E. V. Karshakov

A stochastic estimation problem at aeromagnetometer deviation compensation

A formulation of the problem of magnitometer deviation compensation occurring at aeromagnetic survey is considered in the form of a standard stochastic estimation problem. A specific feature of this approach is the introduction of the model of a geomagnetic field anomaly. The parameters of the stochastic model are selected basing on spectral and variance analysis of the aeromagnetic survey data. Normalization of the problem parameters is made; this makes it possible to estimate the accuracy of compensation and conduct a necessary decomposition. The posed stochastic estimation problem is solved by the method of Kalman filtering.

Algorithm to position an object moving in the low-frequency electromagnetic field

Consideration was given to the problem of relative positioning with the use of alternating magnetic field. The problem was shown to be solvable using a system of three magnetic dipoles emitting magnetic field at different frequencies. Ambiguity of its solution was discussed, and ways to resolve it were proposed. An algorithm for relative positioning based on the solution of this problem was proposed. Error equations of the positioning algorithm and the results of their analysis were presented. Some issues of practical application of this algorithm were discussed.

Specifics of aircraft control algorithms in the case of aerial survey

This paper considers the control problem for a piloted atmospheric aircraft during execution of different flight missions. The basic control schemes are identified in the case of aerial survey. Modern control systems are compared and analyzed. A software complex is developed and applied to aerial survey. Finally, we study the key implementation aspects of control algorithms.

Aeromagnetic Gradiometry and Its Application to Navigation

Modern methods of airborne magnetic field measurements are described. A stochastic algorithm to compensate the deviations between the indications of an aeromagnetometer and an aeromagnetic gradiometer is considered. An integration algorithm for the inertial and correlation-extremal navigation systems is briefly described. An advantage of using magnetic field gradient measurements as navigational data is justified. The performance of the integration algorithm is illustrated by numerical simulation.

On calibration of a navigation system equipped with a magnetic gradiometer

This paper shows how to calculate the magnetic field of an aircraft with the help of measurements taken by an on-board tensor magnetic gradiometer. We assume that the magnetic field of an aircraft obeys a simple linear model. The external magnetic field is modeled by Gauss-Markov processes. It is assumed that magnetic gradiometry measurements are collected during flight with significant angular maneuvers. Under these assumptions, our problem may be reformulated as a well-known linear estimation problem. After solution of the problem, one may execute the so-called compensation procedure, i.e., to filter out aircraft-dependent disturbances from on-board magnetic measurements. After such compensation, measurements of the on-board magnetic gradiometer may be used to correct INS errors.

Combined Frequency Domain and Time Domain Airborne Data for Environmental and Engineering Challenges

ABSTRACT We describe the main properties of the EQUATOR airborne geophysical system and how the system can be employed to solve some engineering and environmental problems. To date, the EQUATOR system has been used for groundwater search in 2014 and 2015 in Siberia. The name “EQUATOR” originates from the intention to EQUATE, or to balance time and frequency domain approaches in airborne electromagnetics, which is why the system was originally designed. To the best of our knowledge, EQUATOR is the only system to collect electromagnetic data both in time and in frequency domains. We further explain the difference between the two methods on some numerical and field examples. Also we describe some advantages of their coupling. In particular, by virtue of our approach, a numerically more robust solution of the one-dimensional electromagnetic inverse problem may be achieved. The recorded full-time measurements are further converted to in-phase, quadrature and off-time responses, as opposed to standard frequency...

Nonlinear algorithm for navigation of a moving object in magnetic field

Consideration was given to the problem of relative positioning with the use of alternating magnetic field. The problem was shown to be solvable using a system of three magnetic dipoles emitting magnetic field at different frequencies. Ambiguity of its solution was discussed, and ways to resolve it were proposed. An algorithm for relative positioning based on the solution of this problem was proposed. Error equations of the positioning algorithm and the results of their analysis were presented. Calibration procedures, improving accuracy of relative positioning, are also considered. One of these procedures, based on nonlinear optimization techniques, was presented in greater details. The paper was supplied with several numerical examples demonstrating effectiveness of proposed algorithms in relative positioning.

The models and structure of onboard measurements of three-dimensional physical fields

The airborne measurement systems of geophysical fields are considered. The applicability of such systems in navigation and geophysics is analyzed. The existing gravimetric, magnetometric and electromagnetic systems are briefly overviewed. The structure of the airborne measurement systems of geophysical fields and the associated mathematical models are discussed in detail. Finally, the issues of data processing are studied and the solution approaches to the ill-posed problems are described.

A feedback in the aircraft's magnetic field control problem

Aeromagnetic compensation problem is considered for the on-board magnetic gradiometer. The purpose is to distinguish the necessary signal - the Earths magnetic field gradient. Compensation is performed using magnetic dipoles by changing their dipole moments to control aircrafts magnetic field. As a feedback for magnetic field control the difference of measurements of two gradiometers is used. These two sensors are set on different distances from fuselage.