{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,9]],"date-time":"2026-01-09T20:03:56Z","timestamp":1767989036356,"version":"3.49.0"},"reference-count":41,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2022,2,22]],"date-time":"2022-02-22T00:00:00Z","timestamp":1645488000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NAKAJIMA FOUNDATION","award":["R2"],"award-info":[{"award-number":["R2"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This study presents a radar-based remote measurement system for classification of human behaviors and falls in restrooms without privacy invasion. Our system uses a dual Doppler radar mounted onto a restroom ceiling and wall. Machine learning methods, including the convolutional neural network (CNN), long short-term memory, support vector machine, and random forest methods, are applied to the Doppler radar data to verify the model\u2019s efficiency and features. Experimental results from 21 participants demonstrated the accurate classification of eight realistic behaviors, including falling. Using the Doppler spectrograms (time\u2013velocity distribution) as the inputs, CNN showed the best results with an overall classification accuracy of 95.6% and 100% fall classification accuracy. We confirmed that these accuracies were better than those achieved by conventional restroom monitoring techniques using thermal sensors and radars. Furthermore, the comparison results of various machine learning methods and cases using each radar\u2019s data show that the higher-order derivative parameters of acceleration and jerk, and the motion information in the horizontal direction are the efficient features for behavior classification in a restroom. These findings indicate that daily restroom monitoring using the proposed radar system accurately recognizes human behaviors and allows early detection of fall accidents.<\/jats:p>","DOI":"10.3390\/s22051721","type":"journal-article","created":{"date-parts":[[2022,2,22]],"date-time":"2022-02-22T22:35:00Z","timestamp":1645569300000},"page":"1721","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Machine Learning-Based Classification of Human Behaviors and Falls in Restroom via Dual Doppler Radar Measurements"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2088-1231","authenticated-orcid":false,"given":"Kenshi","family":"Saho","sequence":"first","affiliation":[{"name":"Department of Intelligent Robotics, Toyama Prefectural University, Imizu 939-0398, Japan"},{"name":"Department of Electronic and Computer Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan"}]},{"given":"Sora","family":"Hayashi","sequence":"additional","affiliation":[{"name":"Department of Electronic and Computer Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan"}]},{"given":"Mutsuki","family":"Tsuyama","sequence":"additional","affiliation":[{"name":"Department of Electronic and Computer Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4351-6923","authenticated-orcid":false,"given":"Lin","family":"Meng","sequence":"additional","affiliation":[{"name":"Department of Electronic and Computer Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan"}]},{"given":"Masao","family":"Masugi","sequence":"additional","affiliation":[{"name":"Department of Electronic and Computer Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan"}]}],"member":"1968","published-online":{"date-parts":[[2022,2,22]]},"reference":[{"key":"ref_1","unstructured":"World Population Prospects (2022, January 17). 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