• Title/Summary/Keyword: 피치 가속도

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A Study on Polar Converting Logic of BTT Missiles (BTT 유도탄의 하중계수 분배논리 연구)

  • Lee, Yong-In;Kim, Eul-Gon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.10
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    • pp.77-82
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    • 2004
  • This paper presents polar converting logic(PCL) of BTT missiles against slowly moving or stationary targets. A guidance commands expressed in rectangular coordinates must be converted in the form of polar coordinates for BTT control. Since conventional PCL has nonlinear and discontinuous function, the missiles may lose controllability when pitch acceleration command equals to zero. Further, roll coupling may have a serious unstabilizing influence on homing guidance with two gimbals seeker. In this paper, a linear homotopy equation is introduced to improve the controllability and a command following performance at midcourse phase. We also design a PCL which is less sensitive to pitch acceleration command so that it may improve the stability of the homing loop. To substantiate our conclusion, results of the computer simulation have been illustrated.

In-Flight Simulation for the Evaluation of Flight Control Law (비행제어계 평가를 위한 항공기 공중모의 비행시험)

  • Go,Jun-Su;Lee,Ho-Geun;Lee,Jin-Yeong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.10
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    • pp.79-88
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    • 2003
  • The paper presented here covers the work associated with the flight control law design, ground based and in flight simulation and handling qualities assessment of the Fly-by-Wire type Aircraft (FBWA). The FBWA configurations are of the same generic form of the Korean advanced trainer. The normal acceleration (Nz) and pitch rate (q) feedback control system is employed for longitudinal axis and roll rate (p) and lateral acceleration (Ny) feedback flight control law is developed in lateral/ directional axis. The flight tests for the FBW A dynamics evaluation were executed for the target aircraft (FBWA) on the IFS (In-Flight-Simulator) aircraft . The test results showed that Level 1 handling qualities for the most unstable flight regime and Level 1/2 for the landing approach flight regime were achieved. And the designed FBWA flight control law has revealed acceptable CHR (Cooper-Harper handling qualities Ratings).

An Experimental Study on Heat Transfer Augmentation by Square Rod in Impinging Air Jet System(Effect of Rod Width) (사각로드를 이용한 충돌분류계의 열전달증진에 관한 연구(로드폭의 영향))

  • Kum, Seong-Min;Lee, Yong-Hwa;Seo, Jeong-Yun
    • Solar Energy
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    • v.15 no.3
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    • pp.127-140
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    • 1995
  • This experimental study was carried out to examine the heat transfer characteristics of a 2-dimensional impinging air jet on a flat plate with a set of square rods. The objectives of the study were to investigate the flow and heat transfer characteristics caused by the square rods. Experiment was carried out first without using the rods to establish the baseline heat transfer performance. Then, rods of different widths and clearances were installed to cause the turbulence on the fluid flow. When rods are installed in front of the plate, the acceleration of the flow and the turbulence generation due to the rods and reattachment of the flow seem to contribute to the observed heat transfer augmentation and the heat transfer augmentation increases as the clearance decreases. With wider individual rod the heat transfer coefficient is higher, which is due to the increased acceleration and development of the eddies just before the rods.

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A Study on the Appication of Semi-Active Supension Units for a Combat Vehicle by Using HILS (HILS를 활용한 전투차량의 반능동 현수장치 적용에 관한 연구)

  • Kim, Chi-Ung;Kim, Moon-June;Rhee, Eun-Jun;Lee, Kyoung-Hoon;Woo, Kwan-Je
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.6
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    • pp.967-975
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    • 2010
  • There have been a lot of efforts on the improvement for the ride comfort and handling stability of the combat vehicles. Especially most of vehicles for military purpose have bad inertial condition and severe operating condition such as the rough road driving, and need a high mobility in the emergency status. It is necessary to apply the controlled suspension system in order to improve the vehicle mobile stability and ride comfort ability of crews. A feasibility study is performed on the application of the semi-active suspension system with a magneto-rheological controlled shock absorber for a $6{\times}6$ combat vehicle. First, the dynamic simulation model of the vehicle including the control model for the semi-active suspension system was executed. Based on this model, a hardware-in-the-loop simulation(HILS) system which has a semi-active suspension controller hardware was constructed. After full vehicle simulations were performed in virtual proving courses with this system, the semi-active suspension system was proven to give better ride comfort and handling stability in comparison with the conventional passive suspension system.

Effect of Disturbance Modeling on IMMU-Based Orientation Estimation Accuracy (교란성분 모델링이 IMMU기반 자세추정 정확성에 미치는 영향)

  • Choi, Mi Jin;Lee, Jung Keun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.8
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    • pp.783-789
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    • 2017
  • In terms of 3D orientation estimation based on nine-axis IMMU(inertial and magnetic measurement unit), there are two disturbance components decreasing estimation accuracy: one is external acceleration disturbing accelerometer's signals and the other is magnetic disturbance related to magnetometer's signals. In order to minimize effects by these two disturbances, two approaches including switching approach and model-based approach have been suggested and further research comparing these two has also been conducted. Nevertheless, effect of disturbance modeling differences on orientation estimation accuracy in model-based approach has not been studied before. This paper compares the recently reported two orientation estimation algorithms that have difference in disturbance models, in order to investigate the effect of disturbance models on accuracy of IMMU-based orientation estimation under various operating conditions. This research shows that the difference in disturbance models leads to difference in process noise covariance matrix. Consequently, this affected the orientation estimation, i.e., the estimation differences between the algorithms were root mean square errors of $1.35^{\circ}$ in average and $3.63^{\circ}$ in yaw estimation.

A Parallel Kalman Filter for Estimation of Magnetic Disturbance and Orientation Based on Nine-axis Inertial/Magnetic Sensor Signals (9축 관성/자기센서를 이용한 자기교란 및 자세 추정용 병렬 칼만필터)

  • Lee, Jung Keun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.7
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    • pp.659-666
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    • 2016
  • Magnetic disturbance is one of the main factors that deteriorate the accuracy of orientation estimation methods based on inertial/magnetic sensor signals. This paper proposes a parallel Kalman filter(KF) that explicitly detects magnetic disturbances and thus can accurately estimate 3D orientation in magnetically disturbed environments. Due to the parallel nature of the proposed KF, even severe magnetic disturbances only affect yaw estimation, while roll and pitch values remain accurate. Consequently, the proposed KF can be effectively used in various applications that involve magnetically inhomogeneous environments, such as robots, ships, and planes.

Comparative Analysis of Absorption Doses between Exposed and Unexposed Area on Major Organs During CT Scan (전산화 단층촬영시 주선속내 외의 주요장기 흡수선량 비교분석)

  • 사정호;서태석;최보영;정규회
    • Progress in Medical Physics
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    • v.11 no.1
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    • pp.59-71
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    • 2000
  • It is possible to obtain a fast CT scan during breath holding with spiral technique. But the risk of radiation is increased due to detailed and repeated scans. However, the limitation of X-ray doses is not fully specified on CT, yet. Therefore, the purpose of the present study is to define the limitation of X-ray doses on CT The CT unit was somatom plus 4. Alderson Rando phantom, Solenoid water phantom, TLD, and reader were used. For determining adequate position and size of organs, the measurement of distance(${\pm}$2mm) from the midline of vertebral body was performed in 40 women(20~40 years). On the brain scan for 8:8(8mm slice thickness, 8mm/sec movement velocity of the table) and 10:10(10mm slice thickness, 10mm/sec movement velocity of the table) methods, the absorption doses of exposed area of the 10:10 were slightly higher than those of 8:8. The doses of unexposed uterus were negligible on the brain scan for both 8:8 and 10:10. On the chest scan for 8:8, 8:10(8mm slice thickness, 10mm/sec movement velocity of the table), 10:10, 10:12(10mm slice thickness, 12mm/sec movement velocity of the table) and 10:15(10mm slice thickness, 15mm/sec movement velocity of the table) methods, 8:8 method of the absorption doses of exposure area was the most highest and 10:15 method was the most lowest. The absorption doses of 8:10 method was relatively lower than those of the other methods. In conclusion, the 8:10 method is the most suitable to give a low radiation burden to patient without distorting image quality.

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Tutorial on the Principle of Borehole Deviation Survey - An Application of the Coordinate Transforms (시추공 공곡 측정의 원리 - 좌표계 변환의 응용)

  • Song, Yoonho
    • Geophysics and Geophysical Exploration
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    • v.23 no.4
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    • pp.243-252
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    • 2020
  • To share an understanding of trajectory measurement in surveys using borehole, this tutorial summarizes the relevant mathematical principles of the borehole deviation survey based on coordinate transform. For uncased or open holes, calculations of the azimuth-deviation-tool face rotation using three-component accelerometer and magnetometer measurements are summarized. For the steel-cased holes, calculations are based on the time-derivative formula of the coordinate transform matrix; yaw-pitch-roll angles through time are mathematically determined by integrating the threecomponent angular velocity measurements from the gyroscope while also removing the Earth's rotation effect. Sensor and data fusion to increase the accuracy of borehole deviation survey is explained with an example of the method. These principles of borehole deviation surveys can be adapted for attitude estimation in air-borne surveys or for positioning in tunnels where global positioning system (GPS) signals cannot be accessed. Information on the optimization filter that must be incorporated in sensor fusion is introduced to help future research.

A Study on Orbit Stability and Control Method for Displaced Non-Keplerian Orbits by Using Pitch Angle Variation (변위 비케플러 궤도의 안정성 분석 및 피치각 변화를 이용한 제어기법 연구)

  • Kim, Mingyu;Lee, Jeongpyo;Kim, Jeongrae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.10
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    • pp.823-832
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    • 2014
  • Displaced non-Keplerian orbit, center of mass is displaced from orbit plane, enables special spacecraft missions. It requires continuous thrust to maintain the orbit, and solar sail is useful for this purpose. Equations for feasible region and stability analysis are derived for non-Keplerian orbit for general continuous thrust. Differences for solar sail spacecraft are discussed. Non-keplerian orbits are classified into four types. Location-specific required accelerations for orbit maintenance are calculated. Orbit stabilities of each orbit type are analyzed and verified by numerical simulations. In order to control non-Keplerian orbit in unstable region, a control algorithm using the real-time LQR control is developed and evaluated by numerical simulations.

Ion Migration Failure Mechanism for Organic PCB under Biased HAST (고온고습 전압인가(Biased HAST) 시험에서 인쇄회로기판의 이온 마이그레이션 불량 메커니즘)

  • Huh, Seok-Hwan;Shin, An-Seob;Ham, Suk-Jin
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.1
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    • pp.43-49
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    • 2015
  • By the trends of electronic package to be smaller, thinner and more integrative, organic printed circuit board is required to be finer Cu trace pitch. This paper reports on a study of failure mechanism for PCB with fine Cu trace pitch using biased HAST. In weibull analysis of the biased HAST lifetime, it is found that the acceleration factor (AF) of between $135^{\circ}C/90%RH/3.3V$ and $130^{\circ}C/85%RH/3.3V$ is 2.079. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the failure mode. It is found that $Cu_xO/Cu(OH)_2$ colloids and Cu dendrites were formed at anode (+) and at cathode (-), respectively. Thus, this gives the evidence that Cu dendrites formed at cathode by $Cu^{2+}$ ion migration lead to a short failure between a pair of Cu nets.