• 제어로봇시스템학회논문지
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• 제18권6호
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• pp.509-512
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• 2012

This paper presents the state feedback control design for discrete time nonlinear systems where there exists a time delay in input. It is shown that under some boundedness condition, the time delay nonlinear systems can be transformed into the time delay linear systems with time varying parameters. Sufficient conditions for existence of stabilizing state feedback controller are characterized by linear matrix inequalities. Finally, an illustrative example is given in order to show the effectiveness of our design method.

• 한국시뮬레이션학회논문지
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• 제17권4호
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• pp.71-80
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• 2008

본 연구에서는 조선 공정 계획의 수립 완성도 향상을 위한 다양한 시뮬레이션 시스템의 개발을 지원하는 시뮬레이션 프레임 워크(simulation framework)를 제안하였다. 그리고 제안된 시뮬레이션 프레임워크의 핵심 부분인 시뮬레이션 커널을 구현하였다. 구현된 시뮬레이션 커널은 이산 사건(discrete event)과 이산 시간(discrete time) 시뮬레이션뿐만 아니라 이들이 혼합된 형태의 시뮬레이션도 처리 가능하도록 하였다. 제안된 시뮬레이션 프레임워크의 효율성과 효용성을 평가하기 위해, 이를 조선 분야의 블록 탑재 공정(block erection process)에 적용하였다. 그 결과, 제안된 시뮬레이션 프레임워크가 조선 공정 계획을 위한 다양한 시뮬레이션 시스템을 개발하는데 효과적으로 사용될 수 있음을 확인하였다.

• 대한전기학회논문지
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• 제37권7호
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• pp.484-489
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• 1988

Sufficient conditions concerning the perturbation region of system parameters, which guarantee the asymptotic stability of linear time- varying systems, are presented. These conditions are obtained by Lyapunov function approach for continuous-time and discrete-time systems. Also, a computational algorithm using nonlinear programming is proposed for finding the maximum perturbation region which satisfies the sufficient condition for the continuous-time systems. The technique of finding the solution for the continuous-time systems can also be applied to the discrete-time systems. In the continuous-time case, it is shown by an example that the method proposed in this paper yields much larger perturbation region of parameters than other previously reported results. An example of the perturbation region of system paramters for the discrete-time system is also given.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1564-1569
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• 1991

In this paper we describe Flexible Manufacturing Systems (FMS) using Petri nets, since Petri nets provide a powerful tool for modeling dynamical behavior of discrete concurrent processes. We deal with off-Line and on-Line rule-based scheduling of FMS. The role of the rule-base is to generate appropriate priority rule for resolving conflicts, that is, for selecting one of enabled transitions to be fired in a conflict set of the Petri nets. This corresponds to select a part type to be processed in the FMS. Towards developing more Intelligent Manufacturing Systems (IMS) we propose a conceptual framework of a futuristic intelligent scheduling system.

• Transactions on Control, Automation and Systems Engineering
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• 제1권2호
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• pp.113-120
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• 1999

One of the important challenges facing control engineers in developing automated machineryis to be able to monitor the machines using remote sensors. Observrs are often used to reconstruct the machine variables of interest. However, conventional observers are unalbe to observe the machine variables when the machine models, upon which the observers are based, have inputs that cannot be measured. Since this is often the case, the authors previsously developed a steady-state optimal state and input observer for time-invariant systems [1], this paper extends that work to time-variant systems. A recursive observer, similar to a Kalman-Bucy filter, is developed . This optimal observer minimizes the trace of the error variance for discrete , linear , time-variant, stochastic systems with unknown inputs.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국제학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.772-776
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• 1988

In quantized control systems, the control values can take only given discrete (e.g. integer) values. In case of dealing with the control problem on the discrete-time, final-stage fixed, quantized control systems with multidimensional performance functions, the first thing, new definition on noninferior solutions in these systems is necessary because of their discreteness in state variables, and the efficient search for those solutions at final-stage is unavoidable for seeking their discrete-time optimal controls to these systems. In this paper, to the quantized control problem given by the formulation of Halkin-typed linear control systems with two performance functions, a new definition on noninferior solutions of this system control problem and a heuristic effective search on these noninferior solutions are stated. By use of these concepts, two definitions on noninferior solutions and the algorithm consisted of 8 steps and attained by geometric approaches are given. And a numerical example using the present algorithm is shown.

• 제어로봇시스템학회논문지
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• 제22권6호
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• pp.424-428
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• 2016

A simple new sufficient condition for asymptotic stability of the positive linear time-varying discrete-time systems, with unstructured time-varying uncertainty in delayed states, is established in this paper Compared with previous results that cannot be applied to time-varying systems; the time-varying system and delay time are considered simultaneously in this paper. The proposed conditions are compared with suitable conditions for the typical discrete-time systems. The considerations are illustrated by numerical examples of previous work.

• 제어로봇시스템학회논문지
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• 제15권2호
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• pp.121-127
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• 2009

This paper deals with the design problem of robust stabilization and non-fragile controller for discrete-time singular systems with parameter uncertainties and time-varying delays in state and input by delay-dependent Linear Matrix Inequality (LMI) approach. A new delay-dependent bounded real lemma for singular systems with time-varying delays is derived. Robust stabilization and robust non-fragile state feedback control laws are proposed, which guarantees that the resultant closed-loop system is regular, causal and stable in spite of time-varying delays, parameter uncertainties, and controller gain variations. A numerical example is given to show the validity of the design method.

• 한국시뮬레이션학회논문지
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• 제17권4호
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• pp.219-227
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• 2008

DEVS 형식론은 이산 사건 시스템을 계층적이고 모듈러하게 표현할 수 있다. MATLAB/Simulink는 연속 시스템과 이산 시간 시스템을 모델링하고 시뮬레이션을 수행하는 데 널리 쓰인다. 본 논문은 MATLAB/Simulink 환경에서 DEVS 형식론을 구현하는 방법론을 제안한다. 본 논문에서 제안하는 방법론을 이용하여MATLAB/Simulink에서 제공하는 다양한 공학 방정식과 알고리즘을 사용할 수 있다. 또한 동일한 시뮬레이션 환경에서 연속 시스템과 이산 사건 시스템이 혼합된 하이브리드 시스템에 대한 시뮬레이션을 수행할 수 있다. 이를 위해 본 논문은 Simulink-DEVS 모델과 이 모델을 시뮬레이션을 수행하는 데 필요한 시간 진행 알고리즘을 제안한다. 특히 시간 진행 알고리즘은 시스템의 유형에 상관없이 적절한 시간 진행을 수행한다. 두 가지 실험 결과를 통해 본 논문에서 제안하는 방법론의 효용성을 입증한다.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
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• pp.453-458
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• 2001

A mobile agent is an autonomous software agent capable of moving from one computer to another while performing its tasks. We view the agent as a discrete event system in the view of its computation and communication. This paper presents a methodology far modeling and simulation of such a mobile agent system as a discrete event system. The methodology is based on the Mobile Discrete Event System Specification (MDEVS) formalism and the associated simulation environment AgentSim which are previously developed by the authors. Within the methodology an atomic model represents dynamics of a mobile agent; a coupled model is modeled as mobile agent servers for representation of structural changes between atomic agents. Being based on the object-oriented environment the modeling methodology exploits inheritance of basic classes AtomicModel and CoupledModel provided by AgentSim.