• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.173-177
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• 1992

The Helicopter has a lot of flight modes. The most characteristic flight mode is Hovering. It enables the helicopter to be used in many situations. However, a helicopter has nonlinear dynamics so its mathematical modeling is very difficult. Hence it is not easy to control helicopter in hover. In this paper, RC model helicopter is selected as a plant. To stabilize the behavior of RC model helicopter, Fuzzy alogrithm is used as a controller and one camera is used as a sensor. To get proper Information from camera Image, three characteristic points are attatched to the helicopter and a position recognition algorithm is developed. Experiments are performed to stabilize 3 rotational motions synchronousely with fuzzy control algorithm. As a result, Fuzzy control represents better performances than the conventional PID control.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.1
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• pp.32-37
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• 1998

This paper deals with the implementation of a robust multivariable controller using DSP board and the application to real systems. The LQG/LTR (Linear Quadratic Gaussian with Loop Transfer Recovery) controller proposed by Doyle et al.[1,2] is adopted to design the control system. A helicopter propeller setup is taken as the controlled system in the current paper, and the mathematical model is derived to design the multivariable controller. The performance of the controller is evaluated via simulations, and implementation and application to the MIMO system shows that the control performances are satisfactory and superior to those of the PID controller.

• Journal of Industrial Technology
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• v.19
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• pp.217-226
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• 1999

A single phase to three phase power converter with cost effective and simple structure is proposed. The converter consists of rectifier and inverter. The rectifier is composed of a half wave rectifier, a dc link capacitor, and a current limiting inductor, and the inverter is of only two switches with PWM control. For negative sequence operation the inverter output voltage leads the line input by $60^{\circ}$, and for positive sequence operation the inverter output voltage leads by $60^{\circ}$. We can see that positive sequence operation shows higher output voltage, slight harmonic distortion(2%), and better performances such as high efficiency and high power factor. A mathematical model for system analysis is provided, and specifications for selection and control scheme both for start-up and for steady state are analyzed. comparison and operational limits of positive and negative sequence operation are performed, and simulations and experiments are executed to verify the proposed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.46-52
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• 2003

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.901-906
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• 1994

In designing and evaluating manipulators, itis important to understand the capability of kinematic and static performances. Both workspace and manipulability can be considered as such performance measures. In general, the measure of manipulability is related to the kinematics for serial type manipulators. However.in case of parallel manipulators such as Stewart Platform, the manipulability can be interpreted as the static capability of transforming the input forces of actuators to the wrench of the end-effector. In this paper, the mathematical and physical meanings of manipulability suggested in some research works have been examined, and more meaningful measure of manipulability using the absolute minimum eigenvalues of J $^{T}$ .del. J has been suggested, which has been applied to a Stewart Platform in order to investigate the manipulability of this mechanism..

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.391-395
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• 1996

This paper presents a robust force tracking control of a small-sized SMA gripper with two fingers using shape memory alloy(SMA) actuators. The mathematical governing equation of the proposed system is derived by Hamilton's principle and Lagrangian equation and then, the control system model is integrated with the first-order actuator dynamics. Uncertain system parameters such as time constant of the actuators are also included in the control model. A robust two degree of freedom(TDF) controller using H$_{\infty}$ control theory, which has inherent robustness to model uncertainties and external disturbances, is adopted to achieve end-point force tracking control of the two-finger gripper. Force tracking control performances for desired trajectories represented by sinusoidal and step functions are evaluated by undertaking both simulation and experimental works.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.1
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• pp.83-94
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• 2002

Analysis technology is widely accepted and quite popular these days. Incorporation of the analysis result into design process is a key factor for the success of the analysis area. A few design software products have been commercialized. Generally, they are trying to make an interface between various design methods and analysis software. Optimization is a representative design method. The products are investigated and compared for the aspects of user convenience and algorithm performance. A few popular products are selected. Graphic user interface (GU) is compared for the function and efficiency. The performances of the optimization algorithms are tested by mathematical and engineering examples. The results are discussed.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2218-2223
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• 2008

A nose shape is strongly related with the aerodynamic performances of train. Therefore shape definition and aerodynamic performance analysis are important for train nose shape design. In this study, a new design method was suggested for train nose shape design by configuration function. To this end, the nose shape was classified by box type and each box shape is defined. After that the 3-D shape of train was defined as several mathematical functions by combination of each box shape. Also it was shown that the wind shield of driver's seat and complex curves of surface can be expressed using superposition of functions. This methodology can be used for grid generation of numerical analysis, and applied to aerodynamic optimization design of nose shape.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.583-592
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• 1999

In order to control systems which contain nonlinearities control strategies must deal with the effects of them. Since most of control methods based on system mathematical models have been mainly developed focused on stability robustness against nonlinearities or uncertainties under the assumption that controlled systems are linear time invariant they have certain amount of limita-tions to smartly improve control perfomances of systems disturbed by nonlinearities or uncertainties. In this paper the fuzzy PID control law is suggested which can improve control performances of the nonlinear heavy load hydraulic systems disturbed by nonlinearities and uncertainties. Although the derivation process is based on the design process similar to general fuzzy logic con-troller resultant control law has analytical forms with time varying PID gains rather than linguis-tic forms so that implementation using commn-used versatile microprocessors can be achieved easily and effectively in real-time control aspect.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.06a
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• pp.3-8
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• 2003

A Simulation S/W is developed to evaluate performances of MLS (Microwave Landing System) and IBLS(Integrated Beacon Landing System) in precision auto-landing. For this study classical PID and optimal LQG controllers are developed as well as mathematical models of MLS and IBLS. Ship-landing condition is also considered by assuming sinusoidal movement of the ship in the pitch direction. The simulated aircraft is F-16 in the study of precision auto-landing. For the integrated simulation environment GUI windows are designed for input of parameter values necessary for simulation, such as vehicle performance and environmental data. For validation and verification of models various comparison graphs of simulation outputs are comprised in the GUI design as well as 3D visual simulation of vehicle dynamics.