{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T02:47:06Z","timestamp":1779245226213,"version":"3.51.4"},"reference-count":72,"publisher":"SAGE Publications","issue":"12-14","license":[{"start":{"date-parts":[[2021,6,16]],"date-time":"2021-06-16T00:00:00Z","timestamp":1623801600000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["The International Journal of Robotics Research"],"published-print":{"date-parts":[[2021,12]]},"abstract":"<jats:p>Untethered small-scale soft robots have promising applications in minimally invasive surgery, targeted drug delivery, and bioengineering applications as they can directly and non-invasively access confined and hard-to-reach spaces in the human body. For such potential biomedical applications, the adaptivity of the robot control is essential to ensure the continuity of the operations, as task environment conditions show dynamic variations that can alter the robot\u2019s motion and task performance. The applicability of the conventional modeling and control methods is further limited for soft robots at the small-scale owing to their kinematics with virtually infinite degrees of freedom, inherent stochastic variability during fabrication, and changing dynamics during real-world interactions. To address the controller adaptation challenge to dynamically changing task environments, we propose using a probabilistic learning approach for a millimeter-scale magnetic walking soft robot using Bayesian optimization (BO) and Gaussian processes (GPs). Our approach provides a data-efficient learning scheme by finding the gait controller parameters while optimizing the stride length of the walking soft millirobot using a small number of physical experiments. To demonstrate the controller adaptation, we test the walking gait of the robot in task environments with different surface adhesion and roughness, and medium viscosity, which aims to represent the possible conditions for future robotic tasks inside the human body. We further utilize the transfer of the learned GP parameters among different task spaces and robots and compare their efficacy on the improvement of data-efficient controller learning.<\/jats:p>","DOI":"10.1177\/02783649211021869","type":"journal-article","created":{"date-parts":[[2021,6,16]],"date-time":"2021-06-16T04:17:03Z","timestamp":1623817023000},"page":"1331-1351","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":29,"title":["Task space adaptation via the learning of gait controllers of magnetic soft millirobots"],"prefix":"10.1177","volume":"40","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6177-8372","authenticated-orcid":false,"given":"Sinan O.","family":"Demir","sequence":"first","affiliation":[{"name":"Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany"},{"name":"Stuttgart Center for Simulation Science (SC SimTech), University of Stuttgart, Stuttgart, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7788-6124","authenticated-orcid":false,"given":"Utku","family":"Culha","sequence":"additional","affiliation":[{"name":"Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1241-0800","authenticated-orcid":false,"given":"Alp C.","family":"Karacakol","sequence":"additional","affiliation":[{"name":"Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany"},{"name":"Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Abdon","family":"Pena-Francesch","sequence":"additional","affiliation":[{"name":"Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany"},{"name":"Department of Materials Science and Engineering, Robotics Institute, University of Michigan, Ann Arbor, MI, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sebastian","family":"Trimpe","sequence":"additional","affiliation":[{"name":"Institute for Data Science in Mechanical Engineering, RWTH Aachen University, Aachen, Germany"},{"name":"Intelligent Control Systems Group, Max Planck Institute for Intelligent Systems, Stuttgart, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8249-3854","authenticated-orcid":false,"given":"Metin","family":"Sitti","sequence":"additional","affiliation":[{"name":"Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"179","published-online":{"date-parts":[[2021,6,16]]},"reference":[{"key":"bibr1-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1126\/sciadv.abc6414"},{"key":"bibr2-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1177\/027836498400300205"},{"key":"bibr3-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1109\/RoboSoft48309.2020.9116011"},{"key":"bibr4-02783649211021869","author":"Brochu E","year":"2010","journal-title":"Preprint arXiv:1612.06830 [cs\/LG]"},{"key":"bibr5-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1007\/s10472-015-9463-9"},{"key":"bibr6-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1098\/rsif.2017.0101"},{"key":"bibr7-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1109\/TRO.2019.2958211"},{"key":"bibr8-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1016\/j.neucom.2017.10.028"},{"key":"bibr9-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0192052"},{"key":"bibr10-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1002\/aisy.201900171"},{"key":"bibr11-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1038\/s41578-018-0022-y"},{"key":"bibr12-02783649211021869","doi-asserted-by":"publisher","DOI":"10.15607\/RSS.2020.XVI.070"},{"key":"bibr13-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1038\/nature14422"},{"key":"bibr14-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1109\/IJCNN.2017.7966379"},{"key":"bibr15-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1109\/LRA.2020.2967269"},{"key":"bibr16-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1109\/ICRA.2017.7989250"},{"key":"bibr17-02783649211021869","volume":"24","author":"Duvenaud DK","year":"2011","journal-title":"Advances in Neural Information Processing Systems"},{"key":"bibr18-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1038\/nature14541"},{"key":"bibr19-02783649211021869","doi-asserted-by":"publisher","DOI":"10.1109\/TRO.2018.2861900"},{"key":"bibr20-02783649211021869","unstructured":"GPy (2012) GPy: A Gaussian process framework in Python. 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