• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.4
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• pp.1-6
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• 2005

This paper presents optimization of a pneumatic control system whose design parameters have been optimized so that the desired dynamic characteristics of cylinder position was obtained. The pneumatic system is used as transferring and stacking equipment for solid freeform fabrication system which has been widely used in design verification applications. The pneumatic system mainly consists of pneumatic control valves and cylinders. The system was modeled by using several principles for pneumatic components. The system was optimized to obtain dynamic performance with enough damping to reduce cylinder vibration. A fuzzy controller has been applied to fulfill the dynamic performance requirements of the pneumatic system. The simulation results show that the fuzzy controller is more effective than a PD controller.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.2
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• pp.20-26
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• 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.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.1
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• pp.1-6
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• 2007

The typical hydraulic system of hoist is composed of a hydraulic supply unit, a directional control valve, two pilot operated check valves, two flow control valves. The capacity coefficients of flow control valves should be adjusted for the hoist to operate at moderate speed and minimize the hydraulic energy loss. However, it is difficult to adjust the four capacity coefficients of flow control valves by trial and error for optimal operation. The steady state model of the hoist hydraulic system is derived and the optimal capacity coefficients of flow control valves are obtained using the complex method that is one kind of constrained direct search method.

• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.1
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• pp.23-30
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• 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.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.160-163
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• 1993

In this paper, design of an automatic grinding robot system for car brazing bead is introduced. Car roof and side panels are joined using brazing, and then the brazing bead is processed so that the bead is invisible after painting. Up to now the grinding process is accomplished manually. The difficulties in automation of the grinding process are induced by variation of position and shape of the bead and non-uniformity of the grinding area due to surface deformation. For each car, the grinding area including the brazing bead is sensed and then modeled using a 2-D optical sensor system. Using these model data, the position and the direction of discrete points on the car, body surface are obtained to produce grinding path for a 6 degrees of freedom grinding robot. During the process, it is necessary to sense the reaction forces continuously to prepare for the unexpected circumstances. In addition, to meet the line cycle time it is necessary to reduce the required time in sensing, signal processing, modeling, path planning and data transfer by utilizing real-time communication of the information. The key technique in the communication and integration of the complex information is obtaining in-field reliability. This automatic grinding robot system may be regarded as a jump in the intelligent robot processing technique.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.164-167
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• 1993

Telemanipulator became one of refocused fields with the help of various technology integration concerned. As one of key technologies much simpler opeartion of manipulator by operators and feedback method to operator can be counted. For such purpose virtual reality techniques are being implemented and in this paper tactile feeling among human 5 feelings will be discussed. Movement manipulation in free space and gripper manipulation methods are discussed in combination with operator's organs. Tactile signal of telemanipulator's gripper is also integrated into tactile VR control system. Such tactile VR technology is regarded as one of important roles for advanced robot technology.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.9
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• pp.1462-1469
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• 1997

This study presents a genetic algorithm-based method for optimizing control parameters in fluid power systems. Genetic algorithms are general-purpose optimization methods based on natural evolution and genetics. A genetic algorithm seeks control parameters maximizing a measure that evaluates system performance. Five control gains of the PID-PD cascade controller fr an electrohydraulic speed control system with a variable displacement hydraulic motor are optimized using a genetic algorithm in the experiment. Optimized gains are confirmed by inspecting the fitness distribution which represents system performance in gain spaces. It is shown that optimization of the five gains by manual tuning should be a task of great difficulty and that a genetic algorithm is an efficient scheme giving economy of time and in labor in optimizing control parameters of fluid power systems.

• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.1
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• pp.1-9
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• 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.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.1
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• pp.13-19
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• 2008

The typical hydraulic system of hoist is composed of a hydraulic supply unit, a directional control valve, counter balance valve, and flow control valves. The flow capacity coefficients of flow control valves should be adjusted so that the hoist is operated at moderate speed and the hydraulic energy loss is minimized. However, it is difficult to adjust the flow coefficients of flow control valves by trial and error for optimal operation. Here, the steady state model of the hoist hydraulic system including the differential cylinder circuit is derived and the optimal flow capacity coefficients of flow control valves are obtained using the complex method that is one kind of constrained direct search method.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.4
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• pp.32-37
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• 2008

For the bucket tip position control of the excavator, a traditional hydraulic excavator system was exchanged into an electro-hydraulic one. EPPR valves are attached to the traditional MCV and hydraulic joysticks are replaced by electronic ones to develop the electro-hydraulic system. To control the electronic pump with a good performance, the control logic for the pump is deduced from the AMESim simulation and the experimental method on the test bench. To get a good position control performance of the excavator bucket tip, PI+AntiWindup controller is selected as a position controller. The experimental results showed the good controllability for the electro-hydraulic excavator system on the test bench.