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Model Reference Tracking Control Design of T-S Fuzzy Systems with Polynomial Input Functions
ByeongKeun Park,Dongyeop Kang,Sangchul Won 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
This paper proposes a fuzzy tracking control design for Takagi-Sugeno (T-S) fuzzy systems. T-S fuzzy model is used to represent the nonlinear systems subject to external disturbance. Based on Lyapunov"s direct method, the model reference tracking control scheme based on the augmented system is proposed and a nonlinear control law is derived with robust H∞ performance. Sufficient condition is derived in terms of a state-dependent nonlinear matrix inequality and then it is converted into a sum-of-squares (SOS) optimization problem. Semi-definite programming and SOS decomposition techniques are employed to solve the optimization problem. Simulation example is given to illustrate tracking performance of the proposed method.
ByeongKeun Choi 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.7
This paper investigates how intentional mistuning of bladed disks reduces their sensitivity to unintentional random mistuning. The class of intentionally mistuned disks considered here is limited, for cost reasons , to arrangements of two types of blades (A and B, say). A two-step procedure is then described to optimize the arrangement of these blades around the disk to reduce the effects of unintentional random mistuning. First, a pure optimization effort is undertaken to obtain the pattern (s) of the A and B blades that yields small/the smallest value of the largest amplitude of response to a given excitation in the absence of unintentional random mistuning using Genetic Algorithm. Then, in the second step , a qualitative/quantitative estimate of the sensitivity for the optimized intentionally mistuned bladed disks with respect to unintentional random mistuning is performed by analyzing their amplification factor, probabil- ity density function and passband/stopband structures. Examples of application with simple bladed disk models demonstrate the significant benefits of using this class of intentionally mistuned disks.
Diagnosis of Cryogenic Pump-Motor Systems Using Vibration and Current Signature Analysis
ByeongKeun Choi,HakEun Kim,DongSik Gu,HyoJung Kim,HanEul Jeong 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.7
In general, to send out natural gas via a pipeline network across the nation in LNG terminal, high-pressure cryogenic pump supply highly compressed LNG to high-pressure vaporization facilities. The Number of cryogenic pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high vibration at cryogenic pumps-motor system in LNG terminal, vibration spectrum analysis and motor current signature analysis have been performed together. Through the analysis, motor rotor bar problems are estimated by the vibration analysis and confirmed by the current analysis. So, it is demonstrated through the case study in this paper, how performing vibration analysis and current signature analysis together can reliable diagnosis rotor bar problems in pump-motor system.