ScaFi: Length-Scalable, Compliant, Parametric Robotic Fish Design for Operation in Multiple Environmental Niches

ScaFi: Length-Scalable, Compliant, Parametric Robotic Fish Design for Operation in Multiple Environmental Niches | 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 ScaFi: Length-Scalable, Compliant, Parametric Robotic Fish Design for Operation in Multiple Environmental Niches Nana Obayashi, Alexandros Anastasiadis, Jessica Gumowski, Kai Junge, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7577054/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Aquatic creatures provide inspiration for robotic design, their morphologies spanning a vast range of scales. These scaled forms are suited to the performance and environmental demands of their respective habitats, influencing characteristics like speed and tail beat frequency. However, in artificial systems, the design of a single robot that can operate effectively across a wide range of physical sizes remains a significant challenge, with current tethered or untethered designs lacking generalizability. To address this, we propose a design of a compliant robot fish, ScaFi, which requires only a single motor and can scale from several tens of centimeters to a few meters in body length. The tail design, inspired by subcarangiform swimmers, consists of a rigid front-end and a compliant tail with fiberglass rods and a 'cross-over' tendon routing. By applying a scaling law derived from tail deflection, we can ensure a consistent kinematic behavior across scales, allowing the robot to generate a bio-inspired wake regardless of its size. The primary goal of this work is to develop a parametrically length-scalable design for a compliant robotic fish that can be deployed in diverse environmental niches. We demonstrate the scalability of the design in three physical prototypes that span lengths from 50 cm to over 2.5 meters. Particle image velocimetry tests confirm that the motion generates bio-inspired vortex wakes, while swimming experiments and field deployments demonstrate the practical utility of a multi-scale design and its ability to adapt to diverse aquatic conditions. Biological sciences/Ecology Earth and environmental sciences/Ecology Physical sciences/Engineering Physical sciences/Physics Full Text Additional Declarations No competing interests reported. Supplementary Files Scalingfishsupplement.pdf SupplementaryVideo1.mkv SupplementaryVideo2.mp4 SupplementaryVideo3.mp4 SupplementaryVideo4.mp4 SupplementaryVideo5.mp4 Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 07 Dec, 2025 Reviews received at journal 20 Nov, 2025 Reviewers agreed at journal 17 Nov, 2025 Reviews received at journal 26 Oct, 2025 Reviewers agreed at journal 01 Oct, 2025 Reviewers agreed at journal 29 Sep, 2025 Reviewers invited by journal 29 Sep, 2025 Editor assigned by journal 27 Sep, 2025 Submission checks completed at journal 15 Sep, 2025 First submitted to journal 09 Sep, 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. 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