• 전자공학회논문지T
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• 제36T권3호
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• pp.41-49
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• 1999

본 논문에서는 μ-합성법으로 제어기를 설계하여 센서와 구동부가 동일위치에 있지 않은(noncollocated) 탄성-질량 시스템에 적용한다. 스프링 상수값과 제어대상의 부하 질량은 불확실하다고 가정한다 매개변수 불확실성을 포함하고 있는 제어대상은 상태 공간 방정식, 특히 묘사형(descriptor form)을 사용하여 모델링 한다. μ-합성법으로 설계된 H/sub ∞/ 제어기를 표준 H/sub ∞/ 제어기와 비교한다. 두 개의 H/sub ∞/ 제어기 성능을 비교하기 위해, μ-합성 제어기가 구조적 불확실성을 가지고 있다는 것을 제외하고는 서로 동일한 하중함수를 가지고 설계한다. 표준 H/sub ∞/ 제어기와 비교하여 설계된 제어기는 만족스러운 강건 안정성과 강건 성능을 가지는 것을 시뮬레이션과 실험을 통해 확인한다.

• 전자공학회논문지SC
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• 제41권1호
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• pp.9-16
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• 2004

본 논문에서는 특징점 기반 시각 구동 제어 시스템을 이용하여 파라미터 불확실성을 가지는 로봇 매니플레이터에 대한 강인 제어기를 제안한다. 시스템 내부 서부 루틴인 동력학 제어부에 적분 작용을 포함시켜 파라미터 변동에 의한 로봇 매니플레이터의 정상 상태 오차를 개선하기 위하여 시스템 내부 서부 루틴인 동력학 제어부에 적분 작용을 포함되도록 하였다. 이적분 작용은 이미지 평면상의 특징점 추정 오차도 개선시킨다. 폐루프 시스템의 안정도는 Lyapunov 기법에 의하여 해석한다. 5링크 2 자유도의 로봇에 적용한 컴퓨터 시뮬레이션 및 실험을 통하여 제안된 제어기법의 실용성을 보인다. .

• International Journal of Control, Automation, and Systems
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• 제3권3호
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• pp.387-396
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• 2005

The Rotational/Translational Actuator (RTAC) benchmark problem considers a fourth-order dynamical system involving the nonlinear interaction of a translational oscillator and an eccentric rotational proof mass. This problem has been posed to investigate the utility of a rotational actuator for stabilizing translational motion. In order to experimentally implement any of the model-based controllers proposed in the literature, the values of model parameters are required which are generally difficult to determine rigorously. In this paper, an approach to the least-squares estimation of the parameters of a system is formulated and practically applied to the RTAC system. On the other hand, this paper shows how to model a nonlinear system as a linear uncertain system via nonparametric system identification, in order to provide the information required for linear robust $H_\infty$ control design. This method is also applied to the RTAC system, which demonstrates severe nonlinearities, due to the coupling from the rotational motion to the translational motion. Experimental results confirm that this approach can effectively condense the whole nonlinearities, uncertainties, and disturbances within the system into a favorable perturbation block.

• 전자공학회논문지SC
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• 제37권1호
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• pp.1-9
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• 2000

본 논문에서는 파라미터 변동 범위가 유한한 로봇 매니퓰레이터에 대한 출력궤환 강인제어기를 고이득 관측기를 사용하여 설계하였다. 적분제어를 포함하는 제안된 제어기는 이득제한에 따른 추종오차를 개선시키도록 하였다. 관절의 속도 측정치를 사용할 때의 문제점을 개선하기 위하여 고이득 관측기를 사용하였다. 미지의 파라미터 변동 범위에 대한 제한을 받지 않도록 제어기를 구성하였으며 전체 폐루프시스템의 상태궤적의 수렴성을 입증하였다. 제안된 방법을 2-링크 로봇 매니퓰레이터의 궤적제어에 적용하고 시뮬레이션을 통하여 성능을 확인하였다.

• 한국항공우주학회지
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• 제37권1호
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• pp.76-81
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• 2009

본 논문에서는 가변 추력 고체추진기관을 모사할 수 있는 상온기체 시험장치를 이용하여 고체추진기관의 연소실 압력을 능동적으로 제어할 수 있는 비선형 압력 제어알고리듬을 제안하였다. 제안된 제어기법은 고체추진기관의 비선형성과 시변성을 고려하여 설계되었으며, 압력 및 온도조건 등에 따른 물리적 변수들의 변화를 적응제어 알고리듬을 통하여 보상하였다. 비선형 압력제어 알고리듬의 효과를 상온기체 모사장치를 이용한 압력제어 실험을 통하여 검증하였으며, 실험결과 일반적인 비례 제어기 및 비례-적분 제어기에 비하여 제안된 제어기법이 더 좋은 압력제어 성능을 보임을 확인하였다.

• Earthquakes and Structures
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• 제3권1호
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• pp.17-35
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• 2012

Simplified equations for fundamental period of vibration of skeletal structures provided by most seismic design provisions suffer from the absence of any associated confidence levels and of any reference to their empirical basis. Therefore, such equations may typically give a sector of designers the false impression of yielding a fairly accurate value of the period of vibration. This paper, although not addressing simplified codes equations, introduces a set of mathematical equations utilizing the theory of error propagation and First-Order Second-Moment (FOSM) techniques to determine bounds on the relative error in theoretically calculated fundamental period of vibration of skeletal structures. In a complementary step, and for verification purposes, Monte Carlo simulation technique has been also applied. The latter, despite involving larger computational effort, is expected to provide more precise estimates than FOSM methods. Studies of parametric uncertainties applied to reinforced concrete frame bents - potentially idealized as SDOF systems - are conducted demonstrating the effect of randomness and uncertainty of various relevant properties, shaping both mass and stiffness, on the variance (i.e. relative error) in the estimated period of vibration. Correlation between mass and stiffness parameters - regarded as random variables - is also thoroughly discussed. According to achieved results, a relative error in the period of vibration in the order of 19% for new designs/constructions and of about 25% for existing structures for assessment purposes - and even climbing up to about 36% in some special applications and/or circumstances - is acknowledged when adopting estimates gathered from the literature for relative errors in the relevant random input variables.

• 대한기계학회논문집A
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• 제30권8호
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• pp.897-905
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• 2006

This study considers an experimental design of disturbance compensation control to improve stabilization performance of main battle tanks. An adaptive non-parametric design technique based on the Filtered-x Least Mean Square(FXLMS) algorithm is applied in the consideration of model uncertainties. The optimal compensator is designed by two-step design procedures: determination of frequency response function of the disturbance compensator which can cancel the disturbance of series of single harmonics by using the FXLMS algorithm and determination of the compensator polynomial which can fit the frequency response function obtained in the first step optimally by using a curve fitting technique. The disturbance compensator is applied to a simple experimental gun-torsion bar-motor system which simulates gun driving servo-system. Along with experimental results, the feasibility of the proposed technique is illustrated. Experimental results demonstrate that the proposed control reduces the standard deviation of stabilization error to 47.6% that by feedback control alone. The directional properties of the FXLMS Algorithm such as the direction of convergence and its convergence speed are also verified experimentally.

• Wind and Structures
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• 제21권5호
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• pp.489-503
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• 2015

This paper surveys and complements contributions by the National Institute of Standards and Technology to techniques ensuring that the wind tunnel procedure for the design of high-rise structures is based on sound methods and allows unambiguous inter-laboratory comparisons. Developments that enabled substantial advances in these techniques include: Instrumentation for simultaneously measuring pressures at multiple taps; time-domain analysis methods for estimating directional dynamic effects; creation of large simulated extreme directional wind speed data sets; non-parametric methods for estimating mean recurrence intervals (MRIs) of Demand-to-Capacity Indexes (DCIs); and member sizing based on peak DCIs with specified MRIs. To implement these advances changes are needed in the traditional division of tasks between wind and structural engineers. Wind engineers should provide large sets of directional wind speeds, pressure coefficient time series, and estimates of uncertainties in wind speeds and pressure coefficients. Structural engineers should perform the dynamic analyses, estimates of MRIs of wind effects, sensitivity studies, and iterative sizing of structural members. The procedure is transparent, eliminates guesswork inherent in frequency domain methods and due to the lack of pressure measurements, and enables structural engineers to be in full control of the structural design for wind.

• Earthquakes and Structures
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• 제8권4호
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• pp.915-934
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• 2015

Within the context of Structural Health Monitoring (SHM), it is often the case that structural systems are described by uncertainty, both with respect to their parameters and the characteristics of the input loads. For the purposes of system identification, efficient modeling procedures are of the essence for a fast and reliable computation of structural response while taking these uncertainties into account. In this work, a reduced order metamodeling framework is introduced for the challenging case of nonlinear structural systems subjected to earthquake excitation. The introduced metamodeling method is based on Nonlinear AutoRegressive models with eXogenous input (NARX), able to describe nonlinear dynamics, which are moreover characterized by random parameters utilized for the description of the uncertainty propagation. These random parameters, which include characteristics of the input excitation, are expanded onto a suitably defined finite-dimensional Polynomial Chaos (PC) basis and thus the resulting representation is fully described through a small number of deterministic coefficients of projection. The effectiveness of the proposed PC-NARX method is illustrated through its implementation on the metamodeling of a five-storey shear frame model paradigm for response in the region of plasticity, i.e., outside the commonly addressed linear elastic region. The added contribution of the introduced scheme is the ability of the proposed methodology to incorporate uncertainty into the simulation. The results demonstrate the efficiency of the proposed methodology for accurate prediction and simulation of the numerical model dynamics with a vast reduction of the required computational toll.

• 전기학회논문지
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• 제66권2호
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• pp.387-393
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• 2017

This paper focuses on a horizontal waypoint tracking and a speed control of large diameter unmanned underwater vehicles (LDUUVs) with X-stern configuration plane. The concerned design problem is converted into an asymptotic stabilization of the error dynamics with respect to the desired yaw angle and surge speed. It is proved that the error dynamics under the proposed control scheme based on the linear control and the feedback linearization can be considered as a cascade system; the cascade system is asymptotically stable if its nominal systems are so. This stability connection enables to separately deal with the waypoint tracking problem and the speed control one. By using the sector nonlinearity, the nominal system with nonlinearities is modeled as a polytopic linear parameter varying (LPV) system with parametric uncertainties. Then, sufficient linear matrix inequality (LMI) conditions for its asymptotic stabilizability are derived in the sense of Lyapunov stability criterion. An example is given to show the validity of the proposed methodology.