• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.6
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• pp.1-6
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• 2000

In this paper, the problem of the stability analysis for linear neutral delay-differential systems with nonlinear perturbations is investigated. Using Lyapunov second method, a new delay-dependent sufficient condition for asymptotic stability of the systems in terms of linear matrix inequalities (LMIs), which can be easily solved by various convex optimization algorithms, is presented. A numerical example is given to illustrate the proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.472-477
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• 1996

This paper presents a new approachtothe design of adaptive control system using DSPs(TMS320C30) for robotic manipulators to achieve trajectory tracking by the joint angles. Digital signal processors are used in implementing real time adaptive control algorithms to provide an enhanced motion control for robotic manipulators. In the proposed control scheme, adaptation laws are derived from the improved Lyapunov second stability analysis method based on the adaptive model reference control theory. The adaptive controller consists of an adaaptive feedforward controller, feedback controller, and PID type time-varying auxillary control elements. The prpposed adaptive control scheme is simple in structure, fast in computation, and suitable for implementation of real-time control. Moreover, this scheme does not require an accurate dynamic modeling, nor values of manipulator parameters and payload. Performance of the adaptive controller is illustrated by simulation and experimental results for a SCARA robot.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.12
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• pp.518-525
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• 2006

This paper presents the adaptive robust control method for the flight control systems with model uncertainties. The proposed control system can be composed simply by a combination of the adaptive dynamic surface control (DSC) technique and the self recurrent wavelet neural network (SRWNN). The adaptive DSC technique provides us with the ability to overcome the 'explosion of complexity' problem of the backstepping controller. The SRWNNs are used to observe the arbitrary model uncertainties of flight systems, and all their weights are trained on-line. From the Lyapunov stability analysis, their adaptation laws are induced and the uniformly ultimately boundedness of all signals in a closed-loop adaptive system is proved. Finally, simulation results for a high performance aircraft (F-16) are utilized to validate the good tracking performance and robustness of the proposed control system.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.172-175
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• 2001

This paper presents a new energy function reflecting the damping effect in multi-machine power systems. The Lyapunov direct method provides precise and rigorous theoretical backgrounds for stability analysis of nonlinear systems. Incorporating damping effects into accurate estimates of the domain of attraction, which is a minor but crucial point, has been attempted with long history to yield partial success for single machine systems. In this paper, the damping-reflected energy function presented in the previous work has been generalized for application to multi-machine systems. The generalized energy function is tested for the WSCC 9-bus system to show the semi-negativeness of its time derivative.

• Proceedings of the KIEE Conference
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• summer
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• pp.242-244
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• 2004

본 논문에서는 전력계통에서 에너지 함수를 이용하여 탭의 영향이 고려된 전압안정도 해석방법을 제시하였다. 전력계통의 전압안정도 해석은 부하단 변압기 탭의 특성과 밀접하게 연관되어 있으며 역학적 등가모델(EMM)을 이용하여 탭의 영향을 고려한 새로운 에너지함수를 유도하였다. 이 에너지 함수는 Lyapunov 함수의 조건을 만족시키며, 유도된 에너지함수로부터 안정평형점과 불안정평형점을 구하여 두 점에서의 에너지의 차이로서 전압붕괴를 예측할 수 있음을 1기 무한대 모선에 대하여 검증해 보았다.

• Journal of Ocean Engineering and Technology
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• v.16 no.4
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• pp.54-60
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• 2002

본 연구는 슬라이딩 모드개념을 이용한 비선형 견실 상태 추정기의 선박 위치제어시스템에 대한 적용에 관한 연구이다. 개발된 상태추정기는 제어기 설계에 필요한 동적 모델에 있어서 고려되지 않은 비선형성과 불확실성 및 외란이 존재하더라도 견실히 상태추정을 수행할 수 있는 장점을 가지고 있다. 또한 선박의 속도 및 유체력으로 인한 외란의 추정이 가능하며, 파랑으로 인한 고주파 운동응답을 여과시킴으로 불필요한 작동기의 동작과 과도한 연료손실을 방지할 수 있다. 특히 상태 추정기에 불연속 함수를 도입함으로 비선형성, 외란 및 불확실성에 대해 강인한 특성을 가지고 있다. 제안된 상태추정기에 기초하여 Observer backstepping 방법을 이용한 위치 제어기가 설계되었으며, 제어시스템의 안정성을 Lyapunov 법을 이용하여 검증하였다. 일련의 수치 시뮬레이션을 수행함으로서 제안된 상태추정기 및 제어기의 선박위치제어시스템으로서의 성능을 예증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.45.3-45
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• 2002

$\textbullet$ In this paper, a new method of estimating the rotor speed and flux is proposed. $\textbullet$ The stator currents and voltages are measurable and all the system parameters are known. $\textbullet$ There are a number of common terms in the error dynamics. $\textbullet$ This is utilized to find a simpler error model involving some auxiliary variables. $\textbullet$ Using this error model, the state estimation problem is converted into a parameter estimation prob. $\textbullet$ Some stability properties are given on the basis of Lyapunov analysis. $\textbullet$ The effectiveness of the proposed scheme is demonstrated through simulations and experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.4
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• pp.312-316
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• 2004

In this paper, it is presented an adaptive robust control system to implement real-time control of a robot manipulator. There are Quantitative or qualitative differences between a real robot manipulator and a robot modeling. In order to compensate these differences, uncertain factors are added to a robot modeling. The uncertain factors come from imperfect knowledge of system parameters, payload change, friction, external disturbance, etc. Also, uncertainty is often nonlinear and time-varying. In the proceeding work, we proposed a class of robust control of a robot manipulator and provided the stability analysis. In the work, we propose a class of adaptive robust control of robot manipulator with bound estimation. Through experiments, the proposed adaptive robust control scheme is proved to be an efficient control technique for real-time control of a robot system using DSP.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.597-602
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• 1988

In this paper, we consider conventional and modified proportional navigation guidance(PNG) laws for a random maneuvering target. By means of Lyapunov function approach, we show that an ideal missile guided by the conventional PNG law can always intercept a random maneuvering target if some specified initial conditions are satisfied and the navigation constant is chosen sufficiently high. In addition, we propose a modified PNG law. At the final phase of pursuit, the proposed guidance law has a better acceleration profile than the conventional PNG law.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.3
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• pp.171-176
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• 2016

In this paper, we consider a regulation problem of nonlinear systems under two triangular conditions where there possibly exist unbounded parameters in the systems. We propose a state feedback controller with dynamic gains in order to deal with unbounded parameters based on the condition of the time-varying rate of the growing parameter. The analysis of our control scheme is carried out by Lyapunov stability method. Our control method is verified by simulation results.