This ‘Fossil Robot’ will teach us about locomotion
450M-year-old organism comes back to life in robot form
Source: Carnergie Mellon
To understand fundamental principles of locomotion, the research group from Canergie Mellon developed a biomimetic soft robot inspired on the echinoderms—pleurocystitids. They show that these Paleozoic echinoderms were likely able to move over the sea bottom by means of a muscular stem that pushed the animal forward (anteriorly). We also demonstrate that wide, sweeping gaits could have been the most effective for these echinoderms and that increasing stem length might have significantly increased velocity with minimal additional energy cost. ‘The overall approach followed here, which we call “Paleobionics,” is a nascent but rapidly developing research agenda in which robots are designed based on extinct organisms to generate insights in engineering and evolution’, according to the research group.
“Rhombot” rhombiferan robot based on morphology of the pleurocystitid. The stem is composed of a soft elastomer embedded with shape memory alloy (SMA) muscle wire for flexural actuation. The soft robot stem is designed based on 3D scans from pleurocystitid fossils.
Pleurocystites is an extinct blastozoan echinoderm genus belonging to Pleurocystidae known from the Ordovician to Devonian Periods and which are thought to have been mobile in epibenthic conditions, i.e., on the seabed and/or sediment surface. These echinoderms were among the first capable of locomotion with the aid of a muscular stem. This innovation, combined with development of two feeding appendages (brachioles), thecal flattening, and enlargement of the periproct, likely gave them an advantage at the water-sediment interface (detritivorous) when exploring for food rather than alternative methods such as suspension feeding (suspensivores). However, their mode of locomotion remains uncertain, and understanding how pleurocystitids moved is especially challenging due to the lack of a modern analogue. Wagging, sweeping, sculling, or sinusoidal movements of the stem, and even swimming like a tadpole have been suggested by several researchers, but these remain untested (22–24). To explore these questions, the team developed an experimental and computational pipeline to understand locomotion without relying on reference to an extant species or fossil trackways.
Using this simulation and robot pipeline, the team showed that pleurocystitids likely moved forward (anteriorly, i.e., brachiole-first) due to large performance advantages over stem-first (dragging the theca behind) locomotion. Second, they used the simulation and experimental robot testbed to study how variations in the length of the stem and the parameters of the gait will affect speed and efficiency. Based on the fossil evidence that pleurocystitids developed longer stems through their ontogeny and possibly also in evolutionary history they hypothesized that longer stems will result in more effective locomotion.
Find the full research here: https://www.pnas.org/doi/10.1073/pnas.2306580120
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