Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard

Maladen, Ryan D.; Ding, Yanheng; Li, Chen; Goldman, Daniel I.

doi:10.1126/science.1172490

Cited by 362 publications

(508 citation statements)

References 26 publications

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“…These studies should help to a better understanding of the drag force with depth in the case of the vertical motion under gravity [36,37] and the direction of the motion in the penetration-extraction problem [38,39] in order to be extended for the understanding of the animal locomotion in sand [40].…”

Section: Discussionmentioning

confidence: 99%

Local rheological measurements in the granular flow around an intruder

et al. 2016

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The rheological properties of granular matter within a two-dimensional flow around a moving disk is investigated experimentally. Using a combination of photoelastic and standard tessellation techniques, the strain and stress tensors are estimated at the grain scale in the time-averaged flow field around a large disk pulled at constant velocity in an assembly of smaller disks. On the one hand, one observes inhomogeneous shear rate and strongly localized shear stress and pressure fields. On the other hand, a significant dilation rate, which has the same magnitude as the shear strain rate, is reported. Significant deviations are observed with local rheology that justify the need of searching for a non-local rheology.

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Section: Discussionmentioning

confidence: 99%

Local rheological measurements in the granular flow around an intruder

et al. 2016

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“…[http://dx.doi.org/10.1063/1.4979998] Ingenious mobility strategies have been evolved in animals [1][2][3][4][5] and plant roots 6,7 in a granular environment such as soil, where mobility is significantly reduced by intergranular resistance. Some Erodium and Pelargonium species, flowering plants belonging to a genus of the family Geraniaceae, produce seeds with an appendage that is used for the seed dispersal and burial.…”

mentioning

confidence: 99%

Reduction of granular drag inspired by self-burrowing rotary seeds

et al. 2017

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We present quantitative measurements and mat hematical analysis of the granular drag reduction by rotation, as motivated by the digging of Erodium and Pelargonium seeds. The seeds create a motion to dig into soil before germination using their moisture-responsive awns, which are originally helical shaped but reversibly deform to a linear configuration in a humid environment. We show that the rotation greatly lowers the resistance of soil against penetration because grain rearrangements near the intruder change the force chain network. We find a general correlation for the drag reduction by relative slip, leading to a mathematical model for the granular drag of a rotating intruder. In addition to shedding light on the mechanics of a rotating body in granular media, this work can guide us to design robots working in granular media with enhanced maneuverability.

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“…We used our robot simulation to test whether a device with a finite number of segments (7) could advance using a simple open loop (traveling wave sinusoid) control scheme and calculated the motor torque requirements for the robot. We then built and tested a prototype of the device to validate the biological observations and predictions from the RFT [1] and simulations that limbless body undulations were sufficient to propel the robot forward. Our findings show that the device can swim, and that it translates faster by increasing its oscillation frequency just as the sandfish does.…”

Section: Discussionmentioning

confidence: 99%

“…Previously, Maladen et al [1] obtained these forces empirically by dragging a rod (representative segment) through the media the animal was tested in. With these forces as input and by propagating a sinusoidal traveling wave along the body, the RFT shows that translational motion within granular media without limb use is possible.…”

Section: B Resistive Force Theory For Granular Mediamentioning

confidence: 99%

Robotics: Science and Systems VI

2010

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Abstract-Previous study of a sand-swimming lizard, the sandfish, Scincus scincus, revealed that the animal swims within granular media at speeds up to 0.4 body-lengths/cycle using body undulation (approximately a single period sinusoidal traveling wave) without limb use [1]. Inspired by this biological experiment and challenged by the absence of robotic devices with comparable subterranean locomotor abilities, we developed a numerical simulation of a robot swimming in a granular medium (modeled using a multi-particle discrete element method simulation) to guide the design of a physical sand-swimming device built with off-the-shelf servo motors. Both in simulation and experiment the robot swims limblessly subsurface and, like the animal, increases its speed by increasing its oscillation frequency. It was able to achieve speeds of up to 0.3 body-lengths/cycle. The performance of the robot measured in terms of its wave efficiency, the ratio of its forward speed to wave speed, was 0.34±0.02, within 8 % of the simulation prediction. Our work provides a validated simulation tool and a functional initial design for the development of robots that can move within yielding terrestrial substrates.

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Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard

Cited by 362 publications

References 26 publications

Local rheological measurements in the granular flow around an intruder

Local rheological measurements in the granular flow around an intruder

Reduction of granular drag inspired by self-burrowing rotary seeds

Robotics: Science and Systems VI

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