeve. Employing a disturbance observer, the lack of the system damping of the valve is improved by feeding back the estimated velocity of the spool, as well as the estimated disturbance is fed back to eliminate effectively the hysteresis between input voltage and output displacement of the PZT devices.

• Journal of Biosystems Engineering
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• v.34 no.5
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• pp.305-314
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• 2009

The purpose of this paper was to design an effective control system of 1-axis exciter for a seat vibration test of agricultural tractors using MATLAB simulation. The developed simulation model was composed with a hydraulic pump, a hydraulic servo valve, a hydraulic cylinder and load system. Also it was verified by comparing the simulation results with experimental results of actual control system in order to optimize the control performance. And in order to improve its control performance, the designed PID controller in this research was tuned using Ziegler-Nichols 2nd law and zero's moving method of PID controller's transfer function. As the result of these research, the developed position control system was able to control the system's position accurately within 5% errors.

• Journal of Biosystems Engineering
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• v.17 no.1
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• pp.18-26
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• 1992

A mechanical-hydraulic hitch control system has been adapted to most agricultural tractors. But it has various defects due to friction, inertia and hysteresis. Recently a number of electronic-hydraulic hitch control systems have been developed in several countries to improve control performance of the agricultural tractors equipped with a mechanical-hydraulic hitch control system. This study was conducted to develop a new electronic-hydraulic hitch control system using an electro-hydraulic servo valve instead of an on-off valve and to carry out computer simulation of the system. According to the result of computer simulation, the control system showed the best performance when the proportional constants were 9 and 4 for position and draft control respectively. The step and frequency responses were improved as flow rate increased.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.3
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• pp.1-6
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• 2010

This paper deals with the issue of simple adaptive position control for a pump-controlled cylinder system. A fixed displacement pump is utilized instead of servo valve and its speed is controlled by AC motor. The whole control system is composed of a pair of interconnected subsystems, that is, a feedback control system and a feedforward control system. From experiments it is shown that position control using simple adaptive control can accomplish significant reduction in position tracking error comparing to a conventional PID control.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.385-389
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• 1992

The position control of the electro-hydraulic servo indexing system in a flexible forging machine was investigated. The role of an Electro-hydraulic servoindexing system is to rotate a workpiect fast and accurately to a desired position. Since the inertia of a workpiece changes during each forging step, an adapt control scheme could be adopted to the position control of the workpiece. A generalized predictive control method which depends on predicting the plant output over several steps ahead based on the assumption about future control actions is proposed. The perormance of the proposed GPC algorithm is investigated experimentally and compared with that of PID control. Experimental results show that the proposed GPC algorithm is satisfactory for the position control of the workpiece of an electrohydraulic indexing system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.171-176
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• 2008

Active suspension controls stiffness and damping between unsprung mass and sprung mass in order to increase the ride quality. However, to increase the riding quality, the handling quality should be decreased and the rattle space should be increased. So, active suspension should cope with these conflict conditions. Therefore its actuating devices have to produce sufficient actuating force and have sufficiently short response time. In this paper, the dynamic characteristics of 1/4 car model with an active suspension is studied according to hydraulic design variables. The active suspension consists of a hydraulic servo valve and a hydraulic cylinder. It shows better performance when it has more powerful and faster actuator.