{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,22]],"date-time":"2026-05-22T05:06:20Z","timestamp":1779426380536,"version":"3.53.1"},"reference-count":41,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,5,10]],"date-time":"2026-05-10T00:00:00Z","timestamp":1778371200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Foundation for Science and Technology, I. P.","award":["UID\/05549\/2025"],"award-info":[{"award-number":["UID\/05549\/2025"]}]},{"name":"Foundation for Science and Technology, I. P.","award":["LASI-LA\/P\/0104\/2020"],"award-info":[{"award-number":["LASI-LA\/P\/0104\/2020"]}]},{"name":"Agenda Mobilizadora para a inova\u00e7\u00e3o empresarial do setor das Duas Rodas","award":["01\/C05-i01\/2021"],"award-info":[{"award-number":["01\/C05-i01\/2021"]}]},{"DOI":"10.13039\/100031478","name":"Next Generation EU","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100031478","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Digital"],"abstract":"<jats:p>Manual assembly remains critical in Industry 5.0 high-mix\/low-volume manufacturing, but it introduces resilience challenges due to cognitive load, training demands and frequent product changes. While AI-based supervision can mitigate errors, deploying such systems is often hindered by the cost of collecting and labelling thousands of real images for each product variant. This paper presents a Human-in-the-Loop semantic-twin pipeline that generates approximately 45,000 labelled synthetic images from a single CAD-based configuration and uses them to train an object detection model for real-time assembly supervision. Experiments on seven virtual environment configurations show that removing realistic lighting or camera motion reduces F1-score on real images from 0.87 to 0.46, confirming their critical role for synthetic-to-real transfer. A controlled laboratory study on a single bicycle chainring assembly task with 10 participants and 100 monitored cycles demonstrates the feasibility of automatic KPI extraction, with error events associated with a 25.6% increase in average cycle time (from 58.4 s to 73.3 s) under the tested conditions. Compared to manual annotation, where labelling 3000 images required approximately 4 h, the semantic-twin configuration takes around 4 to 6 h including image generation that enables rapid creation of large labelled datasets for new product variants without additional human annotation. These results provide a proof-of-concept foundation for resilient, data-efficient supervision of high-mix manual workstations, with full industrial validation across multiple products, stations and operator demographics identified as the necessary next step.<\/jats:p>","DOI":"10.3390\/digital6020039","type":"journal-article","created":{"date-parts":[[2026,5,11]],"date-time":"2026-05-11T17:17:42Z","timestamp":1778519862000},"page":"39","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Resilient Assembly Supervision: A Synthetic-to-Real Semantic Twin Pipeline for Data-Efficient Operator Guidance"],"prefix":"10.3390","volume":"6","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-0744-9853","authenticated-orcid":false,"given":"Luis","family":"Vilas Boas","sequence":"first","affiliation":[{"name":"2Ai\u2014School of Technology, IPCA, Instituto Polit\u00e9cnico do Cavado e do Ave, 4750-810 Barcelos, Portugal"},{"name":"LASI\u2013Associate Laboratory of Intelligent Systems, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4873-5458","authenticated-orcid":false,"given":"Jo\u00e3o M.","family":"Faria","sequence":"additional","affiliation":[{"name":"2Ai\u2014School of Technology, IPCA, Instituto Polit\u00e9cnico do Cavado e do Ave, 4750-810 Barcelos, Portugal"},{"name":"LASI\u2013Associate Laboratory of Intelligent Systems, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4178-8693","authenticated-orcid":false,"given":"Joaquin","family":"Dillen","sequence":"additional","affiliation":[{"name":"2Ai\u2014School of Technology, IPCA, Instituto Polit\u00e9cnico do Cavado e do Ave, 4750-810 Barcelos, Portugal"},{"name":"LASI\u2013Associate Laboratory of Intelligent Systems, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jos\u00e9","family":"Figueiredo","sequence":"additional","affiliation":[{"name":"Sistrade, 4250-380 Porto, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lu\u00eds","family":"Cardoso","sequence":"additional","affiliation":[{"name":"Miranda, 3750-871 \u00c1gueda, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5880-033X","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Borges","sequence":"additional","affiliation":[{"name":"2Ai\u2014School of Technology, IPCA, Instituto Polit\u00e9cnico do Cavado e do Ave, 4750-810 Barcelos, Portugal"},{"name":"LASI\u2013Associate Laboratory of Intelligent Systems, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2148-9146","authenticated-orcid":false,"given":"Antonio H. J.","family":"Moreira","sequence":"additional","affiliation":[{"name":"2Ai\u2014School of Technology, IPCA, Instituto Polit\u00e9cnico do Cavado e do Ave, 4750-810 Barcelos, Portugal"},{"name":"LASI\u2013Associate Laboratory of Intelligent Systems, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Bai, X., Huerta, O., Unver, E., Allen, J., and Clayton, J.E. (2021). A Parametric Product Design Framework for the Development of Mass Customized Head\/Face (Eyewear) Products. Appl. Sci., 11.","DOI":"10.3390\/app11125382"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"102121","DOI":"10.1016\/j.aei.2023.102121","article-title":"Towards new-generation human-centric smart manufacturing in Industry 5.0: A systematic review","volume":"57","author":"Zhang","year":"2023","journal-title":"Adv. Eng. 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