• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.96-103
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• 2011

Rotor grip is used as a component of rotor system in unmanned helicopter. Instead of usual machining, hot forging process has been considered to improve its proof stress against repeated loading conditions and crash in the farm-field. Die design and forming analysis have been performed according to the conditions such as billet volume, flash, cavity filling, and the distribution of damage during the forming by using FE analysis. In the results of analysis, the possibility of structural failure in the model has not been found because its maximum effective stress is much lower than yield strength of the titanium alloy. In the forging die design, flash has been allowed because of low production in the industrial field. Preform design was studied by using FE-analysis, and its optimal dimension was obtained in the hot forging of rotor grip with titanium alloy.

• 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 the Korean Society for Aviation and Aeronautics
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• v.23 no.1
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• pp.67-73
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• 2015

The previous limited authority system capable of implementing attitude command response type and translational command response type by operating SAS actuator has the problem of early saturation of SAS actuator since SAS actuator should compensate the mechanical linkage displacement caused by control sick movement. In this paper, a limited authority system where flight control computer receives the command from the control stick which is not connected to the mechanical linkage is described. In this system the compensation by the SAS actuator is not necessary and SAS actuator saturate later. SAS actuator saturation problem can be further relaxed by using the trim actuator. This new limited authority system is applied to BO-105 model, simulation is performed for the doublet input and pirouette maneuver is also simulated and analyzed.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2453-2455
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• 2005

We represent an efficient intelligent digital redesign method for a Takagi-Sugeno (T-S) fuzzy system Intelligent digital redesign means that an existing analog fuzzy-model-based controller converts to equivalent digital counter part in the sense of state-matching. The proposed method performs previous work, moreover, it allows re matching the states of the overall closed-loop T-S fuzzy system with the predesigned analog fuzzy-model-based controller. And the problem of stability represent convex optimization problem and cast into linear matrix inequality (LMI) framework. This method applies to the helicopter systems which are the nonlinear plant and determine the feasibility and effectiveness of the proposed method.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2283-2285
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• 2001

This paper proposed to a neural network based fuzzy control (neuro-fuzzy control) technique for attitude control of helicopter with strongly dynamic nonlinearities and derived a helicopter aerodynamic torque equation of helicopter and the force balance equation. A neuro-fuzzy system is a feedforward network that employs a back-propagation algorithm for learning purpose. A neuro-fuzzy system is used to identify nonlinear dynamic systems. Hence, this paper presents methods for the design of a neural network(NN) based fuzzy controller(that is, neuro-fuzzy control) for a helicopter of nonlinear MIMO systems. The proposed neuro-fuzzy control determined to a input-output membership function in fuzzy control and neural networks constructed to improve through learning of input-output membership functions determined in fuzzy control.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1811-1813
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• 2005

We represent an efficient intelligent digital redesign method for a Takagi-Sugeno(T-S) fuzzy system. Intelligent digital redesign means that an existing analog fuzzy-model-based controller converts to equivalent digital counter part in the sense of state-matching. The proposed method performs previous work, moreover, it allows to matching the states of the overall closed-loop T-S fuzzy system with the predesigned analog fuzzy-model-based controller. And the problem of stability represent convex optimization problem and cast into linear matrix inequality(LMI) framework. This method applies to the helicopter systems which are the nonlinear plant and determine the feasibility and effectiveness of the proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.902-905
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• 2004

Recently, the composite materials are widely used for manufacturing the helicopter rotor blades. furthermore, composites show great potential on the design of rotor blades due to the advantages of strength, durability and weight of the materials. To keep with this advantages, it is necessary to calculate natural frequencies of a rotating blades for avoiding resonance. In this paper, the structural design process of airfoil cross section is introduced, and natural frequencies of composite rotor blades with variable rpm we investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.9-17
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• 2005

In the early stage of helicopter design, an optimal configuration is usually determined after a numerous parametric study about the aerodynamic performance due to geometric variation. In order to improve the aerodynamic performance of a shrouded tail rotor, optimization of the tip clearance gap between blade and shroud, the blade planform shape, and the arrangement of blade spacing is required. In the present study, the aerodynamic performance characteristics of a shrouded tail rotor due to geometric variation was investigated by using an inviscid compressible unstructured mesh flow solver for rotary wings.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.298-303
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• 2004

This paper deals with a stochastic stabilization of observer-based output-feedback control Takagi-Sugeno (T-S) fuzzy system with Markovian input delay. The finite Markovian process is adopted to model the input delay of the overall control system. It is assumed that the zero and hold devices are used for control input. The continuous-time T-S fuzzy system with the Markovian input delay is discretized for easy handling delay, accordingly, the discretized T-S fuzzy system is represented by a discrete-time T-S fuzzy system with jumping parameters. The stochastic stabilizability of the jump T-S fuzzy system is derived and formulated in terms of linear matrix inequalities (LMIs). The usefulness of the proposed algorithm is also certificated by simulation of 2 degree of freedom helicopter model.

• Journal of Biosystems Engineering
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• v.34 no.2
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• pp.89-94
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• 2009

Aerial application using an agricultural unmanned helicopter was suggested for an alternative against current pesticide application methods. Centrifugal clutches play important roles in the performance and safety of the helicopter operation. A previous study analyzed and verified the power transfer theory of the guide type centrifugal clutch. Based on the clutch theory, optimal designs of the clutch became possible and feasible using a simulation method. Design criteria of the clutch were the power transfer capacity of 24.66 kW(33.5 PS) at the rated engine speed and the engaging range speed of 3,000${\sim}$3,500 rpm. Various designs were accomplished using the simulation. An optimal clutch was simulated by determining the values of spring constant and mass of friction sector, which were 94,700 N/m and 123.7 g, respectively. The design performed the power capacity of 24.86 kW(33.8 PS) and engagement speed of 3,069 rpm, meeting the design criteria. Using the designed clutch, an efficient transfer of the power would be possible for the unmanned agricultural helicopter.