• Title/Summary/Keyword: magnetic filter

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Bias Estimation of Magnetic Field Measurement by AHRS Using UKF (UKF를 사용한 AHRS의 자기장 측정 편차 추정)

  • Ko, Nak Yong;Song, Gyeongsub;Jeong, Seokki;Lee, Jong-Moo;Choi, Hyun-Taek;Moon, Yong Seon
    • Journal of Ocean Engineering and Technology
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    • v.31 no.2
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    • pp.177-182
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    • 2017
  • This paper describes an unscented Kalman filter approach to estimate the bias in magnetic field measurements. A microelectromechanical systems attitude heading reference system (MEMS AHRS) was used to measure the magnetic field, together with the acceleration and angular rate. A magnetic field is usually used for yaw detection, while the acceleration serves to detect the roll and pitch. Magnetic field measurements are vulnerable to distortion due to hard-iron effect and soft-iron effect. The bias in the measurement accounts for the hard-iron effect, and this paper focuses on an approach to estimate this bias. The proposed method is compared with other methods through experiments that implement the navigation of an underwater robot using an AHRS and Doppler velocity log. The results verify that the compensation of the bias by the proposed method improves the navigation performance more than or comparable to the compensation by other methods.

The Study on Miniaturization and Weight Reduction of Auxiliary Power Unit in Magnetic Levitation Train

  • Lee, Na Ri;Shin, Hee Keun;Choi, Sung Ho;Kim, Ju Bum;Lim, Jae Won;Park, Doh Young;Mok, Hyung Soo
    • International Journal of Railway
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    • v.8 no.1
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    • pp.10-14
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    • 2015
  • Due to the characteristics of the vehicle structure, the magnetic levitation train has a confined bottom space thus a study on miniaturization and weight reduction of auxiliary power unit is essential. This auxiliary power unit is an essential device used for illumination, air conditioning, heating and air brake equipment excluding the motor. The previous auxiliary power unit for magnetic levitation train has used the hard switching having a high switching frequency with heavy loss in order to reduce the size of filter reactor and transformer but the reduction in volume was not significant. In this paper, by reducing the loss, reducing the size of the cooling unit and by increasing the switching frequency using the soft switching of resonant converter, it has miniaturized and reduced the weight of filter reactor and transformer which occupy significant space in the auxiliary power unit. This study has verified the performance of 50KVA grade prototype through simulated interpretation and analysis, and compared the size and weight of auxiliary power unit of the previous magnetic levitation train.

CALIBRATION OF VECTOR MAGNETOGRAMS BY SOLAR FLARE TELESCOPE OF BOAO

  • MOON YONG-JAE;PARK YOUNG DEUK;YUN HONG SIK
    • Journal of The Korean Astronomical Society
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    • v.32 no.1
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    • pp.65-73
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    • 1999
  • In this study we present a new improved nonlinear calibration method for vector magnetograms made by the Solar Flare Telescope of BOAO. To identify Fe I 6302.5 line, we have scanned monochromatic images of the line integrated over filter passband, changing the location of the central transmission wavelength of a Lyot filter. Then we obtained a filter-convolved line profile, which is in good agreement with spectral atlas data provided by the Sacramento Peak Solar Observatory. The line profile has been used to derive calibration coefficients of longitudinal and transverse fields, employing the conventional line slope method under the weak field approximation. Our improved nonlinear calibration method has also been used to calculate theoretical Stokes polarization signals with various angles of inclination of magnetic fields. For its numerical test, we have compared input magnetic fields with the calibrated ones, which have been derived from the new improved non-linear method and the conventional method respectively. The numerical test shows that the calibrated fields obtained from the improved method are consistent with the input fields, but not with those from the conventional method. Finally, we applied our new improved method to a dipole model which characterizes a typical field configuration of a single, round sunspot. It is noted that the conventional method remarkably underestimates the transverse field component near the inner penumbra.

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Analyzed Model of The Active Filter combined with SMES

  • Kim A-Rong;Kim Jae-Ho;Kim Hae-Jong;Kim Seok-Ho;Seong Ki-Chul;Park Min-Won;Yu In-Keun
    • Progress in Superconductivity and Cryogenics
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    • v.8 no.2
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    • pp.20-24
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    • 2006
  • Recently, utility network is becoming more and more complicated and huge due to IT and OA devices. In addition to, demands of power conversion devices which have non-linear switching devices are getting more and more increased. Consequently, because of the non-linear power semiconductor devices, current harmonics are unavoidable. Sometimes those current harmonics flow back to utility network and become one of the main reasons which can make the voltage distortion. Also, it makes noise and heat loss. On the other hands, voltage sag from sudden increasing loads is also one of the terrible problems inside of utility network. In order to compensate the current harmonics and voltage sag problem, AF(active filter) systems could be a good solution method. SMES is a very good promising source due to it's high response time of charge and discharge. Therefore, the combined AF and SMES system can be a wonderful device to compensate both harmonics current and voltage sag. However, SMES needs a superconducting magnetic coil. Because of using this superconducting magnetic coil, quench problem caused by unexpected reasons have always been unavoidable. Therefore, to solve out mentioned above, this paper presents a decisive method using shunt and series active filter system combined with SMES. Especially, authors analyzed the change of original energy capacity of SMES regarding to the size of resistance caused by quench of superconducting magnetic coil.

Sensor Information Filter for Enhancing the Indoor Pedestrian Localization Accuracy (보행자의 실내 위치 추정 정확도 향상을 위한 다양한 센서 정보 필터)

  • Kim, Jooyoung;Lee, Sooyong
    • The Journal of Korea Robotics Society
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    • v.7 no.4
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    • pp.276-283
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    • 2012
  • Due to the low localization accuracy and the requirement of special infrastructure, current LBS(Localization Based Service) is limited to show P.O.I.(Point of Interest) nearby. Improvement of IMU(Inertial Measurement Unit) based deadreckoning is presented in this paper. Additional sensors such as the magnetic compass and magnetic flux sensors are used as well as the accelerometer and the gyro for getting more information of movement. Based on the pedestrian movement, appropriate sensor information is selected and the complementary filter is used in order to enhance the accuracy of the localization.

A Design of Multi-layer Planar Type Microwave Filter (다층 평면형 초고주파 필터의 설계)

  • Lee Hong-Seop;Hwang Hee-Yong
    • Journal of The Institute of Information and Telecommunication Facilities Engineering
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    • v.4 no.1
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    • pp.31-36
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    • 2005
  • In this paper, a planar type bandpass filter in multilayered PCB is presented. The multilayered PCB structure has some advantages on fabricating microwave devices such as the size reduction and ability of tight coupling by folding or embedding. The proposed BPF has two transmission zeros at the both sides of the center frequency by using independent electric and magnetic coupling structure. The designed BPF with four layer teflon PCBs of dielectric constant 2.94 has dimensions of 24x20x1.524 in mm, center frequency of 2.47GHz and bandwidth of about l00MHz. A good agrement is achieved between the measured result and the simulated one. The influences of air gaps between the layers are also analyzed and presented.

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Design of State-estimator using Extended Kalman Filter for Magnetic Levitation System (자기부상시스템에서의 확장칼만필터를 이용한 상태추정자 설계)

  • Sung H.K.;Jung B.S.;Cho J.M.;Jang S.M.;Kim D.S.;Yu M.H.
    • Proceedings of the KIEE Conference
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    • summer
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    • pp.1334-1336
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    • 2004
  • The existing problems of the Electro-Magnetic Suspension system such as air-gap disturbance, mass variation and actuator/sensor failure are described in amore specific manner. These problem can not be solved by conventional state-feedback and output-feedback control. Extended Kalman Filter is to linearize about a trajectory that is continually updated with the state estimates resulting from the measurements. In this paper, first, the physical properties of the EMS system are described. second, Extended Kalman Filer designed as form appliable EMS system. It is shown that state estimation performance can be obtained with the use of Extended Kalman filter, and that results from simulation, stability analyze.

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3-Dimensional Attitude Estimation using Low Cost Inertial Sensors and a Magnetic Compass (저가 관성센서와 마그네틱 컴퍼스를 이용한 3차원 자세추정)

  • Park Sang-Kyeong;Kang Hee-Jun;Suh Young-Soo;Kim Han-Sil;Son Young-Duk
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1429-1432
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    • 2005
  • This work is towards the development of a low-cost, small-sized inertial navigation system(INS) which consists of 3 accelerometers, 3 semiconductor gyros and a magnetic compass sensor. This paper explains in detail the structure of the developed system and proposes a 3 dimensional attitude estimation algorithm with Indirect Kalman Filter. The experiments are performed with the developed system attached to a 6 DOF robot for showing the effectiveness of the algorithm.

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Interface Engineering in Quasi-Magnetic Tunnel Junctions with an Organic Barrier

  • Choi, Deung-Jang;Lee, Nyun-Jong;Kim, Tae-Hee
    • Journal of Magnetics
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    • v.15 no.4
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    • pp.185-189
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    • 2010
  • Spin polarized tunneling through a hybrid tunnel barrier of a Spin filter (SF) based on a EuO ferro-magnetic semiconductor and an organic semiconductor (OSC) (rubrene in this case) was investigated. For quasi-magnetic tunnel junction (MTJ) structures, such as Co/rubrene/EuO/Al, we observed a strong spin filtering effect of the EuO layer exhibiting I-V curves with high spin polarization (P) of up to 99% measured at 4 K. However, a magnetoresistance (MR) value of 9% was obtained at 4.2 K. The low MR compared to the high P could be attributed to spin scattering caused by structural defects at the interface between the EuO and rubrene, due to nonstoichiometry in the EuO.

Design and Inquiry of Band-pass Filter Using the Dielectric Resonator (유전체 공진기를 이용한 대역통과 여과기의 설계와 고찰)

  • Gil, Sang-Geun;Kim, Nam;Park, Han-Kyu
    • Proceedings of the Korean Institute of Communication Sciences Conference
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    • 1984.04a
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    • pp.25-28
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    • 1984
  • This paper describes the design of band-pass filter using the dielectric resonator and microstrip line depends mainly upon the magnetic field and is principal parameter as band-pass filter. Because dielectric resonator band~pass filter has a very high-Q, the bandwidth of this filter is very narrow. as a result of experiment, the dielectric resonator bandwidth of this filter is very narrow. As a result of experiment, the dielectric resonator band-pase filter has various modes central frequencies due to the mode change and good characteristric as a band-pass filter.

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