title: Feasibility of Using Synthetic Aperture Radar to Aid UAV Navigation.
abstract: This study explores the potential of Synthetic Aperture Radar (SAR) to aid Unmanned Aerial Vehicle (UAV) navigation when Inertial Navigation System (INS) measurements are not accurate enough to eliminate drifts from a planned trajectory. This problem can affect medium-altitude long-endurance (MALE) UAV class, which permits heavy and wide payloads (as required by SAR) and flights for thousands of kilometres accumulating large drifts. The basic idea is to infer position and attitude of an aerial platform by inspecting both amplitude and phase of SAR images acquired onboard. For the amplitude-based approach, the system navigation corrections are obtained by matching the actual coordinates of ground landmarks with those automatically extracted from the SAR image. When the use of SAR amplitude is unfeasible, the phase content can be exploited through SAR interferometry by using a reference Digital Terrain Model (DTM). A feasibility analysis was carried out to derive system requirements by exploring both radiometric and geometric parameters of the acquisition setting. We showed that MALE UAV, specific commercial navigation sensors and SAR systems, typical landmark position accuracy and classes, and available DTMs lead to estimated UAV coordinates with errors bounded within ±12 m, thus making feasible the proposed SAR-based backup system.
authors.affiliation: Geophysical Applications Processing s.r.l., Via Amendola 173, 70126 Bari, Italy. davide.nitti@gapsrl.eu.
authors.forename: Davide O
authors.initials: DO
authors.lastname: Nitti
authors.affiliation: National Research Council of Italy, ISSIA institute, Via Amendola 173, 70126 Bari, Italy. bovenga@ba.issia.cnr.it.
authors.forename: Fabio
authors.initials: F
authors.lastname: Bovenga
authors.affiliation: Dipartimento di Fisica "M. Merlin", Politecnico di Bari, Via Amendola 173, 70126 Bari, Italy. chiaradia@ba.infn.it.
authors.forename: Maria T
authors.initials: MT
authors.lastname: Chiaradia
authors.affiliation: IDS-Ingegneria Dei Sistemi S.p.A., Via Enrica Calabresi 24, 56121 Pisa, Italy. m.greco@idscorporation.com.
authors.forename: Mario
authors.initials: M
authors.lastname: Greco
authors.affiliation: IDS-Ingegneria Dei Sistemi S.p.A., Via Enrica Calabresi 24, 56121 Pisa, Italy. g.pinelli@idscorporation.com.
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Pinelli
keywords: ATR; Geo-referencing; SAR; UAV; feasibility; interferometry; navigation