• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.689-696
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• 2000

In this paper, an improved method is proposed to eliminate the chattering for Sliding Mode Controller. The differential-calculus of a switching function is converged to a particular constant or the proportional term so that the chattering in transient state is eliminated in the conventional method. However, by using the improved method, it is converged to its proportional-integral term so that the chattering is eliminated in transient state and steady state both. The computer simulation for brushless DC motor speed controller is used to compare the improved method with the conventional method and to verify the useful effect of the method in this paper.

• Journal of IKEEE
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• v.9 no.1 s.16
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• pp.47-56
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• 2005

A new improved robust variable structure tracking controller is presented to provide an accurately prescribed tracking performance for brushless direct drive(BLDD) servo motors(SM) under uncertainties and load variations. A special integral sliding surface suggested for removing the reaching phase problems can define its ideal sliding mode and virtual ideal sliding trajectory from an initial position of SM. The tracking error caused by the nonzero value of the sliding surface is derived. A corresponding continuous control input with the disturbance observer is suggested to track a predetermined virtual ideal sliding trajectory within a prescribed value under all the uncertainties and load variations. The usefulness of the proposed algorithm is demonstrated through the comparative simulations for a BLDD SM under load variations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.591-597
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• 2017

This study is to develop a vehicle Integrated Dynamics Control System(IDCB) that can stabilize the lateral dynamics and maintain steerability. To accomplish this task, an eight degree of freedom vehicle model and a nonlinear observer are designed. The IDCB independently controls the brake systems of four wheels with a fuzzy logic control and a sliding model control. The result shows that the nonlinear observer produced satisfactory results. IDCB tracked the reference yaw rate and reduced the body slip angle under all tested conditions. It indicates that the IDCB enhanced lateral stability and preserved steerability.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.71-80
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• 2009

The response characteristics of EHA systems are sensitive to the temperature change of working fluid because the temperature of working fluid causes the variation of system parameters such as effective bulk modulus and viscous friction coefficient. In this paper, a precise position control of EHA system using the adaptive sliding mode control system is suggested. The adapted system parameters such as effective bulk modulus and viscous friction coefficient can be used for monitoring failures in the EHA system which has potential applications in the industrial fields. Not only the accuracy of adapted system parameters but also the improved performance and robustness in a given reference position of the cylinder are verified by computer simulation using AMESim software.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.249-252
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• 1996

The inverted pendulum system is mechanical system which can handle the modern control theory and practical applications. In theoretical field, it is used as the experimental device identifying the effects of control method and in applicative field. There are difficulties in designing or linearizing the practical controller because it is so sensitive to the parameter variation and has the highly non-linear characteristic. In this paper, we suggested the systems which compensate the non-linearity throughout the internal control method and designed controller which is robust to the parameter variation using sliding mode.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.396-404
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• 2011

This paper proposes a performance improvement of a grid-connected wind turbine using sliding-mode based direct power control under an unbalanced grid fault. The proposed control method has some advantages for grid connected control. At first, it doesn't need the synchronous phase angle of the grid voltage. It has also fast dynamic characteristics compared with a conventional current controller. In addition, it is suitable for an unbalance compensation control. The effectiveness and robustness of the proposed algorithm are verified by simulations and experiments.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.127-134
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• 2015

In this note, a continuous sliding surface transformed variable structure systems by the saturation function is presented for MIMO uncertain linear plants. A discontinuous sliding surface transformed VSS is proposed theoretically. The closed loop exponential stability together with the MIMO existence condition of the sliding mode on the predetermined sliding surface is investigated. For practical applications, a continuous approximation of the discontinuous VSS is made by means of the saturation function. The discontinuity of the control input as the inherent property of the VSS is much improved in view of the practical aspects. Through a design example and simulation studies, the usefulness of the proposed continuous transformed VSS controller is verified.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.2
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• pp.164-170
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• 2002

Sliding mode control, as a typical method of variable structure control, has the robust characteristics for the uncertainty and the disturbance of the nonlinear system. Because, however, sliding mode control input includes a sign function that Is discontinuous on the predefined switching surface, its applications are primarily limited by the need of alleviation or reduction of chattering. In this paper, we propose a chattering alleviation strategy based on a special nonlinear function and a fuzzy system. By using the proposed control scheme, we can reduce the steady state error. Its tracking performance is as fast as that of conventional method using the fixed boundary layer. Especially, in the proposed method, we can adjust the trade-off between the steady state error and the degree of chattering by regulating the proper range of the output variable of the fuzzy system. To verify the validity of the proposed algorithm, the analysis of the control method using the fixed boundary layer and the computer simulations are shown to compare with them.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1145-1146
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• 2011

최근에 영구자석 동기전동기의 구동방식에서 회전자의 위치 및 속도 검출기가 없는 센서리스 방식이 많이 연구되고 있다. 대부분의 센서리스제어 방식에서 위치 및 속도추정은 전동기 전압방정식으로부터 계산된다. 따라서 파라미터 오차는 센서리스 제어성능에 큰 영향을 미치게 된다. 본 연구는 파라미터 보정에 의한 영구자석 동기전동기의 센서리스 제어 성능 개선에 관한 연구로서 파라미터 보상을 가지는 슬라이딩 모도 관측기를 제안하고 종래의 방식과 비교하여 본 연구에서 제안한 방식을 검증한다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.3
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• pp.30-39
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• 2011

In this note, a systematic design of a new robust nonlinear continuous variable structure control system(VSCS) based on the modified state dependent nonlinear form is presented for the control of uncertain affine nonlinear systems with mismatched uncertainties and matched disturbance. After an affine uncertain nonlinear system is represented in the form of state dependent nonlinear system, a systematic design of a new robust nonlinear VSCS is presented. The uncertainty of the nonlinear system function is separated into the tow parts, i.e., state dependent term and state independent term for extension of target plants. To be linear in the closed loop resultant dynamics and in order to easily satisfy the existence condition of the sliding mode, the transformed linear sliding surface is applied. A corresponding control input is proposed to satisfy the closed loop exponential stability and the existence condition of the sliding mode on the linear transformed sliding surface, which will be investigated in Theorem 1. For practical application, the discontinuity of the control input as the inherent property of the VSS is improved dramatically. Through a design example and simulation studies, the usefulness of the proposed controller is verified.