• Title/Summary/Keyword: Delay of Flight

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Fault Tolerant Control of Hexacopter for Actuator Faults using Time Delay Control Method

  • Lee, Jangho;Choi, Hyoung Sik;Shim, Hyunchul
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.1
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    • pp.54-63
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    • 2016
  • A novel attitude tacking control method using Time Delay Control (TDC) scheme is developed to provide robust controllability of a rigid hexacopter in case of single or multiple rotor faults. When the TDC scheme is developed, the rotor faults such as the abrupt and/or incipient rotor faults are considered as model uncertainties. The kinematics, modeling of rigid dynamics of hexacopter, and design of stability and controllability augmentation system (SCAS) are addressed rigorously in this paper. In order to compare the developed control scheme to a conventional control method, a nonlinear numerical simulation has been performed and the attitude tracking performance has been compared between the two methods considering the single and multiple rotor faults cases. The developed control scheme shows superior stability and robust controllability of a hexacopter that is subjected to one or multiple rotor faults and external disturbance, i.e., wind shear, gust, and turbulence.

Ad-hoc based Multiple Access Scheme for VHF Oceanic Network (VHF 대양 네트워크를 위한 Ad-hoc 기반 다중접속기법)

  • Koo, Jayeul;Baek, Hoki;Lim, Jaesung
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.21 no.1
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    • pp.15-22
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    • 2013
  • In oceanic flight routes, HF radio and satellite data links have weather restrictions, long propagation delay and low data throughput. In this paper, we propose oceanic aeronautical communications scheme in the VHF band based on ad-hoc communication. The proposed scheme organizes autonomously a multi-hop network that is divided into multiple local network using aircraft to fly long-distance communication and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. In addition, several algorithms to apply spatial reuse of transmission to multi-hop long range communication environments have been proposed. The proposed system proves performance improvement on delay time as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

Correlation Analysis between Delay and Turnaround Time at Jeju International Airport (제주국제공항의 지연과 Turnaround Time 간의 상관관계 분석)

  • Lee, Choongsub;Kim, Dongsin;Kim, Hyewook;Baik, Hojong
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.30 no.1
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    • pp.1-11
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    • 2022
  • The capacity of Jeju International Airport has reached its limit due to a surge in air traffic demand such as passengers and cargo and the continuous expansion of Low Cost Carriers (LCC). Despite COVID-19 that has began in November 2019, Jeju International Airport still has continuous demand in terms of passenger and cargo transportation. As a result, it is undeniable that the delay rate also unexpectedly increased as the air traffic volume at Jeju International Airport continued to increase. In this study, the correlation between Turnaround Time and delay rates of national airlines is analyzed based on past flight data at Jeju International Airport, and the cumulative delay time trend for sampled airlines is compared with Turnaround Time. Through this study, it is expected to contribute to securing aircraft operation efficiency and on-time by analyzing delays related to Turnaround Time at Jeju International Airport.

Disturbance Observer and Time-Delay Controller Design for Individual Blade Pitch Control System Driven by Electro-Mechanical Actuator (전기-기계식 구동기 기반 개별 블레이드 피치 조종 시스템의 제어를 위한 외란 관측기와 시간 지연제어기 설계)

  • Jaewan Choi;Minyu Kim;Younghoon Choi
    • Journal of Aerospace System Engineering
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    • v.18 no.1
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    • pp.29-36
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    • 2024
  • Recently, the concept of Urban Air Mobility (UAM) has expanded to Advanced Air Mobility (AAM). A tilt rotor type of vertical take-off and landing aircraft has been actively studied and developed. A tilt-rotor aircraft can perform a transition flight between vertical and horizontal flights. A blade pitch angle control system can be used for flight stability during transition flight time. In addition, Individual Blade Control (IBC) can reduce noise and vibration generated in transition flight. This paper proposed Disturbance Observer Based Control (DOBC) and Time Delay Control (TDC) for individual blade control of an Electro-Mechanical Actuator (EMA) based blade pitch angle control system. To compare and analyze proposed controllers, numerical simulations were conducted with DOBC and TDC.

Display Synchronization Scheme for Flight Simulator Considering Frame Per Second (프레임률을 고려한 항공기 시뮬레이터의 영상 동기화 방안)

  • Lee, SunYoung;Mun, Dae-Han;Lee, ChungJae;Kim, Ki-Il
    • IEMEK Journal of Embedded Systems and Applications
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    • v.11 no.1
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    • pp.39-46
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    • 2016
  • According to general architecture of flight simulator made up of several independent rendering display systems, display synchronization problem between them naturally happens. In addition, since the flight simulator is usually implemented in the same networks where network delay is not big concern, it is necessary to consider different factors of existing synchronization technique. Among them, in this paper, we propose a new display synchronization scheme for flight simulator where each system has different rendering capacity. In the proposed scheme, each system is synchronized by considering maximum and minimum frames per second (FPS) while considering level of detail and latency. Also, experimental results are given to demonstrate the suitability of the proposed scheme for display synchronization scheme.

Development of Operation Network System and Processor in the Loop Simulation for Swarm Flight of Small UAVs (소형 무인기들의 군집비행을 위한 운영 네트워크 시스템과 PILS 개발)

  • Kim, Sung-Hwan;Cho, Sang-Ook;Cho, Seong-Beom;Park, Choon-Bae
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.5
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    • pp.433-438
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    • 2012
  • In this paper, a operation network system equipped with onboard wireless communication systems and ground-based mission control systems is proposed for swarm flight of small UAVs. This operating system can be divided into two networks, UAV communication network and ground control system. The UAV communication network is intend to exchange the informations of navigation, mission and flight status with minimum time delay. The ground control system consisted of mission control systems and UDP network. Proposed operation network system can make a swarm flight of various UAVs, execute complex missions decentralizing mission to several UAVs and cooperte several missions. Finally, PILS environments are developed based on the total operating system.

Development of Flight Control System and Troubleshooting on Flight Test of a Tilt-Rotor Unmanned Aerial Vehicle

  • Kang, Youngshin;Park, Bum-Jin;Cho, Am;Yoo, Chang-Sun;Koo, Sam-Ok;Tahk, Min-Jea
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.1
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    • pp.120-131
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    • 2016
  • The full results of troubleshooting process related to the flight control system of a tilt-rotor type UAV in the flight tests are described. Flight tests were conducted in helicopter, conversion, and airplane modes. The vehicle was flown using automatic functions, which include speed-hold, altitude-hold, heading-hold, guidance modes, as well as automatic take-off and landing. Many unexpected problems occurred during the envelope expansion tests which were mostly under those automatic functions. The anomalies in helicopter mode include vortex ring state (VRS), long delay in the automatic take-off, and the initial overshoot in the automatic landing. In contrast, the anomalies in conversion mode are untrimmed AOS oscillation and the calibration errors of the air data sensors. The problems of low damping in rotor speed and roll rate responses are found in airplane mode. Once all of the known problems had been solved, the vehicle in airplane mode gradually reached the maximum design speed of 440km/h at the operation altitude of 3km. This paper also presents a comprehensive detailing of the control systems of the tilt-rotor unmanned air vehicle (UAV).

Performance Evaluation of Double-Differencing Position-Domain Hatch Filter By a Landing Experiment (착륙 실험에 의한 이중차분 위치영역 Hatch 필터의 성능 분석)

  • Kim, Hee-Sung;Joo, Jung-Min;Lee, Hyung-Keun
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.18 no.1
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    • pp.19-26
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    • 2010
  • To expand the application area of global navigation satellite systems, precision landing is one of the most critical area to be solved. For the development and validation of the precision landing system, many aspects need to be analyzed including the system architecture, signal characteristics, atmospheric delay, communication delay, accuracy, integrity, and availability. Among them, the signal characteristics analysis requires the processing of measurements collected by real-flight experiments. This paper presents the processing results of the real measurements collected by a flight and landing experiment. To process and analyze the data, double differencing position-domain hatch filter is utilized. Accuracy of the proposed filter is evaluated utilizing reference trajectory generated by commercial software. Finally, by comparing with conventional range domain characteristics of position domain filter is analyzed.

Performance Analysis of Pseudolite Tropospheric Delay Models Using Radiosonde Meteorological Data

  • So, Hyoungmin;Park, Junpyo;Song, Kiwon
    • Journal of Positioning, Navigation, and Timing
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    • v.2 no.1
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    • pp.49-57
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    • 2013
  • When pseudolite navigation system is applied to wide area, the tropospheric delay is the main error factor. In this study, we experimentally compared and analyzed the performance of the conventional pseudolite tropospheric delay models. The integration method using radiosonde meteorological data was suggested to derive the reference value for the comparison and analysis. Flight tests were carried out to analyze the performance of the tropospheric delay models according to the elevation angle and distance conditions between the user receiver and the pseudolite. As the results of this study, we provided the basis for the choice of tropospheric delay model appropriate to the relative location characteristics of the pseudolite and the user.

Mass Spectrometric Study of Carbon Cluster Formation in Laser Ablation of Graphite at 355 nm

  • Koo, Young-Mi;Choi, Young-Ku;Lee, Kee-Hag;Jung, Kwang-Woo
    • Bulletin of the Korean Chemical Society
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    • v.23 no.2
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    • pp.309-314
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    • 2002
  • The ablation dynamics and cluster formation of $C_n^+$ ions ejected from 355 nm laser ablation of a graphite target in vacuum are investigated using a reflectron time-of-flight (RTOF) mass spectrometer. At low laser fluence, odd-numbered cluster ions with $3{\leq}n{\leq}15$ are predominantly produced. Increasing the laser fluence shifts the maximum size distribution towards small cluster ions, implying the fragmentation of larger clusters within the hot plume. The temporal evolution of $C_n^+$ ions was measured by varying the delay time of the ion extraction pulse with respect to the laser irradiation, providing significant information on the characteristics of the ablated plume. Above a laser fluence of $0.2J/cm^2$ , large cluster ions ($n{\geq}30$) are produced at relatively long delay times, indicating that atoms or small carbon clusters aggregate during plume propagation. The dependence of the intensity of ablated $C_n^+$ ions on delay time after laser irradiation shows that the most probable velocity of each cluster ion decreases with cluster size.