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1. A bio-inspired sand-rolling robot: effect of body shape on sand rolling performance

   Liao, Xingjue; Liu, Wenhao; Wu, Hao; Qian, Feifei (September 2024, IEEE International Conference on Robotics and Automation (ICRA))

   The capability of effectively moving on complex terrains such as sand and gravel can empower our robots to robustly operate in outdoor environments, and assist with critical tasks such as environment monitoring, search-and-rescue, and supply delivery. Inspired by the Mount Lyell salamander’s ability to curl its body into a loop and effectively roll across sand and gravel, in this study we develop a sand-rolling robot and investigate how its locomotion performance is governed by the shape of its body. We experimentally tested three different body shapes: Hexagon, Quadrilateral, and Triangle. We found that Hexagon and Triangle can achieve a faster rolling speed on sand, but also exhibited more frequent failures of getting stuck in sand. Analysis of the interaction between robot and sand revealed the failure mechanism: the deformation of the sand produced a local “sand incline” underneath robot contact segments, increasing the effective region of supporting polygon (ERSP) and preventing the robot from shifting its center of mass (CoM) outside the ERSP to produce sustainable rolling. Based on this mechanism, a highly-simplified model successfully captured the critical body pitch for each rolling shape to produce sustained rolling on sand, and informed design adaptations that mitigated the locomotion failures and improved robot speed by more than 200%. Our results provide insights into how locomotors can utilize different morphological features to achieve robust rolling motion across deformable substrates. 

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2. Rolling Acrobatic Apparatus

   https://doi.org/10.1090/noti2312  

   Segerman, Henry (August 2021, Notices of the American Mathematical Society)

   null (Ed.)
3. Cellular Manipulation Using Rolling Microrobots

   https://doi.org/10.1109/MARSS55884.2022.9870486  

   Rivas, David; Mallick, Sudipta; Sokolich, Max; Das, Sambeeta (July 2022, IEEE)
4. Rolling Helical Microrobots for Cell Patterning

   https://doi.org/10.1109/MARSS58567.2023.10294113  

   Yang, Yanda; Kirmizitas, Fatma Ceren; Sokolich, Max; Valencia, Alejandra; Rivas, David; Karakan, M Çağatay; White, Alice E; Malikopoulos, Andreas A; Das, Sambeeta (October 2023, IEEE)
5. Following the Sand Grains

   https://doi.org/10.3390/jmse10050631  

   FitzGerald, Duncan M.; Hughes, Zoe J.; Staro, Alice; Hein, Christopher J.; Sakib, Md Mohiuddin; Georgiou, Ioannis Y.; Novak, Alyssa (May 2022, Journal of Marine Science and Engineering)

   When longshore transport systems encounter tidal inlets, complex mechanisms are involved in bypassing sand to downdrift barriers. Here, this process is examined at Plum Island Sound and Essex Inlets, Massachusetts, USA. One major finding from this study is that sand is transferred along the coast—especially at tidal inlets—by parcels, in discrete steps, and over decadal-scale periods. The southerly orientation of the main-ebb channel at Plum Island Sound, coupled with the landward migration of bars from the ebb delta to the central portion of the downdrift Castle Neck barrier island, have formed a beach protuberance. During the constructional phase, sand is sequestered at the protuberance and the spit-end of the barrier becomes sediment starved, leading to shoreline retreat and a broadening of the spit platform at the mouth to Essex Bay (downdrift side of Castle Neck). Storm-induced sand transport from erosion of the spit and across the spit platform is washed into Essex Bay, filling channels and enlarging flood deltas. This study illustrates the pathways and processes of sand transfer along the shoreline of a barrier-island/tidal-inlet system and provides an important example of the processes that future hydrodynamic and sediment-transport modeling should strive to replicate. 

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