{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T21:12:34Z","timestamp":1792789954571,"version":"4.5.0"},"reference-count":26,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T00:00:00Z","timestamp":1790121600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Agency for Defense Development Grant","id":[{"id":"https:\/\/ror.org\/05fhe0r85","id-type":"ROR","asserted-by":"crossref"}]},{"id":[{"id":"https:\/\/ror.org\/05fhe0r85","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Terrain-referenced navigation (TRN) relies on nonlinear terrain matching, which can produce multimodal position uncertainty that should be retained during estimation. Accuracy can deteriorate when the relative probabilities of ground and canopy returns vary over time because a fixed measurement model cannot adapt to the changing return regime. To address this problem, an interacting multiple-model (IMM) extension of the Rao\u2013Blackwellized point-mass filter (RBPMF) is developed, yielding an IMM-RBPMF that adapts between measurement hypotheses while retaining the non-Gaussian navigation posterior. The extension uses grid-resolved posterior mixing to remap complete mode-conditioned RBPMF representations onto a common grid; nonlinear-state point masses are combined using global IMM interaction probabilities, whereas conditional Gaussian components are combined using state-dependent local responsibilities. Monte Carlo simulations over rough and rough\u2013flat\u2013rough terrain compare the proposed filter with single-model and fixed-mixture RBPMFs. Relative to the best baseline for each metric, the filter reduces overall horizontal-position root-mean-square error (RMSE) by up to 44% and altitude RMSE by 53%, demonstrating improved robustness to ambiguous radar returns and weakly informative terrain.<\/jats:p>","DOI":"10.3390\/s26196024","type":"journal-article","created":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T11:09:08Z","timestamp":1790161748000},"page":"6024","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["An IMM Extension of RBPMF for Terrain-Referenced Navigation Under Radar Return Ambiguity"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7033-4941","authenticated-orcid":false,"given":"Kyung Jun","family":"Han","sequence":"first","affiliation":[{"name":"Department of Mechanical and Aerospace Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea"},{"name":"4th R&D Institute, Agency for Defense Development, Yuseong, Daejeon 34186, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"software","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5824-4639","authenticated-orcid":false,"given":"Chang-Ky","family":"Sung","sequence":"additional","affiliation":[{"name":"4th R&D Institute, Agency for Defense Development, Yuseong, Daejeon 34186, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"software","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8013-6711","authenticated-orcid":false,"given":"ByungSu","family":"Park","sequence":"additional","affiliation":[{"name":"4th R&D Institute, Agency for Defense Development, Yuseong, Daejeon 34186, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"visualization","vocabulary":"credit"},{"role":"software","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9638-5707","authenticated-orcid":false,"given":"Taeyun","family":"Kim","sequence":"additional","affiliation":[{"name":"4th R&D Institute, Agency for Defense Development, Yuseong, Daejeon 34186, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"visualization","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7403-951X","authenticated-orcid":false,"given":"Chan Gook","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Mechanical and Aerospace Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"resources","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1109\/37.768538","article-title":"Terrain navigation using Bayesian statistics","volume":"19","author":"Bergman","year":"1999","journal-title":"IEEE Control Syst. 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