• Title/Summary/Keyword: Relative Velocity

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Relative Motion Control Methodology Using the Minimum Relative Error Between Two Systems (두 시스템간의 편차 최소화를 적용한 상대적 동작제어 방법)

  • 김성권
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.12
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    • pp.994-1000
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    • 2003
  • A new relative motion control methodology for a following system to an independent leading system is proposed for controlling relative position, velocity, and tension etc. It is based on maintaining minimum relative error between two independent systems. The control command of the following system to a leading system is generated by adding the current command and the output of the relative error compensation. The proposed control method is implemented on the experimental equipment which is a wire winding-unwinding system to control the tension of the line. The results show the unwinding system(follower) following the independent motion of the winding system(leader) to control the constant tension of the line in order to keep the roller dancer in reference position. The relative motion control method proposed in this paper can be applied to high precision equipment for unwinding and winding fine wire, fine fiber, and tape etc.

Navigation System of UUV Using Multi-Sensor Fusion-Based EKF (융합된 다중 센서와 EKF 기반의 무인잠수정의 항법시스템 설계)

  • Park, Young-Sik;Choi, Won-Seok;Han, Seong-Ik;Lee, Jang-Myung
    • Journal of Institute of Control, Robotics and Systems
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    • v.22 no.7
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    • pp.562-569
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    • 2016
  • This paper proposes a navigation system with a robust localization method for an underwater unmanned vehicle. For robust localization with IMU (Inertial Measurement Unit), a DVL (Doppler Velocity Log), and depth sensors, the EKF (Extended Kalman Filter) has been utilized to fuse multiple nonlinear data. Note that the GPS (Global Positioning System), which can obtain the absolute coordinates of the vehicle, cannot be used in the water. Additionally, the DVL has been used for measuring the relative velocity of the underwater vehicle. The DVL sensor measures the velocity of an object by using Doppler effects, which cause sound frequency changes from the relative velocity between a sound source and an observer. When the vehicle is moving, the motion trajectory to a target position can be recorded by the sensors attached to the vehicle. The performance of the proposed navigation system has been verified through real experiments in which an underwater unmanned vehicle reached a target position by using an IMU as a primary sensor and a DVL as the secondary sensor.

A Numerical Study on the Short-term Dispersion of Toxic Gaseous and Solid Pollutant in an Open Atmosphere : Chemical Species, Temperature, Relative Velocity (고-기상 독성오염물질 단기 대기확산에 관한 수치해석적 연구 : 화학종, 온도, 상대속도)

  • 나혜령;이은주;장동순;서영태
    • Journal of the Korean Society of Safety
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    • v.10 no.3
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    • pp.68-80
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    • 1995
  • A series of parametric calculations have been performed in order to investigate the short-term and short-range plume and puff behavior of toxic gaseous and solid pollutant dispersion in an open atmosphere. The simulation is made by the use of the computer program developed by this laboratory, in which a control-volume based finite-difference method is used together with the SIMPLEC algorithm for the resolution of the pressure-velocity coupling appeared In Wavier-Stokes equation. The Reynolds stresses are solved by the standard two-equation k-$\varepsilon$ model modified for buoyancy together with the RNG(Renormalization Group) k-$\varepsilon$ model. The major parameters considered in this calculation are pollutant gas density and temperature, the relative velocity of pollutants to that of the surrounding atmospheric air, and particulate size and density together with the height released. The flow field is typically characterized by the formation of a strong recirculation region for the case of the low density gases such as $CH_4$ and air due to the strong buoyancy, while the flow is simply declining pattern toward the downstream ground for the case of heavy molecule like the $CH_2C1_2$and $CCl_4$, even for the high temperature, $200^{\circ}C$. The effect of gas temperature and velocity on the flow field together with the particle trajectory are presented and discussed in detail. In general, the results are physically acceptable and consistent.

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A Study on the Crust Deformation in and Around Korean Peninsula Using DGPS Data

  • Cho, Jin-Dong;Park, Jun Ku
    • Journal of the Korean Geophysical Society
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    • v.9 no.3
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    • pp.151-158
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    • 2006
  • Highly accurate surface velocity estimation using modern geodetic techniques plays very important role in the geological and geophysical interpretation. Researches with GPS are ongoing in many countries of the world. This study aims to estimate the amount of crustal deformation and the direction of deformation in the Korean Peninsula and in its neighbor. We used GAMIT that is a comprehensive GPS analysis package developed at MIT. Then, a Global Kalman filter called GLOBK is used to combine the results from GAMIT and to estimate the relative and absolute velocity vector for the crustal deformations. To estimate station velocity accuracy and reliably, it is extremely important to pay great attention to the reference frame. Firstly, using the Suwon (SUWN) of Eurasian plate as main frame, we estimate the relative amount of crustal deformation and a direction of Eurasian plate and North American plate, Secondly, using ITRF 2000 as main frame, we estimate the absolute crustal deformation of Eurasian plate and North American plate. The continent of Eurasian where has the Korean Peninsula deforms 33.36 mm per year to East-Southeast (ESE), and Japanese Tsukuba (TSKB) in North American plate deforms to South-Southwest (SSW). Finally, the Korean Peninsula is approaching the Japanese Island and the rate of horizontal crustal deformation between the Suwon and the Tsukuba is about 31.98 mm per year in the moving direction of N85.9oW (274.1o) for the past three years.

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Design of Transfer Alignment Algorithm with Velocity and Azimuth Matching for the Aircraft Having Wing Flexibility (유연성을 가지는 비행체를 위한 속도/방위각 정합 전달 정렬 알고리즘 설계)

  • Suktae Kang
    • Journal of the Korea Institute of Military Science and Technology
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    • v.26 no.3
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    • pp.214-226
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    • 2023
  • A transfer alignment is used to initialize, align, and calibrate a SINS(Slave INS) using a MINS(Master INS) in motion. This paper presents an airborne transfer alignment with velocity and azimuth matching to estimate inertial sensor biases under the wing flexure influence. This study also considers the lever arm, time delay and relative orientation between MINS and SINS. The traditional transfer alignment only uses velocity matching. In contrast, this paper utilizes the azimuth matching to prevent divergence of the azimuth when the aircraft is stationary or quasi-stationary since the azimuth is less affected by the wing flexibility. The performance of the proposed Kalman filter is analyzed using two factors; one is the estimation performance of gyroscope and accelerometer bias and the other is comparing aircraft dynamics and attitude covariance. The performance of the proposed filter is verified using a long term flight test. The test results show that the proposed scheme can be effectively applied to various platforms that require airborne transfer alignment.

Shear Strength Estimation of Clean Sands via Shear Wave Velocity (전단파 속도를 통한 모래의 전단강도 예측)

  • Yoo, Jin-Kwon;Park, Duhee
    • Journal of the Korean Geotechnical Society
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    • v.31 no.9
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    • pp.17-27
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    • 2015
  • We perform a series of experimental tests to evaluate whether the shear strength of clean sands can be reliably predicted from shear wave velocity. Isotropic drained triaxial tests on clean sands reconstituted at different relative densities are performed to measure the shear strength and bender elements are used to measure the shear wave velocity. Laboratory tests reveal that a correlation between shear wave velocity, void ratio, and confining pressure can be made. The correlation can be used to determine the void ratio from measured shear wave velocity, from which the shear strength is predicted. We also show that a unique relationship exists between maximum shear modulus and effective axial stress at failure. The accuracy of the equation can be enhanced by including the normalized confining pressure in the equation. Comparisons between measured and predicted effective friction angle demonstrate that the proposed equation can accurately predict the internal friction angle of granular soils, accounting for the effect of the relative density, from shear wave velocity.

A Study of Target Motion Analysis For a Passive Sonar System with the IMM (IMM을 이용한 수동소나체계의 기동표적추적기법 향상 연구)

  • 유필훈;송택렬
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.148-148
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    • 2000
  • In this paper the IMM(Interacting Multiple model) algorithm using the MGEKF(Modified Gain Extended Kalman Filter) which modes are variances of the process noises is proposed to enhance the performance of maneuvering target tracking with bearing and frequency measurements. The state are composed of relative position, relative velocity, relative acceleration and doppler frequency. The mode probability is calculated from the bearing and frequency measurements. The proposed algorithm is tested a series of computer simulation runs.

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Study of Ultrasonic Nonlinearity in Heat-Treated Material (열처리된 재료의 초음파 비선형성에 관한 연구)

  • Li, Weibin;Lee, Jae-Sun;Cho, Youn-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.6
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    • pp.751-756
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    • 2010
  • Ultrasonic nonlinearity is very sensitive to changes in material properties. This paper describes the study of the correlation between heat treatment and ultrasonic nonlinearity by taking nonlinear factors into consideration. A modified formula was proposed for ultrasonic velocity. This formula indicated that the changes occurring in nonlinearity during heat treatments cause changes in the ultrasonic velocity. The experimental results show that the relative nonlinearity parameters calculated from the modified ultrasonic velocities and the ratio of amplitudes of the second harmonic and fundamental wave are in good agreement. The experimental results prove that heat treatment can result in changes in material nonlinearity. Moreover, the relative nonlinearity parameter calculated from the modified velocity formula is has a large value. Since this parameter has high sensitivity to changes in nonlinearity, it can be used to represent the relative nonlinearity change calculated in this study by using the modified formula for ultrasonic velocity.

An Experimental Study on Frost Generation Mechanism from Evaporator Tube in Air Conditioning System (공조용 열교환기 증발관에서의 서리 발생에 관한 메커니즘의 실험적 연구)

  • Park Sang-Kyun;Oh Cheal
    • Journal of Navigation and Port Research
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    • v.30 no.1 s.107
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    • pp.113-117
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    • 2006
  • The object qf this experiment was the evaluation of the growth rate of frost layer conditioned by inlet air's velocity, temperature and relative humidity on the copper tube in evaporator. In this experiment, the inlet air's velocity were $0.3^m/_s,\;0.6^m/_s,\;0.9^m/_s,$ temperature were $15^{\circ}C,\;20^{\circ}C,\;25^{\circ}C$ and the variation of relative humidity was $70\%~90\%$. And the brine temperature flowing through the copper tubes was kept $-15{\circ}C$ because generally cooling temperature range is constantly $-15^{\circ}C$ in the heat exchanger for air conditioning system It was found that the amount of frost generation increased so that the relative humidity, velocity and temperature of supply air increased.