• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.203-210
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• 2012

The main rotor control system is an important structural part of a helicopter that manages the thrust and control force of the helicopter. The main rotor control system consists of a swashplate assembly, scissor assembly, pitch rod assembly, guide, etc. The main rotor control system must endure various loads, such as the thrust and control force, and must meet the optimized fatigue safety life. The rotating swashplate is an important structure influenced by the pitch rod load and rotating scissor load. In this paper, the accuracy of a result about the rotating swashplate part of the main rotor control system is proven through comparison between fatigue test and FEM results. Based on this result, we estimate the lifetime and deduce the fatigue safe lifetime.

• Journal of Computing Science and Engineering
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• v.7 no.2
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• pp.122-131
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• 2013

The MPI CyberMotion Simulator provides a unique motion platform, as it features an anthropomorphic robot with a large workspace, combined with an actuated cabin and a linear track for lateral movement. This paper introduces the simulator as a tool for studying human perception, and compares its characteristics to conventional Stewart platforms. Furthermore, an experimental evaluation is presented in which multimodal human control behavior is studied by identifying the visual and vestibular responses of participants in a roll-lateral helicopter hover task. The results show that the simulator motion allows participants to increase tracking performance by changing their control strategy, shifting from reliance on visual error perception to reliance on simulator motion cues. The MPI CyberMotion Simulator has proven to be a state-of-the-art motion simulator for psychophysical research to study humans with various experimental paradigms, ranging from passive perception experiments to active control tasks, such as driving a car or flying a helicopter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.397-402
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• 1999

In this paper, we derive dynamic equation of a simulated helicopter and propose the control method base on a neural network to control its attitude. The coupling coefficients are adjusted to minimize the error between the output of a control system and the reference value. The gain of the proposed controller are automatically adjusted by the back propagation of a neural network. Simulation results using MATLAB are given in this paper.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.86-88
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• 1997

The helicopter system is non-linear and complex. Futhermore, because of absence of an accurate mathematical model, it is difficult accurately to control its attitude therefore, we propose a fuzzy control technique to control efficiently its elevation angle and azimuth one. This controller is on the basis of expert's knowledges and his experiences. The simulation results using MATLAB are introduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.236-241
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• 2011

An active trailing-edge flap blade named as Seoul National University Flap (SNUF) blade is designed for reducing helicopter vibratory loads and the relevant aeroacoustic noise. Unlike the conventional rotor control, which is restricted to 1/rev frequency, an active control device like the present trailing-edge flap is capable of actuating each individual blade at higher harmonic frequencies i.e., higher harmonic control (HHC) of rotor. The proposed blade is a small scale blade and rotates at higher RPM. The flap actuation components are located inside the blade and additional structures are included for reinforcement. Initially, the blade cross-section design is determined. The aerodynamic loads are predicted using a comprehensive rotorcraft analysis code. The structural integrity of the active blade is verified using a stress-strain recovery analysis.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.534-536
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• 1998

The helicopter system is non-linear and complex. Futhermore, because of absence of accurate mathematical model, it is difficult accurately to control its attitude. therefore, we propose a PID Neural Networks control technique to control efficiently its elevation angle and azimuth one. The coefficients of PID controller are automatically adjusted by the back-propagation algorithm of a neural network. The simulation results using MATLAB are introduced.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.3
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• pp.442-453
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• 2016

A significant source of vibration in helicopters is the main rotor system, and it is a technical challenge to reduce the vibration in order to ensure the comfort of crew and passengers. Several types of passive devices have been applied to conventional helicopters in order to reduce the vibration. In recent years, helicopter manufacturers have increasingly adopted active vibration control systems (AVCSs) due to their superior performance with lower weight compared with passive devices. AVCSs can also maintain their performance over aircraft configuration and flight condition changes. As part of the development of AVCS software for light civil helicopter (LCH) applications, a test bench is constructed and vibration control tests and simulations are performed in this study. The test bench, which represents the airframe, is excited using a pair of counter rotating force generators (CRFGs) and a multiple input single output (MISO) AVCS that consists of three accelerometer sensors and a pair of CRFGs; a filtered-x least mean square (LMS) algorithm is applied for the vibration reduction. First, the vibration control tests are performed with uniform sensor weights; then, the change in the control performance according to changes in the sensor weight is investigated and compared with the simulation results. It is found that the vibration control performance can be tuned through adjusting the weights of the three sensors, even if only one actuator is used.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.497-506
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• 1991

In this paper, a new construction for training simulator of R/C helicopter based on two types of servo controller is proposed. Two modified algorithms (algorithm I and II) for servo controller design are presented. Algorithm I is developed by adopting Davison's method in the case that the expressions for the homogeneous differential equations of reference input and disturbance are different types, and algorithm II is done by considering error weighting function for the servo controller of algorithm I . The linear fractional transformation method is incorporated in both design methods in order to assign the closed loop poles of the servo system in a specified region. The helicopter simulator is composed by the gimbals with two freedom of rolling and pitching. The reliability and validity for the design methods of the proposed servo controller are investigated through the practical experiment for the simulator by using 16bits micro-computer with A/D and D/A converters. It can be observered from the experimental results that the proposed servo controller is applicable to practical plants since the simulator is robust for the arbitrary disturbance and it follows to the given reference input without significant steady state error.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.4
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• pp.50-56
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• 2012

Rotor system is a very important part which produce lift, thrust and control force in helicopter. Component of rotor system must have structural integrity for applied load. The estimation of structural integrity is regarded greatly as important in aerospace field. In this study, the process of structural analysis performed for bearingless main rotor system of helicopter. The composite flexbeam and torque tube of bearingless main rotor are very thick, so 3D layered soild elements of MSC.PATRAN were used to get the finite element analysis results. To estimate structural integrity, non-linear static analysis considering geometric non-linearity is performed. In addition, detailed finete element analysis and non-linear static analysis are performed to consider the stress concentration for fitting effect and contact surface. The estimation process of structural integrity for bearingless main rotor system of helicopter may help the design.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.213-216
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• 2005

This paper describes the design, analysis and manufacture procedure of the composite blade for hingeless rotor system of unmanned helicopters. Helicopter rotor system is the key structural unit that produces thrust and control forces for intended flight conditions. In this work, a hingeless rotor system is adopted, and base on the design requirements for rotor system, composite blade section design and calculation of material properties were performed. In order to avoid the unstable state such as resonance, vibration characteristics of rotor system were analyzed. Finally, this paper describes simply the forming and manufacture of composite blade.