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H–/H∞ Sensor Fault Detection and Isolation in Linear Time-Invariant Systems
지성철,이호재,주영훈 제어·로봇·시스템학회 2012 International Journal of Control, Automation, and Vol.10 No.4
This paper addresses sensor fault detection and isolation problems for continuous- and discrete-time li-near time-invariant systems. To that end, we employ a bank consisting of the same number of observers as there are sensors. Both the observer gain and the residual gain are considered. Unlike earlier work, the design conditions with H–/H∞ performance are derived in terms of linear, rather than nonlinear, matrix inequalities. An illustrative example is provided to show the effectiveness of the pro-posed methodology.
이산시간 상태지연 시스템을 위한 ?_/?<sub>∞</sub> 고장검출 및 분리
지성철,이호재,Jee, Sung-Chul,Lee, Ho-Jae 제어로봇시스템학회 2011 제어·로봇·시스템학회 논문지 Vol.17 No.10
In this paper, an $\mathfrak{H}$_/$\mathfrak{H}_{\infty}$ fault detection and isolation (FDI) observer design problem is investigated for discrete-time delayed systems. To that end, a bank consisting of the sensor's number of observers is introduced. Each residual should be sensitive to a certain partial group of faults, but robust against the disturbance as far as possible. We formulate this multiobjective FDI problem as $\mathfrak{H}$_/$\mathfrak{H}_{\infty}$ observers design problem. Sufficient design condition is expressed as iterative linear matrix inequalities. The fault is then detected and isolated by evaluating the residuals through an FDI decision logic. A computer simulation is provided for verification of the proposed technique.
지성철,이호재,김도완 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.2
A direct discrete-time design methodology for sampled-data sensor fault detection for nonlinear systemsin Takagi–Sugenos form is proposed. Contrary to the conventional schemes in this way that rely on an approximatediscrete-time model of the nonlinear system, our result is established based on an exact one. Condition to designthe observer and the residual gain under anH =H∞ performance criterion is presented in matrix inequality format. An example is given to illustrate the effectiveness of the proposed methodology.
유압실린더 내부 누유 검출을 위한 H<sub>∞</sub> 관측기 설계
지성철,강형주,이문직,이계홍,Jee, Sung Chul,Kang, Hyungjoo,Lee, Mun-Jik,Li, Ji-Hong 제어로봇시스템학회 2016 제어·로봇·시스템학회 논문지 Vol.22 No.2
This paper presents the internal oil leakage detection problem for a hydraulic double-rod cylinder. We represent the dynamics of the hydraulic cylinder as a convex combination of linear equations. To detect oil leakage, we propose a model-based fault detection observer design scheme. The observer is designed to be robust against disturbance. Sufficient design conditions are derived in the form of linear matrix inequalities. A numerical example is provided to verify the proposed techniques.
Real-Time Inertia Compensation for Multi-Axis CNC Machine Tools
지성철,이정승 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.
Variation of the effective moment of inertia due to load disturbance in a CNC feed drive system may increase control error for each axis of motion and thereby degrading total precision including contouring accuracy. Although some investigations have been made on estimation and control of variation of the effective moment of inertia, most of them are for individual axis control: there has been no research that considered the improvement of contouring accuracy in CNC machine tools under load variation. In this paper, a real-time inertia compensation method is proposed including a newly defined contour error model that represents error caused by load disturbance. Position error due to load variation is calculated based on the estimated disturbance torque by a full-order disturbance observer for each drive axis. The position error is then used to establish the new contour error model considering the effect of load variation. The proposed compensation method is realized by adjusting velocity loop gains in the control system using the least square method such that the effect of variation of the effective moment of inertia on the contour error is minimized. The proposed method is evaluated with a 3-axis open CNC testbed.
볼엔드 밀링에서의 일정 절삭력을 위한 NURBS 곡면 인터폴레이터
지성철,구태훈,Ji, Seong-Cheol,Gu, Tae-Hun 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.9
This study presents a new type of CNC interpolator that is capable of generating cutter paths for ball-end milling of NURBS surfaces. The proposed surface interpolator comprises real-time algorithms for cutter contact (CC) path scheduling and CC path interpolator. Especially in this study, a new interpolator module to regulate cutting forces is developed. This propose algorithm utilizes variable-feedrate commands along the CC path according to the curvature of machined surfaces during the interpolation process. Additionally, it proposes an OpenGL graphic library for computer graphics and animation of interpolated tool-position display. The proposed interpolator is evaluated and compared with the existing method based on constant feedrates through computer simulations.
지성철,유상필,Ji, Seong-Cheol,Yu, Sang-Pil 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.8
In this study, the cross-coupling control (CCC) with three new features is proposed to maintain contour precision in high-speed nonlinear contour machining. One is an improved contour error model that provides almost exact calculation of the errors. Another is the utilization of variable controller gains based on the instantaneous curvature of the contour and the variable command. For this scheme, a stability is analyzed. As a result, the stability region is obtained, and the variable gains are decided within that region. The other scheme in the proposed CCC is a real-time feedrate adaptation module to regulate cutting force fur better surface finish through regulation of material removal rate (MRR). The simulation results show that the proposed CCC system can provide better precision than the existing method particularly in high-speed machining of nonlinear contours.
대규모 T—S 퍼지 시스템의 <기호> 고장검출을 위한 관측기 설계
지성철,이호재,주영훈,김도완 한국지능시스템학회 2010 한국지능시스템학회논문지 Vol.20 No.1
In this paper, we discuss a decentralized observer design problem for the fault detection in the large-scale continuous-time T—S (Takagi—Sugeno) fuzzy system. Since the fault detection residual is desired to be as sensitive as possible, on the fault, we use <기호> index performance criterion. Sufficient conditions for the existence of such a observer is presented in terms of linear matrix inequalities. Simulation results show the effectiveness of the proposed method. 본 논문은 대규모 연속시간 T—S (Takagi—Sugeno) 퍼지 시스템의 고장검출을 위한 관측기 설계 문제를 논의한다. 관측기의 출력신호로부터 고장 여부를 판단하기 위해서 관측기는 고장신호에 가능한 민감해야하며 이를 위해 <기호> 성능지수를 도입한다. 설계 조건은 선형행렬부등식으로 표현되며 수치적 예제로부터 그 효용성을 확인한다.