• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.52-64
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• 1996

This paper presents an active position control of a single-rod cylinder system featuring an electrorheological(ER) fluid-based valve. The ER fluid consisting of silicone oil and chemically treated particles is firstly composed and its Bingham property is tested as a function of imposed electric field. A multi-channel plate type of ER valve is then designed and manufactured on the basis of the field-dependent Bingham model. Performance test of the ER valve is undertaken by evaluating pressure drop with respect to the number of electrode as well as the intensity of the electric field. Subsequently, the ER valve-cylinder system is constructed and its governing equation of motion is derived. A neural control scheme for position control of the cylinder is formulated by incorporating proportional-plus-derivative(PD) controller and implemented. Experimental results of both regulating and tracking control responses are presented in order to demonstrate the efficacy of the proposed ER valve-cylinder control system.

• Journal of Biosystems Engineering
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• v.34 no.5
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• pp.331-341
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• 2009

A double-end rod hydraulic cylinder is widely used with a steering valve for the steering control system in large tractors. For the development of automatic steering controller, the feasibility of using a proportional control valve replacing the conventional manual steering valve to control the position of hydraulic steering cylinder was investigated in terms of the max. overshoot, the steady-state error and the rise time. A simulation model for the electrohydraulic steering system with load using AMESim package was developed to be valid so that the proper control algorithm could be chosen through the computer simulation. It could be concluded that the P-control algorithm was sufficient to control the electrohydraulic steering system, where the control frequency should be no greater than 20 Hz at the P-gain of 5. In particular, the performance of the developed steering controller was satisfactory even at the conditions of varying flow rates and loads.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1305-1306
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• 2010

• Journal of Drive and Control
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• v.16 no.2
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• pp.30-35
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• 2019

EPPR (Electro-hydraulic Proportional Pressure Reducing) valves are pressure control valves. In this study, an independent metering valve (IMV), which is a combination of a spool valve opened and closed with the help of an EPPR valve, was discussed. The overall performance of the valve (IMV) was obtained by the respective modeling and simulation of the system. The valve investigated in this study is to be used for independent metering of hydraulic excavator actuator e.g. boom, arm, bucket etc. To design the model, continuity equations and force balance equations were used. The set of differential equations were then simulated in Simulink using ODE45 option in the configuration toolbox. The valve has to be able to control the flow rate going in and out of the cylinder separately, which is why the particular configuration was needed and selected.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.597-606
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• 2021

Due to the characteristics of the farmland in Korea, forward and reverse shift is the most used. The fatigue of farmers is caused by forward and reverse shifting with a manual transmission. Therefore, it is necessary to improve the convenience of forward and backward shifting. This study was a basic study on the development of a current control system for forward and reverse shifting of agricultural tractors using proportional control valves and a controller. A test bench was fabricated to evaluate the current control accuracy of the control system, and the stability of the controller was evaluated through CPU (central processing unit) load measurements. A controller was selected to evaluate the stability of the proportional valve controller. The stability evaluation was performed by comparing and analyzing the command current of the controller and the actual current measured. The command current was measured using a CAN (controller area network) communication device and DAQ (data acquisition). The actual current was measured with a current probe and an oscilloscope. The control system and stability evaluation was performed by measuring the CPU load on the controller during control operations. The average load factor was 12.27%, and when 5 tasks were applied, it was shown to be 70.65%. This figure was lower than the CPU limit of 74.34%, when 5 tasks were applied and was judged to be a stable system.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.698-703
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• 1990

This paper describes an Electronically-controlled Power Steering system which is developed by the modification of a conventional power steering based on so called rotary valve technology. The steering effort is influenced by the electrohydraulic flow rate control of the pressurized oil to rotary valve. The vehicle speed and the steering angular velocity are used to calculate and output a signal to proportional flow rate control valve by the Electronic Control Unit. The improvement of the steering feel was satisfactory compared with that of the original conventional power steering.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.797-803
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• 2012

Proportional solenoid valves are a modulating type that can control the displacement of valves continuously by means of electromagnetic forces proportional to the solenoid coil current. Because the solenoid-type modulating valves have the advantages of fast response and compact design over air-operated or motor-operated valves, they have been gaining acceptance in chemical and power plants to control the flow of fluids such as water, steam, and gas. This paper deals with the auto tuning of the position controller that can provide the proportional and integral gain automatically based on the dynamic system identification. The process characteristics of the solenoid valve are estimated with critical gain and critical period at a stability limit based on implemented relay feedback, and the controller parameters are determined by the classical Ziegler-Nichols design method. The auto-tuning algorithm was verified with experiments, and the effects of the operating point at which the relay control is activated as well as the relay amplitude were investigated.

• Journal of Drive and Control
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• v.9 no.4
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• pp.32-41
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• 2012

Most diagnosis methods for servo valves requires installing spool displacement sensor or flow sensor as well as pressure sensor. The measurement of flow is hard to implement and many kinds of servovalves or proportional direction valves do not have a built-in spool displacement sensor. In this study, static performances of servovalve or proportional-direction-valve are studied theoretically and a diagnosis technique, which uses only load pressure and input current signal, is assessed. An experimental setup was made based upon a personal computer and the LabVIEW graphical language. A series of diagnosis tests were performed and the analysis results showed it possible to measure the pressure gain, hysteresis and null bias in a relatively simple methodology.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.7-11
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• 2010

Various transmission technologies have been developed to satisfy environmental issues recently. Especially, the technology of the proportional control solenoid valve (PCSV) to ensure high level performance by electronic control has been studied. This study builds an analysis process for designing of the PCSV and characteristic predictions.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.1
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• pp.100-107
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• 1993

In this study, it is analyzed that an electromagnet whose generating force is proportional to constant current through coil in its coperating range. To find arelation between magnetic force and the structure in electromagnet, computer simulation method is used by permeance modeling method. When the electromagnet is applied to flow control valve, the relation between input current and flow is found. In order to get a reliability of computer simluation, the simulation results are compared to the experimental result. As the simulation is processed repeatedlyl. it is found that the gap size between plunger and guide steel and the length of tapered brass ring are important factors in electromaget.