• 한국지능시스템학회논문지
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• 제12권6호
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• pp.559-564
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• 2002

This Paper Proposes a design method of a fuzzy output feedback controller for the nonlinear systems with the unknown time- delay. Recently, Cao et ai. proposed a stabilization method for the nonlinear time-delay systems using a fuzzy controller when the time-delay is known. However, the time-delay is likely to be unknown in practical. We represent the nonlinear systems with the unknown time-delay by Takagi-Sugeno (T-5) fuzzy model and design the fuzzy observer and the parallel distributed compensation (PDC) law based on this observer. By applying Lyapunov-Krasovskii theorem to the closed-loop system, the sufficient condition for the asymptotic stability of the equilibrium Point is derived and converted into the linear matrix inequality (LMI) Problem.

• Advances in Computational Design
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• 제5권3호
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• pp.233-260
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• 2020

The main purpose to introduce model based controller in proposed control technique is to provide better and fast learning of the floating dynamics by means of fuzzy logic controller and also cancelling effect of nonlinear terms of the system. An iterative adaptive dynamic programming algorithm is proposed to deal with the optimal trajectory-tracking control problems for autonomous underwater vehicle (AUV). The optimal tracking control problem is converted into an optimal regulation problem by system transformation. Then the optimal regulation problem is solved by the policy iteration adaptive dynamic programming algorithm. Finally, simulation example is given to show the performance of the iterative adaptive dynamic programming algorithm.

• 한국인터넷방송통신학회논문지
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• 제22권2호
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• pp.123-128
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• 2022

SRM(Switched Reluctance Motor)의 토크는 인덕턴스의 기울기에 비례하여 발생하기 때문에 비선형 토크 특성을 가지며 토크 맥동이 크고 소음이 심한 단점을 가지고 있다. 특히 SRM의 상용화에 가장 큰 장해 요인으로 작용하고 있는 것은 회전축에서 발생하는 맥동 토크로 이에 의해 기기자체는 물론이고 주변장치에까지 여러 가지 악영향을 미친다. 따라서 맥동 토크를 저감시키는 방법으로 다양한 방안이 국내외 연구자들에 의하여 발표되었고 히스테리시스 제어기의 경우 초핑 제어에 비해 평활한 전류를 흘려줄 수 있다는 장점이 있다는 연구결과가 있다. 그러나 히스테리시스 밴드를 결정함에 있어서 밴드가 너무 작을 경우 많은 스위칭으로 인한 스위칭 손실과 엔코더의 사용 시 불안정한 초기 기동을 야기할 수 있는 둥의 단점을 가지고 있다. 따라서 본 논문에서는 속도오차에 따른 히스테리시스 밴드의 변화를 통하여 보다 안정적이고 빠른 속도응답을 가지면서 정상상태에서 토크 리플을 줄일 수 있는 가변 히스테리시스 제어기에 대하여 연구하였다.

• 한국항행학회논문지
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• 제24권6호
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• pp.549-556
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• 2020

이 논문에서는 마코프 프로세스로 모델링되는 전송 오류나 전송 지연이 있는 네트워크 제어 시스템을 위한 제어기 설계 방법들을 제안한다. 마코프 지연을 갖는 제어 시스템을 위한 안정화 조건을 지연 의존적인 리아프노프-크라소프스키 범함수가 증가된 제어 시스템의 리아프노프 함수와 동일한 형태를 갖는다는 점을 이용하여 찾는다. 유도된 안정화 조건으로부터 복잡도를 줄이기 위한 수 개의 제어 설계기 방법을 제안한다. 모의 실험을 통하여 제안된 방법 중 행렬 변수의 탐색 공간을 블록 대각 행렬로 제한하는 제한 부분 공간 방법이 성능과 복잡도 사이에서 가장 좋은 트레이드오프를 제공함을 확인되었다.

• 한국소음진동공학회논문집
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• 제12권5호
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• pp.365-373
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• 2002

This paper concerns the design and application of an electro-rheological (ER) fluid damper to semiactive vibration control of rotor systems. In particular, the system under present study is constructed structurally flexible in order to explore multiple critical speeds within operation range. To this end, the dynamic models of the proposed ER damper and its associated amplifier are derived in the first place. Subsequently entire rotor system model is assembled along with the dynamics of the end effector based on a finite element method enabling prediction as to its free and forced vibration characteristics. Next, an artificial intelligent (AI) feedback controller is synthesized taking into account the peculiarity of Coulomb damping effect in rotor applications. Finally, computational and experimental results are presented including model validation and control performances. In practice, such an AI control proved effective whether the spin speed was either before or after critical speeds.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.285-294
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• 2023

Autonomous radiation source detection has long been studied for radiation emergencies. Compared to conventional data-driven or path planning methods, deep reinforcement learning shows a strong capacity in source detection while still lacking the generalized ability to the geometry in unknown environments. In this work, the detection task is decomposed into two subtasks: exploration and localization. A hierarchical control policy (HC) is proposed to perform the subtasks at different stages. The low-level controller learns how to execute the individual subtasks by deep reinforcement learning, and the high-level controller determines which subtasks should be executed at the current stage. In experimental tests under different geometrical conditions, HC achieves the best performance among the autonomous decision policies. The robustness and generalized ability of the hierarchy have been demonstrated.

• Earthquakes and Structures
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• 제23권4호
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• pp.329-338
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• 2022

This work addresses the optimization controller design problem combining the AI evolution bat (EB) optimization algorithm with a fuzzy controller in the practical application of a reinforced concrete frame structure. This article explores the use of an intelligent EB strategy to reduce the dynamic response of Lead Rubber Bearing (LRB) composite reinforced concrete frame structures. Recently developed control units for plant structures, such as hybrid systems and semi-active systems, have inherently non-linear properties. Therefore, it is necessary to develop non-linear control methods. Based on the relaxation method, the nonlinear structural system can be stabilized by properly adjusting the parameters. Therefore, the behavior of a closed-loop system can be accurately predicted by determining the behavior of a closed-loop system. The performance and durability of the proposed control method are demonstrated by numerical simulations. The simulation results show that the proposed method is a viable and feasible control strategy for seismically tuned composite reinforced concrete frame structures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.1042-1045
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• 1987

This paper describes a User Guidance System that extracts Conceptual Structure from the input sentence by use of en theory and performs Question Answering in Teletex Manual domain. It uses Frame typed knowledge base and Frame recognizer as Link procedure between CD structure and Frame controller.

• 대한전자공학회논문지
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• 제25권2호
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• pp.168-175
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• 1988

This paper describes a User guidance System aimed for user-friendly workstation guider that extracts Conceptual Structure from the input sentence by use of CE theory and performs Question Answering in Teletex Manual domain. It uses Frame typed knowledge base and CD recognizer as link procedure between CE structure and Frame controller.

• International Journal of Internet, Broadcasting and Communication
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• 제12권2호
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• pp.8-14
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• 2020

Recently, there was an increasing demand for an integrated access control system which is capable of user recognition, door control, and facility operations control for smart buildings automation. The market available door lock access control solutions need to be improved from the current level security of door locks operations where security is compromised when a password or digital keys are exposed to the strangers. At present, the access control system solution providers focusing on developing an automatic access control system using (RF) based technologies like bluetooth, WiFi, etc. All the existing automatic door access control technologies required an additional hardware interface and always vulnerable security threads. This paper proposes the user identification and authentication solution for automatic door lock control operations using camera based visible light communication (VLC) technology. This proposed approach use the cameras installed in building facility, user smart devices and IoT open source controller based LED light sensors installed in buildings infrastructure. The building facility installed IoT LED light sensors transmit the authorized user and facility information color grid code and the smart device camera decode the user informations and verify with stored user information then indicate the authentication status to the user and send authentication acknowledgement to facility door lock integrated camera to control the door lock operations. The camera based VLC receiver uses the artificial intelligence (AI) methods to decode VLC data to improve the VLC performance. This paper implements the testbed model using IoT open-source based LED light sensor with CCTV camera and user smartphone devices. The experiment results are verified with custom made convolutional neural network (CNN) based AI techniques for VLC deciding method on smart devices and PC based CCTV monitoring solutions. The archived experiment results confirm that proposed door access control solution is effective and robust for automatic door access control.