GPS/INS/Magnetometer 결합항법시스템을 위한 Magnetometer 보정 알고리즘 연구 및 실험 데이터를 이용한 검증

한정화,윤석창,이병진,이영재,성상경 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.11

본 논문은 GPS (Global Positioning System)/ INS (Inertial Navigation System)/Magneto meter 결합항법시스템에서 Magnetometer의 더 정확한 측정치를 얻기 위한 보정 알고리즘을 연구하고 이를 실험 데이터를 이용하여 검증하는데 목적을 두고 있다. 기존 GPS/INS/Ma gnetometer 결합항법시스템은 Magnetometer를 heading 측정치로 사용하기 때문에 외부 자기장 환경에 의해 heading 오차가 발생할 수 있다. 본 논문에서는 외부 자기장 환경변화에 강인한 실시간 Magnetometer 보정 알고리즘을 제안한다. 보정 알고리즘은 정상 자기장 범위를 설정하고 그것을 기준으로 보정을 수행하였으며 Magnetometer와 GPS heading을 이용하였다. 마지막으로, 후처리한 실외실험 데이터에 Magnetometer 보정 알고리즘을 적용하여 기존 시스템보다 개선됨을 확인했다 The objective of Paper is Research of Magnetometer correction algorithm of GPS (Global Positioning System)/INS (Inertial Navigation System)/Magnetometer integrated Navigation System and verification using real-outdoor data. generally, Magnetometer used heading measurement of GPS/INS/Magnetometer integrated Navigation System and it influenced by environment of magnetic field. This paper suggest Magnetometer correction algorithm using Magnetometer and GPS heading that robust about environment of magnetic field change. the algorithm correct heading according to set the normal magnetic field range. finally, Magnetometer correction algorithm is applied post-processed out-door test data and confirm that suggested algorithm make better performance than general System.

자기장크기 측정이 가능한 3-축 Flux-gate 마그네토미터 제작

손대락(Derac Son) 한국자기학회 2019 韓國磁氣學會誌 Vol.29 No.5

Magnetic field measurement under vibration and rotation condition of the magnetometer, total field measuring magnetometers have been used, because orthogonality error and scale factor differene of the 3-axis magnetometer can not measure total magnetic field with high precission. In this study, we developed total magnetic field sensor by orthogonality correction for the 3-axis flux-gate magnetometer. To correct orthogonality and scale factor, 24 bit 3-channel simultaneous digitizing ADC and DSP were used. To demonstrate the performance of the developed magnetometer under condition of vibration, the magnetometer was installed on dron and measured magnetic anormality of passenger cars. We can measure total magnetic field with resolution of 1 nT for the developed orthogonality corrected 3-axis flux-gate magnetometer.

Search Coil Magnetometer Based on Multi-parameter Joint Optimization Design in Ultra Low-Frequency Communication

Chunteng Li,Yuzhong Jiang,Guanghui Yang,Fangjun Liu 한국자기학회 2018 Journal of Magnetics Vol.23 No.2

In order to design a kind of high-sensitive, narrow-band and portable search coil magnetometer, based on the principle of magnetic measuring, an equivalent model of search coil magnetometer with parallel matched capacitor is established. The formula of the induced coil is derived, low-noise integrated operational amplifier is designed and made as the preamplifier circuit of search coil magnetometer. The parameters of the inductive coil based on multi-parameter joint optimization are obtained under consideration of the sensitivity, bandwidth, weight and volume of the inductive coil simultaneously. The search coil magnetometer test is completed in the electromagnetic shielding room. And the result shows that the sensitivity of the designed search coil magnetometer is 40 fT√Hz @80 Hz, under the precondition of guaranteeing the weight, volume and bandwidth, which is basically the same as that of the simulation.

An Attitude Filtering and Magnetometer Calibration Approach for Nanosatellites

Soken, Halil Ersin The Korean Society for Aeronautical Space Sciences 2018 International Journal of Aeronautical and Space Sc Vol.19 No.1

We propose an attitude filtering and magnetometer calibration approach for nanosatellites. Measurements from magnetometers, Sun sensor and gyros are used in the filtering algorithm to estimate the attitude of the satellite together with the bias terms for the gyros and magnetometers. In the traditional approach for the attitude filtering, the attitude sensor measurements are used in the filter with a nonlinear vector measurement model. In the proposed algorithm, the TRIAD algorithm is used in conjunction with the unscented Kalman filter (UKF) to form the nontraditional attitude filter. First the vector measurements from the magnetometer and Sun sensor are processed with the TRIAD algorithm to obtain a coarse attitude estimate for the spacecraft. In the second phase the estimated coarse attitude is used as quaternion measurements for the UKF. The UKF estimates the fine attitude, and the gyro and magnetometer biases. We evaluate the algorithm for a hypothetical nanosatellite by numerical simulations. The results show that the attitude of the satellite can be estimated with an accuracy better than $0.5^{\circ}$ and the computational load decreases more than 25% compared to a traditional UKF algorithm. We discuss the algorithm's performance in case of a time-variance in the magnetometer errors.

Research on the Influence of Alkali Polarization on an All-Optical Atomic Spin Magnetometer Based on Hybrid Pumping Potassium and Rubidium

Hong Zhang,Sheng Zou,Xi-Yuan Chen,Yang Liu 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.8

An all-optical atomic spin magnetometer using a hybrid cell of K and Rb atoms is demonstrated in this paper. Via deriving and solving the Bloch equations, we established the models for the polarization rate of Rb and the magnetometer’s output signal, respectively. In order to achieve the maximum sensitivity, we carried out research on the influence of the pump power on the polarization rate and magnetometer’s output signal. The magnetometer’s sensitivity was found to be proportional to the polarization rate of Rb, which was confined by the pump power. In a certain context, theoretical predictions indicated that the larger the pump power was, the higher magnetometer’s sensitivity that could be realized. However, the theoretical estimate deviated from the experimental results. An analysis of the errors between the actual value and the theoretical value showed that the different molar ratio between the two species of alkali-metal atoms was the primary reason causing the deviation. By comparing the experimental measurement result with simulation result, we found the difference in the molar ratio to be approximate 4 times. After various parameters had been optimized, a sensitivity of 18 fT/Hz1/2 was achieved by analyzing the signal-to-noise ratio.

An Attitude Filtering and Magnetometer Calibration Approach for Nanosatellites

Halil Ersin Söken 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.1

We propose an attitude filtering and magnetometer calibration approach for nanosatellites. Measurements from magnetometers, Sun sensor and gyros are used in the filtering algorithm to estimate the attitude of the satellite together with the bias terms for the gyros and magnetometers. In the traditional approach for the attitude filtering, the attitude sensor measurements are used in the filter with a nonlinear vector measurement model. In the proposed algorithm, the TRIAD algorithm is used in conjunction with the unscented Kalman filter (UKF) to form the nontraditional attitude filter. First the vector measurements from the magnetometer and Sun sensor are processed with the TRIAD algorithm to obtain a coarse attitude estimate for the spacecraft. In the second phase the estimated coarse attitude is used as quaternion measurements for the UKF. The UKF estimates the fine attitude, and the gyro and magnetometer biases. We evaluate the algorithm for a hypothetical nanosatellite by numerical simulations. The results show that the attitude of the satellite can be estimated with an accuracy better than 0.5◦ and the computational load decreases more than 25% compared to a traditional UKF algorithm. We discuss the algorithm’s performance in case of a time-variance in the magnetometer errors.

기구학적 모델링과 지자기센서 최소사용을 결합한 IMU 기반 하지 위치추정

정우창(Woo Chang Jung),이정근(Jung Keun Lee) 제어로봇시스템학회 2020 제어·로봇·시스템학회 논문지 Vol.26 No.4

The lower limb positions of pedestrians are an important physical attribute required in various fields, such as augmented reality, sports science, and physical medicine and rehabilitation. Due to the advantages of the wearability of inertial measurement units (IMUs), IMU-based position estimation of human lower limbs has attracted much attention. In IMU-based estimation, magnetometers are usually used to estimate the headings of tracking objects, e.g., lower limb segments. However, the heading estimation performance can be compromised by magnetic disturbances. In particular, in the case of pedestrian lower limb tracking, a foot-attached magnetometer is exposed to severe magnetic disturbances caused by the wires or structural materials embedded in the building floor or ground, resulting in significant position estimation errors. This paper proposes an IMU-based position estimation of lower limbs via a combination of kinematic modeling with minimal utilization of magnetometers. The proposed method uses only a thigh-attached magnetometer to minimize the effects of magnetic disturbance occurring on the ground or floor and estimates the heading of the entire lower limb using only the thigh magnetometer through kinematic modeling. As our treadmill walking test results, the averaged heading estimation error and position estimation error were 3.4° and 7.2 m, respectively, outperforming the conventional methods both with multiple magnetometers and without any magnetometers.

자력계를 이용한 초소형 위성 CINEMA의 자세 제어 시스템 운영

신유철,윤세영,선종호,진호,이동훈,김성우,박상영 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.11

경희대학교에서 제작 중인 초소형 위성 CINEMA(Cubesat for Ion, Neutron, Electron and MAgnetic field)의 자세제어 시스템은 태양 센서와 자력계를 자세 감지 센서로 사용하고 있다. 태양 센서로는 V-slit의 태양 센서와 태양 전지판을 사용하고 있다. 그리고 자력계로는 3축 자력계인 MAGIC(MAGnetometer by Imperial College London)을 사용한다. 자세제어의 운용 모드 상 태양 센서는 V-slit 센서보다 태양 전지판에 대부분 의존을 하므로 많은 노이즈를 발생시키게 된다. 따라서 태양 센서를 제외한 자력계만을 이용한 위성의 자세를 결정하는 방법을 고려하였다. 자세결정의 필터링 방법으로는 실시간 Uscented Kalman Filter 알고리즘을 사용하였다. 또한 지상에서 자세 결정 시뮬레이션 수행하여 그 결과를 위성에 보내어 위성의 자세를 제어하는 자료로 사용하도록 하였다. Attitude Control System of CINEMA(Cubesat for Ion, Neutron, Electron and MAgnetic field) producing in Kyung Hee University is composed of attitude sensors of sun sensor and magnetometer. There are V-slit sun sensor and solar panel in the sun sensor, and 3-axis magnetometer(MAGIC : MAGnetometer by Imperial College London) is used. For operational reasons, the solar panel is more dependent than V-slit sun sensor and this solar panel makes a lot of noises. Thus, Unscented Kalman Filter algorithm can be used to estimate the attitude of satellite using only magnetometer. The attitude control of the satellite is performed based on the attitude determination conducted in the ground station.

Performance Enhancement and Countermeasure for GPS Failure of GPS/INS Navigation System of UAV Through Integration of 3D Magnetic Vector

No, Heekwon,Song, Junesol,Kim, Jungbeom,Bae, Yonghwan,Kee, Changdon The Institute of Positioning 2018 Journal of Positioning, Navigation, and Timing Vol.7 No.3

This study examined methods to enhance navigation performance and reduce the divergence of navigation solutions that may occur in the event of global positioning system (GPS) failure by integrating the GPS/inertial navigation system (INS) with the three-dimensional (3D) magnetic vector measurements of a magnetometer. A magnetic heading aiding method that employs a magnetometer has been widely used to enhance the heading performance in low-cost GPS/INS navigation systems with insufficient observability. However, in the case of GPS failure, wrong heading information may further accelerate the divergence of the navigation solution. In this study, a method of integrating the 3D magnetic vector measurements of a magnetometer is proposed as a countermeasure for the case where the GPS fails. As the proposed method does not require attitude information for integration unlike the existing magnetic heading aiding method, it is applicable even in case of GPS failure. In addition, the existing magnetic heading aiding method utilizes only one-dimensional information in the heading direction, whereas the proposed method uses the two-dimensional attitude information of the magnetic vector, thus improving the observability of the system. To confirm the effect of the proposed method, simulation was performed for the normal operation and failure situation of GPS. The result confirmed that the proposed method improved the accuracy of the navigation solution and reduced the divergence speed of the navigation solution in the case of GPS failure, as compared with that of the existing method.

Performance Enhancement and Countermeasure for GPS Failure of GPS/INS Navigation System of UAV Through Integration of 3D Magnetic Vector

노희권,송준솔,김정범,배영환,기창돈 사단법인 항법시스템학회 2018 Journal of Positioning, Navigation, and Timing Vol.7 No.3

This study examined methods to enhance navigation performance and reduce the divergence of navigation solutions that may occur in the event of global positioning system (GPS) failure by integrating the GPS/inertial navigation system (INS) with the three-dimensional (3D) magnetic vector measurements of a magnetometer. A magnetic heading aiding method that employs a magnetometer has been widely used to enhance the heading performance in low-cost GPS/INS navigation systems with insufficient observability. However, in the case of GPS failure, wrong heading information may further accelerate the divergence of the navigation solution. In this study, a method of integrating the 3D magnetic vector measurements of a magnetometer is proposed as a countermeasure for the case where the GPS fails. As the proposed method does not require attitude information for integration unlike the existing magnetic heading aiding method, it is applicable even in case of GPS failure. In addition, the existing magnetic heading aiding method utilizes only one-dimensional information in the heading direction, whereas the proposed method uses the two-dimensional attitude information of the magnetic vector, thus improving the observability of the system. To confirm the effect of the proposed method, simulation was performed for the normal operation and failure situation of GPS. The result confirmed that the proposed method improved the accuracy of the navigation solution and reduced the divergence speed of the navigation solution in the case of GPS failure, as compared with that of the existing method.