• Journal of the Korean Society for Precision Engineering
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• v.14 no.7
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• pp.73-81
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• 1997

An new class of robust position/force hybrid control law is proposed for uncertain robot manipulators. The uncertainty is nonlinear and (plssibly fast) time-varying. Therefore, the uncertain factors such as imper- fect modeling, friction, payload change, and external disturbance are all addressed. Based on the possible bound of the uncertainty, the controller is constructed and the stability study based on Lyapunov function is presented. To show that the proposed control laws are indeed applicable, the theoretical result is applied to a SCARA-type robot manipulator and simulation result is presented.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.215-216
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• 2015

A suspending force control based on fuzzy logic control is proposed to apply on a novel hybrid bearingless switched reluctance motor(BLSRM) which has separated torque and suspending force pole. In this paper, two fuzzy controller targeted at x-axis direction and y-axis direction are adopted to maintain the shaft at center position, which is very necessary for stable operation of BLSRM. Useing the modified fuzzy logic controller, the suspending system can behave a good performance, and the proposed scheme can be verified by simulation results.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.362-362
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• 2000

The purpose of this thesis is to reduce force ripple of linear pulse motor(LPM) using neural network and to enhance precision. In order to this, we propose a new controller using a neural network to compensate disturbances. The structure includes adaptation block which learns the dynamics of the periodic disturbance and forces the interferences, caused by disturbances. The proposed controller compensates an unmodeled dynamics in the LPM. The neural network changes a current command to reduce position error and force ripple of the LPM. We compare proposed controller with PI controller. Simulation result shows that the proposed controller has better performance than a PI controller without neural network.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.7
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• pp.34-39
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• 2001

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.77-79
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• 1997

This paper describes a nonlinear state observer to identify the rotor position and velocity of a hybrid-type linear pulse motor(LPM). Since the observer's error dynamics of a hybrid-type LPM is highly nonlinear, the stability of the proposed observer is analyzed using an approximated error model. The optimal choices of the proposed observer gains are also discussed. Our extensive simulation study shows that the proposed observer can identify rotor position and velocity and is robust with respect to uncertainties in mechanical parameters and load force.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.278-281
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• 2006

A Hybrid type LPM(Linear Pulse Motor) is designed as single side stator structure. Experimental results are shown that the static and dynamic characteristics. By the computer simulation, the permanent magnet design method is also clarified to desired thrust force. And microstep driver is adopted to the position controller to the designed LPM. The driver suppressed position errors within ${\pm}1501{\mu}m$.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.211-214
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• 1997

This paper describes the position accuracy performance improvement of hybrid type LPM. The harmonics are included in the thrust force component of LPM, those are generated from the the nonlinearity of intrinsic magnetic saturation characteristic and mechanical construction, and so on. In this paper, the performance improvable methode is proposed for the better thrust force by the corrected exciting current injection, and precise position control is achieved.

• Structural Engineering and Mechanics
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• v.46 no.2
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• pp.153-177
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• 2013

Pendulums can be used as passive vibration control devices in several structures and machines. In the present work, the nonlinear behavior of a pendulum-tower system is studied. The tower is modeled as a bar with variable cross-section with concentrated masses. First, the vibration modes and frequencies of the tower are obtained analytically. The primary structure and absorber together constitute a coupled system which is discretized as a two degrees of freedom nonlinear system, using the normalized eigenfunctions and the Rayleigh-Ritz method. The analysis shows the influence of the geometric nonlinearity of the pendulum absorber on the response of the tower. A parametric analysis also shows that, with an appropriate choice of the absorber parameters, a pendulum can decrease the vibration amplitudes of the tower in the main resonance region. The results also show that the pendulum nonlinearity cannot be neglected in this type of problem, leading to multiplicity of solutions, dynamic jumps and instability. In order to improve the effectiveness of the control during the transient response, a hybrid control system is suggested. The added control force is implemented as a non-linear variable stiffness device based on position and velocity feedback. The obtained results show that this strategy of nonlinear control is attractive, has a good potential and can be used to minimize the response of slender structures under various types of excitation.

• Journal of Mechanical Science and Technology
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• v.18 no.4
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• pp.606-621
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• 2004

A dynamic analysis using a hybrid finite element method was performed to characterize the effects of a number of manufacturing errors on bearing forces and critical tooth stress in the elements of a planetary gear system. Some tolerance control guidelines for managing bearing forces and critical stress are deduced from the results. The carrier indexing error for the planet assembly and planet runout error are the most critical factors in reducing the planet bearing force and maximizing load sharing, as well as in reducing the critical stress.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.734-739
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• 2003

Many types of smart materials and control laws are available to actively adjust the structure from various external disturbances. Usually, a certain type of control laws to activate a specific smart material is well established, but the effectiveness of the control scheme is limited by the choice of the smart materials and the responses of the structure. ER fluid is adequate to provide relatively large control force, on the other hand, the PZT patches are suitable to provide small but arbitrary control forces at any point along the structure. It was found that active vibration control mechanism using ER fluid failed to suppress the excitation off the resonant frequency with changed structural characteristics along the frequency response function of the closed loop of the control system. To compensate this additional peak of the closed loop system, PPF control using PZT as an actuator is added to construct a hybrid controller.