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오도창,정은태,이갑래,박홍배 대한전자공학회 1998 電子工學會論文誌, S Vol.s35 No.5
This paper is on the discrete model reduction method over disc-type analytic domains. We define hankel singular value over the disc that is mapped by standard bilinear mapping. And the generalized singular perturbation approximation and the direct truncation are generalized to GSPA and DT over a disc. Furthermore, it is shown that the reduced order model over a smaller domaing has a smaller .inf.-norm error bound. And the poposed reduction method is used to obtain the regional pole placement property.
이산시스템의 positive real 특성을 유지하는 일반화된 특이 섭동 근사화
오도창,김재권,방경호,박홍배 대한전자공학회 1997 電子工學會論文誌, S Vol.s34 No.9
This paper is on the generalized singular perturbation approximation (GSPA) preserving the discrete positive real property. We transform the discrete positive real(PR) system into a stochastically banlanced system and get the reduced order discrete system from the GSPA of the full order stochastically balanced system. eSPECIALLY, WHEN THE FREE PARAMETER OF THE gspa IS .+-.1, we show that the reduced order discrete system retains stability, minimality, and positive real and stochstically balancing properties. And we derived the .inf.-norm error bound with the reduced order discrete strictly positive real(SPR) system by the proposed method. Finally, we give an example to ascertain the properties of the proposed reduced order discrete system and to compare with the conventional methods.
Model Reduction for the Descriptor Systems by Linear Matrix Inequalities
오도창,정은태 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.4
In this paper we propose the singular structure preserving model reduction for SISO(single-input/single-output) descriptor systems. A continuous-time descriptor system is decomposed into the slow system and the fast system, and then the fast system is projected into a discrete-time system with controllability and observability matrices the same as those of the original fast system. As a result, we found the respective solutions of H2 and H∞ model reduction problems for the singular system using corresponding linear matrix inequalities. Especially frequency weighted H∞ model reduction and mixed H2 and H∞ model reduction are suggested as giving better frequency characteristics. The validity of the proposed method is shown by a numerical example.
오도창,정은태,박홍배 대한전자공학회 1997 電子工學會論文誌, S Vol.s34 No.3
This paper is on a discrete controller order reduction with the closed-loop stability and performance guaranteed. to achieve this, after finding the solutionsof two lyapunov inequalities and balancing the full order controller system, we find the reudced order controlers using the balanced truncation (BT) and the balanced singular perturbation approximation (BSPA). When the solutions of the two lyapunov inequalities exist, it is shown that the resulting controllers guarantee the closed-loop stability, and .inf.-norm error bounds are derived for the closed-loop performance region for the BT and in low frequency region for the BSPA. Finally, a numerical example is given to illustrate the validity of the proposed method.
오도창,Yong-Un Jo 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.3
Predicting and accurately classifying intentions for human hand gestures can be used not only for active prosthetic hands, rehabilitation robots, and entertainment robots but also for artificial intelligence robots in general. In this paper, first of all, source data of three hand gestures of grasping and three hand gestures of sign language are acquired by using the armband combined with eight sEMG (surface Electromyography) sensors. To classify these hand gestures, basically simple CNN (convolutional neural network) models with raw data, short-time Fourier transform (STFT), wavelet transform (WT), and scale average wavelet transform (SAWT) are applied, and their performances are compared. Finally, it is shown that by using a CNN with SAWT images, the accuracy can be improved up to 94.6% for selected hand gestures with higher accuracy and lower computational burden than conventional multi-channel STFT or WT.
오도창,정은태,박홍배 대한전자공학회 1996 전자공학회논문지-B Vol.b33 No.5
In this paper, we propose the discrete model reduction method of bounded real transfer functions. From the discrete bounded real lemma, we obtain the two riccati equations and define the disrete bounded real balancing using solutions of these two riccati equations. And we get the reduced order discrete model from the GSPA of full order model. Especially, when free parameter of GSPA is .+-.1, we show that the reduced order discrete model retains minimality, stability, and bounded real and BR-balancing properties. And we derive the .inf.-norm error bound between full order model and reduced order model. Finally to illustrate the validity of proposed method, we give an example.
Stability Analysis of Descriptor System Using Generalized Lyapunov Equation
오도창(Do-Chang Oh),이동기(Dong-Gi Lee) 대한전자공학회 2009 電子工學會論文誌-SC (System and control) Vol.46 No.4
이 논문에서는 특별한 형태의 일반화된 연속시간 Lyapunov 방정식과 해의 존재성에 대해 다룬다. 이것은 무한대의 고유치를 가지는 descriptor 시스템에 대해 시스템의 안정성을 분석하기 위해 필요하다. 주요결과로써 먼저 지수 1과 2를 가지는 경우의 descriptor시스템에 대해 안정성을 위한 필요충분조건을 먼저 제안하고 다음으로 일반적인 경우의 descriptor 시스템에 대하여 특별한 형태의 Lyapunov 방정식을 이용하여 비슷한 안정성 조건을 제안한다. 마지막으로 제안한 방법의 타당성을 보이기 위한 예제를 살펴본다. In this paper we consider the specific types of the generalized continuous-time Lyapunov equation and the existence of solution. This is motivated to analyze the system stability in situations where descriptor system has infinite eigenvalue. As main results, firstly the necessary and sufficient condition for stability of the descriptor system with index one or two will be proposed. Secondly, for the general case of any index, the similar condition for stability of descriptor system will be proposed with the specific type of the generalized Lyapunov equation. Finally some examples are used to show the validity of proposed methods.
오도창(Do-Chang Oh),이동기(Dong-Gi Lee),김종해(Jong-Hae Kim) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.6
In this paper, we propose a generalized index independent stability condition for a descriptor systemwithout any transformations of system matrices. First, the generalized Lyapunov equation with a specific right-handed matrix form is considered. Furthermore, the existence theorem and the necessary and sufficient conditions for asymptotically stable descriptor systems are presented. Finally, some suitable examples are used to show the validity of the proposed method.