{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,29]],"date-time":"2026-05-29T11:11:34Z","timestamp":1780053094618,"version":"3.54.0"},"reference-count":51,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,2,10]],"date-time":"2021-02-10T00:00:00Z","timestamp":1612915200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["CNS-1815349"],"award-info":[{"award-number":["CNS-1815349"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["ECCS-1845833"],"award-info":[{"award-number":["ECCS-1845833"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100006021","name":"Direction G\u00e9n\u00e9rale de l\u2019Armement","doi-asserted-by":"publisher","award":["2019.65.0068.00.470.75.01"],"award-info":[{"award-number":["2019.65.0068.00.470.75.01"]}],"id":[{"id":"10.13039\/501100006021","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Global navigation satellite systems (GNSSs) play a key role in intelligent transportation systems such as autonomous driving or unmanned systems navigation. In such applications, it is fundamental to ensure a reliable precise positioning solution able to operate in harsh propagation conditions such as urban environments and under multipath and other disturbances. Exploiting carrier phase observations allows for precise positioning solutions at the complexity cost of resolving integer phase ambiguities, a procedure that is particularly affected by non-nominal conditions. This limits the applicability of conventional filtering techniques in challenging scenarios, and new robust solutions must be accounted for. This contribution deals with real-time kinematic (RTK) positioning and the design of robust filtering solutions for the associated mixed integer- and real-valued estimation problem. Families of Kalman filter (KF) approaches based on robust statistics and variational inference are explored, such as the generalized M-based KF or the variational-based KF, aiming to mitigate the impact of outliers or non-nominal measurement behaviors. The performance assessment under harsh propagation conditions is realized using a simulated scenario and real data from a measurement campaign. The proposed robust filtering solutions are shown to offer excellent resilience against outlying observations, with the variational-based KF showcasing the overall best performance in terms of Gaussian efficiency and robustness.<\/jats:p>","DOI":"10.3390\/s21041250","type":"journal-article","created":{"date-parts":[[2021,2,12]],"date-time":"2021-02-12T16:12:10Z","timestamp":1613146330000},"page":"1250","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":26,"title":["Robust Filtering Techniques for RTK Positioning in Harsh Propagation Environments"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1586-3269","authenticated-orcid":false,"given":"Daniel","family":"Medina","sequence":"first","affiliation":[{"name":"Institute of Communications and Navigation, German Aerospace Center (DLR), 17235 Neustrelitz, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6953-755X","authenticated-orcid":false,"given":"Haoqing","family":"Li","sequence":"additional","affiliation":[{"name":"Electrical and Computer Engineering Department, Northeastern University, Boston, MA 02115, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7858-4171","authenticated-orcid":false,"given":"Jordi","family":"Vil\u00e0-Valls","sequence":"additional","affiliation":[{"name":"Institut Sup\u00e9rieur de l\u2019A\u00e9ronautique et de l\u2019Espace (ISAE-SUPAERO), University of Toulouse, 31055 Toulouse, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5960-6600","authenticated-orcid":false,"given":"Pau","family":"Closas","sequence":"additional","affiliation":[{"name":"Electrical and Computer Engineering Department, Northeastern University, Boston, MA 02115, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,10]]},"reference":[{"key":"ref_1","unstructured":"Dardari, D., Falletti, E., and Luise, M. 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