• Title/Summary/Keyword: inertial frame

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Application of Kalman filtering technique to initial axes alignment of SDINS (SDINS의 좌표축 초기 배열에 관한 칼만 필터링 기법의 응용)

  • 최근국;이만형
    • 제어로봇시스템학회:학술대회논문집
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    • 1986.10a
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    • pp.290-294
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    • 1986
  • Initial alignment of gimballed INS is accomplished by the gyrocompassing techniques. These cannot be used in the case of strapdown system where the inertial instruments are directly strapped down to a vehicle frame. The basic objective of this paper is the development of digital methods performing the initial alignment of a SDINS from vibration and sway currupted data on the launch pad.

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Design and Performance Analysis of NHC/ZUPT Kalman Filter with Mounting Misalignment Estimation (NHC/ZUPT의 장착 비정렬 추정 칼만필터 설계 및 성능분석)

  • Park, Young-Bum;Kim, Kap-Jin;Park, Jun-Pyo
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.5
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    • pp.636-643
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    • 2009
  • NHC means that the velocity of the vehicle in the plane perpendicular to the forward direction is almost zero. The main error source of NHC is the mounting misalignment which is the difference between the body frame of a land vehicle and the sensor frame of an inertial measurement unit. This paper suggests new NHC algorithm that can reduce position errors by real-time estimation of mounting misalignment. Then NHC/ZUPT integrated land navigation system is designed and its performances are analyzed by simulations with van test data. Simulation results show that the proposed NHC/ZUPT land navigation system improves navigation accuracy regardless of misalignment angle and is very useful when SDINS operates stand-alone for land vehicle navigation with large mounting misalignment.

Derivation and Verification of the Relative Dynamics Equations for Aerial Refueling (공중재급유를 위한 상대운동방정식 유도 및 검증)

  • Jang, Jieun;Lee, Sangjong;Ryu, Hyuk
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.21 no.4
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    • pp.1-10
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    • 2013
  • This paper addresses the derivation of 6-DOF equation of Tanker and Receiver's aircraft for aerial refueling. The new set of nonlinear equations are derived in terms of the relative translational and rotational motion of receiver aircraft respect to the tanker aircraft body frame. Further the wind effect terms due to the tanker's turbulence are included. The derivation of absolute dynamic equation for tanker aircraft written in the inertial frame is calculated from the relative dynamics equations of receiver. The derived relative and absolute equations are implemented the simulation in the same flight conditions to verify the relative motion and compare the trim results by using the MATLAB/SIMULINK program.

Finite Element Formulations of the Rotor-Bearing System for Whirl Speed Analysis (로터-베어링 시스템의 훨링속도 해석을 위한 유한요소 정식화)

  • Yun, Seong-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2007.04a
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    • pp.625-630
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    • 2007
  • This paper accounts for derivations and formulations of the finite element dynamic equation of the rotor-bearing system to analyze its whirling speed. It turns out to be a different form from previous researcher's because of different successive sequences of Euler angles. Correspondingly the adoption of other rotation tensor will be needed for a consistent derivation of the dynamic equation. The process of its finite element formulation with consistent mass matrix and gyroscopic matrix involves a general definition of the modal analysis or the Eigen analysis for the damped system in the inertial frame and rotating frame, respectively.

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A Study on the Design of a High-Speed Heddle Frame (고속 직기용 복합재료 헤들 프레임의 설계에 관한 연구)

  • Lee, Chang-Seop;O, Je-Hun;Lee, Dae-Gil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.2
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    • pp.250-263
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    • 2001
  • The up and down speed of heddle frames that produce woven cloth by insertion of weft yarns between warp yarns has been increased recently much for productivity improvement, which induces higher inertial stresses and vibrations in the heddle frame. the heddle frame is required to reduce its mass because the heddle frame contributes the major portion of the stresses in the heddle frames during accelerating and decelerating. Conventional aluminum heddle frames have fatigue life of around 5 months at 550rpm due to their low fatigue flexural strength as well as low bending stiffness. In this work, since carbon/epoxy composite materials have high specific fatigue strength(S/p), high specific modulus(E/p), high damping capacity and sandwich construction results in lower deflections and higher buckling resistance, the sandwich structure composed of carbon/epoxy composite skins and polyurethane foam were employed for the high-speed heddle frame. The design map for the sandwich beams was accomplished to determine the optimum thickness and the stacking sequences for the heddle frames. Also the effects of the number of ribs on the stress of the heddle frame were investigated by FEM analyses. Finally, the high-speed heddle frames were manufactured with sandwich structures and the static and dynamic properties of the aluminum and the composite heddle frames were tested and compared with each other.

A Jacobian Update-Free Newton's Method for Efficient Real-Time Vehicle Simulation (효율적인 실시간 차량 시뮬레이션을 위한 자코비안 갱신이 불필요한 뉴턴 적분방법)

  • Kang, Jong Su;Lim, Jun Hyun;Bae, Dae Sung
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.23 no.4
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    • pp.337-344
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    • 2014
  • While implicit integration methods such as Newton's method have excellent stability for the analysis of stiff and constrained mechanical systems, they have the drawback that the evaluation and LU-factorization of the system Jacobian matrix required at every time step are time-consuming. This paper proposes a Jacobian update-free Newton's method in order to overcome these defects. Because the motions of all bodies in a vehicle model are limited with respect to the chassis body, the equations are formulated with respect to the moving chassis-body reference frame instead of the fixed inertial reference frame. This makes the system Jacobian remain nearly constant, and thus allows the Newton's method to be free from the Jacobian update. Consequently, the proposed method significantly decreases the computational cost of the vehicle dynamic simulation. This paper provides detailed generalized formulation procedures for the equations of motion, constraint equations, and generalized forces of the proposed method.

Modeling, Dynamics and Control of Spacecraft Relative Motion in a Perturbed Keplerian Orbit

  • Okasha, Mohamed;Newman, Brett
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.1
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    • pp.77-88
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    • 2015
  • The dynamics of relative motion in a perturbed orbital environment are exploited based on Gauss' and Cowell's variational equations. The inertial coordinate frame and relative coordinate frame (Hill frame) are used, and a linear high fidelity model is developed to describe the relative motion. This model takes into account the primary gravitational and atmospheric drag perturbations. Then, this model is used in the design of a navigation, guidance, and control system of a chaser vehicle to approach towards and to depart from a target vehicle in proximity operations. Relative navigation uses an extended Kalman filter based on this relative model to estimate the relative position/velocity of the chaser vehicle with respect to the target vehicle. This filter uses the range and angle measurements of the target relative to the chaser from a simulated LIDAR system. The corresponding measurement models, process noise matrix, and other filter parameters are provided. Numerical simulations are performed to assess the precision of this model with respect to the full nonlinear model. The analyses include the navigation errors and trajectory dispersions.

A Gyro-Free INS Algorithm in the Navigation Frame and Its Application to the Spinning Vehicle with High Rotation Rate

  • Lee, Junhak;Kim, Heyone;Oh, Sang Heon;Do, Jae Chul;Nam, Chang Woo;Hwang, Dong-Hwan;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.7 no.2
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    • pp.91-103
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    • 2018
  • Conventional inertial measurement units cannot be used in the spinning vehicle with high rotation rate due to gyro's narrow operation range. By the way, angular acceleration can be measured using the accelerometer array distributed in the vehicle. This paper derives a mechanization for the gyro-free INS in the navigation frame, and proposes a gyro-free INS algorithm based on the derived mechanization. In addition, the proposed algorithm is used to estimate angular velocity, attitude, velocity, and position of a spinning vehicle with high rotation rate. A MATLAB-based software platform is configured in order to show validation of the proposed algorithm. The reference trajectory of a spinning vehicle at 3 round per second, 30 round per second are set up, and the outputs of accelerometer are generated when triads of accelerometer are located at the origin and all the axes. Navigation results of the proposed algorithm for the generated output are presented. The results show that the proposed navigation algorithm can be applied to the spinning vehicle with high rotation rate.

Development of dynamic motion models of SPACE code for ocean nuclear reactor analysis

  • Kim, Byoung Jae;Lee, Seung Wook
    • Nuclear Engineering and Technology
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    • v.54 no.3
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    • pp.888-895
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    • 2022
  • Lately, ocean nuclear power plants have attracted attention as one of diverse uses of nuclear power plants. Because ocean nuclear power plants are movable or transportable, it is necessary to analyze the thermal hydraulics in a moving frame of reference, and computer codes have been developed to predict thermal hydraulics in large moving systems. The purpose of this study is to incorporate a three dimensional dynamic motion model into the SPACE code (Safety and Performance Analysis CodE) so that the code is able to analyze thermal hydraulics in an ocean nuclear power plant. A rotation system that describes three-dimensional rotations about an arbitrary axis was implemented, and modifications were made to the one-dimensional momentum equations to reflect the rectilinear and rotational acceleration effects. To demonstrate the code's ability to solve a problem utilizing a rotational frame of reference, code calculations were conducted on various conceptual problems in the two-dimensional and three-dimensional pipeline loops. In particular, the code results for the three-dimensional pipeline loop with a tilted rotation axis agreed well with the multi-dimensional CFD results.

A Study on GPS/INS Integration Considering Low-Grade Sensors (저급 센서를 고려한 GPS/INS 결합기법 연구)

  • Park, Je Doo;Kim, Minwoo;Lee, Je Young;Kim, Hee Sung;Lee, Hyung Keun
    • Journal of Institute of Control, Robotics and Systems
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    • v.19 no.2
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    • pp.140-145
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    • 2013
  • This paper proposes an efficient integration method for GPS (Global Positioning System) and INS (Inertial Navigation System). To obtain accuracy and computational conveniency at the same time with low cost global positioning system receivers and micro mechanical inertial sensors, a new mechanization method and a new filter architecture are proposed. The proposed mechanization method simplifies velocity and attitude computation by eliminating the need to compute complex transport rate related to the locally-level frame which continuously changes due to unpredictable vehicle motions. The proposed filter architecture adopts two heterogeneous filters, i.e. position-domain Hatch filter and velocity-aided Kalman filter. Due to distict characteristics of the two filters and the distribution of computation into the two hetegrogeneous filters, it eliminates the cascaded filter problem of the conventional loosly-coupled integration method and mitigates the computational burden of the conventional tightly-coupled integration method. An experiment result with field-collected measurements verifies the feasibility of the proposed method.