• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.121-127
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• 2006

An analysis procedure for the combined problem of control algorithm and aeroelastic system which is based on the computational fluid dynamics(CFD) technique has been developed. The aerodynamic forces in the transonic region are calculated from the transonic small disturbance(TSD) theory. An linear quadratic regulator(LQR) controller is designed to suppress the transonic flutter. The optimal control gain is estimated by solving the discrete-time Riccati equation. The system identification technique rebuilds the CFD-based aeroelstic system in order to form an adequate system matrix which involved in the discrete-time Riccati equation. Finally the controller, that is constructed on the basis of system identification technique, is used to suppress the flutter phenomenon of the airfoil with attached store. This approach, that is, the CFD-based aeroservoelasticity design, can be utilized for the development of effective flutter controller design in the transonic region.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.653-658
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• 1994

This paper presents numerical analyses of the low speed yo-yo maneuver of an aircraft to determine controls of thrust, bank-angle and angle-of-attack in the subsonic region in terms of the optimal control theory. Minimum-time flight paths are numerically calculated to overtake an opponent aircraft flying in some steady-state level turnings under several assumptions: both of aircraft are point masses and maneuver in the 3-Dimensional space. Their weights are considered constant in the maneuver. As a result of the analyses, the effectiveness of the low speed yo-yo maneuver is shown.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.91.1-91
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• 2002

1. Introduction Present study presents the basic concept of a Solid Freeform Fabrication System using a rapid prototyping procedure and optimal control for a transferring and accumulating system. And it developed a novel rapid prototyping process that can use ceramic or metal as well as polymer as a basic material. 2. Solid Freeform Fabrication System 2.1 Basic Theory A 3D CAD data of the model is converted to the 2D cross-section data of the slides. A ceramic or metal tape of thickness 0.5-1.5mm is cut by a laser beam with the cross-section data of the slide. A 3D model was obtained by transferring and accumulating the slides. The final product is manufactured by sin...

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1-6
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• 1991

This paper is concerned with the design of a robust tracking controller using a state observer on a robotic manipulator under the disturbance. The controller is designed to follow a step or ramp reference input without steady state error in the presence of a disturbance and a system parameter variation. In most cases, since all the state vectors are not measured, unmeasurable state vectors must be estimated or reconstructed. A reduced order observer is proposed to estimate unmeasurable state vectors of the non-linear system. Some problems are caused by the Coulomb friction, the disturbance, and the spring effect of a link between the drive motor and the manipulator arm. The state variables, directly measured and estimated by the reduced order observer, are fed back to the controller. When the robot system exhibits the 'limit cycle, the feedback gains initially obtained by optimal control theory are changed. As a result, the limit cycle is eliminated by the new controller gains,

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.200-205
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• 1992

The classical control theory has been developed successfully for the design of a system controller and has evolved continually. Even though sophisticated simulation techniques and software packages are available, there is still some difficulty in the design of a complex system controller at the desk. So the trial and error method is sometimes used to design a new controller, but it requires excess time and cost. This paper suggests a controller design method through the experimental approach. The basic concept is to adjust gradually the design parameters of the controller to the simulation results and experimental data of a similar real system. This method will be a very useful and easy way to design an accurate and/or optimal controller for a real plant while reducing time and giving a good solution at a reasonable cost.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.469-474
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• 1990

The implementation of modern guidance law derived from optimal control theory requires accurate current states of target, for example, position, velocity and acceleration etc. But there is no sensors that measure the target states directly. So they are estimated from measurable data. For atmospheric missile engagement, direct application of the modern guidance laws may result In deterioration of Intercept performance because of poor observability associated with angles only-measurements by passive seeker and homing geometry. In this paper, a trajectory modulation method called "adaptive Intermittent maneuvers" is added to the modern guidance law, so the observability is enhanced and, consequently, improved the intercept performance. The estimation algorithm called "modified gain pseudo-measurement filter" is used for tracking filter. It is assumed that the passive seeker measure the angles between line of sight and Inertial frame. The Monte-Carlo simulation for realistic air-to-air Intercept scenario are conducted to demonstrate the effectiveness of intermittent maneuvers.ermittent maneuvers.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.361-361
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• 2000

In the 2-mass system with flexible shaft, a torsional vibration is often generated because of the elastic elements in torque transmission as the newly required speed response which is very close to the primary resonant frequency. This vibration makes it difficult to achieve quick responses of speed and disturbance rejection. In this paper, 2-mass system is designed by using pole placement based on optimal control theory fur fast speed response and torsional vibration elimination and using neural network for disturbance rejection in particular. The simulation results show that the proposed controller based on neural network and full state feedback controller has better performance than 려ll state feedback controller, especially fur disturbance rejection.

• Korean Journal of Optics and Photonics
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• v.9 no.6
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• pp.355-361
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• 1998

Reflectors for reflective LCDs are required to be able to control the direction of the image and viewing angle range for optimal display. To achieve these required characteristics, we performed elementary experiments on conventional reflectors, and theoretical analyzed the reflective property of rough surfaces by using scattering theory. We also proposed a reflector structure by which we can control the direction of the image and viewing angle characteristics simultaneously. If we fabricate and apply this reflector to the reflective LCDs, we can realize high performance display.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1169-1172
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• 2006

The prices of chemical products are fluctuated by several factors. The chemical companies can't predict and be ready to all of these changes, so they are exposed to the risk of a profit fluctuation. But they can reduce this risk by making a well-diversified product portfolio. This problem can be thought as the optimization of the product portfolio. We assume that the profits come from the 'spread' between a naphtha and a chemical product. We calculate a mean and a variation of each spread and develop an automatic module to calculate the optimal portion of each product. The theory is based on the Markowitz portfolio management. It maximizes the expected return while minimizing the volatility. At last we draw an investment selection curve to compare each alternative and to demonstrate the superiority. And we suggest that an investment selection curve can be a decision-making tool.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.1-5
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• 2002

A common way to design a digital control system is to design an analog controller first and discretize it for digital implemention. In this paper, optimal digital controller design is studied within the framework of sampled -data control theory. In particular, multirate discretization of analog controller is considered using an Η$_2$optimality criterion. Solutions are obtained via multirate H2 optimization with a causality constraint due to the multirate structure. In design example, the comparison of the proposed methods is made with the conventional discretization methods, and demonstrate the superiority of the multirate design method.