Scalar compensation of shipboard three-component magnetic measurements and applications for marine geophysical mapping

2021 ◽  
Author(s):  
hugo reiller ◽  
marc munschy ◽  
jean-françois oelher ◽  
sylvain lucas ◽  
didier rouxel
Keyword(s):  
Magnetic Field ◽  
Magnetic Measurements ◽  
Correction Method ◽  
Least Square ◽  
Navigation Systems ◽  
Magnetic Compensation ◽  
Technical Maintenance ◽  
Magnetometer Data ◽  
Linear Least Square ◽  
Geophysical Mapping

<p>Since the 70’s, ship-mounted three-component magnetometers are used for marine geophysical mapping, with the benefits of being able to be operated permanently with a minimum of technical maintenance. However, to obtain accuracies similar to those of ship-towed absolute scalar magnetometers, the intense interfering magnetic fields generated by the hull and steel parts of the ship have to be removed. The most common correction method, called “vector compensation”, uses high precision inertial navigation systems in order to correct the measured data for the ship’s magnetic field and calculate the vector of the compensated magnetic field in the Earth coordinated system.</p><p>This work alternatively uses the “scalar compensation” method applied in airborne magnetism since the 60’s. The aim is to compute the intensity of the compensated magnetic field without measurements of the attitude of the vector and using linear least-square regression analysis. This correction method is applied to shipboard three-component magnetometer data acquired on different vessels during different surveys. Results are compared to those obtained with ship-towed absolute scalar magnetic measurements.</p><p><strong>Keywords</strong>: shipboard three-component magnetic measurements; magnetic compensation; marine magnetics.</p>

scholarly journals Interactive model of magnetic field reconstruction stand for mobile robot navigation algorithms debugging which use magnetometer data

ACTA IMEKO ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 47
Author(s):  
Stanislaw Goll ◽  
Alexander Borisov
Keyword(s):  
Magnetic Field ◽  
Mobile Robot ◽  
Electrical Equipment ◽  
Reference Points ◽  
Mobile Robot Navigation ◽  
Navigation Systems ◽  
Temperature Drift ◽  
Simulink Model ◽  
Working Space ◽  
Magnetometer Data

An important addition to inertial navigation systems is the magnetometer. Areas with magnetic field anomalies serve to determine the reference points. However, magnetometers can be influenced by both the robot’s configuration and its electrical equipment. Compensation for the robot’s self-influence on the readings of the magnetometers is carried out by computer tools. In order to obtain the initial data, live experiments are required in a natural environment. To simplify data acquisition concerning the behaviour of the magnetometric systems of a mobile robot, a special facility that allows for the local compensation of the Earth’s magnetic field is used, and an artificial magnetic field that varies according to a predetermined algorithm is created. Using this facility, we can also simulate the magnetic field that will be present in the intended environment of the application of the robot. The facility features are a working space that is sufficient to place the mobile robot; a coil temperature drift correction; uniformity of the frequency response in operating frequency range; compensation for the power supply interference and similar disturbances; sensitivity equalisation of control channels; compensation for the misalignment of the sensor’s and coil system’s coordinate systems. An interactive Simulink model is designed and evaluated. The automated stand is created as an experimental facility, its parameters proving the proposed model’s adequacy.

scholarly journals Magnetic Repeat Station Network on the Baltic Sea — Why So Needed?

2017 ◽  
Vol 24 (1) ◽  
pp. 19-30
Author(s):  
Elżbieta Welker ◽  
Jan Reda ◽  
Andrzej Pałka
Keyword(s):  
Magnetic Field ◽  
Baltic Sea ◽  
Magnetic Measurements ◽  
Navigation Systems ◽  
Earth’S Magnetic Field ◽  
Area Of Interest ◽  
Secular Variations ◽  
Earth's Magnetic Field ◽  
The Baltic ◽  
Base Data

AbstractThe development of navigation systems requires more and more accurate base data. Currently, attention is paid to utilization of geophysical fields — gravitational and magnetic ones — for navigation purposes. The Earth’s magnetic field distribution — both onshore and offshore — is complicated and variable in time. Hence, it is essential to precisely know the secular variations in the area of interest. In the case of Baltic Sea, this involves establishing (re-establishing) of a marine network of secular points (repeat stations) and regular magnetic measurements of the three independent components of the Earth’s magnetic field. Such measurements require equipment that ensures not only high stability, but also information about sensors’ orientation in relation to geographic north and to the level. This article presents a new project of the Baltic network of repeat stations and gives a solution for the instruments usable for quasi-absolute magnetic measurements.

GPS-DERIVED SECULAR VELOCITY FIELD AROUND SANGIHE ISLAND AND ITS IMPLICATION TO THE MOLUCCA SEA SEISMICITY

GEOMATIKA ◽  
2020 ◽  
Vol 26 (2) ◽  
pp. 107
Author(s):  
Leni Sophia Heliani ◽  
Cecep Pratama ◽  
Parseno Parseno ◽  
Nurrohmat Widjajanti ◽  
Dwi Lestari
Keyword(s):  
Surface Displacement ◽  
Active Regions ◽  
Least Square ◽  
The Other ◽  
Gps Data ◽  
West Side ◽  
Active Deformation ◽  
Secular Motion ◽  
Small Change ◽  
Linear Least Square

<p><em>Sangihe-Moluccas region is the most active seismicity in Indonesia. Between 2015 to 2018 there is four M6 class earthquake occurred close to the Sangihe-Moluccas region. These seismic active regions representing active deformation which is recorded on installed GPS for both campaign and continuous station. However, the origin of those frequent earthquakes has not been well understood especially related to GPS-derived secular motion. Therefore, we intend to estimate the secular motion inside and around Sangihe island. On the other hand, we also evaluate the effect of seismicity on GPS sites. Since our GPS data were conducted on yearly basis, we used an empirical global model of surface displacement due to coseismic activity. We calculate the offset that may be contained in the GPS site during its period</em><em>. </em><em>We remove the offset and estimate again the secular motion using linear least square. Hence, in comparison with the secular motion without considering the seismicity, we observe small change but systematically shifting the motion. We concluded the seismicity in the Molucca sea from 2015 to 2018 systematically change the secular motion around Sangihe Island at the sub-mm level. Finally, we obtained the secular motion toward each other between the east and west side within 1 to 5.5 cm/year displacement. </em></p>

scholarly journals An Indoor Visible Light Positioning System Using Tilted LEDs with High Accuracy

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 920
Author(s):  
Neha Chaudhary ◽  
Othman Isam Younus ◽  
Luis Nero Alves ◽  
Zabih Ghassemlooy ◽  
Stanislav Zvanovec ◽  
...  
Keyword(s):  
Visible Light ◽  
Polynomial Regression ◽  
Power Level ◽  
Least Square ◽  
Line Of Sight ◽  
Received Power ◽  
Strength Based ◽  
Complex Linear ◽  
Linear Least Square ◽  
First Time

The accuracy of the received signal strength-based visible light positioning (VLP) system in indoor applications is constrained by the tilt angles of transmitters (Txs) and receivers as well as multipath reflections. In this paper, for the first time, we show that tilting the Tx can be beneficial in VLP systems considering both line of sight (LoS) and non-line of sight transmission paths. With the Txs oriented towards the center of the receiving plane (i.e., the pointing center F), the received power level is maximized due to the LoS components on F. We also show that the proposed scheme offers a significant accuracy improvement of up to ~66% compared with a typical non-tilted Tx VLP at a dedicated location within a room using a low complex linear least square algorithm with polynomial regression. The effect of tilting the Tx on the lighting uniformity is also investigated and results proved that the uniformity achieved complies with the European Standard EN 12464-1. Furthermore, we show that the accuracy of VLP can be further enhanced with a minimum positioning error of 8 mm by changing the height of F.

scholarly journals A Hybrid Framework for Mitigating Heading Drift for a Wearable Pedestrian Navigation System through Adaptive Fusion of Inertial and Magnetic Measurements

2021 ◽  
Vol 11 (4) ◽  
pp. 1902
Author(s):  
Liqiang Zhang ◽  
Yu Liu ◽  
Jinglin Sun
Keyword(s):  
Magnetic Measurements ◽  
Inertial Sensor ◽  
Angular Rate ◽  
Human Motion ◽  
Navigation Systems ◽  
Pedestrian Navigation ◽  
Hybrid Framework ◽  
Outdoor Environments ◽  
Adaptive Fusion ◽  
Indoor And Outdoor Environments

Pedestrian navigation systems could serve as a good supplement for other navigation methods or for extending navigation into areas where other navigation systems are invalid. Due to the accumulation of inertial sensing errors, foot-mounted inertial-sensor-based pedestrian navigation systems (PNSs) suffer from drift, especially heading drift. To mitigate heading drift, considering the complexity of human motion and the environment, we introduce a novel hybrid framework that integrates a foot-state classifier that triggers the zero-velocity update (ZUPT) algorithm, zero-angular-rate update (ZARU) algorithm, and a state lock, a magnetic disturbance detector, a human-motion-classifier-aided adaptive fusion module (AFM) that outputs an adaptive heading error measurement by fusing heuristic and magnetic algorithms rather than simply switching them, and an error-state Kalman filter (ESKF) that estimates the optimal systematic error. The validation datasets include a Vicon loop dataset that spans 324.3 m in a single room for approximately 300 s and challenging walking datasets that cover large indoor and outdoor environments with a total distance of 12.98 km. A total of five different frameworks with different heading drift correction methods, including the proposed framework, were validated on these datasets, which demonstrated that our proposed ZUPT–ZARU–AFM–ESKF-aided PNS outperforms other frameworks and clearly mitigates heading drift.

A Least Square Method for Measurement and Optimisation in Selected Physical Experiments

2005 ◽  
Vol 295-296 ◽  
pp. 681-686 ◽  
Author(s):  
I. Frollo ◽  
P. Andris ◽  
I. Strolka ◽  
L. Bačiak
Keyword(s):  
Magnetic Field ◽  
Input Parameter ◽  
Target Function ◽  
Least Square Method ◽  
Least Square ◽  
Physical Experiments ◽  
Magnetic Field Homogeneity ◽  
Field Homogeneity ◽  
Basic Parameters ◽  
Shim Coils

The scope of this paper is to demonstrate a least square method for optimisation of basic parameters for selected physical experiment design where large input parameter measurement and adjustment is needed. The speed of calculation and experimentally verified results are promising to use this method in many physical projects. We have demonstrated this method for computation of feeding currents of correcting coils for stationary magnetic field used in NMR imaging. A set of linear equation definition and determination of a target function and optimisation computations are presented with procedures that provide optimal values of currents for shim coils. The proposed method, because of its simplicity and speed of computation, is convenient for basic adjustment of the magnetic field homogeneity by the first magnet installation. It is also suitable for periodic testing and magnet inhomogeneity correction for MRI magnets.

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