• Journal of The Korean Society of Integrative Medicine
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• v.11 no.2
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• pp.207-219
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• 2023

Purpose : This study was conducted to investigate the changes in trunk movement and ground reaction during sit to stand motion using visual feedback. Methods : Fifteen adults (average age: 23.53±1.77 years) participated in this study. An infrared reflective marker was attached to the body each participant for motion analysis, and the participants performed sit to stand motion while wearing a hat attached with a laser pointer, which provided visual feedback. First, the sit to stand action was repeated thrice without obtaining any visual feedback, followed by a three minute break. Next, the laser pointers attached to hats were irradiated on a whiteboard, located at a distance of 5 m in front of the chairs, on which the participants sat; a baseline was set, and the participants performed stand up movements three times under this condition. A visual feedback was provided to the participants to prevent the laser pointers from crossing the set baseline. During each stand-up movement, the position of the reflective marker attached to the subject's body was recorded in real time using an infrared camera for motion analysis. The trunk movement and ground reaction force were extracted through recorded data and analyzed according to the presence or absence of visual feedback. Results : The results indicated that in the presence of a visual feedback during the sit-to-stand movements, the range of motion of the trunk and hip joints decreased, whereas that of the knee and ankle joints increased in the sagittal plane. The rotation angle of the trunk in the horizontal plane decreased. The left and right movement speed of the center of pressure increased, the pressing force decreased, and the forward and backward movement speed of the trunk decreased. Conclusion : The results suggest that the efficiency and stability of the stand up movement of a body increase when a visual feedback is provided.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.5
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• pp.577-584
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• 1999

In this paper, the double inverted pendulum having a single actuator is built and the controller for the system is proposed. The lower link of the target pendulum system is hinged on the plate to free for rotation in the specified range($10^{\cire}$) on the x-z plane. The upper link is connected to the lower link through a DC motor. The double inverted pendulum built can be kept upright posture by controlling the position of the upper link even though it has no actuator in lower hinge. The algorithm to control the inverted pendulum consists of a state feedback controller within a linearizable range and a fuzzy logic controller coupled with a nonlinear feedback compensator for the rest of the range. Conventional state feedback control is employed, and the fuzzy controller is responsible for generating the reference joint angle of the upper link for the nonlinear feedback compensator which drives a DC motor to generate an indirect torque to the lower joint. As a result, we can get the upright posture of the proposed pendulum system. Simulations and experiments are conducted to show the validity of the proposed controller.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.286-290
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• 2001

This paper presents a full-digital low-level controller for a robotic material transfer system which has been developed for a computer-integrated manufacturing model plant. Compared to conventional analog or hybrid type controllers in current industrial environments, this controller system has some advantages such as strong noise-immunity, easy control algorithm implementation, etc The servo-controller consists of two modules, a position controller and a DC servo motor driver. The position controller operates position feedback routines by receiving position encoder data and sending control outputs to the driver. The position controller is implemented in a full-digital way using a recently introduced microcontroller. The DC servomotor driver controls speeds and torques. The driver consists of a micro-controller and insulated-gate-bipolar-transistors (IGBT). The micro-controller provides control signals, and the IGBT's amplifies the control signals and sends them to the motor.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.3
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• pp.1-6
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• 2010

This paper deals with the issue of simple adaptive position control for a pump-controlled cylinder system. A fixed displacement pump is utilized instead of servo valve and its speed is controlled by AC motor. The whole control system is composed of a pair of interconnected subsystems, that is, a feedback control system and a feedforward control system. From experiments it is shown that position control using simple adaptive control can accomplish significant reduction in position tracking error comparing to a conventional PID control.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.653-660
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• 2000

The automatization by industrial robot of today is merely rely on to the simple position repeating works, but requirements of research and development to the force control which would adapt positively to various restriction or contacting works to environment. In this paper, a learning control algorithm using, neural networks is proposed for the position and force control by a direct-drive robot. The proposed controller is the feedback controller to which the learning function of neural network is added on to and has a character of improving controller's efficiency by learning. The effectiveness of the proposed algorithm is demonstrated by the experiment on the hybrid position and force control of a parallelogram link robot with a force sensor.

• Journal of the Korean Society for Railway
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• v.8 no.2
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• pp.155-160
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• 2005

We propose a tram position estimation method for automatic train control system. The accurate train position should be continuously feedback to control system for safe and efficient operation of trains in railway. In this paper, we propose the sensor fusion method integrating a tachometer, a transponder, and a doppler sensor far estimation of train position. The external sensors(transponder, doppler sensor) are used to compensate for the error of internal sensor (tachometer). The Kalman filter is also applied to reduce the measurement error of the sensors. Simulation results are then presented to verify the usefulness of the proposed method.

• International Journal of Control, Automation, and Systems
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• v.6 no.3
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• pp.386-393
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• 2008

A position control method for interpolating aspherical grinding and polishing tool path was reviewed and experimented in a nano precision machine. The position-base algorithm was reformed from the time-base algorithm, proposed in the previous study. The characteristics of the algorithm were in the velocity control loop with position feedback. The aspherical surface was divided by an interval at which each velocity and acceleration were calculated. The theoretical velocity was corrected by position error during processing. In the experiment, a machine was constructed and nano-scale linear encoders were installed at each axis. Relation between process parameters and the variation of position error was monitored and discussed. The best result from optimized parameters showed that the accuracy was 150nm and improved from the previous report.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1037-1038
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• 2010

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.183-187
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• 1989

This paper presents on approach to the position control of a robot manipulator by using a decentralized adaptive control scheme. The large scale system is regarded as the system which consists of many subsystems having interconnection. In each subsystem, a local control system is composed by feedforward and feedback component, one computes the nominal torque from the Newton-Euler equation, the other computes the perturbation equation which reduce the position error of the manipulator along the nominal trajectory. A computer simulation studies was conducted to evaluate and compare the performances of the proposed manipulator control scheme with those of the PD control and centralized control schemes.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.299-304
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• 1988

This paper describes the application of the variable structure control(VSC) concept for the position control of electro-hydraulic servomtor system. The basic philosopy of VSC is that the structure of the feedback control is altered as the state crosses discontinuity surfaces in the state surface with the result that certain desirable properties are achieved. The switching of the control function yields total(or selective) invariance to system parameter variations and disturbances, and closed loop eigen value placement in time-varing and uncertain systems.