• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1063-1066
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• 2003

A flow-meter and its measurement controller was developed for a hydraulic system. This study, for development of positive displacement flow-meter, consist of PIC(Peripheral Interface Controller) controller with MR(Magneto-resistive) sensors. This flow-meter is used valve position indicator for valve control system by hydraulic. The MR sensors are used for the rotation of OVAL gear that detecting device. In the ship environments, consideration that necessary explosive proof. Thus electro device or electro flow-meter needs explosion design for electric circuit. We designed noncontact type flow-meter and evaluated the safety and measuring abilities.

• Journal of Drive and Control
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• v.16 no.4
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• pp.56-64
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• 2019

Recently, as the environmental regulation for earth moving equipment has been tightened, advanced systems using electronic control have been introduced for energy savings. An IMV(Independent Metering Valve), which consists of four 2-way valves, is one of the electro-hydraulic control systems that provides more flexible controllability and potential for energy savings in excavators, when compared to the conventional 4-way spool valve system. To fully realize an IMV, a two-stage bi-directional flow control valve which can regulate the large amount of flow in both directions, should be developed in advance. A simple design that allows proportional flow control to apply the pilot pressure from the current-controlled solenoid to the spring loaded flow control spool and thus valve displacement, is proportional to the solenoid current. However, this open-loop type valve is vulnerable to flow force which directly affects the valve displacement. Force feedback servo of which the position loop is closed by the feedback spring which interconnects the solenoid valve and flow control spool, could compensate for the flow force. In this study, linearity for the solenoid current input and robustness against load pressure disturbance is investigated by linear analysis of the static nonlinear equations for the IMV proportional flow control valve with feedback spring. Gains of the linear system confirm the performance improvement with the feedback spring design.

• Journal of Drive and Control
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• v.12 no.3
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• pp.52-59
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• 2015

An electro hydraulic poppet valve (EHPV) and a variable orifice poppet are assembled in a single block, which is referred to as a RHINO but is also generally called a pilot-operated flow control valve. In this study, we analyzed the structure and the operating principle for a RHINO applied in a 21-ton electric excavator system. The RHINO was experimentally tested to measure the dynamic responses and the pressure energy loss. In this test, we investigated the variation in the conductance coefficient according to the increase in the supply pressure under a constant current and a variation in the flow rate according to the increase in the current. Then, the geometrical shapes and the spring stiffness of the RHINO were considered to develop an analysis model. The characteristics (current-force and hysteresis) for the solenoid based on the experimental data were reflected in the analysis model that was developed, and the reliability of the analysis model was also verified by comparing the experimental and analytical results. The developed model is thus considered to be reliable for use in a wide range of applications, including optimum design, sensitivity analysis, parameter tuning, etc.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.3
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• pp.41-47
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• 2003

In this study an elevator plant model is made with an electro-hydraulic servo valve and a single rod cylinder. A PID controller, a velocity feedback PID controller and a MRAC controller ate designed. Experimental apparatus including an elevator plant model and these controllers are constructed. In case of experiment, external load which is made with a hydraulic cylinder and a pressure control valve burdens varying load to the elevator plant model being driven. With experiment, the control performances of three proposed control methods are compared.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1636-1647
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• 1997

As most of today's automatic transmissions in passenger car adopt a electro-hydraulic control system, the role of electronically controlled solenoid valves occupies an important position and it is essential to predict solenoid transient characteristics in order to design and evaluate the performance of the hydraulic control system. However, in general, both the magnetic and electrical parameters f the solenoid system are hardly known and it is not easy to model this section with moderate complexity although mechanical system could be developed using the classical second order system. This paper presents a dynamic modelling technique of a solenoid valve, that is controlled by pulse width modulation for an automatic transmission, in terms of system identification theory. In nonlinear computer simulation, it is shown that the identified systems which produce magnetic force to input duty cycle for various excitation signals predict the static and dynamic performance very well near the operating point and in experiment conducted to confirm the validity of identification theory for PWM solenoid valve, we find that there is a good agreement between the experimental data and simulation result. Hence, this model can be utilized in the development of pressure control system with PWM solenoid valve.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.46-52
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• 2003

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.565-568
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• 1995

This paper presents the position control of a closed-loop cylinder system using ER(electro-rheological)valve actuators. Following the field-dependent pressure analysis of the ER valve actuators on the basis of Bingham model of ER fluids, a 3 d.o.f. close-loop sylinder system having the heave, roll and pitch motions is proposed. The governing equations of motion are derived using Lagrange's equation, and a control model is established by considering system uncertain parameters such as load conditions. A sliding mode controller which has inherent robustness to system uncertainties is adopted to achieve robust tracking control performance. Tracking control results for sinusoidal trajectory were presented in order to demonstrate the effectiveness of the proposed control system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1139-1143
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• 2003

HILS(Hardware-In-the-Loop Simulation) is a scheme that incorporates hardware components of primary concern in the numerical simulation environment. Due to its advantages over actual vehicle test and pure simulation, HILS is being widely accepted in automotive industries as test benches for vehicle control units. Developed in this study is a HILS system for EHB(Electro-Hydraulic Brake) systems that include a high pressure generator and a valve control system that independently modulates the brake pressures at four wheels. An EHB control logic was tested in the HILS system. Test results under various driving conditions are presented and compared with the VDC logic.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.1
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• pp.95-100
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• 2005

Making the best use of the features of the electro-rheological(ER) valve, a two-port pressure control valve using ER fluids is proposed and manufactured. The ER-Valve characteristics are evaluated by changing the intensity of the electric field and the number of electrode. In addition, the performance of the plate type ER-Valve is investigated by change the particle concentration of the ER fluid. As only with electrical signal change to the ER-Valve in which ER fluid flowing, ER fluid flow is controlled, so development of simple ER-Valves have been tried. The ER-Valves and pressure drop check method are considered to be applied to the fluid power control system. Using the minかnぉd pressure control valve, a one-link manipulator with FHA in robot system is driven. As a result, it is experimentally confirmed that the pressure control valve using ER fluids is applicable to use in driving actuator. If it applies characteristics of the ER fluids, it will be able to apply in the control system fir the ER Valve which occurs from industrial controller(PLC).