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Chief among these is the lengthy and costly development process to get an exoskeleton from conception to implementation and the necessity for a broad set of expertise. In addition, many exoskeletons are designed for a specific utility and are confined to the laboratory environment, limiting the flexibility of the designed system to adapt to answer new questions and explore new domains. To address these barriers, we present OpenExo, an open-source modular untethered exoskeleton framework that provides access to all aspects of the design process, including software, electronics, hardware, and control schemes. To demonstrate the utility of this exoskeleton framework, we performed benchtop and experimental validation testing with the system across multiple configurations, including hip-only incline assistance, ankle-only indoor and outdoor assistance, hip-and-ankle load carriage assistance, and elbow-only weightlifting assistance. All aspects of the software architecture, electrical components, hip and Bowden-cable transmission designs, and control schemes are freely available for other researchers to access, use, and modify when looking to address research questions in the field of wearable exoskeletons. Our hope is that OpenExo will accelerate the development and testing of new exoskeleton designs and control schemes while simultaneously encouraging others, including those who would have been turned away from entering the field, to explore new and unique research questions.<\/jats:p>","DOI":"10.1126\/scirobotics.adt1591","type":"journal-article","created":{"date-parts":[[2025,6,25]],"date-time":"2025-06-25T13:59:24Z","timestamp":1750859964000},"update-policy":"https:\/\/doi.org\/10.34133\/aaas_crossmark","source":"Crossref","is-referenced-by-count":9,"title":["OpenExo: An open-source modular exoskeleton to augment human function"],"prefix":"10.1126","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9029-1029","authenticated-orcid":true,"given":"Jack R.","family":"Williams","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chance F.","family":"Cuddeback","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3019-2977","authenticated-orcid":true,"given":"Shanpu","family":"Fang","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniel","family":"Colley","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-3479-7973","authenticated-orcid":true,"given":"Noah","family":"Enlow","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-1202-4651","authenticated-orcid":true,"given":"Payton","family":"Cox","sequence":"additional","affiliation":[{"name":"School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8370-6388","authenticated-orcid":true,"given":"Paul","family":"Pridham","sequence":"additional","affiliation":[{"name":"Department of Industrial and Operations Engineering, University of Michigan, Ann Arbor, MI, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7359-436X","authenticated-orcid":true,"given":"Zachary F.","family":"Lerner","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, USA."},{"name":"College of Medicine\u2013Phoenix, University of Arizona, Phoenix, AZ, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"221","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1186\/s12984-020-00663-9"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1109\/TBME.2021.3137447"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1109\/TNSRE.2020.2965029"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1109\/LRA.2024.3477093"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-023-50387-8"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41551-022-00984-1"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1186\/1743-0003-11-92"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1186\/s12984-016-0162-5"},{"key":"e_1_3_2_10_2","doi-asserted-by":"publisher","DOI":"10.1017\/wtc.2022.12"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-019-43628-2"},{"key":"e_1_3_2_12_2","first-page":"1549","article-title":"A wearable hip assist robot can improve gait function and cardiopulmonary metabolic efficiency in elderly adults","volume":"25","author":"Lee H. 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