• 유공압시스템학회논문집
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• 제7권3호
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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.

• 한국항공우주학회지
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• 제41권4호
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• pp.291-298
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• 2013

본 논문에서는 압력보상형 사판식 유압 피스톤 펌프와 밸브 제어형 실린더를 결합한 EHA에 대하여 유압 실린더의 소비 유량이 작으면 펌프 회전 속도를 낮추는 새로운 개념의 하이브리드형 제어 시스템을 제안하였다. 펌프 내 압력조절기의 사판각 제어와 간섭을 피하기 위해 위치 명령 신호의 속도 성분 평균치를 이용하여 펌프의 회전속도를 조절하였고, 시스템 압력이 기준치 이하로 낮아지는 것을 방지하기 위해 압력 스위치 기능을 추가하였다. 시뮬레이션과 실험 결과에 의하면, EHA의 동적인 응답 특성에 영향을 주지 않는 조건에서 하이브리드 제어를 통해 공전 모드에서의 펌프 회전속도를 1,800rpm에서 600rpm로 낮춤으로써 하이브리드 제어를 안 할 경우에 비해 펌프 구동 동력을 약 44%까지 절감시킬 수 있음을 확인하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.181-182
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• 2010

• 한국산업융합학회 논문집
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• 제5권1호
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• pp.21-26
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• 2002

Response time of actuator in a hydraulic system may be important and necessary to avoid failures and to improve the efficiency of operation. Flow restricting devices can result in a decrease in the peak pressure, but may change the response time. The response time has an important effect on both operator and operator perceived smoothness. The response time should correspond to how fast a system responds to a given disturbance at the system boundary, Occasionally the appropriate response time is not easily determined. This study is on the characteristics of response time in the hydraulic system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.77-78
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• 2011

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.69-70
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• 2011

• 한국정밀공학회지
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• 제17권10호
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• pp.162-169
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• 2000

A Direct Drive Valve(DDV) hydraulic actuation system which is commonly used as an aircraft's control surface driving actuator has multi-loop control structure to ensure its safety operation. However, because of not perfect matching of one self channel characteristics with the others, the servo valve driving current of each channel can be widely different. Therefore, the long-time use of DDV actuator without any correction of these channel current offsets will cause the problem of performance or life expectancy degradation due to unwanted heats in the linear motor. A current equalization loop structure which can minimizes current offsets between channels is introduced and designed. The performance of the current equalization loop is investigated and verified through the analytic and experimental ways.

• Journal of Advanced Marine Engineering and Technology
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• 제23권1호
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• pp.69-78
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• 1999

In this study a new pattern of pressure control of hydraulic cylinder using high speed On-Off solenoid valve in the electro-hydraulic system has been suggested. The control valve is 3-way high speed On-Off solenoid valve which is operated by PWM(Pulse Width Modulation)control signal. The high speed On-Off solenoid valve has a tendency to induce severe pressure fluctuation in the hydraulic actuator so it has not been used for the purpose of closed loop control with direct pres-sure feedback. In this study closed loop control with direct pressure feedback is enabled by using a digital filter which has linear minimum mean square filter algorithm. Through some experiments it is confirmed that stable pressure control can be realized by the proposed control technique.

• 소음진동
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• 제7권2호
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• pp.311-317
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• 1997

In this paper the active vibration control system using a linear oscillatory actuator(LOA) is studied to suppress structural vibration. In the LOA, the AC-power-energized armature generates a shift field in an air gap, which produces a oscillating force to the mover in the magnetic field generated by high density permanent magnets. LOA has relatively simple structure with almost maintenance free, compared with a hydraulic actuator. Performance test of the active vibration control system using a LOA is carried out on a steel test structure under base excitation. From this test, it is confirmed that the acceleration level of the test structure is drastically reduced near the resonant region.

• 유공압시스템학회논문집
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• 제2권3호
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• pp.1-5
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• 2005

There are two types of solenoid actuator for force and position control of the fluid power system. One is an on-off solenoid actuator and the other is an electro-magnetic proportional actuator. They have some different characteristics for attraction force according to solenoid shape. Attraction force of the on-off solenoid actuator only depends on flux density. And the stroke-force characteristics of the proportional solenoid actuator are determined by the shape of the control cone. In this paper, steady state characteristics of the solenoid actuator for electro-hydraulic proportional valve determined by the shape of control cone are analyzed using finite element method and it is confirmed that the proportional solenoid actuator has a constant attractive force in the control region independently on the stroke position. And the shape of control cone is optimized using 1+1 evolution strategy to get a constant force. In the optimization algorithm, control cone length, thickness and taper length are used as a design parameter.