• Journal of the Korean Society for Precision Engineering
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• v.19 no.4
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• pp.202-208
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• 2002

An electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to realize not only stable contact work but also accurate force control for the autonomous assembly tasks using hydraulic manipulators. In this report, we applied a compliance control which is based on the position control by a disturbance observer for our manipulator system. And a reference trajectory modification method is proposed in order to achieve accurate force control even though the stiffness and position of environment change. Experimental results show that highly robust force tracking by a 6-link electro-hydraulic manipulator could be achieved under various environment conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.1
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• pp.10-17
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• 2007

For the purpose of optimal control of anti-lock brake system, precise dynamic characteristics analysis of the hydraulic modulator, especially solenoid valve is necessary. However, most of researches so law have dealt with dynamic characteristic analysis of valve itself and the results have been restrictive to apply on the actual ABS modulator, where hydraulic pressure is acting. In this study, mathematical modeling and experimental analysis were executed in order to evaluate the valve dynamic characteristics when the hydraulic pressure applied. High pressure on the master cylinder effects on the valve dynamic characteristics have been analyzed quantitatively and performance improvement methods have been suggested varying the design factor. Consequently, results of solenoid valve dynamic characteristics analysis derived in the study can be utilized criteria for the optimal control of anti-lock brake system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4738-4744
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• 2011

This study proposes the system of new small sluice gate operated without the upper concrete structure. The new mechanism is composed of hydraulic system, driving mechanism to feed the floodgate up and down, hydrological locking device, safety device and etc. The hydraulic pumps and control systems away from the location of the sluice gate systems are installed and controled in place. The feed device with the hydraulic rack, pinion and hydraulic actuator is installed on the side of the sluice gate. The following results take the advantages of cost reduction, operation safety and compact product.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.9-17
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• 2019

Variable guide vanes(VGVs) that consist of link mechanisms and an actuator system are required for an aircraft gas turbine engine to adjust the incidence angle of stator vanes. In this study, we developed a VGV actuator system for three-stage VGVs with two hydraulic actuators. The requirements for the actuator system were derived by analyzing the link mechanisms and air loads, and a hydraulic power-pack was developed based on these requirements. Through a load test using the actuator test-rig and the application of synchronizing control logic with proper control gains, the actuator system could be developed and verified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.805-814
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• 2013

A hydraulic dipod platform is used for tracking and stabilizing an antenna system to designate a satellite on a moving vehicle. The 2-DOF controller is very well suited to this controller design object because it is more flexible than the 1-DOF controller when the design object is not only the consideration between stabilizing and tracking but also the trade-off between performance and robustness. The 2-DOF controller synthesis based on the $H_{\infty}$ framework is divided into two design procedures. In this hydraulic dipod platform example, the single-step method shows better performance whereas the two-step method shows better robustness. The difference between these two synthesis results is compared using the structural property of the interconnection system matrix.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2106-2112
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• 2013

In a traditional hydraulic elevator, elevator car is descended by down control valve, and the oil hydraulic energy must be lost during the descending stroke. In this paper, hybrid type energy saving unit for a hydraulic elevator is researched to save the hydraulic energy which is lost during the descending stroke. The energy is stored as converted electrical energy, and the saved energy is reused as the auxiliary power for the ascending stroke of elevator car or the main power of other parts. The results show that the output characteristics are stable and good and the research is successful and useful to reuse the saved energy during the descending stroke of elevator car.

• Journal of Drive and Control
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• v.4 no.1
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• pp.2-8
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• 2007

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1998.12a
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• pp.422-428
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• 1998

• Journal of Drive and Control
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• v.1 no.3
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• pp.26-31
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• 2004

• Journal of Drive and Control
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• v.14 no.3
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• pp.50-57
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• 2017

Recently, methods of verification for electro-hydraulic servo controllers are various and the required number of testing controllers is continuously increasing in some specific systems. In this study, a PCB-based electronic simulator of hydraulic actuators is designed and developed to simplify test set-up for controllers and to facilitate alteration for characteristics of the simulator. Several features to reduce required time and manpower for verifying controllers are described. Especially, the simulator is considerably efficient to examine some controllers for different hydraulic actuators in a test. Response characteristics of the simulator are compared with those of real actuators to demonstrate validity of this method. Results reveal utilizing the designed simulator for inspecting controllers is equally effective as using hydraulic actuators.