• ICROS
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• v.16 no.4
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• pp.35-41
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• 2010

나이퀴스트 선도와 보우드 선도는 주파수 영역에서 시스템의 안정성을 판별하는 중요한 수단이다. 본 소고에서는 나이퀴스트 판별법의 근간이 되는 편각의 원리, 그리고 이에 기초한 나이퀴스트 판별법, 이를 활용한 안정도 및 안정도 여유 판별법, 그리고 나이퀴스트 선도와 보우드 선도와의 관계 및 활용시의 장단점을 비교함으로써, 제어기 설계시 도움이 되도록 하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.537-544
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• 2009

This paper concerns analysis technique on determining of attitude control gain in the low frequency region using stability area. The stability area is defined by the D-Decomposition method, which was designed by Neimark. In this paper, it is introduced D-Decomposition method from reference paper and design attitude control gain of generic launch vehicle during first stage flight phase. For selecting PD control gain, it is considered the system parameter uncertainty about whole first-stage flight phase, represented the stability area boundary on each case. After deciding the PD control gain using stability area method, it is applied to launch vehicle linear model, and checking the stability margin requirement, frequency response characteristics.

• 전기의세계
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• v.15 no.3
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• pp.8-14
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• 1966

제어이론은 안정성판별을 중심으로 발달하여 왔으며 제어공학자체가 하나의 기술인 이상 안정판별법은 가능한 한 그 표현이 간단명료한 것을 요구하게 되었다. 과거에 연구되어 온 여러가지 안정판별법등은 즉 Routh 및 Hurwitz에 의한 방법, Nyquist 및 Michailov에 의한 방법 등, 정성적방법과 Bode 및 Nichols에 의한 방법, Evans에 의한 Root locus법, Bilharz 및 Frank에 의한 방법, Tsypkin 및 Bromberg에 의한 방법 등, 정량적인 취급방법 등이 연구발표되어 제어계통의 설허 및 해석에 이용되어왔다. 그러나 설계자들은 제어계통의 안정성판별에만 흥미를 갖는것이 아니라 안정도판별 즉 계통응답에 더 주의를 기우리게 된다. 특히 실시간응답에 대하여 명확한 해답을 요구한다. 본 고에서는 두개의 Parameter Plane Method의 기초를 다룬 것으로 특성방정식의 계수중에서 임의의 두개를 Parameter로 하는 것이며 과도해답 및 주파수응답을 요하는데 편리하나 임의의 두개의 계수만을 Paraweter로 하므로서 두개 이상의 Parameter가 존재하는 경우에는 부적당하다. 또한 우리나라에서도 시도된 바가 있다. 이와같은 것을 개선한것이 Siljak의 Parameter Plane Method이며 이것을 여기에 소개하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1813-1818
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• 2014

This paper presents the stability analysis of the haptic system including a human impedance using the Routh-Hurwitz criterion. The reflective force is computed from a virtual spring model and is transferred to a human operator using the first-order-hold method. The stability boundary conditions are induced and the relation among a virtual spring ($K_w$), the mass ($M_h$), the damping ($B_h$) and the stiffness ($K_h$) of a human impedance is analyzed. Hence the stability boundary of the virtual spring ($K_w$) is proposed as $K_w{\leq}54413{\sqrt{(M_h+M_d)(B_h+B_d)}}-0.486K_h$ when the sampling time is 1 ms. The average relative error is about 0.5% when the mathematical analysis results are compared with the results of the stability boundary model.

• IEMEK Journal of Embedded Systems and Applications
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• v.4 no.2
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• pp.97-102
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• 2009

In this paper, the problem of stability analysis for networked control systems with norm-bounded parameter uncertainties is investigated. By construction Lyapunov's functional, a new delay-dependent stability criterion for uncertain networked control system is established in terms of LMIs (linear matrix inequalities) which can be easily by various convex optimization algorithms. One numerical example is included to show the effectiveness of proposed criterion.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2284-2291
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• 2010

In this paper, improved stability criteria for linear systems with time-varying delays are proposed. By constructing a new Lyapunov functional, novel stability criteria are established in terms of linear matrix inequalities (LMIs). Two numerical examples are carried out to support the effectiveness of the proposed method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.2023-2026
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• 2007

In this letter, the problem for a class of neutral differential equation is considered. Based on the Lyapunov method, a stability criterion, which is delay-dependent on both ${\tau}\;and\;{\sigma}$, is derived in terms of linear matrix inequality (LMI). Two numerical examples are carried out to support the effectiveness of the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.1
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• pp.123-131
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• 1995

다주파수 입력을 갖는 강한 비선형 시스템의 유사주기 (quasi-periodic) 해를 해석하기 위하여 개선된 고정 점법(FPA:Fixed Point Alogrithm)을 개발하였다. 안정성 및 천이 특성을 판별하기 위하여 사용되어지는 Floquest 지수인 해석적 자코비언을 구하기 위하여 Poincare 맵상에서 이산 적분법을 새로이 고안, 사용하였다. 본 방법의 우수성을 입증하기 위하여 2개의 주파수 입력을 갖는 선형 시스템과 비선형 시스템을 예로 사용하였다. 본 방법을 이용하여 비선형 시스템에서 발생한 복잡한 chaos 현상을 체계적으로 해석하였다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.79-90
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• 2004

Systematical robust stability analysis and design scheme for the feedback linearization control systems via fuzzy modeling are proposed. It is considered that uncertainty and disturbances are included in the Takagi-Sugeno fuzzy models representing the nonlinear plants. Robust stability of the closed system is analyzed by casting the systems into the diagonal norm bounded linear differential inclusions and by converting the analysis and design problems into the linear matrix inequality optimization, a numerical method for finding the maximum stable ranges of the fuzzy feedback linearization control gains is also proposed. To verify the effectiveness of the proposed scheme, the robust stability analysis and control design examples are given.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2119-2130
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• 2011

This paper proposes new delay-dependent robust stability criteria for neural networks with time-varying delays. By construction of a suitable Lyapunov-Krasovskii's (L-K) functional and use of Finsler's lemma, new stability criteria for the networks are established in terms of linear matrix inequalities (LMIs) which can be easily solved by various effective optimization algorithms. Two numerical examples are given to illustrate the effectiveness of the proposed methods.