• Journal of the Optical Society of Korea
• /
• 제4권2호
• /
• pp.89-93
• /
• 2000

Recently a new signal processing algorithm for white light interferometry was presented. In this paper, the proposed signal processing algorithm was applied for absolute temperature measurement using white light interferometry. Stability testing and absolute temperature measurement were demonstrated. Stability test demonstrated the feasibility of absolute temperature measurement with an accuracy of 0.015 fringe. The test also showed that the absolute temperature measurement system using white light interferometry is capable of obtaining the theoretical minimum detectable change (0.0005 fringe), which is consistent with the performance predicted by the proposed signal processing algorithm.

• International Journal of Control, Automation, and Systems
• /
• 제6권3호
• /
• pp.460-466
• /
• 2008

This paper deals with the stability analysis of a missile guidance loop employing an integrated proportional navigation guidance law. The missile guidance loop is formulated as a closed-loop control system consisting of a linear time-invariant feed-forward block and a time-varying feedback gain. Based on the circle criterion, we have defined the concept of absolute stability margins and obtained the gain and phase margins for the system assuming 1 st order missile/autopilot dynamics. The correlation between the absolute stability margins and the margins derived from the frozen system analysis is also discussed.

• Journal of the Korean Institute of Intelligent Systems
• /
• 제11권7호
• /
• pp.574-578
• /
• 2001

The stability analysis for the fuzzy logic controller (FLC) has widely been reported. Furthermore many research in the FLC has been introduced to decrease the number of parameters representing the antecedent part of the fuzzy control rule. In this paper we briefly explain a single-input fuzzy logic controller (SFLC) or simple-structured FLC which uses only a single input variable. And then we analyze that it is absolutely stale based on the sector bounded condition. We also show the feasibility of the proposed stability analysis through a numerical example of a mass-damper-spring system.

• Journal of the Institute of Electronics and Information Engineers
• /
• 제50권11호
• /
• pp.171-179
• /
• 2013

This paper presents a comparative study on application of Routh-Hurwitz and Llewellyn absolute stability criteria to a scaled telerobotic system. The dynamic equations of the telerobotic system are given, and the transfer function of the system is obtained for further stability analysis. The stable margins of controller gains are obtained using both stability analysis methods, and the differences in the results are described and explained. The paper is concluded by a numerical example verifying performed stability analysis.

• The Korean Journal of Ecology
• /
• 제24권4호
• /
• pp.239-243
• /
• 2001

One of the most important justifications of conservation of ecosystem and biodiversity is that diversity begets stability. Impact of biodiversity on community and ecosystem function has long been debated in science. Here we report the stability analysis of soil oribatid mite communities from environmentally stressed habitat(Namsan) and relatively well preserved habitat (Kwangreung) with the perspective of consistency as a primary criteria of stability. Stability of oribatid mite communities were evaluated with turnover rate, constancy analysis, b diversity index, and absolute abundance, abundance ranking, and the presence or absence of species over time. Out of 6 criteria, three consented that oribatid community from Kwangreung was more stable than that from Namsan. Those are turnover rate in litter layer, constancy analysis, and absolute abundance. Feasibility of stability analysis using oribatid mites was further discussed, rendering further study.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 한국퍼지및지능시스템학회 2001년도 춘계학술대회 학술발표 논문집
• /
• pp.47-51
• /
• 2001

According as the controlled plants become more complex and large-scaled, the development of more intelligent control schemes is required in the control field. A fuzzy logic control (FLC) is one of proper schemes for this tendency. Recently, fuzzy control has been applied successfully to many industrial applications due to a number of advantages. But it still has some disadvantages. The conventional FLC has many tuning parameters: membership functions, scaling factors, and so forth. In order to improve this problem, a single-input fuzzy logic control (SFIC) which greatly simplifies the design process of the conventional FLC was proposed. Many research has also been proposed to develop the stability analysis of the FLC. In this paper we analyze the absolute stability of the SFLC. We first expand a nonlinear controlled plant into a Taylor series about a nominal operating point. And a fuzzy control system is transformed into a Lure system with nonlinearities. We also prove that the closed-loop system with the SFLC satisfies the sector condition globally.

• Journal of Mechanical Science and Technology
• /
• 제18권7호
• /
• pp.1131-1139
• /
• 2004

A new impedance controller is proposed for bilateral teleoperation under a time delay. The proposed controller does not need to measure or estimate the time delay in the communication channel using the force loop-back. In designing a stable impedance controller, absolute stability is used as a stability analysis tool, which results in a less conservative controller than the passivity concept. Moreover, in order to remove the conservatism associated with the assumption of infinite port impedances, the boundaries of human and environment impedance are set to finite values. Based on this, this paper proposes a parameter design procedure for stable impedance controllers. The validity of the proposed control scheme is demonstrated by experiments with a 1-dof master/slave system.

• Journal of the Korean Society for Precision Engineering
• /
• 제1권1호
• /
• pp.34-49
• /
• 1984

The stability of machine tool systems is analyzed by considering the machining process as a stochastic process without decomposing into machine tool structural dynamics and cutting processes. In doing so the time series analysis technique developed by Wu and Pandit is applied systematically to the relative vibration between cutting tool and work- piece measured under actual working conditions. Various characteristic properties derived from the fitted ARMA(Autoregressive Moving Average) Models and those from raw data directly are investigated in relation with the system stability. Both damping ratio and absolute value of the characteristic roots of the AR part of the most significant dynamic mode are preferred as stability indicating factors to the other pro-perties such as theoretical variance .gamma. (o) or absolute power of the most dominant dynamic mode. Maximum aplitude during a certain interval and variance estimated from raw data are shown to be very sensi- tive to the type of the signal and the location of measurement point although they can be obtained rather easily. The relative vibration signal is also analyzed by FFT(Fast Fourier Transform) Analyzer for the purpose of comparison with the spectrums derived from the fitted ARMA models.

• Journal of Convergence for Information Technology
• /
• 제11권2호
• /
• pp.124-129
• /
• 2021

In this paper, an optimal controller design that guarantees absolute stability is proposed. The order of application of the thesis determines whether the delay time is included, and if the delay time is included, the delay time is approximated through the Pade approximation method. Then, the open loop transfer function for the process model and the controller transfer function is obtained, and the absolute stability interval is calculated by the Routh-Hurwitz discrimination method. In the last step, the optimal Proportional and Integral and Derivative(PID) control parameter value is calculated using a genetic algorithm using the interval obtained in the previous step. As a result, it was confirmed that the proposed method guarantees stability and is superior to the existing method in performance index by designing an optimal controller. If we study the compensation method for the delay time in the future, it is judged that better performance indicators will be obtained.

• 전기의세계
• /
• 제16권2호
• /
• pp.17-21
• /
• 1967

In reactor operation, it is widely known that the absolute stability may not exist for multiple feedback paths even though the single lumped negative temperature coefficient feedback case is clearly stable at all frequencies above those creating xenon poisoning effects. However, interesting and useful stability information may be obtained from a two-path temperature coefficient feedback which can be represented in a water-cooled, water-moderated hetergeneous reactor. In this paper, the outline of an operating stability of a reactor having two-path temperature coefficient feedback is analyzed and described neglecting poison effects.