• International Journal of Ocean System Engineering
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• 제3권2호
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• pp.50-60
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• 2013

This paper presents a novel approach to the design of an adaptive fuzzy sliding mode controller for depth control of an autonomous underwater vehicle (AUV). So far, AUV's dynamics are highly nonlinear and the hydrodynamic coefficients of the vehicles are difficult to estimate, because of the variations of these coefficients with different operating conditions. These kinds of difficulties cause modeling inaccuracies of AUV's dynamics. Hence, we propose an adaptive fuzzy sliding mode control with novel fuzzy adaptation technique for regulating vertical positioning in presence of parametric uncertainty and disturbances. In this approach, two fuzzy approximator are employed in such a way that slope of the linear sliding surface is updated by first fuzzy approximator, to shape tracking error dynamics in the sliding regime, while second fuzzy approximator change the supports of the output fuzzy membership function in the defuzzification inference module of fuzzy sliding mode control (FSMC) algorithm. Simulation results shows that, the reaching time and tracking error in the approaching phase can be significantly reduced with chattering problem can also be eliminated. The effectiveness of proposed control strategy and its advantages are indicated in comparison with conventional sliding mode control FSMC technique.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.289-292
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• 1997

In this paper, a continuous sliding mode controller for robot manipualator is proposed. The proposed scheme guarantees that the tracking error converges to zero maintaining the smoothness of the actual control signal. In order to estimate the acceleration data, a sliding mode observer is used, and the stability of the closed-loop system is shown.

• 대한전자공학회논문지SP
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• 제46권3호
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• pp.138-142
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• 2009

본 논문에서는 보이스 피싱 (Voice Pishing) 예방을 위한 알고리즘을 최소 분류 오차 기법 (Minimum Classification Error)을 기반으로 제한하다. 휴대폰으로 전송되어진 신호를 기반으로 3GPP2 Selectable Mode Vocoder (SMV)의 복호화 과정에서 자동적으로 추출되는 중요 특징벡터를 사용하여 Gaussian Mixture Model (GMM)을 구성하고 이를 기반으로 구해지는 로그(Log) 기반의 우도 (Likelihood)를 사용한 변별적 가중치 학습을 사용하여 보이스 피싱 예방을 위한 검출 알고리즘을 제안하다. 실험 결과 제안된 보이스 피싱 알고리즘이 기존의 방법에 비해 우수한 성능을 보인 것을 알 수 있었다.

• 한국공작기계학회논문집
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• 제18권1호
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• pp.90-102
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• 2009

In this paper, a tracking control problem for a mechanical servo system with nonlinear dynamic friction is treated. The nonlinear friction model contains directly immeasurable friction state and the uncertainty caused by incomplete modeling and variations of its parameter. In order to provide the efficient solution to these control problems, we propose a hybrid control scheme, which consists of a robust friction state observer, a RFNN estimator and an approximation error estimator with sliding mode control. A sliding mode controller and a robust friction state observer is firstly designed to estimate the unknown infernal state of the LuGre friction model. Next, a RFNN estimator is introduced to approximate the unknown lumped friction uncertainty. Finally, an adaptive approximation error estimator is designed to compensate the approximation error of the RFNN estimator. Some simulations and experiments on the mechanical servo system composed of ball-screw and DC servo motor are presented. Results demonstrate the remarkable performance of the proposed control scheme.

• Journal of Advanced Marine Engineering and Technology
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• 제24권1호
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• pp.82-87
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• 2000

The component mode synthesis method(CMS) used for vibration analysis has demerit that error becomes larger, as degree of natural frequency grows higher. The reason of error occurrence is that Guyan's static reduction is used and the number of modes taken in each component is deficient. This paper proposes the substructure synthesis method using dynamic reduction to solve the problem from the component mode synthesis method. Computer simulation for the proposed method. FEM and the component mode synthesis method(CMS) on a rectrangular plate has been carried out to prove the avilability of the proposed method.

• 한국생산제조학회지
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• 제9권5호
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• pp.65-72
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• 2000

This paper presents the study of the tension control in a web transfer system. In this study the sliding mode controller is applied to a time-varying nonlinear mathematical model. The model was derived to consider the effects of changing the roll radius in tension variation during winding and unwinding. The uncertainty in modeling may be due to unmodelled dynamics, on variations in system model. Designed sliding mode controller made the system error always staying in the suggested surface from the beginning. Through this, system is maintained to be robust against a disturbance and uncertainty. To verify the designed controller has a good performance, various inputs such as desired velocity, step input, and trapezoidal input are applied. When the sliding mode controller was used, the system(the tension control) performance was improved comparing to the PID controller. The robustness of the controller with respect to an estimation error was verified through simulations.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.535-549
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• 2004

This paper proposes a sliding mode controller with fuzzy adaptive perturbation compensator(FAPC) to get a good control performance and reduce the chatter, The proposed algorithm can reduce the chattering because the proposed fuzzy adaptive perturbation compensator compensates the perturbation terms. The compensator computes the control input for compensating unmodeled dynamic terms and disturbance by using the observer-based fuzzy adaptive network(FAN) The weighting parameters of the compensate. are updated by on-line adaptive scheme in order to minimize the estimation error and the estimation velocity error of each actuator. Therefore, the combination of sliding mode control and fuzzy adaptive network gives the robust and intelligent routine to get a good control performance. To evaluate the control performance of the proposed approach, tracking control is experimentally carried out for the hydraulic motion platform which consists of a 6-DOF parallel manipulator.

• International Journal of Precision Engineering and Manufacturing
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• 제3권4호
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• pp.94-100
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• 2002

The conventional sliding mode control (SMC) technique requires a priori knowledge of the upperbounds of disturbances and/or modeling uncertainties to assure robustness. This, however, may not be easy to obtain in practical situation. This paper presents a new methodology, a sliding mode control with disturbance estimator (SMCDE), which offers a robust control performance without a priori knowledge about the disturbance. The proposed technique is featured by an average value of the imposed disturbance over a certain period. A nonlinear spring-mass-damper system and a two-link robot system are adopted as illustrative application examples. Control performances such as estimation error and tracking error are compared between the proposed methodology and conventional scheme.

• 전자공학회논문지SC
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• 제40권6호
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• pp.1-7
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• 2003

본 논문은 비선형 시스템에서 시스템의 출력이 주기적인 특징을 가지는 궤적을 따라가도록 하는 슬라이딩 모드 반복 제어기를 소개한다. 본 논문에서 제안하는 제어기는 전체 시스템을 안정화시키며 출력오차를 어떤 범위 안으로 지수적으로 수렴시키는 슬라이딩 모드 제어기와 추적 오차의 수렴을 위해서 사용되는 반복 제어기로 구성되어 있다. 본 논문에서는 제안하는 슬라이딩 모드 제어기는 기존의 방법과는 다르게 제어입력의 크기가 추적오차의 크기에 비례하게 되어 있어서 시스템의 차수를 올리지 않고 정상상태에서의 채터링(chattering) 문제를 크게 개선하는 특징을 가지고 있다.

• 제어로봇시스템학회논문지
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• 제12권11호
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• pp.1081-1087
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• 2006

Generally, biped walking is difficult to control because a biped robot is a nonlinear system with various uncertainties. In this paper, we propose a hybrid sliding-mode control method using a WNN uncertainty observer for stable walking of the 5-link biped robot with model uncertainties and the external disturbance. In our control system, the sliding mode control is used as main controller for the stable walking and a wavelet neural network(WNN) is used as an uncertainty observe. to estimate uncertainties of a biped robot model, and the error compensator is designed to compensate the reconstruction error of the WNN. The weights of WNN are trained by adaptation laws that are induced from the Lyapunov stability theorem. Finally, the effectiveness of the proposed control system is verified through computer simulations.