• 제목/요약/키워드: inertia

검색결과 2,013건 처리시간 0.036초

과학기술위성 3호 실시간 관성모멘트 추정 기법 연구 (A Study on Real-Time Inertia Estimation Method for STSAT-3)

  • 김광진;이상철;오화석
    • 한국항공운항학회지
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    • 제20권4호
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    • pp.1-6
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    • 2012
  • The accurate information of mass properties is required for the precise control of the spacecraft. The mass properties, mass and inertia, are changeable by some reasons such as consumption of propellant, deployment of solar panel, sloshing, environmental effect, etc. The gyro-based attitude data including noise and bias reduces the control accuracy so it needs to be compensated for improvement. This paper introduces a real-time inertia estimation method for the attitude determination of STSAT-3, Korea Science Technology Satellite. In this method we first filter the gyro noise with the Extended Kalman Filter(EKF), and then estimate the moment of inertia by using the filtered data from the EKF based on the Recursive Least Square(RLS).

Inertia Force Problem and Nozzle Contact Mechanism of Linear Motor Drive Injection Molding Machine

  • Bang, Young-Bong;Susumu Ito
    • International Journal of Precision Engineering and Manufacturing
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    • 제4권5호
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    • pp.34-40
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    • 2003
  • This paper presents the inertial force problem of ultrahigh-speed injection molding machine using linear motors, and presents its solutions. To make very thin products by injection molding, very high injection speed is required, and linear motors are used for this purpose. However, direct drive by linear motors may cause brief nozzle separation from the sprue bushing because of the inertia force which is as large as the total output thrust of the linear motors, and this momentary separation can cause molten plastic to leak. In this paper, two solutions are proposed for this inertia force problem. One is the mechanical cancellation of the inertia force, and the other is to increase the nozzle contact force. With the latter solution, the stationary platen bending worsens, so a new nozzle contact mechanism is also proposed, which can prevent the stationary platen bending.

Eigenfrequencies of simply supported taper plates with cut-outs

  • Kalita, Kanak;Haldar, Salil
    • Structural Engineering and Mechanics
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    • 제63권1호
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    • pp.103-113
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    • 2017
  • Free vibration analysis of plates is necessary for the field of structural engineering because of its wide applications in practical life. Free vibration of plates is largely dependent on its thickness, aspect ratios, and boundary conditions. Here we investigate the natural frequencies of simply supported tapered isotropic rectangular plates with internal cutouts using a nine node isoparametric element. The effect of rotary inertia on Eigenfrequencies was demonstrated by calculating with- and without rotary inertia. We found that rotary inertia has a significant effect on thick plates, while rotary inertia term can be ignored in thin plates. Based on comparison with literature data, we propose that the present formulation is capable of yielding highly accurate results. Internal cutouts at various positions in tapered rectangular simply supported plates were also studied. Novel data are also reported for skew taper plates.

Nonlinear vibration of Timoshenko beam due to moving loads including the effects of weight and longitudinal inertia of beam

  • Wang, Rong-Tyai
    • Structural Engineering and Mechanics
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    • 제10권3호
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    • pp.197-209
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    • 2000
  • The effects of weight and axial inertia of a beam are taken into account for studying the nonlinear vibration of the Timoshenko beam due to external loads. The combination of Galerkins method and Runge-Kutta method are employed to obtain the dynamic responses of the beam. A concentrated force and a two-axle vehicle traversing on the beam are taken as two examples to investigate the response characteristics of the beam. Results show that the effect of axial inertia of the beam increases the fundamental period of the beam. Further, both the dynamic deflection and the dynamic moment of the beam obtained with including the effect of axial inertia of the beam are greater than those of the beam without including that effect of the beam.

리니어모터식 사출성형기의 반력문제 및 노즐터치기구 (Inertia Force Problem and Nozzle Contact Mechanism on Linear Motor Drive Injection Molding Machine)

  • 방영봉;윤등진
    • 한국정밀공학회지
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    • 제19권10호
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    • pp.171-177
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    • 2002
  • This paper presents the inertial force problem of ultrahigh-speed injection molding machine using linear motors, and presents its solutions. To make very thin products by injection molding, very high injection speed is required, and linear motors are used for this purpose. But direct drive by linear motors may cause brief nozzle separation from the sprue bushing because of the inertia force as large as the total output thrust of the linear motors, and this momentary separation can cause molten plastic leakage. In this paper, two solutions are proposed for this inertia force problem. One is the mechanical cancellation of the inertia force, and the other to increase the nozzle contact force. With the latter solution, the stationary platen bending worsens, so a new nozzle contact mechanism is also proposed, which can prevent the stationary platen bending.

회전관성과 전단변형을 고려한 수평 곡선보의 자유진동 (Free Vibrations of Horizontally Curved Beams with Rotatory Inertia and Shear Deformation)

  • 이병구;모정만;이태은;안대순
    • 한국소음진동공학회논문집
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    • 제13권1호
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    • pp.63-69
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    • 2003
  • The ordinary differential equations governing free vibrations of elastic horizontally curved beams are derived, in which the effects of rotatory inertia and shear deformation as well as the effects of both vertical and torsional inertias are included. Frequencies and mode shapes are computed numerically for parabolic curved beams with the hinged-hinged, hinged-clamped and clamped-clamped ends. Comparisons of natural frequencies between this study and ADINA are made to validate the theories and numerical methods developed herein. The lowest three natural frequency parameters are reported. with and without the effects of rotatory inertia and shear deformation. as functions of the three non-dimensional system parameters: the horizontal rise to span length ratio. the slenderness ratio and the stiffness parameter.

방향전환 기동 시 액체연료가 위성체의 관성모멘트 및 자세운동에 미치는 영향 분석 (Effects of Liquid Fuel on Spacecraft's Moment of Inertia and Motion during Reorientation)

  • 강자영;이상철
    • 한국항공운항학회지
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    • 제17권1호
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    • pp.1-8
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    • 2009
  • In this paper, reorientation based on angular momentum exchange is applied for a bias momentum stabilized satellite, which is equipped with a spherical fuel tank, and the effect of liquid slosh on the attitude properties such as inertia tensor and angular rate is investigated. In order to represent the slosh motion of liquid an equivalent mechanical model is adopted and full nonlinear equations of motion for three-body system are derived. Computer simulations are performed for several cases, which use the viscosity of liquid and the center location of the tank as input parameters, mainly in order to observe how the viscosity of liquid and the center location of the tank influence the spacecraft’s attitude. The investigation includes observing time-variations of the inertia tensor, especially presence of components of product of inertia during the maneuver.

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벡터제어 유도전동기를 이용한 축소형 관성 시뮬레이터 (A miniature inertia simulator using vector controlled induction motor)

  • 김길동;한영재;박현준;변윤섭;장동욱;조정민
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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    • pp.413-415
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    • 2001
  • A railroad vehicle(Light weight electric rail car, Urban railroad, High-speed railroad) need to construct propulsion- system capacity experiment equipment to test performance or to estimate confidence. Experiment equipment in interior have been used Flywheel which is equal to the same inertia as railroad straight moment. But mechanical inertia using flywheel don't change inertia and can't embody traveling-struggle which is similar to actual traveling-struggle. We propose the method to embody electric railroad load system with inertia using electric servo motor in order to get the characteristic of real vehicle load, and confirm this algorithm with simulation and experiment.

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부하관성모멘트 변화를 보상한 유도전동기의 퍼지 PI 속도제어 (Fuzzy PI Speed Controller of Induction Motor Compensation the Variation of Load Inertia)

  • Cho, Soon-Bong;Hyun, Dong-Seok
    • 대한전기학회논문지
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    • 제43권2호
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    • pp.233-243
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    • 1994
  • Generally, fuzzy PI controller that regulates the gains using fuzzy algorithm shows high performance in speed response. However, it has some problems to the load inertia variation, because the change of speed error(CE) is in a fixed range. As load inertia increases, CE is decreased and the usuage of fuzzy table is limited. Therefore, the output of the fuzzy controller has a limited range. This paper proposes an improved fuzzy PI controller. To reduce the speed overshoot, we adapt a control method that selects a proper CE range with respect to the load inertia variation. The proposed controller is applied to the vector controlled system with 2.2kW induction motor. Some simulation and experimental results are exhibited. With these results, we can easily find that proposed PI controller is more robust than the conventional fuzzy PI controller against the load inertia variation.

자유수면(自由水面)에서의 비틀림 수평(水平)굽힘의 연성진동(連成振動)을 하는 선체단면형(船體斷面形)의 이차원적(二次元的) 부가관성(附加慣性) Moment에 관(關)한 연구(硏究) (The Study on the Added Moment of Inertia of Two Dimensional Cylinder induced by the Torsional Vibration coupled with the Flexural Vibration)

  • 김사수
    • 대한조선학회지
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    • 제7권2호
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    • pp.3-18
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    • 1970
  • An investigation was made for the added mass moment of inertia induced by the rotational motion of the cylinder with hull section on water in order to obtain the information to estimate the natural frequency of the torsional vibration of ships. The special consideration to the effect of the draught upon the added mass moment of inertia is taken into account in the study. In this paper, the general expression for the added mass coefficients of moment of inertia of arbitary two dimensional forms induced by the torsional vibration, was derived by the author. Hence, the coefficients for these forms are represented as functions of parameters, the section area coefficient and draft beam ratio, from which the added mass coefficients for arbitrary forms can be obtained. The result was shown in a chart for estimation of the added mass moment of inertia induced by the torsional vibration, as first trial, for the convenience of practical use.

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