Low Frequency Radio Polarization Sensor With Applications in Attitude Estimation

• Published in: IEEE sensors journal Vol. 15; no. 12; pp. 7304 - 7311
• Main Authors: Maguire, Sean T. G., Robertson, Paul A.
• Format: Journal Article
• Language: English
• Published: IEEE 01.12.2015
• Subjects: Algorithms; Antenna arrays; Antenna measurements; Arrays; attitude; Channels; Frequency measurement; Linear polarization; Low frequencies; low frequency; Magnetic sensors; Polarization; Radio; Receiving antennas; Sensors; UAV; magnetic sensors; polarization; UAV; low frequency; Antenna arrays; attitude
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2015.2469679

A novel method of attitude (orientation) estimation is proposed, which makes use of measurements of the polarization of the magnetic (H-) field of Low Frequency (LF) radio signals. This offers advantages relative to existing accelerometer-based systems in high-acceleration, cost-constrained environments, such as small fixed-wing unmanned aerial vehicles. In order to validate this method, a sensor system is presented, which is capable of determining the H-field polarization of LF radio signals from three-axis measurements. The sensor system consists of an array of three orthogonal loop antennas, a three channel radio receiver circuit, a datalogging and control module, and data processing algorithms. This system is shown to accurately measure the axis of H-field polarization for signals with linear or almost linear polarization, subject to a sign ambiguity. A representative AM radio broadcast in the LF band is shown to have a substantially linear polarization, measurements of which are used to determine a receiver's heading angle. The stability of these polarization measurements over time and the distorting effect of certain structures are quantified. The feasibility of this method of attitude determination is therefore demonstrated.