• 전기학회논문지
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• 제58권2호
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• pp.391-398
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• 2009

In this study, we introduce the design methodology of an optimized fuzzy cascade controller with the aid of hierarchical fair competition-based genetic algorithm(HFCGA) for ball & beam system. The ball & beam system consists of servo motor, beam and ball, and remains mutually connected in line in itself. The ball & beam system determines the position of ball through the control of a servo motor. The displacement change the position of ball leads to the change of the angle of the beam which determines the position angle of a servo motor. Consequently the displacement change of the position of the moving ball and its ensuing change of the angle of the beam results in the change of the position angle of a servo motor. We introduce the fuzzy cascade controller scheme which consists of the outer(1st) controller and the inner(2nd) controller as two cascaded fuzzy controllers, and auto-tune the control parameters(scaling factors) of each fuzzy controller using HFCGA. The inner controller controls the position of lever arm which corresponds to the position angle of a servo motor and the outer controller decides the set-point value of the inner controller. HFCGA is a kind of parallel genetic algorithms(PGAs), and helps alleviate the premature convergence being generated in conventional genetic algorithms (GAs). For a detailed comparative analysis from the viewpoint of the performance results and the design methodology, the proposed method for the ball & beam system which is realized by the fuzzy cascade controller based on HFCGA, is presented in comparison with the conventional PD cascade controller based on serial genetic algorithms.

• 대한물리의학회지
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• 제4권4호
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• pp.221-229
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• 2009

Purpose : The purpose of this study was to assess the effect of bridging stabilization exercises of trunk muscles activity on a Swiss ball according to change of position. Methods：30 healthy university students volunteered to participate in this study. Subjects were required to complete following three exercise positions. Exercise position 1; Supine bridge with Swiss ball, Exercise position 2; Side bridge with Swiss ball, Exercise position 3; Prone bridge with Swiss ball. Surface electromyography from selected trunk muscles was normalized to maximum voluntary isometric contraction. Results : A repeated measures of ANOVA with Duncan's correction was used to determine the influence of exercise type on muscle activity for rectus abdominis, external oblique, erector spinae. The erector spinae of exercise position 1 showed significantly higher muscle activity than exercise position 2, 3(p<.05). The external oblique of exercise position 2, 3 showed significantly higher muscle activity than exercise position 1(p<.05). The rectus abdominis of exercise position 3 showed significantly higher muscle activity than exercise position 1, 2(p<.05) Conclusion： These results indicate that muscle activity can be influenced by addition of a Swiss ball in bridging exercises. It is recommend to use a Swiss ball for trunk stabilization exercise.

• 한국산업융합학회 논문집
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• 제22권4호
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• pp.435-445
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• 2019

Ball screw drives are widely used in industry, and many studies have been devoted on precise, fast and robust control of ball screw drives. In this study, a novel position control algorithm for ball screw drives is proposed, which consist of a PD controller, a friction feedforward and a disturbance observer. The dynamics and the position error of such controller are analyzed to establish an error model, which can be used to predict the resulting position error of the given desired trajectory. Using the proposed error model, the desired trajectory can be modified so that the predicted position error can be compensated in a feedforward manner. The proposed algorithm does not require the model of the system for the error prediction, and thus can be easily applied to conventional control systems. The performance of the system is verified through simulations and experiments.

• 제어로봇시스템학회논문지
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• 제20권11호
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• pp.1136-1141
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• 2014

This paper proposes a new contact type ball tracking sensor to improve the control performance of a low cost ball-and-beam system. It is well-known that the impulsive measurement noise contained in ball position measurement is one of the factors which severely degrades the ball-and-beam control performance. The impulsive ball position measurement noises often appear under the sporadical ball floating on the beam. This fact motivates us to devise a simple analog preprocessing circuit to determine whether the ball loses the contact or not. Once the abnormal ball position measurement is detected, the design problem of the ball tracking sensor can be cast into the typical state estimation problem with missing data. In order to tackle the real-time implementation issue, a steady-state Kalman filter is applied to the problem. Through the experimental results, the usefulness of the proposed scheme is demonstrated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.1940-1942
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• 2001

Magnetic Levitation System(MLS) levitates a steel ball to the desired position in the gravity field using electromagnetic force. MLS consists of light sensor to measure the position of steel ball and an electromagnet to control the position of the ball, that composes a feedback control system. This work does not use a steel ball with constant mass but variable mass steel balls as magnetic levitation targets. Differential equation of electric circuit for electromagnet and motion equation of the movement of steel ball are derived for modeling nonlinear system, that will be linearized at the nominal operating point. We propose a digital control that can levitate a steel ball of which weight is not known for ED-4810 system. Algorithm for estimating ball weight and feedback control are implemented in digital scheme under pentium PC equiped with A/D and D/A converter, ACL-8112, using C-language. Simulation and experimental results are given to show the usefulness of the proposed controller.

• 한국응용과학기술학회지
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• 제36권2호
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• pp.448-455
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• 2019

본 연구는 오르막 퍼팅 시 좌, 우 경사에 따른 볼의 움직임이 어떻게 변화되는지에 대해 알아보는 것을 목적으로 한다. 본 연구를 위해 한국프로골프협회에서 15년 이상의 골프경기 경험이 있는 피험자들이 참여하였고, 본인들의 퍼터를 이용하여 실제 그린과 유사한 환경에서 퍼팅 동작을 수행하였다. 비디오 카메라를 이용하여 피험자들의 오르막 그린 경사에 따른 퍼팅 동작을 수집 후 동작분석을 실시하였으며, 통계적 유의수준을 a=.05로 설정하였다. 연구결과로 좌, 우 경사별 오르막 퍼팅에서 볼의 위치가 왼쪽에서 오른쪽으로 위치 할 때 볼 움직임의 속도와 각속도가 증가하는 것이 확인되었으며, 여러 경사도 중 성공률을 높여야 하는 오르막 퍼팅에서 경사에 따른 어드레스 볼 위치를 변화할 때, 임팩트 시 클럽 페이스와 볼 움직임이 어떻게 변화하는지를 검증하고, 현장적용 측면에 도움을 주는 과학적 자료를 제시하고자 본 연구를 진행하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.501-504
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• 2001

The use of error compensation techniques has been recognized as an effective way in the improvement of the accuracy of a machine tool. The laser measurement method for identifying position errors of machine tool has the disadvantages such as high cost, long calibration time and usage of volumetric error synthesis model. Accordingly, this paper deals with analysis of the position errors of a machine tool using ball bar test without using complicated error synthesis model. Statistical analysis method was adopted in this paper for deriving position errors using hemispherical helix ball bar test.

• 한국산업융합학회 논문집
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• 제11권4호
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• pp.209-216
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• 2008

The ball screw position control system driven by a pneumatic motor using continuous sliding mode is proposed. The design and performance of proposed servo system are presented by means of examples tested under practical service conditions. Results of experimental implementation on the proposed system illustrate the effectiveness of the ball screw position control system driven by a pneumatic motor using continuous sliding mode as a servo pneumatic actuator driven by a pneumatic motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3004-3006
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• 1999

In this paper, we present the ball position and path plain method for the robot-soccer using optical flow. As we compare a optical flow method with a general method within the accurate and effective ball position information of robot-soccer or the path planning, we prove accurate and effective optical flow algorithm to apply ball position and path plain for robot-soccer

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.993-993
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• 2014

Increasing the density magnetic recording of a hard disk drive needs to improve position control of a slider. We have troubles analyzing position of a slider by nonlinear property of pivot ball bearing. Many researches analyze a hard disk drive to change pivot ball bearing part from balls to springs. Pivot ball bearing operates by rotation and movement of balls. This study considers Hertzian contact force when balls contact with outer race to analyze nonlinear movement of a ball bearing. Experiment of this study measures movement of a circular center of a pivot ball bearing. We also verify the simulation results and the experiment results.