Characterization of Quad-Copter Positioning Systems and the Effect of Pose Uncertainties on Field Probe Measurements

Abstract

When measuring the Radar Cross Section (RCS) of a test object, many uncertainties must be accounted for, such as the non-homogeneous nature of the medium between the radar test equipment and the platform under test. There are a variety of other error sources, including clutter and Radio Frequency Interference (RFI), motivating the development of techniques to measure and model the uncertainties in RCS measurements. The following research, in unison with prior and current efforts, intends to reduce the impact of these uncertainties by utilizing a unique two-way field probe in the form of a geodesic sphere encompassing a commercial quad-copter aircraft. The probe is used to measure the incident fields in the target volume in an effort to quantify one of the key sources of uncertainty in an RCS measurement, distortions in the incident wave. In order to do this, the geodesic sphere must be fully understood. This research determined the uncertainty of the probe by creating a calibrated data set of the probe’s RCS, extracting the calibrated RCS based on the measurement flight path, comparing the measured with the calibrated data, and determining the deviation in the difference. The accuracy of the comparison, and therefore the measurement, depends on the accuracy of the flight path. An uncertainty in the probe’s position and orientation during flight translates into a field measurement uncertainty. These uncertainties were determined for the Parrot Bebop quad-copter, a differential GPS, and a Vicon™ system. Each uncertainty was fed into the measurement model and their measurement uncertainties were determined. Field measurement accuracies of \u3c 2° in phase and \u3c 0.05V/m in magnitude were demonstrated