• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.153-160
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• 2019

Electro-mechanical actuator system for aircraft has advantages in compactness and its lightweight, compared to the hydraulic actuator system. Hinge line actuator has low air resistance and is suitable for special purpose such as stealth. This paper describes design contents of 10,000 lbf-in class dual redundant hinge line electro-mechanical actuator system for performance test. The control structure was designed to minimize impact of torque fighting. A mathematical model is proposed to analyze and validate the performances of actuator by comparison with experiment results.

• Journal of Drive and Control
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• v.15 no.2
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• pp.46-51
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• 2018

Many research studies have been carried out related to saving energy and environmental pollution in the field of construction machinery. The best solution for reducing the related environmental pollution is to reduce fuel consumption by upgrading the energy efficiency of machinery used in this field. An efficiency upgrade in the field of construction machinery would mean minimizing the pressure loss in hydraulic pipe lines or achieving optimal operating conditions while responding to a load. One way to achieve this is to make an equivalent circuit, like an electrohydrostatic actuator, or to improve the spool type valve using the 4/3 way method. This study deals with an electrohydraulic proportional flow control valve. SimulationX software is used as a simulation tool for analyzing the dynamic characteristics. The analysis results, including the performance and characteristics of design parameters, are discussed and the validity of the theoretical analysis is also evaluated.

• Journal of Drive and Control
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• v.16 no.2
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• pp.15-21
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• 2019

In this study, the maximum system efficiency of the electro-hydrostatic actuators was experimentally investigated, where small size external gear pumps with volumetric displacement under 1.3 cc/rev were combined with a 400W servomotor as the prime mover. Since the efficiency data of the servomotor, gear pumps and hydraulic cylinder were not provided by the suppliers, experimental apparatuses for their efficiency measurement were extra built up. When a gear pump with a volumetric displacement of 1.27cc/rev was used on an electro-hydrostatic actuator system, the maximum system efficiency was not higher than 70%. This was because the most effective operation ranges of the motor and pump did not coincide each other. In order to match their operation ranges as one of the most crucial design factors, a speed reduction mechanism can be used, such as a timing belt. It was shown in the study that the maximum system efficiency could be increased from 70% to 76% in that way.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.141-146
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• 2002

During dynamic flight by propulsion of rocket engine, in the atmosphere, the attitude control of flight vehicle can be accomplished by the aerodynamic fin actuator. But, in the outer space, the method of TVC(Thrust Vector Control) is only depend on for it. There are many systems which were developed for TVC. In our research, among them we adopted gimbal engine actuation system which could control the vector of thrust by swivelling rocket engine connected by gimbal. There are electro-hydraulic, electro-mechanical and pneumatic system which can be used as gimbal engine actuation system, but the electro-hydraulic system that has high ratio of output power to mass is preferred for the high power system. In this note, we made a mathematical model of the electro-hydraulic gimbal engine actuation system for the TVC of KSR-III in detail and on the base of this model we performed a simulation study. And then, we verified the model by making a comparison between the simulation and the experiments on the real system.

• Journal of Drive and Control
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• v.15 no.4
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• pp.55-60
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• 2018

Force-controlled electro-hydrostatic actuators have to exhibit high backdrivability, to quickly compensate for force control errors caused by externally disturbed rod movement. To obtain high backdrivability, the servomotor for driving the hydraulic pump, should rotate exactly to such a revolution to compensate for force control errors, compressing or decompressing cylinder chambers. In this study, we proposed a modified velocity control structure, including a robust internal-loop compensator (RIC)-based velocity controller, for the servomotor to improve backdrivability of a force-controlled EHA. Performance improvement was confirmed experimentally, wherein sinusoidal velocity disturbance was applied to the force-controlled EHA, with constant reference input. Its dynamic force control errors reduced effectively, with the proposed control scheme, compared to test results with a conventional motordriver, for motor velocity control.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.162-170
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• 2005

In KSLV-I, actuation system for thrust vector control of kick motor was configured as electro-hydraulic servo actuation system and consisted of actuators, hydraulic power supply system, hydraulic power distribution system and control system. In case of hydraulic power supply system, we use EMDP(Electric Motor Driven Pump) to supply hydraulic power. Generally, we use brushed DC motor for EMDP but it is not easy to operate EMDP using brushed DC motor at a high altitude. Hence, we are developing EMDP using brushless DC motor to use at a high altitude. In this study, we will explain control system for BLDC motor to drive hydraulic pump.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.919-920
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.775-776
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• 2012

• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.358-365
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• 2006

The hydraulic pump of an Electro-hydrostatic Actuator should be able to quickly feed large volume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil through low-speed operation so that the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and wear rate of valve plate in the low-speed range with mixed lubrication. The results showed that the friction torque of the valve plate mated with a TiN coated cylinder barrel could be reduced to 22% of that with an uncoated original one when load pressure was 300 bar and rotational speed 100 rpm. It means that the torque efficiency of the test pump was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to $40\sim50%$.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.12
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• pp.698-704
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• 2005

Passive suspensions with fixed design constants are very restrictive in the inherent suspension problem, the trade-off between the ride quality and the suspension travel. Active suspensions are used to solve some drawbacks of passive suspensions. In this paper, we propose a controller design for vehicle active suspensions considering variable driving conditions. Our controller estimates the current driving conditions by detecting the road frequencies gotten from Fourier Transform and decides which factor must be emphasized between the ride quality and the suspension travel. In one case of focusing on the ride quality, we use the skyhook control law and in the other case of focusing on the suspension travel, the double skyhook control law is used. The control law modified by various road situations outputs the reference force value the electro-hydraulic actuator in active suspension system must generate. To track the reference force, we adopt the sliding control law which is very useful in controlling the nonlinear system like the electro-hydraulic actuator.