• 한국지진공학회논문집
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• 제5권6호
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• pp.37-46
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• 2001

본 연구에서는 부분적으로 정상상태 확률과정으로 모델링할 수 있는 가진입력에 대하여 확률적으로 정의된 구조물의 최대응답에 대한 구속조건을 만족시키면서 제어력을 최소화 할 수 있는 최적설계 방법을 제안한다. 최적화 과정에서 안정성의 확보를 위해 제어기를 전상태 피드백 LQR제어기의 형태로 한정하였으며 가중치 행렬을 설계변수로 하고 Riccati 행렬을 매개변수로 하여 목적함수와 구속조건 함수 및 그 기울기를 계산한다. 제안된 방법을 통해 설계된 전상태 피드백 LQR제어기는 목표 응답성능을 만족시킬 수 있었고 이에 필요한 최대 제어력을 확률적으로 정량화하여 제어금기의 제작에 유용한 자료가 될 수 있도록 하였다. 상태변수 추정을 위해 독립적으로 설계된 Kalman 필터와 최적화된 LQR 제어기가 결합된 LQG 제어기 및 그 차수를 축소시킨 제어기는 모두 큰 성능의 저하가 없었으며 따라서 제안된 설계방법을 이용하여 구조물의 최대응답에 관한 구속조건을 만족시키는 출력 피드백 제어기 설계가 충분히 가능함을 확인하였다.

• Journal of Mechanical Science and Technology
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• 제15권6호
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• pp.776-787
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• 2001

The turbofan engine performance analysis for a medium scale commercial aircraft was carried out and the LQR control scheme for performance optimization was studied. By using scaled component maps from well-known CF6 engine characteristics, the steady-state performance analysis result was compared with BR715-56 engine performance data. The transient performance analysis was performed with four fuel schedules. The linear simulation was done at the maximum take-off condition. The real time linear simulation was performed by interpolation of the system matrices, which used the least square method as the function of LPC rotational speed. By using linear system matrices of design point, the LQR controller which used control variables for the fuel flow and the LPC bleed air was designed.

• 한국정밀공학회지
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• 제20권5호
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• pp.99-107
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• 2003

In a winding process, important control specifications include regulation of web tension and velocity. In this research, an adaptive controller has been developed for controlling web tension and velocity in winding processes. For the controller design, the linear quadratic regulator theory has been adopted and a gain-scheduling scheme has been incorporated. A prototype winding system has been constructed, and the controller has been implemented in a real-time PC-based environment. The performance of the closed loop system has been evaluated via simulation and experiments, and it was observed that both the web tension and velocity could be regulated within a small tolerance.

• 조명전기설비학회논문지
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• 제17권5호
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• pp.111-117
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• 2003

제안한 Taylor모델 개념은 단지 입출력 데이터만을 이용하여 제어기를 설계하기 위해 사용되는데, Taylor모델의 매개변수는 입출력 데이터들을 사용하여 추정되고 제어기는 Taylor모델을 통하여 얻어진다. Taylor모델 근사화의 정확성은 관측창의 크기와Taylor모델의 차수가 커짐에 따라 좋아진다. Taylor모델을 이용한 전력계통의 안정화를 위해 LQR 제어기가 제안되고 컴퓨터 시뮬레이션을 통해 기존의 방법과의 성능을 비교한다.

• Journal of Mechanical Science and Technology
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• 제18권1호
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• pp.122-131
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• 2004

A constraint equation-based control law design for large angle attitude maneuvers of flexible spacecraft is addressed in this paper The tip displacement of the flexible spacecraft model is prescribed in the form of a constraint equation. The controller design is attempted in the way that the constraint equation is satisfied throughout the maneuver. The constraint equation leads to a two-point boundary value problem which needs backward and forward solution techniques to satisfy terminal constraints. An observer-based tracking control law takes the constraint equation as the input to the dynamic observer. The observer state is used in conjunction with the state feedback control law to have the actual system follow the observer dynamics. The observer-based tracking control law eventually turns into a stabilized system with inherent nature of robustness and disturbance rejection in LQR type control laws.

• 한국통신학회논문지
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• 제28권11C호
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• pp.1062-1069
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• 2003

본 논문에서는 요구된 성능을 만족시키는 강인한 최적 PID 제어기 설계를 위한 새로운 루프 형성 기법을 제안 하고자 한다. 설계하고자 하는 PID 제어기의 영점들을 플랜트의 최대 극점에 근접하도록 가중치 요소 Q와 R을 선택하면 루프 형상이 고주파수 영역의 센서잡음 장벽으로부터 최대한 멀어지게 된다. 2차 시스템에 대하여 강인한 최적 PTD 제어기 설계가 가능한 새로운 루프 형성 기법은 LQR 방법에서 발전되었다.

• 전기학회논문지
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• 제59권7호
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• pp.1309-1313
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• 2010

In this paper, we propose a novel guidance law for controlling an UAV(Unmanned Air-Vehicle) to follow a reference line in vertical plane. A kinematics model representing the relative motion of the UAV to the reference line is derived. And then LQR(Linear Quadratic Regulator) theory is applied to the model to derive the VLFG(Vertical Line Following Guidance) law. The resultant guidance law forms a gain-scheduling controller scheduled by a simple parameter $\sigma$ which is a function of the UAV's velocity, axial acceleration, gravity, and the slope of the reference line. Also derived is a stability condition for the $\sigma$ variation based on Lyapunov theory. Simulation results show that the proposed guidance law can be applied effectively to UAV guidance algorithm design.

• 대한조선학회논문집
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• 제49권1호
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• pp.14-25
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• 2012

Recently, the application and installation of the pod propeller to the cruise ship is dramatically increased. It is because pod propulsion system allows a lot of flexibility in design of the internal arrangement of a ship. To reflect this trend, many researches have conducted to use the pod propeller for the roll stabilization of a ship. In the paper, a roll stabilization controller is designed by using fins and pod propellers as the control actuators for cruise ships. Two kinds of control algorithms are adopted for the roll control system; LQR (Linear Quadratic Regulator) algorithm and frequency-weighted LQR algorithm. Through the numerical simulation, the effect of the turning rate of the pod propeller on the roll control system is analyzed. Analysis of the simulation results indicated that the turning rate of the pod propellers is one of the important parameters which give the significant effects on the roll stabilization.

• 한국지능시스템학회논문지
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• 제18권2호
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• pp.236-242
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• 2008

본 논문은 회전형 역 진자 시스템(Rotary Inverted Pendulum System : RIPS)에 대한 계층적 공정 경쟁 기반 유전자 알고리즘(Hierarchical Fair Competition-based Genetic Algorithms : HFCGA) 기반 최적 퍼지 제어기 설계를 제안한다. 회전형 역 진자 시스템의 제어를 위해 퍼지제어기를 사용하였으며, 이때 퍼지제어기의 규칙은 LQR(Linear Quadratic Regulator) 제어기를 기반으로 하여 설계하였다. 유전자 알고리즘은 전역해를 구할 수 있는 장점이 있어 많은 분야에 성공적으로 적용되고 있지만 조기수렴 문제로 인하여 지역해에 빠질 수 있다. 이러한 문제를 해결하기 위하여 병렬유전자 알고리즘이 개발되었으며, HFCGA는 병렬유전자 알고리즘을 개선한 방법 중의 하나이다. 본 논문에서는 퍼지 제어기의 파라미터의 최적화를 위해 계층적 공정 경쟁 기반 유전자 알고리즘을 사용하였다. 시뮬레이션 및 실험을 통하여 LQR 제어기, 기존 단순유전자 알고리즘(SGA)을 이용한 퍼지제어기와 제안된 HFCGA 기반 퍼지제어기의 성능 비교를 통하여 제안된 방법의 우수성을 보인다.

• International Journal of Control, Automation, and Systems
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• 제6권4호
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• pp.506-514
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• 2008

This paper presents an intelligent model; named as free model, approach for a closed-loop system identification using input and output data and its application to design a power system stabilizer (PSS). The free model concept is introduced as an alternative intelligent system technique to design a controller for such dynamic system, which is complex, difficult to know, or unknown, with input and output data only, and it does not require the detail knowledge of mathematical model for the system. In the free model, the data used has incremental forms using backward difference operators. The parameters of the free model can be obtained by simultaneous perturbation stochastic approximation (SPSA) method. A linear transformation is introduced to convert the free model into a linear model so that a conventional linear controller design method can be applied. In this paper, the feasibility of the proposed method is demonstrated in a one-machine infinite bus power system. The linear quadratic regulator (LQR) method is applied to the free model to design a PSS for the system, and compared with the conventional PSS. The proposed SPSA-based LQR controller is robust in different loading conditions and system failures such as the outage of a major transmission line or a three phase to ground fault which causes the change of the system structure.