{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,13]],"date-time":"2026-01-13T07:01:55Z","timestamp":1768287715637,"version":"3.49.0"},"reference-count":36,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2021,6,7]],"date-time":"2021-06-07T00:00:00Z","timestamp":1623024000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100013293","name":"Active and Assisted Living programme","doi-asserted-by":"publisher","award":["AAL-2017-066"],"award-info":[{"award-number":["AAL-2017-066"]}],"id":[{"id":"10.13039\/100013293","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Inertial sensors can potentially assist clinical decision making in gait-related disorders. Methods for objective spatio-temporal gait analysis usually assume the careful alignment of the sensors on the body, so that sensor data can be evaluated using the body coordinate system. Some studies infer sensor orientation by exploring the cyclic characteristics of walking. In addition to being unrealistic to assume that the sensor can be aligned perfectly with the body, the robustness of gait analysis with respect to differences in sensor orientation has not yet been investigated\u2014potentially hindering use in clinical settings. To address this gap in the literature, we introduce an orientation-invariant gait analysis approach and propose a method to quantitatively assess robustness to changes in sensor orientation. We validate our results in a group of young adults, using an optical motion capture system as reference. Overall, good agreement between systems is achieved considering an extensive set of gait metrics. Gait speed is evaluated with a relative error of \u22123.1\u00b19.2 cm\/s, but precision improves when turning strides are excluded from the analysis, resulting in a relative error of \u22123.4\u00b16.9 cm\/s. We demonstrate the invariance of our approach by simulating rotations of the sensor on the foot.<\/jats:p>","DOI":"10.3390\/s21113940","type":"journal-article","created":{"date-parts":[[2021,6,7]],"date-time":"2021-06-07T22:23:00Z","timestamp":1623104580000},"page":"3940","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Orientation-Invariant Spatio-Temporal Gait Analysis Using Foot-Worn Inertial Sensors"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8133-0789","authenticated-orcid":false,"given":"V\u00e2nia","family":"Guimar\u00e3es","sequence":"first","affiliation":[{"name":"Fraunhofer Portugal AICOS, 4200-135 Porto, Portugal"},{"name":"Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8488-256X","authenticated-orcid":false,"given":"In\u00eas","family":"Sousa","sequence":"additional","affiliation":[{"name":"Fraunhofer Portugal AICOS, 4200-135 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6065-9358","authenticated-orcid":false,"given":"Miguel Velhote","family":"Correia","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"},{"name":"Institute for Systems and Computer Engineering, Technology and Science (INESC TEC), 4200-465 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,6,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1630003","DOI":"10.1142\/S0219519416300039","article-title":"Gait analysis: Systems, technologies, and importance","volume":"16","author":"Akhtaruzzaman","year":"2016","journal-title":"J. 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