• 유공압시스템학회논문집
• /
• 제7권1호
• /
• pp.11-19
• /
• 2010

A gas-assisted hydraulic breaker uses both hydraulic and pneumatic energies and the appropriate balance between them mostly effects its performance. Mathematical modeling of the breaker is established and verified by experiment. Through sensitivity analysis using AMESim, the key design parameters are selected, which mostly affect the performance of the breaker. Taguchi method is used to optimize the key design parameters to maximize the output power for long and short strokes through simulation. As the result, the output power as well as the impact energy are increased significantly compared with the existing design. The pressure pulsation in the supply line is reduced to a tolerable level and the dynamic characteristics of the piston displacement is also improved by the optimization.

• 유공압시스템학회논문집
• /
• 제7권3호
• /
• pp.13-19
• /
• 2010

Hydraulic systems are widely used as a power transfer and/or power control system due to its flexibility, controllability, accuracy and high power density. Valve controlled and/or pump capacity controlled systems are normally adopted as a control device, but nowadays pump speed controlled systems are emerging as a new energy-efficient hydraulic control system. In this paper the pump speed controlled system for the cylinder position control of a counter balance circuit is investigated by simulation study and position control experiments were carried out. As a result, the possibility and efficiency of the pump speed controlled system were verified.

• 유공압시스템학회논문집
• /
• 제5권2호
• /
• pp.20-26
• /
• 2008

The most vehicle active suspension system is activated by a hydraulic source and transmission system which has nonlinear characteristics. Even though we have designed a proper controller for this system, it sometimes cannot show remarkable performance characteristics because of many factors that undercut the performance of the hydraulic system, such as nonlinearity, modelling errors, parameter variations etc. So, the robust controller that prevents a system from lowering its performance is needed. In this study, the sliding mode control which is the representative one of robust controllers is adopted to investigate system parameter sensibility. As a result, the sliding mode controller shows robustness to the system parameters variations relative to the other controllers.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.176.3-176
• /
• 2001

Hydraulic servo system has the characteristic of high power in itself, as combining its characteristics with excellent electro equipment that comes from the development of electronics, electro-hydraulic servo system is widely used in industry that are requested high precision and power Electro-hydraulic servo system is characteristic of very strong non-linearity in itself and it is mainly applied the field of the inner or outer fluctuating load or disturbance in industry. Evolutionary computation based on the natural evolutionary process may solve many engineering problems. Algorithms can represent the natural selection in crossovers, mutations, production of the offspring, selection, etc. Nature has already shown is the superiority through ...

• 유공압시스템학회논문집
• /
• 제1권1호
• /
• pp.23-30
• /
• 2004

This paper deals with the issue of trajectory tracking control of a hydraulic excavator using disturbance observer in order to compensate external disturbances occuring from coupling between attachment, asymmetry of a single rod cylinder, and deadzone of main control valve. Disturbance compensation control system with disturbance observer has been constructed for the boom and arm respectively. Simulation results were compared with experimental results to validate the computer simulation system of hydraulic excavator itself. Computer simulation shows that disturbance compensation control is effective for compensating system nonlinearity and thus improves positioning accuracy and trajectory tracking performance. Steady state error has been decreased by adding PI controller to this control scheme.

• 유공압시스템학회논문집
• /
• 제1권1호
• /
• pp.1-9
• /
• 2004

This paper addresses an approximation and tracking control of recurrent neural networks(RNN) using two-dimensional iterative learning algorithm for an electro-hydraulic servo system. And two dimensional learning rule is driven in the discrete system which consists of nonlinear output function and linear input. In order to control the trajectory of position, two RNN's with the same network architecture were used. Simulation results show that two RNN's using 2-D learning algorithm are able to approximate the plant output and desired trajectory to a very high degree of a accuracy respectively and the control algorithm using two same RNN was very effective to control trajectory tracking of electro-hydraulic servo system.

• 유공압시스템학회논문집
• /
• 제1권3호
• /
• pp.14-19
• /
• 2004

The Direct Drive Valve used in this study contains a pressure-feedback-loop in itself, then it can eliminate nonlinearity such as the square-root-term in flow rate calculation and the change of bulk modulus of hydraulic oil. In this study, assuming that the dynamic characteristic of the DDV is modelled as a first order lag system, an parameter identification method using the input data and the output data is applied to obtain DDV's mathematical model. Then, a state feedback controller was designed to implement the force control of hydraulic system, and the control performance was evaluated.

• 드라이브 ㆍ 컨트롤
• /
• 제10권3호
• /
• pp.7-13
• /
• 2013

Hydraulic vane pumps are widely used in various hydraulic systems because of its compactness and light weight. It is well known that the vanes and cam ring are separated by very thin liquid films which result in the EHL state. Contrary to the case of cylindrical roller bearings, the inlet and side boundary pressures are much higher than the atmospheric pressure. In this paper, a numerical solution of the EHL of finite line contacts between the cam ring and vane tip with profiled ends is presented. Using a finite difference method with non-uniform grids and the Newton-Raphson method, converged solutions are obtained for moderate load and material parameters. The EHL pressure distribution and film shape are considerably affected by pump delivery pressure and the side boundary condition applied. Both the maximum pressure and the minimum film thickness always occurred near the edge regions. The present results can be used in the design of optimum vane profile in hydraulic vane pump.

• 한국자동차공학회논문집
• /
• 제8권5호
• /
• pp.207-215
• /
• 2000

This study theoretically investigated the roll-off cleanliness operation to eliminate the built-in contaminants which are primarily the result of manufacturing and assembly procedures first. A rigorous analytical examination of the cleaning process associated with hydraulic systems was performed by developing the general filtration process equations. The sloughing process by which built-in contaminant is entrained in the system fluid was examined during the development of a general analytical expression for sloughing rate. This sloughing rate expression in conjunction with the filtration process equations have lead to a relationship rate expression in conjunction with the filtration process equations have lead to a relationship which describes the flushing and clean-up operation for the hydraulic systems. The effects of the primary roll-off cleanliness factors was discussed and illustrated on the figures. Then, the analytical results was shown to be usefully applied into the design of roll-off flushing equipment for the hydraulic system of a tractor.

• 유공압시스템학회논문집
• /
• 제1권4호
• /
• pp.1-8
• /
• 2004

The optimum design parameters of several hydraulic systems are obtained using the complex method that is one kind of constrained direct search method. First, the parameters of lead-lag controller of the direct drive servovalve is designed using the complex method to satisfy the steady-state error requirement. Second, the optimum locating point of hydraulic cylinder Is determined to minimize the cylinder force in the operation range of rotational sluice gate. For the third application case, the optimum piston area of hydraulic cylinder is determined to minimize the man power to elevate the manually operated sluice gate.