Magnetic Gradient Tensor Framework for Attitude-Free Position Estimation

The magnetic field is a potentially robust and widely available source of information available for determining position on Earth. Certain measurements of the magnetic field can be obtained without the need for precise sensor attitude, facilitating position determination using only vector magnetometers in a gradiometer arrangement. A magnetic field tensor gradiometer system could provide greater spatial resolution compared to previous efforts to determine position using scalar magnetometers. This paper provides the theoretical framework for a navigation sensor capable of determining position without independent measurement of sensor attitude relative to the mapped global magnetic field.