• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.661-664
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• 2002

A control of the body posture and movement is maintained by the vestibular system, vision, and proprioceptors. Afferent signals from those receptors are transmitted to the vestibular nuclear complex, and the efferent signals from the vestibular nuclear complex control the eye movement. The postural disturbance caused by loss of the vestibular function results in nausea, vomiting, vertigo and loss of craving for life. The purpose of this study is to develop a off-vertical rotatory system for evaluating the function of semicircular canals and otolith organs, selectively, and visual stimulation system for stimulation with horizontal, vertical and 3D patterns. The Off-vertical axis rotator which stimulates semicircular canals and otolith organs selectively is composed of a comportable chair, a DC servo-motor with reducer and a tilting table controlled by PMSM. And a double feedback loop system containing a velocity feedback loop and a position feedback loop is applied to the servo controlled rotatory chair system. Horizontal, vertical, and 3D patterns of the visual stimulation for applying head mounted display are developed. And wireless portable systems for optokinetic stimulation and recording system of the eye movement is also constructed. The Gain, phase, and symmetry is obtained from analysis of the eye movement induced by vestibular and visual stimulation. Detailed data were described.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.101-108
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• 2004

An electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to obtain stable control performance. In this report, we applied disturbance estimation and compensation type robust control to all axes in a 3-link electro-hydraulic manipulator. From the results of experiment, it was confirmed that the performance of trajectory tracking and attitude regulating is greatly improved by the disturbance observer, which model is the same for each axis. On the other hand, for the autonomous assembly tasks, it is said that compliance control is one of the most available methods. Therefore we proposed compliance control which is based on the position control by disturbance observer for our manipulator system. To realize more stable contact work, the states in the compliance loop are feedback, where not only displacement but also velocity and acceleration are considered. And we applied this compliance control to Peg-in-Hole insertion task and analyzed mechanical relation between peg and hole. Also we proposed new method of shifting the position of end-effector periodically for the purpose of smooth insertion. As a result of using this method, it is experimentally confirmed that Peg-in-Hole insertion task with a clearance of 0.05［mm］can be achieved.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.11
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• pp.1117-1123
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• 2008

This paper implements dual-kernel system using standard Linux and real-time embedded Linux for the real-time control of intelligent robot systems. Such system provides more useful services including standard Linux thread that is easy to implement complicated tasks and real-time tasks for the deterministic response to velocity control. Here, an open source real-time embedded Linux, XENOMAI, is ported on embedded target board. And for interfacing with motor controller we adopted a real-time serial device driver. The real-time task was implemented with a priority to keep the cyclic control command for trajectory control. In order to validate deterministic response of the proposed system, the performance measurement of the delay in performing trajectory control with feedback loop is evaluated with non real-time standard Linux. The proposed software architecture is anticipated to take advantage of features in both standard Linux and real-time operating systems for the intelligent robot systems.

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.229-244
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• 2015

H-infinity norm relates to the maximum in the frequency response function and H-infinity control method focuses on the case that the vibration is excited at the fundamental frequency, while 2-norm relates to the output energy of systems with the input of pulses or white noises and 2-norm control method weighs the overall vibration performance of systems. The trade-off between the performance in frequency-domain and that in time-domain may be achieved by integrating two indices in the mixed vibration control method. Based on the linear fractional state space representation in the modal space for a piezoelectric flexible structure with uncertain modal parameters and un-modeled residual high-frequency modes, a mixed dynamic output feedback control design method is proposed to suppress the structural vibration. Using the linear matrix inequality (LMI) technique, the initial populations are generated by the designing of robust control laws with different H-infinity performance indices before the robust 2-norm performance index of the closed-loop system is included in the fitness function of optimization. A flexible beam structure with a piezoelectric sensor and a piezoelectric actuator are used as the subject for numerical studies. Compared with the velocity feedback control method, the numerical simulation results show the effectiveness of the proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.462-465
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• 1995

In this research a 2-dimensional motion producer based on two linear motors was developed. When the tester provides some motion through the level attached to the upper moving part of the motion producer, it provides the arbitrary intertia, damping and stiffness characteristics without actual change in physical structure of the motion producer. That is, the active impedance is implemented by controlling input currents supplied to the linear motors. A PID controller with feedforward loop was used to control the currents and pre-processing of input velocity and accleration singals from the encoder and the current singnal from the motor driver circuit are conducted to improve the performance.

• Structural Engineering and Mechanics
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• v.44 no.2
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• pp.127-138
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• 2012

The composite materials may be exposed to environmental (thermal or hygral or both) condition during their service life. The effect of environmental condition is usually adverse from the point of view of design of composite structures. In the present research study the effect of hygrothermal condition on the design of laminated composite structures is investigated. The active fiber composite (AFC) which may be utilized as actuator or sensor is considered in the present analysis. The sensor layer is used to sense the level of response of the composite structures. The sensed voltage is fed back to the actuator through the controller. In this study both displacement and velocity feedback controllers are employed to reduce the response of the composite laminate within acceptable limit. The Newmark direct time integration scheme is employed along with modal superposition method to improve the computational efficiency. It is observed from the numerical study that the laminated composite structures become weak in the presence of hygrothermal load. The response of the structure can be brought to the acceptable level once the AFC layer is activated through the feedback loop.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.5
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• pp.482-488
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• 2009

Dancer system is typically used equipment for attenuation of tension disturbances. In industrial converting machines, a composite type of dancer system is applied which is mixture of active and passive dancer. It includes feedback position control loop of roll with pendulum dancer and its characteristics is different from passive and active one. In this paper, a mathematical model of the pendulum dancer was derived including PI position feedback controller and it was analyzed by using a pole-zero map and bode plot under various conditions. It was found out that velocity, length of span and inertia were associated with the performance of regulation. It was suggested that the length of upstream span should be greater than that of the downstream and the inertia should be smaller for improvement of the performance. The results can be used for design guidelines of the industrial dancer system.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.24-26
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• 2004

The PM(Permanent Magnet) stepping Motor has been used widely to a variety of industries because of the open-loop control characteristic, a relatively large frequency range of velocity control and non-accumulated error of the step angle. Moreover, It has been gradually applied to office automation, machine intelligence, digital appliance, and automobile parts. This paper presents the optimal design results by use of the experimental method. The design variables of the PM stepping motor are shape of the claw-pole, material of core, and air-gap. As a result, a superior claw-pole PM stepping motor for OA machinery was developed.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.1-6
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• 2010

Direct Drive Valves (DDV) with electric closed loop spool position control are suitable for electrohydraulic position, velocity, pressure or force control systems including those with high dynamic response requirements. The spool drive device is a permanent magnet linear force motor which can actively stroke the spool from its spring centered position in both directions. This basic study is carried out to drive the design parameters for developing a domestic DDV. The static and dynamic characteristics of DDV are examined. The simulation results are compared with data of manufacture's catalog to show the validity of the modelling.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.472-477
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• 1994

The lockup clutch is embeded on torque converter of automatic transmission to prevent the efficiency deterioration of torque converter in high speed. For improving fuel consumption rate, it is desirable to engage the lockup clutch earlier. But, it results in degrading shift quality, due to the transient torque. The transient clutch pressure which affects the shifting quality, should be controlled properly. In this study, to solve the problem, it is analysed the hydraulic circuit of lockup system including line pressure regulating circuit, established the nonlinear model, and designed the PID controller. The line pressure is supplied to the lockup clutch through the lockup control valve by switching the lockup solenoid valve on. In order to control the transient pressure actively, it is needed to control the lockup solenoid valve by closed loop control. The lockup solenoid valve is 2-way on-off valve, and is adequate for PWM control. To reduce the pressure chattering, the carrier frequency is increased. Target pressure profile is computed from optimized velocity difference profile throuth dynamic equation of vehicle system.