• Journal of Biosystems Engineering
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• v.15 no.4
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• pp.290-297
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• 1990

The purposes of this study were to perform theoretical analysis of an electronic-hydraulic hitch control system for position and draft control of tractor implements and to investigate the performance of the control system through computer simulation. Computer simulation models which could predict the responses of the system to the step and sinusoidal inputs in position and draft controls were developed using the simulation package "TUTSIM". The effects of control mode, hydraulic flow rate, deadband, and proportional constant on control performance of the system were investigated. The simulated results were compard with the experimental ones to verify the simulation models. The simulation models appeared to be a useful means for the analysis and the design of the electronic-hydraulic hitch control system.

• Tribology and Lubricants
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• v.29 no.3
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• pp.171-179
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• 2013

In this study, hydraulic systems of the rope brake system of an elevator are modeled to evaluate design parameters that consider friction characteristics such as cylinder pressure, piston displacement, and flow rate. Hydraulic systems of the rope brake system are analyzed using the commercial program AMESim. Analysis modeling data are compared with data obtained from experiments, and the analysis modeling results are found to be reliable. The analysis results will be used to design hydraulic systems of the rope brake system of elevators.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.180-186
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• 2004

The simulator of a vehicle equipped with mechanical transmission and hydraulic accumulator type-braking energy regeneration system is developed using a PC. The simulator receives the shift lever position, the accelerator pedal angle and the brake pedal angle generated by the operator using the keyboard, updates the state variables of the energy regeneration system responding to the input signals, and draws the moving pictures of the accumulator piston and pump/motor plate angle every drawing time on the PC monitor. Also, the operator can observe the shift lever position, the accel pedal angle, brake pedal angle, pressures of accumulators, vehicle speed, hydraulic torque, engine torque and air brake torque representing the operation of braking energy regeneration system through the PC monitor every drawing time. The simulator can be a very useful tool to design and improve the braking energy regeneration system.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.83-86
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• 2005

This paper proposed a hydraulic pump system which uses a variable SR drive and constant capacity pump. The base and maximum speed, torque are determined from displacement capacity of the pump and maximum pressure. The drive system is set to have a minimum power consumption having hydraulic preset pressure, which is operated within a maximum capacity and maximum preset pressure. This is achieved by controlling motor speed and power with feedback signal of pressure of the hydraulic pump. A 2.2kw, 12/8-pole SR motor and DSP based digital controller are designed and prototype drive system is manufactured. The proposed variable speed SR drive system is simulated and tested with experimental set-up. The test results show that the system has some good features such as high efficiency and high response characteristics.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.181-188
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• 2007

This paper presents a torque control method of a hydraulic actuation system for measuring the dynamic stiffness of missile fin actuators. We propose a new control technique called Dual Dynamic Torque Feedback Control(DDTFC), which improves the stability of the torque control system and enables fast tracking of torque command. The developed control scheme is derived from the physical understanding based on mathematical modelling and analysis. The dynamics of hydraulic torque control servo-system is unravelled via physics-based modelling and nonparametric system identification. In order to verify the effectiveness of the method, the experiment is carried out with a test equipment for measuring the dynamic stiffness. The experiment and simulation results show that DDTFC gives stability improvement.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.371-374
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• 1999

This paper present the nonlinear control and the Lyapunov analysis of the nonlinear electro-hydraulic system for steering control of UCT. Electro-hydraulic system itself has the high nonlinearities arisen from the nonlinear characteristics of the pressure-fluid flow in valve and friction in cylinder. These nonlinearities are unmodeled terms in the transfer function. This paper presents the system modeling, analysis of stability based on the Lyapunov function and simulation of the nonlinear hydraulic servo system.

• Journal of Drive and Control
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• v.10 no.1
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• pp.29-36
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• 2013

Excavation is an important work in mining, earth removal and general earthworks. Nowadays, automation in excavator has been studied by several researchers. In the excavator research methods, simulation is one of the low cost methods for applied to test safely. In this paper, designed a virtual hydraulic excavator that with the control and the dynamic. At first, the simulation of hydraulic system for excavator's attachment such as boom, arm and bucket using Matlab/Simhydraulic is presented. Second, the dynamic model of excavator is distributed to combine with the hydraulic system. For controlling this system, electric joysticks are used to operate the orifice open areas in Main Control Valve. The simulation result is described to analysis the performance of this virtual excavator.

• Journal of Drive and Control
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• v.14 no.1
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• pp.23-28
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• 2017

A wind power heat generation system that converts wind power directly to heat instead of electric power is considered in this study. The system consists of a wind turbine part and a heat generation part. The heat generation part is materialized by a hydraulic system including a hydraulic pump, a flow control valve, a hydraulic oil tank, etc. The flow control valve primarily converts hydraulic energy generated in the pump to heat energy. It should have a function of overspeed protection under excessive wind speeds. In this study, a novel flow control valve design is proposed for excellent flow control characteristics under excessive pump driving torque (excessive wind speed). The performance of the suggested valve is analyzed using numerical simulation.

• Journal of Drive and Control
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• v.18 no.3
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• pp.8-15
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• 2021

A rear axle steering (RAS) system is attached to the rear of medium and large commercial vehicles that transport large cargo. The existing RAS systems are driven by electro-hydraulic actuator (EHA), and most commercialized EHAs consist of electric motors, hydraulic pumps, relief valves, prefill valves and cylinders. The prefill valve required for such EHAs is a type of check valve with extremely low cracking pressure that should not allow RAS to have noise or vibration, and the prefill valve prevents system negative pressure as well as unstable operation. Most papers on this topic rely on experiments to predict valve performance, and theoretically detailed modeling of valves or pipelines is performed, but it is very rare to evaluate hydraulic vibration characteristics by analysing everything from hydraulic pumps to valves comprehensively. In this study, we proposed an experimental circuit that can predict the performance of the prefill valve. The study also analysed the pressure-flow pulsation that is transmitted to the valve through the pipeline, and how the transmitted pressure-flow pulsation affects the valve vibration.

• Nuclear Engineering and Technology
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• v.38 no.2
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• pp.185-194
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• 2006

Transient operations for an integral type reactor, SMART-P, have been experimentally investigated using a thermal-hydraulic integral test facility, VISTA (Experimental Verification by Integral Simulation of Transients and Accidents), in order to verify the system design and performance of the SMART-P, a pilot plant of SMART. The VISTA facility was subjected to various accident conditions such as feedwater increase and decrease, loss of coolant flow, and control rod withdrawal accidents in order to elucidate the thermal-hydraulic responses following such accidents and finally to verify the system design of the SMARTP. Full functional control logics have been implemented in the VISTA facility in order to control the required control action for an accident simulation. As one of the sensitivity tests to verify the PRHRS performance, the effects of the initial water level in the compensation tank are experimentally investigated. When the initial water level is 16%, the water is quickly drained and nitrogen gas is then introduced into the PRHR system, resulting in deterioration of the PRHRS performance. It is thus found that nitrogen ingression should be prevented to ensure stable PRHRS operation.