• Title/Summary/Keyword: mission modeling

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Design on Yawing And Depth Controller And Analysis of Disturbance Characteristic about the AUV ISiMI (자율무인잠수정 이심이의 선수각 및 심도 제어기 설계와 외란 특성 분석)

  • Ma, Sung-Jin;Jun, Bong-Huan;Lee, Pan-Mook;Kim, Sang-Bong
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2006.11a
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    • pp.351-354
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    • 2006
  • In underwater environment, the control of AUV is difficult, because of the existence of parameter uncertainties and disturbances as well as highly nonlinear and coupled system dynamics. The requirement for the simple and robust controller which works satisfactorily in those dynamical uncertainties, call for a design using the PD or sliding mode controller. The PD controller is very popular controller in the industrial field and the sliding mode controller has been used successfully for the AUV controller design. In this paper, the two controllers arc designed for ISiMI(Integrated Submergible Intelligent Mission Implementation) AUV and the performances are compared by numerical simulation under the modeling uncertainty and disturbances. The design process of PD and sliding mode controller for ISiMI AUV and simulation results are included to compare the performances of the two controllers.

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Approximated Generalized Torques by the Hydrodynamic Forces Acting on Legs of an Underwater Walking Robot

  • Jun, Bong-Huan;Shim, Hyung-Won;Lee, Pan-Mook
    • International Journal of Ocean System Engineering
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    • v.1 no.4
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    • pp.222-229
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    • 2011
  • In this paper, we present the concept and main mission of the Crabster, an underwater walking robot. The main focus is on the modeling of drag and lift forces on the legs of the robot, which comprise the main difference in dynamic characteristics between on-land and underwater robots. Drag and lift forces acting on the underwater link are described as a function of the relative velocity of the link with respect to the fluid using the strip theory. Using the translational velocity of the link as the rotational velocity of the joint, we describe the drag force as a function of joint variables. Generalized drag torque is successfully derived from the drag force as a function of generalized variables and its first derivative, even though the arm has a roll joint and twist angles between the joints. To verify the proposed model, we conducted drag torque simulations using a simple Selective Compliant Articulated Robot Arm.

Active Control of On-board Jitter Isolation for Spacecraft (인공위성의 내부 진동 분리를 위한 능동 제어 연구)

  • Oh, Se-Boung;Bang, Hyo-Choong;Tahk, Min-Jea
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.9
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    • pp.80-87
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    • 2004
  • Active control of on-orbit spacecraft jitter is a significant problem for future spacecraft mission requiring stringent pointing performance. Jitter is major disturbance source degrading payload pointing performance. Both passive and active jitter isolation techniques have been studied during the last decade. We present active jitter isolation for a model device in this work. The device provides active control capability by 3 degree-of-freedom control of payload in feedback control strategy. Mathematical modeling of the device is pursued which is naturally used for a baseline controller design. Simulation results are used to validate the designed control law.

H Controller Design of Flexible Space Structure with the Uncertainty of Damping Ratio (감쇠비 불확실성을 고려한 유연구조물의 H 제어기 설계)

  • Chae, Jang-Su;Park, Tae-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.4
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    • pp.602-608
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    • 2002
  • The flexible structure like solar array and antenna in spacecraft shows very sensitive responses to the inner or outer disturbance and noise. And the spacecraft becomes more complex and larger as it has various mission and role. But since the spacecraft need to have the limited mass, the thin and light material should be selected and this necessity induces the decrease d natural frequency and structural stiffness. It reduces the ability of adapting to the disturbance and induces the structural unstability. Certainly, the disturbance does not only make the structural unstability, but also give the bad effect to the precise attitude control. So it is necessary to control the vibration in the space. In this paper, the flexible structure control modeling with piezo sensor and piezo actuator is developed. The model uncertainty of damping ratio is overcome by robust control. The system equation is induced by the finite element method.

L.E.O. Satellite Power Subsystem Reliability Analysis

  • Zahran M.;Tawfik S.;Dyakov Gennady
    • Journal of Power Electronics
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    • v.6 no.2
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    • pp.104-113
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    • 2006
  • Satellites have provided the impetus for the orderly development of reliability engineering research and analysis because they tend to have complex systems and hence acute problems. They were instrumental in developing mathematical models for reliability, as well as design techniques to permit quantitative specification, prediction and measurement of reliability. Reliability engineering is based on implementing measures which insure an item will perform its mission successfully. The discipline of reliability engineering consists of two fundamental aspects; $(1^{st})$ paying attention to details, and $(2^{nd})$ handling uncertainties. This paper uses some of the basic concepts, formulas and examples of reliability theory in application. This paper emphasizes the practical reliability analysis of a Low Earth Orbit (LEO) Micro-satellite power subsystem. Approaches for specifying and allocating the reliability of each element of the power system so as to meet the overall power system reliability requirements, as well as to give detailed modeling and predicting of equipment/system reliability are introduced. The results are handled and analyzed to form the final reliability results for the satellite power system. The results show that the Electric Power Subsystem (EPS) reliability meets the requirements with quad microcontrollers (MC), two boards working as main and cold redundant while each board contains two MCs in a hot redundant.

A Study on Mariners' Standard Behavior for Collision Avoidance (1) - A concept on modeling for collision avoidance based on human factors -

  • Park, Jung-Sun;Kobayashi, Hiroaki;Yea, Byeong-Deok
    • Journal of Navigation and Port Research
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    • v.31 no.4
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    • pp.281-287
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    • 2007
  • Human factors have been considered the primary reason of marine accidents. Especially, the collision between vessels is mostly mused by human behavior. However, there have not been many researches to clarify the reason of marine accidents mused by human factors quantitatively. In order to understand human factors and to enhance safe navigation systematically, using a full mission ship-handling simulator, we've investigated the characteristics of avoiding behavior taken by mariners. Further in order to apply the characteristics more widely and effectively, it's necessary to formulate the standard behavior for ship-handling in the condition of collision avoidance. Is this study, therefore, we intended to propose the concept to model the mariner's standard behavior on the handling of collision avoidance as the first step. As a result, we confirmed the contents of information processing in ship-handling that mariner's generally taking to avoid collision.

Three Dimensional Positioning Accuracy of KOMPSAT-1 Stereo Imagery

  • Jeong, Soo;Kim, Yong-Soo
    • Korean Journal of Remote Sensing
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    • v.16 no.4
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    • pp.339-345
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    • 2000
  • KOMPSAT-1 was launched on 21 December, 1999 and the main mission of the satellite is the cartography to provide the imagery from a remote earth view for the production of maps of Korean territory. For this purpose, the satellite has capability to tilt the spacecraft utmost $\pm$45 degrees to acquire stereo satellite imagery in different paths. This study aims to estimate the three dimensional positioning accuracy of stereo satellite imagery from EOC(electro-optical camera), a payload of KOMPSAT-1 satellite. For this purpose, the ground control points and check points were obtained by GPS surveying. The sensor modeling and the adjustment was performed by PCI software installed in KARI (Korea Aerospace Research Institute), which contained mathematical analysis module for KOMPSAT-1 EOC. The study areas were Taejon and Nonsan, placed in the middle part of Korea. As a result of this study, we found that the RMSE(root mean square error) value of three dimensional positioning KOMPST-1 stereo imagery can be less than 1 pixel (6.6 m) if we can use about 10 GCPs(ground control points). Then, a standarrd of FGDC (Federal Geographic Data Committee) of USA was applied to the result to estimate the three dimensional positioning accuracy of KOMPSAT-1 stereo imagery.

The Impact of Strategic Planning Factors on Service Quality: An Empirical Study of Private Universities in Oman

  • AL-AZRI, Mahmood;AL-JUBARI, Ibrahim;ALBATTAT, Ahmad
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.7
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    • pp.557-569
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    • 2021
  • The study investigates the impact of strategic planning (SP) factors on service quality (SQ) in private universities (PUs) in Oman and how they fit together in the development of higher education institutions (HEIs). The reports of the Ministry of Higher Education (MoHE) in Oman revealed that the service quality in private universities is unsatisfactory. This study employs a quantitative method. Data were collected from a sample of 730 academics and administrators. Structural Equation Modeling (SEM) based on AMOS software was applied for data analysis. The results of the structural paths showed that, among the strategic planning factors, only environmental scanning and leadership had a direct significant impact on service quality. However, mission statement and participation had insignificant direct impact on service quality. The findings suggest that environmental scanning and leadership are critical factors in predicting service quality dimensions of private universities. The findings add to the body of knowledge particularly in the Omani context, which can be useful in the neighboring countries as well. The study combines two different popular models in addressing service quality. The study also clarified the importance of each factor of the strategic planning process, which give a comprehensive picture of the university.

Gas Turbine Engine Based Hybrid Propulsion System Modeling and Simulation (가스터빈엔진 기반 하이브리드 추진시스템 모델링 및 시뮬레이션)

  • Lee, Bohwa;Kim, Chuntaek;Jun, Sangook;Huh, Jae-Sung;Kim, Jae-Hwan
    • Journal of the Korean Society of Propulsion Engineers
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    • v.26 no.3
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    • pp.1-9
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    • 2022
  • The aircraft targeted in this study is a vertical take-off and landing aircraft with 4 to 5 passengers, and the propulsion system for the aircraft is a distributed hybrid propulsion system that uses a gas turbine engine and a battery pack as the main power source to supply the power required by multiple motors. In this study, a design/analysis platform for a hybrid propulsion system was developed using the MATLAB/Simulink program based on the preliminary design results. Through simulation analysis, the output characteristics and operating range of each power source according to the mission profile were confirmed, and through this, the feasibility of the preliminary design result was confirmed.

Optimal Hierarchical Design Methodology for AESA Radar Operating Modes of a Fighter (전투기 AESA 레이더 운용모드의 최적 계층구조 설계 방법론)

  • Heungseob Kim;Sungho Kim;Wooseok Jang;Hyeonju Seol
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.46 no.4
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    • pp.281-293
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    • 2023
  • This study addresses the optimal design methodology for switching between active electronically scanned array (AESA) radar operating modes to easily select the necessary information to reduce pilots' cognitive load and physical workload in situations where diverse and complex information is continuously provided. This study presents a procedure for defining a hidden Markov chain model (HMM) for modeling operating mode changes based on time series data on the operating modes of the AESA radar used by pilots while performing mission scenarios with inherent uncertainty. Furthermore, based on a transition probability matrix (TPM) of the HMM, this study presents a mathematical programming model for proposing the optimal structural design of AESA radar operating modes considering the manipulation method of a hands on throttle-and-stick (HOTAS). Fighter pilots select and activate the menu key for an AESA radar operation mode by manipulating the HOTAS's rotary and toggle controllers. Therefore, this study presents an optimization problem to propose the optimal structural design of the menu keys so that the pilot can easily change the menu keys to suit the operational environment.