• Journal of Welding and Joining
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• v.16 no.6
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• pp.68-76
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• 1998

A CCD camera with a laser stripe was applied to realized the automatic weld seam tracking. The 3-dimensional information obtained from the vision system made it possible to generate the weld torch path. The adaptive Hough transformation was used to extract laser stripes an to obtain specific weld points. It takes relatively long time to process image on-line control using the basic control using the basic Hough transformation, but it has a tendency of robustness over the noises such as spatter. For this reason, it was complemented with adaptive Hough transformation to have an on-line processing ability for scanning specific weld points. The dead zone, where the sensing of weld line is impossible, was eliminated by rotating the camera with its rotating axis centered at the weld torch. When weld lines were detected, the camera angle was controlled in order to get the minimum image data for sensing of weld lines. Consequently, the image processing time was reduced.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.139-141
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• 2009

This paper presents a design and analysis of torque characteristics of a two-phase SRM(Switched Reluctance Motor) for high speed blower system. To reduce the electrical frequency and core losses at high speed region, In order to reduce torque ripple and torque dead-band, variable rotor air-gap structure is adopted and the air-gap is optimized according to torque production. The optimized torque output is verified by the FEM results.

• Journal of Biosystems Engineering
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• v.32 no.5
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• pp.284-291
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• 2007

This study was to investigate performance of position, basic controls and additional control for man-machine interface on a 3-point hitch of a tractor. The developed additional control was one-touchup, backup, turnup, liftarm limited, PTO on/off and an external control. As a result of experiment, maximum steady state error of response system was lower than $0.8^{\circ}$ and this result showed the function operated normally because the dead band of system set was ${\pm}1^{\circ}$. There was no abnormal situation by switch operation and sensor signal during the performance test. The results of experiment showed the characteristics of the response was sufficient to be used as the position and additional control system for tractors.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.233-235
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• 2000

SVC(Static Var Compensator) is commonly installed with conventional mechanically switched existing reactor or capacitor banks for wide range voltage control. The frequencies of switching of external banks have a great impact on the quality of voltage, but is limited since the life time of the external banks depends severely on the number of switching. So it is a complete multi-objective nonlinear optimization problem with conflicting objectives. This paper presents a method to determine the optimal coordination of SVC and external banks using genetic algorithm based on the multi-objective criteria. Optimal dead band and delay time of external banks is sought for reliable and efficient operation

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.177-186
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• 1999

Dynamic Characteristics of the bridge motions under seismic excitations are analyzed by adopting multi degree - of - freedom system to estimate the effect of restrainers. The applied restrainer is assumed to be a dead - band - system, which has the force clearance and the linear elastic force. The inelastic behaviors of pier and foundation motions are also considered in the study. It is found that the major effect of restrainer is to remarkably decrease the relative displacement between adjacent girders. It is found that restrainers placed on the parts of the bridge system rather than the whole system may increase the unseating failure.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.519-528
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• 2004

For reappearance of driving perception in a driving simulator, a washout algorithm is required. This algorithm can reappear the vehicle driving motions within workspace of the driving simulator. However classical washout algorithm contains several problems such as selection of order, cut-off frequency of filters, generation of wrong motion cues by characteristics of filters, etc. In order to overcome these problems, this paper proposes a new washout algorithm which gives more accurate sensations to drivers. The algorithm consists of an artificial inclination of the motion plate and human perception model with band pass filter and dead zone. As a result of this study, the motion of a real car could be reappeared satisfactorily in the driving simulator and the workspace of motion plate is restrained without scaling factor.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.352-355
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• 1986

In this paper, some candidates suggested for the improvement of the robustness in adaptive control systems are shortly surveyed. Using dead zone concept of error in adaptation process, gain retardation methods such as .sigma.-modification and parameter restriction method are those considered. Feedforward compensation and normalized adaptation technique are also considered. New modeling technique suggested by Donati et al is used for the indirect control of plants containing unmodeled dynamics. The frequency band of input signal, which is used as a test signal and control signal simultaneously, is directly related to the control of plants containing high frequency parastics. Computer simulation results of the some selected algorithms are shown.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.4
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• pp.288-294
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• 2001

In this study, a new PWM method considering the actuation delay of high speed solenoid valves is proposed to improve the response characteristics of electro hydraulic servo systems controlled by high speed solenoid valves. In addition, the decision method for the system gain, the basic period of PWM, and the sampling time is proposed, Since the conventional system controlled by high speed solenoid valves is too slow to apply this method, a high speed driving circuit(Quick-Drive) which enables rapid switching of the high speed solenoid valve at a high speed sampling mode is applied to realize this method. The experimental result shows that it is possible to achieve precision and quiet control without occurrence of limit cycle and wide range dead band.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.136-144
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• 1996

We developed a part of stroke sensing cylinder for position control of automatic excavator and its measurement system. In this paper, for development of stroke sensing cylinder, we consist of 2-axis control instrument system with Hall sensor. A performance of piston rod with magnetic scales is evaluated by the developed measurement system. Furthermore, the position control for good performance of instrument system is achieved by a sliding mode control which is a new method diminishing the chattering in that control by setting 2-dead band along the swtching line. The unknown parameters for sliding mode control are estimated by the signal compression method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1995.11a
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• pp.153-165
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• 1995

When an automatic course-keeping is introduced as is quite popular in modern navigation the closed-loop steering system consists of autopilot device power unit(or telemotor unit) steering gear ship dynamics and magnetic or gyro compass. We derive the mathematical model of each element of the automatic steering system. We provide a method of theoretical analysis on propulsive energy loss related to automatic steering of ships inthe open seas taking account of the on-off mechanism of power unit. Also we paid attention to dead band mechanism of autopilot device which is normally called weather adjustment. Next we make numerical calculation of the effects of autopilot control constants ont he propulsive energy loss for two kinds of ship a fishing boat and an ore carrier. Realistic sea and wind disturbances are employed in the calculation.