• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.302-307
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• 2008

The development technology for the helicopter is improved by the increasing of computing power and advanced test facilities. The increasing efficiency of fuel consuming by the developing of improved lift-to-drag rotor system is the major issue, the noise reduction for ecology(civil area) and increase of survivability to reduce noise detection(battlefield) also are important. This investigation shows the classification of helicopter external noise and requirements, the noise flight test methods, the numerical modeling method for aero-acoustic of rotor blade and the result of CAA(Computational Aero-Acoustic) for main rotor blade.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.302-307
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• 2008

The development technology for the helicopter is improved by the increasing of computing power and advanced test facilities. The increasing efficiency of fuel consuming by the developing of improved lift-to-drag rotor system is the major issue, the noise reduction for ecology(civil area) and increase of survivability to reduce noise detection(battlefield) also are important. This investigation shows the classification of helicopter external noise and requirements, the noise flight test methods, the numerical modeling method for aero-acoustic of rotor blade and the result of CAA(Computational Aero-Acoustic) for main rotor blade.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.344-348
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• 1992

This paper describes a procedure to design a hovering flight controller for a model helicopter using LQG theory. Parameters of the model helicopter in hover are obtained using direct measurements and calculations proposed by other research. A feedback co is by using digital LQG theory. First, a full state feedback controller is designed to the discretized system taking desirable transient response and other assumptions into account. Then a full-state estimator is designed and revised until desirable response is obtained while global stability is maintained. Performance of the controller is tested by computer simulations. Experiments have been performed using a 3-degree-of-freedom gimbal that holds the model helicopter, and the controller exhibited stable hover capability.

• International Journal of Control, Automation, and Systems
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• v.2 no.2
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• pp.156-164
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• 2004

The unmanned tandem helicopter, which is a MIMO nonlinear system with complexity and inherent instability, exists in unstable zero dynamics. In this paper, approximate linearization is presented to design the controller for output tracking of an unmanned tandem helicopter based on the dynamic augment method, and the simulation results are encouraging.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.1
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• pp.54-60
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• 2009

In this paper, a precision landing approach is implemented based on real-time image processing. A full-scale landmark for automatic landing is used. canny edge detection method is applied to identify the outside quadrilateral while circular hough transform is used for the recognition of inside circle. Position information on the ground landmark is uplinked to the unmanned helicopter via ground control computer in real time so that the unmanned helicopter control the air vehicle for accurate landing approach. Ground test and a couple of flight tests for autonomous landing approach show that the image processing and automatic landing operation system have good performance for the landing approach phase at the altitude of $20m{\sim}1m$ above ground level.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.54-64
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• 2006

To augment weakly damped lag mode stability of a hingeless helicopter rotor blade in hover, piezoelectric shunt with a resistor and an inductor circuits for passive damping has been studied. A shunted piezoceramics bonded to a flexure of rotor blade converts mechanical strain energy to electrical charge energy which is dissipated through the resistor in the R-L series shunt circuit. Because the fundamental lag mode frequency of a soft-in-plane hingeless helicopter rotor blade is generally about 0.7/rev, the design frequency of the blade system with flexure sets to be so. Experimentally, the measured lag mode frequency is 0.7227/rev under the short circuit condition. Therefore the suppression mode of this passive damping vibration absorber is adjusted to 0.7227/rev. As a result of damping enhancement using passive control, the passive damper which consists of a piezoelectric material and shunt circuits has a stabilizing effect on inherently weakly damped lag mode of the rotor blades, at the optimum tuning and resistor condition.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2599-2601
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• 2000

A helicopter control problem has been researched with many control theory. Especially, study of the hovering flight attitude control of a helicopter has been brisked since 60s with multivariable control theory. In this paper, the modeling is interpreted through the 6-freedom equation. To getting a entire equation, species of parameters and charts are adapted. The $H_2/H_{\infty}$ controller is acquired by mixing the $H_2$ control theory and the $H_{\infty}$ control theory. The $H_2$ control theory is reasonable one to increase the performance of a plant, and the $H_{\infty}$ control theory secures the robust stability. The simulation shows that the helicopter system is being controlled while maintaining performance and robust stability against perturbation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.551-554
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• 2008

In the recent year, Unmanned helicopters of airline industries are using in various industries such as monitoring system, agriculture and forest fire. A unmanned helicopter is needed a powerful engine for transport weighty payload and have to need a light weight. Therefore it is necessary a light weight transmission of the unmanned helicopter. Initially a rectangular transmission housing has been considered, but an empty space in the housing is not useful for light weight design. In this study, new model has been introduced into the transmission housing by using rapid prototyping. As a result, the weight of new transmission housing can be reduced very much as 67%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.3
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• pp.217-224
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• 2020

The use of a high gain flight control system to achieve high bandwidth performance increase the instability of a helicopter. To investigate these phenomena numerically, high fidelity EC155B1 helicopter model and simplified flight control system that include actuator, digital processor and noise rejection filter was developed. A study conducts an analytical investigation of roll axis stability of the helicopter model as feedback gain increases. And this study analyzes roll-rate and roll-attitude feedback gains limited by rotor flap mode. The results indicate that the phase delays caused by the filter can severely limit the usable values of the roll-rate and roll-attitude feedback gains.

• Journal of Korean Society for Quality Management
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• v.43 no.4
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• pp.589-606
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• 2015

Purpose: In developing new products, reducing performance variation is important for competitiveness factors such as quality, cost, and delivery. This paper aims at evaluating three performance variations; measurement, performance evaluation, and manufacturing variations, and then improving product and process design, focused on paper helicopter making case study. Methods: For measurement system analysis, gage R&R (repeatability and reproducibility), linearity, stability are evaluated. Since gage R&R are not satisfactory, the measurement system is improved by adopting voice memos application of iPhone and providing standard measurement procedure. To evaluate performance variation, product deterioration and environment factor (wind speed) is considered. Since the existing design is sensitive to these noise factors, a new product design is developed, which is proven to be robust to the noise factors. Finally, manufacturing variations are evaluated with five factors which can cause variation in flight time. To reduce the impact of three significant factors, three improvement methods are applied. Results: Three performance variations are evaluated and robust paper helicopter design is presented. Conclusion: To reduce measurement and process variations, improved measurement method and paper helicopter making procedure are proposed. A new product design is also presented which is robust to deterioration and environmental variation. This paper is expected to benefit students and practitioners who want to have hands-on knowledge on new product quality improvement.