{"paper_id":"0671da7b-3a04-487d-897e-2bc4fffd0803","body_text":"SPPIRO: A Soft, Power-Autonomous, Proprioceptive In-Pipe RObot for Adaptive Inspection in Complex Pipeline Environments | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article SPPIRO: A Soft, Power-Autonomous, Proprioceptive In-Pipe RObot for Adaptive Inspection in Complex Pipeline Environments Zexiong Chen, Xinqi Zhang, Jiaqi Wang, Xiaonan Huang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7331030/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Subterranean and industrial pipelines are critical infrastructure for transporting water, oil, and gas, yet their internal complexity—featuring varying diameters, sharp turns, and multi-directional junctions—poses significant challenges for conventional inspection robots. We present SPPIRO, a fully untethered soft robot designed for adaptive pipeline inspection in such environments. SPPIRO integrates compact, custom-designed PCBs for onboard power, sensing, and control, enabling fully untethered operation. Its anchoring modules use motor-driven six-bar linkages with 3D-printed, honeycomb-inspired soft wheels, allowing adaptation to pipeline diameters ranging from 140 mm to 200 mm. The propulsion module consists of three self-sensing pneumatic Kresling origami actuators arranged at 120◦, providing omnidirectional steering and real-time body shape estimation. Using a Piecewise Constant Curvature (PCC) model, SPPIRO reconstructs both its own configuration and the surrounding pipe geometry during motion. Liquid-metal-based capacitive sensors embedded in the feet enable contact-aware anchoring, even in opaque pipelines. Experiments demonstrate SPPIRO’s ability to traverse vertical and horizontal segments, 90-degree turns, and T-junctions, achieving speeds up to 7.86 mm/s—outperforming prior untethered soft in-pipe robots. These results position SPPIRO as a promising platform for autonomous, geometry-aware pipeline inspection. Physical sciences/Energy science and technology Physical sciences/Engineering Untethered soft robot 3D-printing soft actuator In-pipe robot Kresling Origami Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementaryVideo.zip Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 30 Oct, 2025 Reviews received at journal 27 Oct, 2025 Reviews received at journal 12 Oct, 2025 Reviewers agreed at journal 06 Oct, 2025 Reviewers agreed at journal 18 Sep, 2025 Reviewers invited by journal 08 Sep, 2025 Editor assigned by journal 24 Aug, 2025 Submission checks completed at journal 14 Aug, 2025 First submitted to journal 08 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {\"props\":{\"pageProps\":{\"initialData\":{\"identity\":\"rs-7331030\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Article\",\"associatedPublications\":[],\"authors\":[{\"id\":514598544,\"identity\":\"96b0b697-1401-4266-b256-c58af6ad503c\",\"order_by\":0,\"name\":\"Zexiong Chen\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Michigan–Ann Arbor\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Zexiong\",\"middleName\":\"\",\"lastName\":\"Chen\",\"suffix\":\"\"},{\"id\":514598545,\"identity\":\"29d06da3-62ab-4e75-9d37-7fe15d7e4954\",\"order_by\":1,\"name\":\"Xinqi 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