• International Journal of Control, Automation, and Systems
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• 제5권2호
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• pp.170-183
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• 2007

This paper presents a delay-dependent approach to robust filtering for linear parameter-varying (LPV) systems with discrete and distributed time-invariant delays in the states and outputs. It is assumed that the state-space matrices affinely depend on parameters that are measurable in real-time. Some new parameter-dependent delay-dependent stability conditions are established in terms of linear matrix inequalities (LMIs) such that the filtering process remains asymptotically stable and satisfies a prescribed $H_{\infty}$ performance level. Using polynomially parameter-dependent quadratic (PPDQ) functions and some Lagrange multiplier matrices, we establish the parameter-independent delay-dependent conditions with high precision under which the desired robust $H_{\infty}$ filters exist and derive the explicit expression of these filters. A numerical example is provided to demonstrate the validity of the proposed design approach.

• 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.

• 한국시뮬레이션학회논문지
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• 제3권1호
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• pp.89-98
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• 1994

In this paper, a criteria for selecting an appropriate load redistribution algorithm is devised so that a fault-tolerance distributed system can operte at its optimal efficience. To present the guideline for selecting redistributing algorithms, simulation models of fault-tolerant system including redistribution algorithms are developed using SLAM II. The job arrival rate, service rate, failure and repair rate of nodes, and communication delay time due to load migration are used as parameters of simulation. The result of simulation shows that the job arrival rate and the failure rate of nodes are not deciding factors in affecting the relative efficiency of algorithms. Algorithm B shows relatively a consistent performance under various environments, although its performance is between those of other algorithms. If the communication delay time is longer than average job processing time, the performance of algorithm B is better than others. If the repair rate is relatively small or communication delay time is longer than service time, algorithm A leads to good performance. But in opposite environments, algorithm C is superior to other algorithms.

• 정보처리학회논문지A
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• 제19A권4호
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• pp.181-186
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• 2012

분산 환경의 계측 및 제어 시스템에서 분산된 디바이스들의 복잡한 동기화 구조를 해결하기 위한 기술의 필요성이 요구되며 그러한 분산시스템 환경에서 시간 동기화를 위해 IEEE 표준인 정밀 클럭 동기화 프로토콜(Precision Clock Synchronization Protocol)을 사용함으로써 문제를 해결 할 수 있다. 본 논문에서는 정확한 시간 동기화를 계측하기 위해 지연 요청-응답(Delay Request-Response) 메커니즘을 이용하여 IEEE 1588v2 PTP를 계측하고 제어 할 수 있는 기능을 BlueScope BL6000A에 구현하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.395-400
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• 2004

In most physical processes, the transfer function includes time-delay, and in the general distributed control system using computer network, there exists inherent time-delay caused by the spatial separation between controllers and actuators. This work deals with the synthesis of a discrete-time controller for a nonlinear system and proposes a new effective method to compensate the influence of input time-delay. The controller is synthesized by using input/output linearization. Under the circumstance that input time-delay exists, the system response has more overshoot and tends to diverge. For these reasons, the controller has to produce future input value that will be needed for the system. In order to calculate the future input value, some predictors are adopted. Using the discretization via Euler's method, numerical simulations about the Van der Pol system are performed to evaluate the performance of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.548-552
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• 2005

In most physical processes, the transfer function includes a time-delay, and in the general distributed control system using a computer network, an inherent time-delay exists due to the spatial separation between controllers and actuators. Under the circumstance where an input time-delay exits, the system response overshoots and tends to diverge. For this reasons described above, a controller design method is proposed for a discrete nonlinear system including input time-delay, which adopts the time-discretization using Taylor series. Controllers are synthesized using an input/output linearization method. Finally, several cases of the computer simulations were conducted, and the results validate the proposed methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3100-3116
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• 2016

With the rapid development of urban traffic system and fast increasing of vehicle numbers, the traditional centralized ways to generate the source-destination shortest path in terms of travel time(the optimal path) encounter several problems, such as high server pressure, low query efficiency, roads state without in-time updating. With the widespread use of smart cameras in the urban traffic and surveillance system, this paper maps the optimal path finding problem in the dynamic road network to the shortest routing problem in the smart camera networks. The proposed distributed optimal path generation algorithm employs the delay routing and caching mechanism. Real-time route update is also presented to adapt to the dynamic road network. The test result shows that this algorithm has advantages in both query time and query packet numbers.

• Journal of applied mathematics & informatics
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• 제27권1_2호
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• pp.385-400
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• 2009

The adverse effect of harmful plankton on the marine ecosystem is a topic of deep concern. To investigate the role of such phytoplankton, a mathematical model containing distinct dynamical equations for toxic and non-toxic phytoplankton is analyzed. Stability analysis of the resulting three equation model is carried out. A continuous time variation in toxin liberation process is incorporated into the model and a stability analysis of the resulting delay model is performed. The distributed delay model is then extended to include the spatial distribution of plankton and the delay-diffusion model is analyzed with spatial and spatiotemporal kernels. Conditions for diffusion-driven instability in both the cases are derived and compared to explore the significance of these kernels. Numerical studies are performed to justify analytical findings.

• 전자공학회논문지SC
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• 제44권1호
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• pp.33-39
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• 2007

LonWorks/IP VDN은 LonWorks 디바이스 네트워크와 IP(데이터) 네트워크와의 통합네트워크로 산업현장에 대한 유비쿼터스 접근을 제공하여 설비에 대한 예지 및 예방보전을 가능하게 한다. 산업현장에 대한 예지 및 예방보전을 위한 실시간 분산제어 환경에서 즉각적인 응답은 필수불가결한 요소이다. LonWorks/IP 가상 디바이스 네트워크(VDN) 상에서 불확실한 시간지연은 산업현장에 대한 실시간 예지 및 예방보전을 위해 분산 제어를 수행할 때 시스템의 안정성과 성능을 악화시킨다. 따라서 네트워킹 된 분산제어시스템의 안정성을 보장하고 성능을 개선하기 위해서는 시간에 따라 가변적인 불확실한 시간지연을 보상할 필요가 있다. 본 논문에서는 LonWorks/IP VDN와 같은 분산제어 환경 하에서 서보 제어를 수행하는 경우에 외란관측기와 위상지연 보상기로 ZPETC(Zero Phase Error Tracking Controller)를 도입한 제어구조가 제시되고 컴퓨터 모의실험이 수행된다. 제안된 제어기의 성능은 컴퓨터 모의실험을 통하여 외란관측기를 도입한 Smith 예측기 기반의 내부모델제어기(IMC)의 제어결과와 비교 제시된다. 제안된 제어기는 외란과 잡음에 강인한 특성을 가지며, 주기적인 신호에 대한 추종성능을 상당히 개선시키므로 가변적인 시간지연을 갖는 LonWorks/IP VDN 상에서 주기적인 작업 수행에 필요한 분산 서보제어에 매우 적합하다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.118.1-118
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• 2002

Recent trends in internet access to the device network require that information be provided from anywhere in the enterprise. One then needs to integrate both device network protocol and data network protocol to realize Virtual Device Network (VDN). Interoperability between devices and equipments is essential to enhance the quality and the performance of VDN. LonWorks technology is incorporated as device network protocol for interoperability. VDN integrating both device network and data network has varying time delay. Inherent varying time delay of VDN can significantly degrade the reliability of Distributed Control System. This study investigates the transmission characteristics of VDN and s...