• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10a
• /
• pp.463-468
• /
• 1990

A VSC law is derived for the attitude control of an orbiting spacecraft in the presence of disturbance and parameters variation using reaction jets. The switching surface was chosen to be a linear function of tracking error, its derivative and integral. Simulation results are presented to show that in the closed-loop system, precise attitude control is accomplished in spite of uncertainty in the system.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.575-577
• /
• 1987

A new control method for DC motor position control with variable structure is presented. The proposed method uses the desired trajectory with optimal input satisfying the given performance requirement as the switching curve and is insensitive to parameter variation and disturbance. To show the validity of the proposed method, digital computer simulation is performed. And the result is compared with that of the optimal state feedback.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.348-348
• /
• 2000

In this paper, we present a fuzzy moving sliding mode control for two-degrree-of-freedom robotic manipulator. 17he sliding surface parameters are designed by fuzzy inference. The proposed sliding mode control makes the error always remain on the surface from beginning and therefore, the system is insensitive to system uncertaintics and external disturbances. Simulation results show the effectiveness of proposed scheme.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.321-321
• /
• 2000

This paper presents a sliding mode controller based on variable structure for the tip position control of a single-link flexible manipulator. Dynamic equations of a single-link flexible manipulator are derived from the Euler-Lagrange equation using a Lagrangian assumed modes method based on Bernoulli-Euler Beam theory. Simulation results are presented to show the validity of the system modeling, controller design.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.1
• /
• pp.60-67
• /
• 1989

In this paper, a methodology is developed to remove the high frequency chattering phenomenon which is the common drawbacks of variable structure control(VSC) system. An improved control law is proposed to achieve continuous control input whose terms are continuous functions during the control process under switching plane, which removes chattering and is robust as well. The methodology developed in this paper is applied to attitude control for spacecraft and the simulated results are compared with those of typical VSC methodology.

• Bulletin of the Korean Chemical Society
• /
• v.19 no.4
• /
• pp.434-436
• /
• 1998

The mechanism of nucleophilic displacement was studied by using three variable systems of ${\rho}_X,\; {\rho}_Y,\; and {\rho}_Z$ obtained from the change of substituent X, Y, and Z for the reaction of (Z)-substituted benzyl (X)-benzensulfonates with (Y)-substituted thiobenzamides in acetone at 45 ℃. The results ${\rho}_Z$<0 and ${\rho}_YZ$>${\rho}_XZ$ indicate that this reaction series proceeded via a dissociative $S_N2$ mechanism. The prediction of the movement of TS by using the sign of ${\rho}_XZ{\cdot}{\rho}_{YZ}$ accorded with the Hammond postulate.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1997.04a
• /
• pp.131-136
• /
• 1997

This paper represent the variable structure adaptive mode control technique which is new approach to implement the robust control of industrial robot manipulator with external disturbances and parameter uncertainties. Sliding mode control is a well-known technique for robust control of uncertain nonlinear systems. The robustness of sliding model controllers can be shown in contiuous time, but digital implementation may not preserve robustness properties because the sampling process limits the existence of a true sliding mode. the sampling process often forces the trajectory to oscillate in the neighborhood of the sliding surface. Adaptive control technique is particularly well-suited to robot manipulators where dynamic model is highly complex and may contain unknown parameters. Adaptive control algorithm is designed by using the principle of the model reference adaptive control method based upon the hyperstability theory. The proposed control scheme has a simple sturcture is computationally fast and does not require knowledge of the complex dynamic model or the parameter values of the manipulator or the payload. Simulation results show that the proposed method not only improves the performance of the system but also reduces the chattering problem of sliding mode control, Consequently, it is expected that the new adaptive sliding mode control algorithm will be suited for various practical applications of industrial robot control system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.10
• /
• pp.2634-2638
• /
• 2009

The variable structure control(VSC) with sliding mode is the discontinuous control law in leads to undesirable chattering in practice. As a method solving this problem, in this paper, we propose a scheme of the VSC with neural network sliding surface. A neural network sliding surface with boundary layer is employed to solve discontinuous control law. The proposed controller can eliminate the chattering problem of the conventional VSC. The effectiveness of the proposed control scheme is verified by simulation results.

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

• The Journal of the Acoustical Society of Korea
• /
• v.16 no.2E
• /
• pp.14-20
• /
• 1997

The future teleconferencing systems will need an appropriate system which controls properly the acoustic echo for the convenient communication. The conventional acoustic echo cancellation algorithms involve large adaptive filters identifying the impulse response of the echo path. The use of adaptive IIR filters appears to be a reasonable way to reduce computational complexity. Effective cancellation of acoustic echo presented in teleconferencing system requires that adaptive filters have a rapid convergence speed. One of the main problems of acoustic echo cancellation techniques is that the convergence properties degrade for an highly correlated signal input such as speech signals. By the way, the introduction of linear prediction filers onto the structure of the acoustic echo cancellation represents one approach to decorrelate the speech signal. And variable step-size LMS algorithm improves the convergence speed through a little increasing of computational complexity. In this paper, we applied these two methods to the acoustic echo canceller(AEC) and showed that these methods have better performances than the conventional AEC.