{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,29]],"date-time":"2026-05-29T11:18:45Z","timestamp":1780053525727,"version":"3.54.0"},"reference-count":60,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2023,5,12]],"date-time":"2023-05-12T00:00:00Z","timestamp":1683849600000},"content-version":"am","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2023,5,12]],"date-time":"2023-05-12T00:00:00Z","timestamp":1683849600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100007297","name":"Office of Naval Research Global","doi-asserted-by":"publisher","award":["N00014-20-1-2373"],"award-info":[{"award-number":["N00014-20-1-2373"]}],"id":[{"id":"10.13039\/100007297","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["advanced.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Advanced Intelligent Systems"],"published-print":{"date-parts":[[2023,8]]},"abstract":"<jats:p>Granular environments, such as sand, are one of the most challenging substrates for robots to move within due to large depth\u2010dependent forces, unpredictable fluid\/solid resistance forces, and limited sensing capabilities. An untethered robot is presented, inspired by biological diggers like sea turtles, which utilize underactuated appendages to enable propulsion and obstacle sensing in granular environments. To guide the robot's design, experiments are conducted on test appendages to identify the morphological and actuation parameters for forward thrust generation. Obstacle sensing is observed in granular media by measuring the increased force on the moving appendage caused by changes in the granular flow around it. These results are integrated into an untethered robot capable of subsurface locomotion in a controlled granular bed like natural, loosely packed sand. The robot achieves subsurface \u201cswimming\u201d at a speed of 1.2\u2009mm\u2009s<jats:sup>\u22121<\/jats:sup>, at a depth of 127\u2009mm, faster than any other reported untethered robot at this depth, while also detecting obstacles during locomotion via force sensors embedded in the appendages. Finally, subsurface robot locomotion in natural sand at the beach is demonstrated, a feat no other robot has accomplished, showcasing how underactuated structures enable movement and sensing in granular environments with limited limb control.<\/jats:p>","DOI":"10.1002\/aisy.202200404","type":"journal-article","created":{"date-parts":[[2023,5,13]],"date-time":"2023-05-13T00:07:05Z","timestamp":1683936425000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":25,"title":["Toward Robotic Sensing and Swimming in Granular Environments using Underactuated Appendages"],"prefix":"10.1002","volume":"5","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2479-7267","authenticated-orcid":false,"given":"Shivam","family":"Chopra","sequence":"first","affiliation":[{"name":"Mechanical and Aerospace Engineering University of California San Diego  9500 Gilman Drive La Jolla CA 92093 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Drago","family":"Vasile","sequence":"additional","affiliation":[{"name":"Mechanical and Aerospace Engineering University of California San Diego  9500 Gilman Drive La Jolla CA 92093 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Saurabh","family":"Jadhav","sequence":"additional","affiliation":[{"name":"Mechanical and Aerospace Engineering University of California San Diego  9500 Gilman Drive La Jolla CA 92093 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael T","family":"Tolley","sequence":"additional","affiliation":[{"name":"Mechanical and Aerospace Engineering University of California San Diego  9500 Gilman Drive La Jolla CA 92093 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9391-2476","authenticated-orcid":false,"given":"Nick","family":"Gravish","sequence":"additional","affiliation":[{"name":"Mechanical and Aerospace Engineering University of California San Diego  9500 Gilman Drive La Jolla CA 92093 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2023,5,12]]},"reference":[{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.1134390"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-fluid-010313-141324"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.1172490"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/aisy.202100195"},{"key":"e_1_2_9_6_1","first-page":"1","author":"Martinez A.","year":"2021","journal-title":"G\u00e9otechnique"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1109\/LRA.2019.2911844"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1109\/ACCESS.2019.2930994"},{"key":"e_1_2_9_9_1","doi-asserted-by":"crossref","unstructured":"B.Liu Y.Ozkan-Aydin D. I.Goldman F. L.Hammond in2nd IEEE Int. Conf. on Soft Robotics (RoboSoft) IEEE Piscataway NJ 2019pp.828\u2013833.","DOI":"10.1109\/ROBOSOFT.2019.8722821"},{"key":"e_1_2_9_10_1","doi-asserted-by":"crossref","unstructured":"A. A.Calder\u00f3n J. C.Ugalde J. C.Zagal N. O.P\u00e9rez-Arancibia inIEEE Int. Conf. on Robotics and Biomimetics (ROBIO) IEEE Piscataway NJ2016 pp.31\u201338.","DOI":"10.1109\/ROBIO.2016.7866293"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.1229163"},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.1063\/1.4898629"},{"key":"e_1_2_9_13_1","doi-asserted-by":"publisher","DOI":"10.1242\/jeb.32.4.802"},{"key":"e_1_2_9_14_1","doi-asserted-by":"publisher","DOI":"10.1177\/0278364911402406"},{"key":"e_1_2_9_15_1","doi-asserted-by":"crossref","unstructured":"A.Sadeghi A.Tonazzini L.Popova B.Mazzolai inIEEE Int. Conf. on Robotics and Automation.IEEE Piscataway NJ 2013 pp.3457\u20133462.","DOI":"10.1109\/ICRA.2013.6631060"},{"key":"e_1_2_9_16_1","doi-asserted-by":"crossref","unstructured":"N. D.Naclerio C. M.Hubicki Y. O.Aydin D. I.Goldman E. W.Hawkes InIEEE Int. Conf. on Intelligent Robots and Systems.IEEE Piscataway NJ2018pp.5918\u20135923.","DOI":"10.1109\/IROS.2018.8593530"},{"key":"e_1_2_9_17_1","doi-asserted-by":"publisher","DOI":"10.1089\/soro.2016.0080"},{"key":"e_1_2_9_18_1","doi-asserted-by":"publisher","DOI":"10.1039\/C9RA00399A"},{"key":"e_1_2_9_19_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41586-019-1322-0"},{"key":"e_1_2_9_20_1","doi-asserted-by":"publisher","DOI":"10.1007\/s10514-015-9479-3"},{"key":"e_1_2_9_21_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0809095106"},{"key":"e_1_2_9_22_1","first-page":"2245","author":"Bledt G.","year":"2018","journal-title":"IEEE Int. Conf. Intell. Robots Syst."},{"key":"e_1_2_9_23_1","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.aao5619"},{"key":"e_1_2_9_24_1","doi-asserted-by":"publisher","DOI":"10.1109\/LRA.2021.3084877"},{"key":"e_1_2_9_25_1","doi-asserted-by":"publisher","DOI":"10.1163\/016918610X538516"},{"key":"e_1_2_9_26_1","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevE.89.042202"},{"key":"e_1_2_9_27_1","doi-asserted-by":"publisher","DOI":"10.1103\/RevModPhys.68.1259"},{"key":"e_1_2_9_28_1","doi-asserted-by":"publisher","DOI":"10.1007\/978-3-030-71151-1_10"},{"key":"e_1_2_9_29_1","unstructured":"S.Jia V. J.Santos inProc. of the RSS Workshop Tactile Sensing for Manipulation: Hardware Modeling and Learning Vol15 2017."},{"key":"e_1_2_9_30_1","doi-asserted-by":"publisher","DOI":"10.1109\/LRA.2022.3191955"},{"key":"e_1_2_9_31_1","doi-asserted-by":"publisher","DOI":"10.1007\/s11214-020-00772-w"},{"key":"e_1_2_9_32_1","doi-asserted-by":"publisher","DOI":"10.1007\/s42235-019-0027-2"},{"key":"e_1_2_9_33_1","volume-title":"Fins Into Limbs: Evolution, Development, and Transformation","author":"Hamrick M. W.","year":"2007"},{"key":"e_1_2_9_34_1","doi-asserted-by":"crossref","unstructured":"R. D.Maladen P. B.Umbanhowar Y.Ding A.Masse D. I.Goldman inProc. \u2013 IEEE Int. Conf. on Robotics and Automation IEEE Piscataway NJ2011pp.1398\u20131403.","DOI":"10.1109\/ICRA.2011.5980301"},{"key":"e_1_2_9_35_1","doi-asserted-by":"crossref","unstructured":"D.Drotman S.Chopra N.Gravish M. T.Tolley in2022 IEEE 5th Int. Conf. on Soft Robotics (RoboSoft).IEEE Piscataway NJ2022pp.261\u2013266.","DOI":"10.1109\/RoboSoft54090.2022.9762155"},{"key":"e_1_2_9_36_1","doi-asserted-by":"publisher","DOI":"10.1039\/D1SM00130B"},{"key":"e_1_2_9_37_1","doi-asserted-by":"publisher","DOI":"10.1126\/sciadv.abe0631"},{"key":"e_1_2_9_38_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.2214017120"},{"key":"e_1_2_9_39_1","doi-asserted-by":"publisher","DOI":"10.1109\/LRA.2021.3057052"},{"key":"e_1_2_9_40_1","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevLett.106.028001"},{"key":"e_1_2_9_41_1","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevLett.105.128301"},{"key":"e_1_2_9_42_1","first-page":"5","volume":"82","author":"Sigren J.","year":"2014","journal-title":"Shore Beach"},{"key":"e_1_2_9_43_1","doi-asserted-by":"publisher","DOI":"10.1080\/00018730600626065"},{"key":"e_1_2_9_44_1","doi-asserted-by":"publisher","DOI":"10.1088\/1748-3182\/8\/2\/026007"},{"key":"e_1_2_9_45_1","first-page":"1","volume":"2018","author":"Fujii J. A.","year":"2018","journal-title":"PeerJ"},{"key":"e_1_2_9_46_1","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevE.103.032605"},{"key":"e_1_2_9_47_1","author":"Diaz K.","year":"2021","journal-title":"bioRxiv"},{"key":"e_1_2_9_48_1","doi-asserted-by":"publisher","DOI":"10.1063\/1.1571826"},{"key":"e_1_2_9_49_1","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.fl.07.010175.000513"},{"key":"e_1_2_9_50_1","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.abe2922"},{"key":"e_1_2_9_51_1","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-ento-112408-085342"},{"key":"e_1_2_9_52_1","doi-asserted-by":"publisher","DOI":"10.1039\/C7SM00806F"},{"key":"e_1_2_9_53_1","doi-asserted-by":"publisher","DOI":"10.1242\/jeb.103564"},{"key":"e_1_2_9_54_1","unstructured":"S. S.Sharpe Ph.D. Thesis Georgia Institute of Technology 2013."},{"key":"e_1_2_9_55_1","doi-asserted-by":"publisher","DOI":"10.1643\/0045-8511(2003)003[0131:VBITSS]2.0.CO;2"},{"key":"e_1_2_9_56_1","doi-asserted-by":"publisher","DOI":"10.1111\/jfb.13789"},{"key":"e_1_2_9_57_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0308251101"},{"key":"e_1_2_9_58_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0800202105"},{"key":"e_1_2_9_59_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.1141971"},{"key":"e_1_2_9_60_1","first-page":"226","volume":"64","author":"Dickinson W. W.","year":"1994","journal-title":"J. Sediment. Res. A: Sediment. Petrol. Process."},{"key":"e_1_2_9_61_1","doi-asserted-by":"publisher","DOI":"10.1098\/rsif.2010.0678"}],"container-title":["Advanced Intelligent Systems"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/advanced.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/aisy.202200404","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/advanced.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/aisy.202200404","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,7]],"date-time":"2025-10-07T19:59:59Z","timestamp":1759867199000},"score":1,"resource":{"primary":{"URL":"https:\/\/advanced.onlinelibrary.wiley.com\/doi\/10.1002\/aisy.202200404"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,5,12]]},"references-count":60,"journal-issue":{"issue":"8","published-print":{"date-parts":[[2023,8]]}},"alternative-id":["10.1002\/aisy.202200404"],"URL":"https:\/\/doi.org\/10.1002\/aisy.202200404","archive":["Portico"],"relation":{},"ISSN":["2640-4567","2640-4567"],"issn-type":[{"value":"2640-4567","type":"print"},{"value":"2640-4567","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,5,12]]},"assertion":[{"value":"2022-11-19","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2023-05-12","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"2200404"}}