• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.11
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• pp.2730-2741
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• 1993

A mathematical model of the seeker scan-loop which is composed of a spin-stabilized gyroscope and its driving signal processors is derived. The derived model has a transmission zero pair on the imaginary axis near to the required bandwidth. The LQG/LTR design methodology is evolved for the derived scan-loop model. To implement the designed LQG/LTR compensator to the actual plant, the compensator order is reduced using the internally balanced realization method. The performances of the LQG/LTR compensator are tested and compared with those of the P-control. Especially, stability-robustnessexperiments for model uncertainties represented in the form of time-delays are performed. It is demonstrated that the LQG/STR compensator is actually very robust to model uncertainties.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.491-497
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• 1993

In MIMO design, input and output units are different from each other. By this reason, the effect of larger units to smaller one is not trivial and there is no method of proper scaling, optimal scaling. In this paper, robust stability of MIMO LQG/LTR design are analised when the plnat inputs and outputs are scalled. The upper bound of model error to guarantee the robust stability is obtained, and gain margin and phase margins are computed with respect to scalling matrices.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.191-196
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• 1991

LQG/LTR method have a theoretical constraint that it cannot applied to nonminimum phase plant. In this paper, we suggest two methods of approximation of minimum phase plant for a given nonminimum phase plant to solve this constraint. Error is described by additive form which can reduce its magnitude in broad frequency range. A optimal approximation method was suggesetd by using Hankel operator theory and Nehari theory. It is showen by example that the methods suggested can resolve the frequency domain constraint arised in Stein and Athans approximation.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.567-571
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• 1992

A guidance loop of the missile system which uses a command to line of sight(CLOS) guidance law is designed based on LQG theory. In the environment of the severe tracking system noise, the system requires small aerodynamic control fin travel and small miss distance simultaneously. Results from a sample airframe shows good performance against a randomly maneuvering target.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.12
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• pp.1209-1216
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• 2014

This paper copes with control design for unmanned aerial vehicle transportation system. Moving pendulum dynamics of slung-load system is derived using two methods: Udwadia-Kalaba equation and Newtonian approach. PID controller is applied to Udwadia-Kalaba equation model for structural consistency and linear quadratic Gaussian / Loop Transfer Recovery (LQG/LTR) technique is employed for Newtonian model with minimal state-space realization. Characteristics of PID and LQG/LTR controller are compared, and two controllers are combined to compensate the drawbacks of each other. Numerical simulation is set for two cases and conducted to evaluate performance of designed controllers. The result proves that combination of LQG/LTR and PID control performs stable and robust.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1280-1283
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• 2007

본 연구는 홀로그래픽 정보저장기기에서 트래킹 서보 제어를 통해 원하는 데이터를 정확하게 기록 및 재생하기 위한 LQG 제어기를 제안하고 검증하는 것을 목적으로 한다. 서보광이라는 추가적인 광을 사용할 것을 제안하여, 서보광과 참조광 간의 간섭에 의해 기록매체에 서보 신호를 얻을 수 있게 하는 홀로그램을 형성한다. 기록 및 재생과정에서 신호광이 기록, 재생됨과 동시에 서보광에 의한 서보 신호가 재생되고, 그 신호의 경로에 설치된 포토 다이오드로부터 디스크 형태에서 발생 할 수 있는 외란을 감지하게 된다. 감지된 외란 신호인 트래킹 에러 신호를 통해 참조광이 디스크의 정확한 위치에 조사되게 하기 위해 평판유리 액츄에이터를 사용한다. 이와 같은 서보 제어를 수행했을 경우 데이터 페이지가 정확하게 재생되며 SNR 과 BER 이 개선되는 것을 확인할 수 있다.

• Transactions of the Society of Information Storage Systems
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• v.3 no.2
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• pp.73-80
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• 2007

Atomic Force Microscopy (AFM)방식을 이용한 Scanning probe Data Storage (SDS) 시스템은 array cantilever 를 이용하여 나노 단위로 데이터 읽기, 쓰기를 하는 시스템이다. 따라서 미디어가 있는 stage 의 x 축과 y 축 및 두 축간 coupling 을 고려한 제어기 설계가 요구된다. 본 논문은 SDS 시스템의 축간 coupling 을 고려하지 않은 기존의 제안된 LQG 에 PI 를 추가한 제어기 구조를 사용한다. 두 축간 coupling 공진의 영향을 최소화 하기 위해 convex optimization 으로 설계된 최적의 position profile를 기준 입력신호로 사용한다. 제안된 제어기를 SDS 시스템에 적용하여 모의실험을 하고 그 결과 position profile 로 인해 각 축간 coupling 공진 영향이 감소하여 tracking performance 가 기존의 LQG 제어기 보다 향상된 것을 확인한다.

• Journal of Advanced Navigation Technology
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• v.4 no.2
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• pp.103-113
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• 2000

There are several methods in the mathematical modeling of a satellite with flexible appendages. In this paper, the hybrid Lagrange's equations of motion using assumed modes method are derived. The assumed modes method is one of approximate methods which have shorter calculation time due to low-dimension compare with FEM. These consist of three-equations about angular velocities and two-equations about flexible deformations, and physically represent interaction between hub and solar panel. In an attitude control, a control law is designed to minimize a given performance index considering not only control input but also vibration suppression. For these purpose, this paper applies LQG and LQG/LTR schemes to this model and finally show the capability for attitude control including vibration suppression. Especially, this paper shows the method of assumption as nonsingular system through singular value division for LQG/LTR design.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.227-229
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• 2000

This paper presents a LQG/LTR method for controlling the PSS and SVC effectively. A one-machine Infinite-bus power system is used as an analysis system, where PSS is installed at the synchronous generator and SVC at the generator bus as a parallel compensation device. The simulation results show that the LQG/LTR controller of PSS and SYC improves the power system stability effectively.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.66-69
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• 1989

In this paper, the LQG/LTR design method is applied of the third order linear time invariant plant model which is the SISO turret-gun servo-mechanism. The dynamic characteristics and the performance of the LQG/LTR controller are analyzed by the computer simulation, and compared with those of PID controller which has been already applied to the turret servomechanism under the sane design specifications.