• Special Issue of the Society of Naval Architects of Korea
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• 2008.09a
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• pp.136-143
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• 2008

This paper presents the application of a robot which aims at grinding automatically welding-bead remained in the removal job of working pieces for shipbuilding. In specific, the investigation on this application is composed of two parts; one topic is on the development of a robot platform vertically movable on a steel plate of hull, while the other topic is of the development of a grinding tool mechanism in order to remove welding-beads by using a diamond wheel installed on a servo cylinder (which can result in high working pressure on the grinding wheel). Besides, the development of a vision system for tracking welding-beads as well as recognizing welding surfaces is added for the convenience of this robot application to the removal of welding-beads remained in the working pieces for shipbuilding.

• Journal of Drive and Control
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• v.18 no.3
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• pp.1-7
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• 2021

In a hydraulic control system, since a hydraulic cylinder drives a relatively large mass of an object, an external load force acts as a disturbance on the control performance of the system. Additionally, as the hydraulic system is used for a long period, there are disturbances that occur gradually, such as a drop in supply pressure because of abrasion of the pump, oil leakage from a valve, and oil leakage from a cylinder. In this study, a state feedback controller based on a linearization technique is applied. To prevent the performance degradation of the controller from the load disturbance, an Extended Luenberger observer (ELO) is used for the Extended system. The case of using the proportional controller, which is a representative linear controller, and the result of using the controller designed in this study are compared and reviewed through simulation. Also, we propose an experimental gain-setting method for a state feedback controller that can be used at industrial sites, and examine how the stability and control performance of the system changes because of the disturbance inputs through the experimental results.

• 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.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1215-1220
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• 2008

The aim of this paper is to perform a finite element analysis that will have the ability to predict the seal performance characteristics, such as deformation, contact load and friction and also is to provide a means of potential seal designs, which can reduce the time and cost of designing the performance of the seal. The material property tests of elastomer seal are performed to obtain the hyperelastic properties and The Mooney-Rivlin constants are determined from these test results. A 2D modelling of the seal cross section is performed to simulate the contact behavior between the seal on the piston and the cylinder bore under operation conditions. The deformation behavior, contact load and friction of an elastomer seal is analyzed by a finite element method which performs three analytic phases of interference fit, the variations of pneumatic pressure and piston movement under the operational conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.603-609
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• 2004

This paper deals with the issue of Neural Network-based control for a rodless pneumatic cylinder system which is utilized for a pneumatic XY-plotter. In order to identify the system design parameters, the open loop response of a pneumatic rodless cylinder controlled by a pneumatic servovalve is investigated by applying a self-excited oscillation method. Based on the system design parameters, the PD feedback compensator is designed and then Neural Network is incorporated with it. The experiment of a trajectory tracking control using a PD-NN has been performed and proved its excellent performance by comparing with that of a PD feedback compensator.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.111-112
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• 2006

A new MR cylinder with built-in valves using Magneto - Rheological fluid (MR valve) is proposed for fluid power control systems. The MR fluid is a newly developed functional fluid whose obvious viscosity is controlled by the applied magnetic field intensity. This MR cylinder, which is composed of cylinder with small clearance and piston with electromagnet, has the characteristics of simple, compact and reliable structure. This paper presents a method to control the pressure of MR cylinder by using Generalized Predictive Control (GPC) algorithm. The differential pressure is controlled by applying magnetic field intensity to MR fluid. The use of GPC controller is to generate a control sequence by minimizing a cost function in such a way that the future system output is driven close to reference over finite prediction horizons. Experimental results from real time control using GPC method compared with conventional PID control method are also shown in this paper.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.102-113
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• 1996

An experimental and theoretical study on a pneumatic servo system has been conducted using on-off valves and a pneumatic cylinder. A V/I converter has been designed for rapid rising and falling of the solenoid current, which significantly improves the positioning accuracy and settling time of the servo system by shortening the valve opening time. Pulse width modulation was modified to operate on-off valves effectively. A state feedback controller which feeds back position, velocity and acceleration is used to control the system. The influence of controller gains on the system performance is studied to develop a scheme that automatically adjusts the gains using fuzzy logic theory. It is shown experimentally that the proposed fuzzy logic tuner works satisfactorily. A new method for measurements of valve effective areas is proposed, and a partially polytropic model is applied to simulation of the pneumatic system. Simulated results show good agreement with experimental data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.614-617
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• 1995

The unbalance heavy-load elevation driving systems are composed of rotating link-mechanism and hydraulic cylinder which actuates elevation and compensates the static unbalance moment of supporting mechanism. Control and compensation of gun driving is very difficult because these mechanism imply highly nonlinearities due to hydraulic fluid characteristics and mechanical rotation of link-mechanism. In this study, through the analysis of manufactured link-mechanism, the optimal link-mechanism design of the elevating system is suggested. Also to estimate the control performance of the unbalance heavy-load elevation servo-control driving system, modeling and simulation of the system are carried out. To prove the reliability of performance estimation program,simulation results are compared with the experimental results. Both results are similar, therefore this program will be helpful to study the control performance improvement of the system.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.2
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• pp.1-7
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• 2011

An inverted pendulum mounted on a cart and actuated by a hydraulic servo cylinder was designed and built. Position information of the cart was acquired via a potentiometer and a angle of the pendulum was sensed by an incremental encoder. These were collected by a DAQ board and processed through the Real-Time Windows Target software(included in simulink). A simulink graphical program was implemented as a controller of the hydraulic system that governed the motion of the cart in order to maintain vertical balance of the inverted pendulum. The purpose of this study is to develop an electro-hydraulic inverted pendulum system for a modeling and controling the intrinsic unstable system. The simulation results were compared with the experimental and verified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1619-1625
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• 1997

This paper concerns a 2-axis PR type pneumatic manipulator system translating in vertical and rotating in horizontal directions. A simplified linear model is mathematically formulated similar to the pneumatic acturators in dynamic responses in order to devise an appropriate position control scheme. A PD controller preceding the on/off solenoid valve turns out not only economical but also effective in reducing rise time and amplitude of limit cycles, if its control gains are determined on the basis of frequency response. And, additional implementation of symmetric or asymmetric deadband at the PD controller output greatly helps minimize valve opening numbers, positional error, and undesirable direction-dependent property due to the gravitational load. Such a control concept is synthesized through numerical simulations and next applied to the experimental set-up, featuring enhanced positional servo characteristics.