• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.398-405
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• 2014

Recently the embedded software has been widely applied to the safety-critical systems in aviation and defense industries, therefore, the higher level of reliability, availability and fault tolerance has become a key factor for its implementation into the systems. The integrity of the software can be verified using the static analysis tools. And recent developed static analysis tool can evaluate code integrity through the mathematical analysis method. In this paper we detect the autocode error and violation of coding rules using the formal verification tool, Polyspace(R). And the fundamental errors on the flight control law model have been detected and corrected using the formal verification results. As a result of verification process, FBW helicopter control law autocode can ensure code integrity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.6
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• pp.443-453
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• 2020

This study using the active vibration control technique attempts to alleviate numerically the airframe vibration of a UH-60A helicopter. The AVCS(Active Vibration Control System) is applied to reduce the 4/rev vibration responses at the specified locations of the UH-60A airframe. The 4/rev hub vibratory loads of the UH-60A rotor is predicted using the nonlinear flexible dynamics analysis code, DYMORE II. Various tools such as NDARC, MSC.NASTRAN, and MATLAB Simulink are used for the AVCS simulation with five CRFGs and seven accelerometers. At a flight speed of 158knots, the predicted 4/rev hub vibratory loads of UH-60A rotor excite the airframe, and then the 4/rev vibration responses at the specified airframe positions such as the pilot seat, rotor-fuselage joint, mid-cabin, and aft-cabin are calculated without and with AVCS. The 4/rev vibration responses at all the locations and directions are reduced by from 25.14 to 96.05% when AVCS is used, as compared to the baseline results without AVCS.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.64-71
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• 2006

For SUAV is required to have the capacity of VTOL and fast forward flight, the SUAV development program has decided to adopt the tiltrotor mechanism which includes helicopter and turboprop mechanisms. From the engine point of view, the key engine parameters such as engine operating mechanism, engine control scheme, the dynamics characteristic of power train, engine intake/exhaust concept, and engine installation requirements should fulfill the requirements of the two different mechanisms, helicopter and turboprop. And for the maximum efficiency of the rotor, rotational speed for the two modes are 20% different, the power train shall find a way to make it so. Meeting these specific requirements for the tiltrotor mechanism, this research begins with a conventional OTS(off-the-shelf) turboshaft engine survey and minimizes engine modification to develop an economical propulsion system. The engine technical review has been performed on the basis of those requirements and capabilities.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.407-408
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• 2016

A drone has been popularized to such an extent as to be seen in the near parks recently. The drone refers to an unmanned aerial vehicle(UVA) which can fly and be steered by a radio wave without a pilot and it has a airplane or helicopter shape. The drone was first started to be used from military purpose, but its usage has been expanded to the private such as broadcast shooting, crop-dusting, field discovery and hobby. However the drone that we can see often in the market is expansive, hard to be repaired when it broken down and has a discomfort of the short flight time. In this paper, to solve an uncomfortable talk on the cheap ATmega128 Using (Quad copter) drone for implementation. Axes gyroscope and accelerometers mcu between posture an attitude control, communications through drone control, pid. Receiver input them into transmitter signals of movements to control drone c the programming was implemented in on the basis of language.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.1
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• pp.74-85
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• 1990

The LQG and LQG/LTR compensators have the same structrues in dynamics. The only difference is the values of the design parameters in the two compensators. The design parameters of the LQG and LQG/LTR compensators are selected in the sense of the least-squares error minimi- zation and loop shaping, respectively. In this paper, the LQG and LQG/ LTR design methods are applied to the helicopter in hover which is modeled as a SISO fourth order system. The dynamic characteristics and the perfor- mance of the two control systems are analyzed by the computer simulation. It is found that the LQG/LTR design method is systematic and has good performance in comparision with the LQG design method.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.457-459
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• 1998

This paper presents a 3-DOF hovering flight controller for a model helicopter using the minimal order LQG/LTR technique. A model helicopter is an unstable multi-input multi-output nonlinear system strongly exposed to disturbances, so a robust multi-variable control theory should be applied to control it. The minimal order LQG/LTR technique which uses a reduced-order observer in the LTR procedure is used to design the controller. Performances for the 3-DOF hovering flight controller are evaluated through computer simulations.

• Journal of Aerospace System Engineering
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• v.6 no.2
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• pp.23-27
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• 2012

The evaluation of simulation models against ADS-33 quantitative rotorcraft handling qualities metrics has, in the past, been a time consuming effort, involving many individual analyses in both the time and frequency domains. Manual tuning of control system parameters to meet handling qualities and performance specifications has been cumbersome and complicated. Performing rigorous trade-off studies for numerous variations in the control system is too time consuming to be practicable. With the complex interaction of time- and frequency based specifications for the closed- and broken-loop responses, it is difficult to know if the design makes the most effective use of the available control power. The Control Designer's Unified Interface (CONDUIT) software makes possible rapid optimization and trade-offs of design configurations against handling qualities specifications.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.9
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• pp.916-924
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• 2008

In this paper dynamic modeling parameters were estimated using a frequency domain estimation method. A systematic flight test method was employed using preprogrammed multistep excitation of the swashplate control input. In addition when one axis is excited, the autopilot is engaged in the other axis, thereby obtaining high-quality flight data. A dynamic model was derived for a small scale unmanned helicopter (CNUHELI-020, developed by Chungnam National University) equipped with a Bell-Hiller stabilizer bar. Six degree of freedom equations of motion were derived using the total forces and moments acting on the small scale helicopter. The dynamics of the main rotor is simplified by the first order tip-path plane, and the aerodynamic effects of fuselage, tail rotor, engine, and horizontal/vertical stabilizer were considered. Trim analysis and linearized model were used as a basic model for the parameter estimation. Doublet and multistep inputs are used to excite dynamic motions of the helicopter. The system and input matrices were estimated in the frequency domain using the equation error method in order to match the data of flight test with those of the dynamic modeling. The dynamic modeling and the flight test show similar time responses, which validates the consequence of analytic modeling and the procedures of parameter estimation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.5
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• pp.517-526
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• 2015

This paper presents the results of study for improving the reliability of quadrotor attitude control by applying a multi-sensor along with a data fusion algorithm. First, a mathematical model of the quadrotor dynamics was developed. Then, using the quadrotor mathematical model, simulations were performed using the improved reliability multi-sensor data as the inputs. From the simulation results, we designed a Gimbal-equipped quadrotor system. With the quadrotor in a hover state, we performed experiments according to the angle change of the user's specifications. We then calculated the attitude control data from the actual experimental data. Furthermore, with additional simulations, we verified the performance of the designed quadrotor attitude control system with multiple sensors.

• Journal of Aerospace System Engineering
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• v.13 no.6
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• pp.52-59
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• 2019

The rotor blade is a key component that generates the lift, thrust, and control forces required for helicopter flight by the torque transmitted through the hub and the blade pitch angle control, and should be designed to factor vibration characteristics so that there is no risk of resonance with structural safety. In this study, the structural design of the main rotor blade for MPUH(Multi-Purpose Unmanned Helicopter) was conducted and the sectional stiffness measurement of the fabricated blade was performed. The evaluation of the vibration characteristics of the main rotor system was then conducted factoring the measured stiffness distribution. The interior of the rotor blade comprised of the skin, spar, and torsion box, and carbon and glass fiber composites were applied. The Ksec2D program was applied to predict the stiffness of blade, and the results were compared to the measured data. CAMRADII, a comprehensive rotorcraft analysis program, was applied to investigate the natural frequency trends and resonance risks due to the rotor rotation.