• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.1
• /
• pp.31-40
• /
• 2021

Modern aircraft are high-performance and lightweight. Thus, the characteristics of the flexible structure appear and affect flight performance or limit it. These flexible characteristics need to be analyzed from the early stages of aircraft design. To this end, a program to analyze the dynamic and static behavior of flexible aircraft has been developed and the results are presented. Based on the multi-body dynamics simulation technique, rigid flight mechanics, structural vibrating behavior, and unsteady aerodynamics have been developed and integrated. Lastly, the level flight and the turn flight of the flexible characteristic aircraft have been analyzed using this integrated simulation program.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1871-1876
• /
• 2005

In this paper, We present a new nonlinear adaptive control law using a disturbance accommodating control (DAC) observer for a Japanese automatic landing flight experiment vehicle called ALFLEX. A future spaceplane must have ability to deal with greater fluctuations in the stability and control derivatives of flight dynamics, because its flight region is much wider than that of conventional aircraft. In our previous studies, digital adaptive flight control systems have been developed based on a linear-parameter-varying (LPV) model depending on dynamic pressure, and obtained good simulation results. However, under previous control laws, it is difficult to accommodate uncertainties represented by disturbance and nonlinearity, and to design a stable flight control system. Therefore, in this study, we attempted to design a nonlinear adaptive control law using the DAC Observer and inverse dynamic methods. A good tracking property of the obtained system was confirmed in numerical simulation.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.3
• /
• pp.254-262
• /
• 2008

In this paper, we propose an adaptive neural dynamic surface control (DSC) approach with $H_{\infty}$ tracking performance for full dynamics of nonlinear flight systems. It is assumed that the model uncertainties such as structured and unstrutured uncertainties, and external disturbances influence the nonlinear aircraft model. In our control system, self recurrent wavelet neural networks (SRWNNs) are used to compensate the model uncertainties of nonlinear flight systems, and an adaptive DSC technique is extended for the disturbance attenuation of nonlinear flight systems. All weights of SRWNNs are trained on-line by the smooth projection algorithm. From Lyapunov stability theorem, it is shown that $H_{\infty}$ performance nom external disturbances can be obtained. Finally, we present the simulation results for a nonlinear six-degree-of-freedom F-16 aircraft model to confirm the effectiveness of the proposed control system.

• Aerospace Engineering and Technology
• /
• v.9 no.2
• /
• pp.105-115
• /
• 2010

This technical paper describes and summarizes the flight test results for the longitudinal and lateal-directional dynamic stability characteristics. The target aircraft is the 4-seat carnard type aircraft, FireFly, which has been developed by KARI. Airborne sensors and real-time telemetry system are constructed to obtain the flight test data. The dynamic stability characteristics should be analyzed and tested by estimaitng the aerodynamic parameters in the dymaic equations of motion. The maximum likelihood estimation technique has been applied to the flight data from chirp, 3211, and doublet control inputs.

• Journal of Advanced Navigation Technology
• /
• v.16 no.4
• /
• pp.571-577
• /
• 2012

In this paper, we design a flight controller using a dynamic compensator for a small unmanned aerial vehicle. The proposed method ensures flight stability during altitude holding and waypoints passing by improving the transient response and steady state error. The control system consists of dual feedback loops with an inner loop and a outer loop. The inner loop has a PD controller to improves the transient response and the outer loop has a dynamic compensator to reduce overshoot in the transient response and improve the steady state error. The performance of the proposed method is evaluated by flight test on a small UAV.

• The Research Journal of the Costume Culture
• /
• v.19 no.5
• /
• pp.1019-1030
• /
• 2011

The aim of this study was to develop a pattern of flight attendant uniform shirts to provide better comfort for their work postures. Flight attendants' work postures were evaluated to determine the problems of clothing and mobility during their work. The pattern of the flight attendants' uniform shirt was altered by applying dynamic wearing ease(DWE). DWE was calculated from four standardized dynamic postures and a static posture. An experimental garment was made with the altered postures. The researcher redesigned the pattern of the uniform shirts, which minimizes physical limitations in movements. The fit and mobility of the shirts were evaluated. Results of this study are as follows. First, the five representative work postures were selected by "clothing stress" and "repetitiveness." These postures included raised arms, twisting midriff and shoulder postures. Five representative postures were selected by using the ergonomic posture assessment device index(OWAS). Second, the experimental garment was developed by applying DWE across the back and at armhole depth, back length, and side length. Third, the fit and mobility of the experimental garments and the original uniform shirts were compared at the flight working environment set and 5 dynamic body postures of raising arms. The experimental garments made with an altered pattern provided better fit and mobility than the original sample shirts.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.25 no.6
• /
• pp.596-605
• /
• 2022

In this study, analysis of dynamic characteristics and flight vibration was performed to unmanned aerial vehicles. The analysis model was supplemented by performing a dynamic characteristic test and a random vibration test using manufactured dummy aerial vehicle. For the dynamic characteristic test, a bungee cable was used to implement the free end boundary condition. Prior to the flight vibration test using a multiple electric shaker, a random vibration test was performed to predict the excitation force during the actual flight vibration test. It was judged that the actual test could be predicted more accurately by supplementing the analysis model from the test results. In addition, it was possible to determine the feasibility of the test by predicting the excitation force of the flight vibration test.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.18 no.4
• /
• pp.1-8
• /
• 2010

In the aerospace field, the study on a morphing-wing is in progress to improve flight performance and perform multi flight mission. There are many concepts of morphing-wing such as camber-change, wing-twist, variable-span, and so on. In this study, the aerodynamic characteristics and flight control of an air vehicle with a variable-span morphing wing (VSMW) have been investigated. VSMW with symmetric span control(SSC) can increase cruising range of aircraft by reducing drag in various flight condition. VSMW with anti-symmetric span control(ASSC) can be used in the roll control of an aircraft. The flight control about pure rolling dynamic system and full dynamic system have been performed about the cruise missile.

• 한국전산유체공학회:학술대회논문집
• /
• 2007.04a
• /
• pp.14-16
• /
• 2007

A critical problem in the integration of stores into new and existing aircraft is the safe separation of the stores from the aircraft at a variety of flight conditions representative of the aircraft flight regime. Typically, the certification of a particular store/aircraft/flight condition combination is accomplished by a flight test. Flight tests are very expensive and do expose the pilot and aircraft to a certain amount of risk. Wind tunnel testing, although less expensive than flight testing, is still expensive. Computational Fluid Dynamics(CFD) has held out the promise of alleviating expensive and risk by simulating weapons separation computationally. The forces and moments on a store at carriage and at various points in the flow field of te aircraft can be computed using CFD applied to the full aircraft and store geometry. This study needs full dynamic characteristics study and flow analysis for securing store separation safety. Present study performs dynamic simulation of store separation with flow analysis using Chimera grid scheme which is usually used for moving simulations.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.4
• /
• pp.327-334
• /
• 2010

Recently developed aircrafts use Fly-By-Wire(FBW) or Fly-By-Light(FBL) system. These systems have some merits; they can perform very complicated missions, they can expand the flight region and improve the reliability of the aircrafts. With the development of flight control systems that use FBW technique, flight envelope protection concept is introduced to guarantee reliability of the aircraft and improve the efficiency of mission achievement. In this study, flight envelope protection system is designed using a dynamic trim algorithm, a peak response estimation, and a gain scheduling technique. The performance of these methods are compared by performing numerical simulation.