Aerial Simultaneous Localization and Mapping Using Earth\u27s Magnetic Anomaly Field

Aerial magnetic navigation has been shown to be a viable GPS-alternative, but requires a prior-surveyed magnetic map. The miniaturization of atomic magnetometers extends their application to small aircraft at low altitudes where magnetic maps are especially inaccurate or unavailable. This research presents a simultaneous localization and mapping (SLAM) approach to constrain the drift of an inertial navigation system (INS) without the need for a magnetic map. The filter was demonstrated using real measurements on a professional survey flight, and on an AFIT unmanned aerial vehicle

Absolute Positioning Using the Earth\u27s Magnetic Anomaly Field

Achieving worldwide alternatives to GPS is a challenging engineering problem. Current GPS alternatives often suffer from limitations such as where and when the systems can operate. Navigation using the Earth\u27s magnetic anomaly field, which is globally available at all times, shows promise to overcome many of these limitations. We present a navigation filter which uses the Earth\u27s magnetic anomaly field as a navigation signal to aid an inertial navigation system (INS) in an aircraft. The filter utilizes highly-accurate optically pumped cesium (OPC) magnetometers to make scalar measurements of the Earth\u27s magnetic field and compare them to a map using a marginalized particle filter approach. We demonstrate navigation accuracy of 13 meters DRMS with a high quality magnetic anomaly map at low altitudes with real flight data. We conduct a simulation over the continental United States to predict accuracies with respect to variables like location and altitude. Finally, we address the problem of map availability by presenting a method for a self-building magnetic anomaly model

Advanced Geoscience Remote Sensing

Nowadays, advanced remote sensing technology plays tremendous roles to build a quantitative and comprehensive understanding of how the Earth system operates. The advanced remote sensing technology is also used widely to monitor and survey the natural disasters and man-made pollution. Besides, telecommunication is considered as precise advanced remote sensing technology tool. Indeed precise usages of remote sensing and telecommunication without a comprehensive understanding of mathematics and physics. This book has three parts (i) microwave remote sensing applications, (ii) nuclear, geophysics and telecommunication; and (iii) environment remote sensing investigations

A parameterized geometric magnetic field calibration method for vehicles with moving masses with applications to underwater gliders

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Journal of Field Robotics 34 (2017): 209-223, doi:10.1002/rob.21660.The accuracy of magnetic measurements performed by autonomous vehicles is often limited by the presence of moving ferrous masses. This work presents a parameterized ellipsoid eld calibration method for magnetic measurements in the sensor frame. In this manner the ellipsoidal calibration coe cients are dependent on the locations of the moving masses. The parameterized calibration method is evaluated through eld trials with an autonomous underwater glider equipped with a low power precision uxgate sensor. A rst set of eld trials were performed in the East Arm of Bonne Bay, Newfoundland in December of 2013. During these trials a series of calibration pro les with the mass shifting and ballast mecha- nisms at di erent locations were performed before and after the survey portion of the trials. Further trials were performed in the Labrador Sea in July of 2014 with two reduced sets of calibration runs. The nominal ellipsoidal coe cients were extracted using the full set of measurements from a set of calibration pro les and used as the initial conditions for the polynomials which de ne each parameterized coe cient. These polynomials as well as the sensor misalignment matrix were then optimized using a gradient descent solver which minimizes both the total magnetic eld di erence and the vertical magnetic eld variance between the modeled and measured values. Including the vertical eld in this manner allows for convergence in spite of severe limitations on the platform's motion and for computation of the vehicle's magnetic heading.This work was supported by the Natural Sciences and Engineering Research Council (NSERC) through the NSERC Canadian Field Robotics Network (NCFRN), the Research Development Corporation, the Marine Institute and Memorial University of Newfoundland.2017-06-0

Advanced Sensing, Fault Diagnostics, and Structural Health Management

Advanced sensing, fault diagnosis, and structural health management are important parts of the maintenance strategy of modern industries. With the advancement of science and technology, modern structural and mechanical systems are becoming more and more complex. Due to the continuous nature of operation and utilization, modern systems are heavily susceptible to faults. Hence, the operational reliability and safety of the systems can be greatly enhanced by using the multifaced strategy of designing novel sensing technologies and advanced intelligent algorithms and constructing modern data acquisition systems and structural health monitoring techniques. As a result, this research domain has been receiving a significant amount of attention from researchers in recent years. Furthermore, the research findings have been successfully applied in a wide range of fields such as aerospace, manufacturing, transportation and processes

Synthetic aperture in controlled source electromagnetic for the monitoring and exploration of reservoirs on land

Abstract: The following doctoral thesis is composed of five scientific papers, structured in three chapters. Three of these papers are already published in international journals, and two are currently under review. According to the stated objectives in this work, these chapters are grouped into two general sections, namely: Section I. Golden zone of sedimentary basins in the Colombian territory; Section II. Exploration of reservoirs on land using electromagnetic methods.Resumen: La primera parte de esta tesis identifica la Zona Dorada en algunas cuencas sedimentarias de Colombia por medio de anomalías magnéticas. En la segunda parte se realiza modelamientos directos 3D de los métodos de apertura sintética en fuente controlada electromagnética y multitransiente electromagnética para la exploración de reservorios sobre tierra.Doctorad

Geomagnetic diurnal variation studies using global models & observatory data at quiet & moderately disturbed times.

In this thesis we investigate and analyse the nature and behaviour of the external field variations of the geomagnetic field for quiet and moderately disturbed days using geomagnetic observatory measurements and field models. We use spherical harmonic modelling, led by available geomagnetic observatory measurements and past models (particularly the Comprehensive Model of Sabaka et al. 2004). As an initial step, we extended the lifespan of the Comprehensive Model (CM4) beyond its 2002.5 lifespan to allow for use of current data. We produced profile plots of the diurnal field and generated global maps of the field and compare these with the CM4 model, to see how well the CM4 model could reasonably predict ground variation of the diurnal field outside its lifespan and for days away from quiet time. The comparison shows that away from quiet time period, the CM4 model is producing more reasonable predictions than expected, despite the lack of active data in the original model dataset. The CM4 model fits the regional type features of the geomagnetic components, but not doing well predicting the short term features during period of rapid variations (seen as ‘wiggles’ in the profile plots) , especially for the X- component. Also, comparing the modelled diurnal maps of the CM4 and observatory data shows that increasing the spherical harmonic degree produces a better match between the CM4 model and the data. Our result reveals that the external field description included in the CM4 model could not sufficiently explain the field variation for days away from quiet time. The CM4 model predicts the Y- and Z- components variations better than the X; this may be due to the fact that the X component is more affected by external field sources. As a result we introduced the use of an additional geomagnetic activity index (the RC index), to enable us to establish the nature of the rapid variation seen in the data for days away from quiet time. We looked for this using eigenanalysis (covariance matrices, eigenvectors and eigenvalues), detrending the data sequences with spline fits, and comparing the observatory data residuals with the RC index values. We also looked at the coherence and correlation between small scale features showing up in the rapid variation, to try to establish the global scale of the variations. We analysed this by simple running average method, correlation and cross-correlation coefficients between the residuals of the observatory data components and the RC index. Our results show that our data for days away from quiet time, particularly the X component, include a strong component in the rapid variations related to large-scale external field variation arising from the magnetospheric ring current. For example we are able to reproduce features in our plots that show a very strong coherence and correlation existing between the X component of our observatory data residuals and the RC index. This is also seen in the same components of the observatories at different locations within the same geographical region, and at some different geographical regions. This allows us to characterise the RC index as being a good representation for rapid variations globally. Also, it makes us optimistic that it may be useful to look at rapid variation observatory results for combined observatory stations as a good technique for remote referencing in aeromagnetic surveying