• 대한전기학회논문지
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• 제43권7호
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• pp.1158-1168
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• 1994

A variable structure control scheme(VSCS) with sliding mode that can be applied to the process with input/output(I/O) delay is proposed and its control performances is evaluated. The proposed VSCS with and output feedback scheme comprises a variable structure controller, a servo dynamic for tracking the set-poing, and a Smith predictor for compensating the effects of time delay. The robustness against the parameter variations and external disturbances can be achieved by the proposed VSCS even when the controlled process includes I/O delay. And the desired transient response is obtained by simple adjustment of the coefficients of the switching surface equation.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권1호
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• pp.22-30
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• 2003

A Coordinate-Transformation Extended Robust Kalman Filter (CERKF) designed in the Krein space is proposed, and then applied to a nonlinear incoming ballistic missile tracking system with parameter uncertainties. First, the Extended Robust Kalman filter (ERKF) is proposed to handle the nonlinearity of measurement equation which occurs whenever the polar coordinate system is transformed into the Cartesian coordinate system. Moreover, linearization error inevitably occurs and deteriorates the tracking performance, which is considerably reduced by the proposed CERKF. Through the simulation results, we show that the proposed CERKF, which uses the measurement coordinate system, has less RMS error than the previous ERKF which is designed in the Krein space using the Cartesian system. We also verify that the robustness and the stability of the proposed filter are guaranteed in two radars: the phased way radar and the scanning radar

• 대한전기학회논문지:시스템및제어부문D
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• 제52권1호
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• pp.31-37
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• 2003

A robust tracking control for nonholonomic dynamic systems is proposed in this paper. Since nonholonomic dynamic systems have constraints imposed on motions that are not integrable, i.e., the constraints cannot be written as time derivatives of some functions of generalized coordinates, advanced techniques are needed for their control. It is shown that if the state of nonholonomic systems is mapped into a bounded space by a coordinate transformation, a robust controller for dynamic models of nonholonomic systems with input disturbances can be designed using sliding mode control. Stability and robustness of the proposed controller are proved in the Lyapunov sense. Numerical simulations on the trajectory tracking of a two-wheeled mobile robot are conducted to validate the effectiveness of the proposed controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2283-2286
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• 2000

Sliding control is a powerful approach to controlling nonlinear and uncertain systems. Conventional sliding mode control suffer' from high control gain and chattering problem. also it needs mathematic! modeling equations for control systems. A Fuzzy controller is endowed with control rules and membership function that are constructed on the knowledge of expert, as like intuition and experience. but It is very difficult to obtain the exact values which are the membership function and consequent parameters. In this paper, without mathematical modeling equations, the plant parameters in sliding mode are estimated by the indirect adaptive fuzzy method. the proposed algorithm could analyze the system's stability and convergence behavior using Lyapunov theory. so sliding modes are reconstructed and decreased tracking error. moreover convergence time took a short. An example of inverted pendulum is given for demonstration of the robustness of proposed methodology.

• 제어로봇시스템학회논문지
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• 제7권12호
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• pp.967-972
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• 2001

In this paper, an adaptive robust nonlinear predictive controller is developed for the continuous time nonlinear systems whose control objective is composed of the system output and its desired value. The basic control law is derived from the continuous time prediction model and its feedback dynamcis shows another from if input and output linearization. In order to cope with the parameter uncertainty, robust control is incorporated into the basic control law and the asymptotic convergence of tracking error to a certain bounded region is guaranteed. For stability and performance improvement within the bounded region, an adaptive control is introduced. Simulation tests for the motion control of an underwater wall-ranging robot confirm the performance improvement and the robustness of this controller.

• 제어로봇시스템학회논문지
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• 제9권8호
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• pp.600-609
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• 2003

A hybrid stabilization approach involving both Passivity Observer/passivity Controller and wave variables is addressed to stabilize the teleoperation system with time delay. To guarantee the stability of master or slave side, Passivity Observer and Passivity Controller are applied. But Passivity Observer and Passivity Controller technique cannot deal with communication delay and even small communication delay cause the system to be unstable. To cope with this problem, wave variables are additionally employed to have robustness to arbitrary delays. To show the validity of our proposed approach, several computer simulation results are illustrated.

• 제어로봇시스템학회논문지
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• 제3권3호
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• pp.214-218
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• 1997

We propose a VSC(Variable Structure Controller) with a PI-type reaching law. In General, conventional VSCs with a reaching law including a discontinuous term have the chattering problem, and thus the system may be unstable due to the disregarded high frequency dynamics in the modeling process. To resolve this problem, the PI-type reaching law is proposed in this paper. The proposed reaching law makes it easy to determine the reaching dynamics as well as the reaching time by utilizing the 2nd-order system analysis. Furthermore, since the discontinous term is not involved in the reaching law, the chattering is considerably reduced. To show the effectiveness of the proposed scheme, the stability of the proposed system is proved by Lyapunov method and the computer simulations are performed for the Ball Balance System.

• International Journal of Control, Automation, and Systems
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• 제5권3호
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• pp.324-328
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• 2007

An analytical framework for fuzzy modeling and control of nonlinear systems using a set of linear models is presented. Fuzzy clustering is applied on the aerodynamic coefficients of a missile to obtain an optimal number of rules in a Tagaki-Sugeno fuzzy rule-set. Next, the obtained membership functions and rule-sets are applied to a set of linear optimal controllers towards extraction of a global controller. Reported simulations demonstrate the performance, stability, and robustness of the controller.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.822-825
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• 1993

A fuzzy logic controller derived from the variable structure control (VSC) theory is designed. Unlike the conventional design of the fuzzy controller, we do not fuzzify the error and the rate of error, but fuzzify the sliding surface. After the fuzzy sliding surface is introduced, the fuzzy rules are defined based on the sliding control theory. It will be shown this sliding mode fuzzy controller is a kind of VSC that introduces the boundary layer in the switching surface and that the control input is continuously approximated in the layer. As a result we can guarantee the stability and the robustness by the help of VSC, which were difficult to insure in the past fuzzy controllers. Simulation results for the inverted pendulum will show the validity.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.1195-1198
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• 1993

We investigate a systematic design procedure of automated rule generation of fuzzy logic based controller for uncertain dynamic systems such as an engine dynamic model.“Automated Tuning”means autonomous clustering or collection of such meaningful transitional relations in the state-space. Optimal control strategies are included in the design procedures, such as minimum squared error, minimum time, minimum energy or combined performance criteria. Fuzzy feedback control systems designed by the cell-state transition method have the properties of closed-loop stability, robustness under parameter variabtions, and a certain degree of optimality. Most of all, the main advantage of the proposed approach is that reliability can be potentially increased even if a large grain of uncertainty is involved within the control system under consideration. A numerical example is shown in which we apply our strategic fuzzy controller design to a highly nonlinear model of engine idle speed contr l.