• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.468-471
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• 1994

This paper presents the digital implementation of an optimal and robust VSS controller with sliding observer. Firstly, a discrete-time VSS control law which enables the system state to move into a sliding sector where the closed-loop system is stable is designed. Then optimal control theory is used to design an optimal sliding sector. Secondly, a sliding observer which provide robust state estimation against model-plant mismatches due to parameter uncertainties is designed for the sampled-data multivariable systems. Finally, modified sliding observer which effectively reduce chattering of state variables in state estimation was proposed. The proposed scheme was applied 10 a two degree of freedom inverted pendulum with passive joint to verify robust motion control. Computer simulation results confirm the viability of the proposed observer-based controller.

• 수산해양기술연구
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• 제27권1호
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• pp.69-74
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• 1991

The Variable Structure System(VSS) will be of much intrest to educators and design engineers who wish to demonstrate and investigate sophisticated position control methods and their applications. This paper describes DC motor position control by means of VSS concept. The control scheme is derived, implemented and tested in the laboratory where IBM AT computer has been used as a digital controller to control a representative servo system. The control system schematic is given and sample results are shown for illustration. This experiment may serve as a basis for further application of VSS.

• 대한산업공학회지
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• 제34권3호
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• pp.328-336
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• 2008

This research proposes a method for economic-statistical design of adaptive moving average (A-MA) charts. The basic idea of the A-MA chart is to accumulate previous samples selectively in order to increase the sensitivity. The A-MA chart is a kind of adaptive chart such as the variable sampling size (VSS) chart. A major advantage of the A-MA chart over the VSS chart is that it is easy to maintain rational subgroups by using the fixed sampling size. A steady state cost rate function is constructed based on Lorenzen and Vance (1986) model. The cost rate function is optimized with respect to five design parameters. Computational experiments show that the A-MA chart is superior to the VSS chart as well as to the Shewhart $\bar{X}$ chart in the economic-statistical sense.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.52-54
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• 1996

A number of algorithm using the VSS(Variable Structure System) for uncertain dynamic system are developed. But, in these algorithms, the assumption that the uncertainties are bounded and their bounds are available to the designer is involved. And bounds on the uncertainties are an important clue to guarantee the stability of the closed loop system. However, sometimes bounds on the uncertainties may not be easily obtained because of the complexity of the structure of the uncertainties. Therefore, a methodology by which the boundary values on the uncertainties can be easily obtained is required. The VSS proposed in this proposal employ the new adaptive VSS scheme for uncertain dynamic system being estimated on line. The resulting control law is simple and easy to apply to on line computer control. It can also suppress chattering and maintain good tracking precision even if unmodeled dynamics are considered. And, a new method using nonlinear switching surface is introduced so that the speed response is improved and the good transient response can be obtained. Simulation results are presented and show the advantage of the proposed adaptive VSS with nonlinear switching surfaces.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.380-382
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• 1993

In this paper, we derive a simple robust nonlinear control scheme for n-link robot manipulators subject to parameter uncertainty. By using the theory of variable structure system(VSS) and taking advantage of the important property of the robot dynamics, the stability of the derived control scheme is proved. This scheme utilizes the desired trajectory outputs, which can be calculated a priori, instead of the actual joint outputs in the nonlinear compensation controller. So the amount of on-line calculations is largely reduced, and as a result, this scheme can be implemented much more efficiently.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2003년도 하계학술대회 논문집
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• pp.177-182
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• 2003

The robust output tracking control problem of general nonlinear MIMO systems is discussed. The robustness against parameter uncertainties is considered. In this paper, we proposed the robust output tracking control scheme for a class of MIMO nonlinear dynamical systems using output feedback linearization method. The presented control scheme is based on the VSS. We assume that the nonlinear dynamical system is minimum phase, the relative degree of the system is r$_{1}$＋r$_{2}$＋…r$_{m}$$\leq$ n and zero dynamics is stable. It is shown that the outputs of the closed-loop system asymptotically track given output trajectories despite the uncertainties while maintaining the boundedness of all signals inside the loop. And we verified that the proposed control scheme is then applied to the control of a two degree of freedom (DOF) robotic manipulator with payload.d.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.702-707
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• 2004

In this paper, we proposed the decoupling VSS controllers for a trajectory control of a two degrees of freedom SCARA type manipulator. We decoupled the position and velocity of a manipulator tip by using a nonlinear error functions. The reference inputs of the controller can be decided directly from the desired position and velocity. Simulation result is provided to verity the effectiveness of the proposed control scheme.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.488-493
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• 1994

The global stability of model reference adaptive control system (MRACS) in the ideal case was resolved in the 1980's. Hoever the improvement of the transient, behaviour of MRACS has not been discussed sufficiently even in the ideal case. Only a few attempts have so far been made at the application of MRACS to the practical systems in contrast to the theoretical systematization. Therefore, when we consider the practical usage of MRACS it is necessary to develop an improved design scheme with respect to transient behaviour. In this paper, we propose two design schemes improving transient behaviour of MRACS by mollifying the input synthesis in the conventional design scheme of MRACS. We present a design scheme of MRACS in which we utilize the design approach of variable structure system(VSS). After describing the above design scheme, we also propose the improved design scheme in which we introduce the dead-zone decided by the magnitude of the output-error between the plant and the reference model. The effectiveness of the proposed two design schemes are shown through computer simulations. As the results, by using these methods, the convergence of the transient response is greatly improved in comparison with the conventional one.

• 한국정보통신학회논문지
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• 제16권12호
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• pp.2731-2740
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• 2012

ASIC(application specific integrated circuit) 과정은 칩을 제작하기 위한 다양한 기술들의 집합이다. 일반적으로 RTL 설계, 합성, 배치 및 배선, 저전력 기법, 클록 트리 합성, 및 테스트와 같은 대표적인 과정들에 대해서는 많은 연구가 진행 되었고, 지금도 많은 연구가 진행 중이다. 본 논문에서는 이러한 ASIC 방법론에서 전력 플랜과 관련하여 경험적이고 실험적인 전력 스트랩 배선(power strap routing) 방법 기법에 대해서 제안하고자 한다. 먼저 수직 VDD 및 VSS와 수평 VDD 및 VSS를 위한 스트랩의 배선을 수행하고, 이 과정에서 발생하는 문제를 해결하기 위한 기법을 제안한다. 배선 가이드를 생성해서 의도하지 않는 배선을 방지하고, 차후를 위해서 배선 가이드에 대한 정보를 저장한다. 다음으로 불필요한 전력 스트랩을 제거하고, 매크로 핀에 대해 미리 배선을 수행한다. 마지막으로 배선 가이드를 이용하여 최종적인 전력 스트랩 배선을 완료한다. 이러한 과정을 통해서 전력 스트랩이 효율적으로 배선되는 것을 확인하였다.

• 상하수도학회지
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• 제8권3호
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• pp.1-8
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• 1994

In the general process of design for aerobic digestion, the design for field plant of which inflow pattern is continuous inflow is performed using the results from lab scale batch reactor. However, the recent researchers reported that the general designs were performed as over-estimated, Therefore, in this study, laboratory batch experiments were carried out at $20^{\circ}C$ and pH 7.5 on the aerobic digestion of waste activated sludge at different solid levels. This treatise could consider the negligence about effective digestion periods the usage of VSS as solid concentration, and the effect of initial solid concentration of solid degration rate coefficient($k_d$) as reasons of the overestimated design, and showed the scheme of how to design for aerobic digestion from batch experiment.