• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.1-10
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• 2006

The purpose of this study was to identify critical parameters of a putting performance using jerk cost function. Jerk is the time rate of change of acceleration and it has been suggested that a skilled performance is characterized by decreased jerk magnitude. Four elite golfers($handicap{\leq}2$) and 4 novice golfers participated in this study for the comparison. The 3D kinematic data were collected for each subject performing 5 trials of putts for each of these distances (random order): 1m, 3m, 5m The putting stroke was divided into 3 phases such as back swing. down swing and follow-through. In this study, it was assumed that there exist smoothness difference between elite and novice golfers during putting. The distance and jerk-cost function of Putting stroke for each phase were analyzed Results showed that there was a significant difference in jerk cost function at putter toe (at media-lateral direction) and at the center of mass between two groups by increasing putting distance. From these it could be concluded that jerk can be used as a kinematic parameter for distinguishing elite and novice golfers.

• International Journal of Control, Automation, and Systems
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• v.5 no.6
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• pp.614-620
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• 2007

This paper considers vibration suppression of a mechanical transfer system, where the work is connected with the hand flexibly. We adopt the idea of jerk reduction of the hand. From the equation of motion, we first derive a state equation including the jerk and acceleration of the hand, but excluding the displacement and velocity of the work. Then, we design optimal state feedback for a suitable cost function, and show by simulation that jerk reduction of the hand is effective for vibration suppression of the work and improvement of the settling time. Since state feedback including the jerk and acceleration is not practical, we propose a computation method for optimal feedback using displacements and velocities in the state only.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.5
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• pp.356-364
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• 2019

In this study, major problems, such as licensing problems due to civil complaints, deterioration of facility period, and damage of modules, are exposed to many problems in domestic businesses. Particularly, the photovoltaic (PV) modules applied to early PV systems have been repaired and replaced over the past two decades, and a new module-based aging detection method is needed to expand the maintenance market and stabilize and repair power supplies. PV modules in a PV system use a string that is configured in series to generate high voltage. However, even if only one module of the solar modules connected in series ages, the power generation efficiency of the aged string is reduced. Therefore, we propose a topology that can measure the instantaneous PV characteristic curve to determine the aging module in the solar string and the aging judgment algorithm using the measured PV characteristic curve.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.40-46
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• 2008

This paper presents the optimal motion control for 3-axis SCARA robot by using $LabVIEW^{(R)}$. Specifically, for optimal motion control of 3-axis SCARA robot, we study velocity profile based on finite jerk(the first derivative of acceleration) and optimal gain tunig based on frequency response method by using $LabVIEW^{(R)}$. The velocity optimization with finite jerk aims at generating the smooth velocity profile of robot. Velocity profile based on finite jerk is acquired and applied to 3-axis SCARA robot by using $LabVIEW^{(R)}$. DSA(Dynamic Signal Analyzer) for frequency response method is programed by using $LabVIEW^{(R)}$. We obtain the bode plot of transfer function about 3-axis SCARA robot by using DSA, and perform the gain tuning considering dynamic characteristic based on the bode plot. These experiments have shown that the proposed motion control can reduce vibration displacement and response error rate each 33.7% and 51.7% of 3-axis SCARA robot.

• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.349-357
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• 2014

The purpose of this study was to examine the differences in the performance of dancing motions depending on the level of skill by investigating pulmonary functions, ground reaction force, and jerk cost. The subjects of this study were 12 professional dancers (career: 16 yrs) and 12 amateur dancers (career: 9 yrs) who had similar physical conditions. We selected four motion phases which included the diagonal line motion, the deep flexion motion, the breath motion, and the turn motion with one leg after a small step walking motion, with Goodguri Jangdan. In the experiment, 6 infrared cameras were installed in order to analyze the value of the jerk costs and the force plate form. Finally, we measured the pulmonary functions of the subjects. For data analysis, independent t-tests according to each event, were carried out in the data processing. According to the results of FVC % Predicted, the professional dancers showed greater lung capacities than the amateur dancers, indicating that the level of dancing skill influences lung capacity. Based on the result of the balance test, the professional dancers used more vertical power than did the amateur dancers when performing maximal flexion motion. The professional dancers used a propulsive force of pushing their body forward by keeping the center of body higher while the amateur dancers used a braking power by keeping their bodies backward. When performing medial-lateral movements, the amateur dancers were less stable than the professional dancers. There were no differences in values of jerk costs between the amateur dancers and the professional dancers.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.151-156
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• 2000

The brake system is important to stop train safely. The train is sloped by regenerative brake and pneumatic brake which are continuously blended at service brake. When service is applied to train, it is controlled by train weight and brake command. The jerk limitation function is applied for impulseless smoothing braking. All brake applications in service condition have a function of the variable load control to keep the braking effort in proportion to each car load. All of control function are performed by brake controller. Therefore, we will propose the design of brake control system in order to control efficiently

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1168-1175
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• 1995

The application of cubic spline is presented for basic curve (DRD motion) of cam motion. The purpose of this paper is to achieve better dynamic characteristics than general cam curves. A cubic spline is a piecewise function that is continuous in displacement, velocity and acceleration. The best cam curve is obtained by changing the weights of the object function. So the method can be used to any machine system case by case. For the proposed object function, the result has improved all characteristics such as velocity, acceleration and jerk compared with that of the modified sine curve.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.25-32
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• 2004

This paper presents a new optimization technique of acceleration curve for dynamic structure's movement in which high speed and low vibration are desirable. This technique is based on a genetic algerian with a penalty function for acceleration optimization under the assumption that an initial profile of acceleration curves constitutes the first generation of the genetic algorithm. Especially the penalty function consists of the violation of constraints and the number of violated constraints. The optimized acceleration of the crane through the genetic algorithm and commercial dynamic analysis software has shown to have accurate movement and low vibration compared to the conventional accelerations with jerk discontinuity.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.25.3-25
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• 2001

This paper describes a control method of a robot cooperating with a human. A task in which a robot and a human move an object cooperatively is considered. To develop the force controller of the robot, the characteristics of human arm are investigated. The arm is forced to move along a trajectory in the experiment and the exerted force and the displacement are analyzed, It is found the force characteristics of the human arm is regarded as an optimal damper with minimizing a cost function. Then, the model is implemented to a robot and the cooperation of the robot and a human operator is examined. The effectiveness of the derived model is investigated and the experimental results show that the human moves the object supported by the robot with a minimum jerk trajectory.

• Science of Emotion and Sensibility
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• v.13 no.4
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• pp.613-620
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• 2010

The purpose of this study was to quantitatively evaluate the effects of the secondary task while simulated driving using the variable indicating control of vehicle and smoothness of motion. Fifteen healthy adults having 1~2years driving experience were participated. 9 markers were attached on the subjects' upper(shoulder, elbow, Wrist) and lower(knee, ankle, toe) limbs and all subjects were instructed to keep the 30m distance with the front vehicle running at 80km/hr speed. Sending text message(STM) and searching navigation(SN) were selected as the secondary task. Experiment consisted of driving alone for 1 min and driving with secondary task for 1 min, and was defined driving and cognition blocks respectively. To indicate the effects of secondary task, coefficient of variation of distance between vehicles and lane keeping(APCV and MLCV) and jerk-cost function(JC) were analyzed. APCV was increased by 222.1% in SN block. MLCV was increased by 318.2% in STM and 308.4% in SN. JC were increased at the drivers' elbow, knee, ankle and toe, especially the total mean JC of lower limbs were increased by 218.2% in STM and 294.7% in SN. Conclusively, Performing secondary tasks while driving decreased the smoothness of motion with increased JC and disturbed the control of vehicle with increased APCV and MLCV.