Mitigating memory effects during undulatory locomotion on hysteretic materials

Schiebel, Perrin; Astley, Henry C.; Rieser, Jennifer M.; Agarwal, Shashank; Hubicki, Christian; Hubbard, Alexander; Diaz, Kelimar; Mendelson, Joseph R.; Kamrin, Ken; Goldman, Daniel I.

doi:10.7554/elife.51412

Cited by 30 publications

(31 citation statements)

References 55 publications

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“…As speed increases, we find that continuum predictions match the data well at three different depths, for λ = 1.1. Incidentally, the same value of λ also matches the rate dependence observed in the Schiebel et al ( 31 ) experiments for horizontally driven intruders at the free surface.…”

Section: Resultssupporting

confidence: 85%

“…A number of previous studies ( 24 – 30 ) have modeled the rate dependence of intrusion force similarly, by adding a term proportional to normal speed squared to a depth-dependent “static” term. Examination of experimental data in ( 26 , 31 ) agrees with a rate-dependent force addition of the form

in simple vertical and horizontal intrusions (see figs. S2 and S3 and movies S1 and S2), where λ is a O (1) scalar fitting constant that accounts for certain approximations in the analysis (see section S1).…”

Section: Resultssupporting

confidence: 61%

“…6A show the observed drag force variations with the drag speed. Experimental studies by Schiebel et al ( 31 ) found the variation of drag forces in such a scenario to follow the trend K ∣ z ∣+ λρ Av 2 (see fig. S1), where K and λ are constants, ∣ z ∣ is the depth of the plate below the free surface, ρ is the effective granular density, A is plate area, and v is horizontal plate velocity.…”

Section: Resultsmentioning

confidence: 86%

“…Large variations in the GM’s stress, momentum, and volume fraction in different regions often result in complicated system dynamics exhibiting multiphase characteristics ( 1 , 2 ). The flow complexity also makes interpreting resistive forces nontrivial if the intruder reinteracts with the deformed region ( 3 , 4 ), as the GM now has a new inhomogeneous state near the surface. The coupled system of intruder and media becomes challenging to model; the media’s inhomogeneous flow and multiphase nature often restrict modeling to discrete particle methods that track the individual grains, unlike fluids that can be solved with the Navier-Stokes equations.…”

Section: Introductionmentioning

confidence: 99%

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Surprising simplicity in the modeling of dynamic granular intrusion

et al. 2021

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Granular intrusions, such as dynamic impact or wheel locomotion, are complex multiphase phenomena where the grains exhibit solid-like and fluid-like characteristics together with an ejected gas-like phase. Despite decades of modeling efforts, a unified description of the physics in such intrusions is as yet unknown. Here, we show that a continuum model based on the simple notions of frictional flow and tension-free separation describes complex granular intrusions near free surfaces. This model captures dynamics in a variety of experiments including wheel locomotion, plate intrusions, and running legged robots. The model reveals that one static and two dynamic effects primarily give rise to intrusion forces in such scenarios. We merge these effects into a further reduced-order technique (dynamic resistive force theory) for rapid modeling of granular locomotion of arbitrarily shaped intruders. The continuum-motivated strategy we propose for identifying physical mechanisms and corresponding reduced-order relations has potential use for a variety of other materials.

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Section: Resultssupporting

confidence: 85%

Section: Resultssupporting

confidence: 61%

Section: Resultsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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Surprising simplicity in the modeling of dynamic granular intrusion

et al. 2021

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“…While our model captures broad trends observed in nature, interesting deviations exist. For example, the shovel-nosed snake Chionactis occipitalis is well-known to slither on sand 35 . This snake exhibits anisotropic skin texture 29 , utilizes a specialized waveform 35 , and belongs to the colubrid family whose members are characterized by more slender bodies relative to sidewinding specialists 33 .…”

Section: Resultsmentioning

confidence: 99%

Friction modulation in limbless, three-dimensional gaits and heterogeneous terrains

et al. 2021

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Motivated by a possible convergence of terrestrial limbless locomotion strategies ultimately determined by interfacial effects, we show how both 3D gait alterations and locomotory adaptations to heterogeneous terrains can be understood through the lens of local friction modulation. Via an effective-friction modeling approach, compounded by 3D simulations, the emergence and disappearance of a range of locomotory behaviors observed in nature is systematically explained in relation to inhabited environments. Our approach also simplifies the treatment of terrain heterogeneity, whereby even solid obstacles may be seen as high friction regions, which we confirm against experiments of snakes ‘diffracting’ while traversing rows of posts, similar to optical waves. We further this optic analogy by illustrating snake refraction, reflection and lens focusing. We use these insights to engineer surface friction patterns and demonstrate passive snake navigation in complex topographies. Overall, our study outlines a unified view that connects active and passive 3D mechanics with heterogeneous interfacial effects to explain a broad set of biological observations, and potentially inspire engineering design.

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The Need for and Feasibility of Alternative Ground Robots to Traverse Sandy and Rocky Extraterrestrial Terrain

Lewis

2022

Advanced Intelligent Systems

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Robotic spacecraft have vastly increased our ability to explore extraterrestrial surfaces. [1][2][3][4][5][6] Mobile robots have enabled exploration beyond a static landing site and allowed discovery-driven investigations on both the Moon and Mars. They have helped us understand the geologic history and surface environments of both bodies, conducting scientific campaigns analogous in many ways to that of a terrestrial field geologist.Since the first deployments on the Moon nearly half a century ago, mobile planetary exploration robots have progressively increased in their capabilities and enabled us to access a range of scientific targets on extraterrestrial surfaces. [2][3][4][5] To date, all of the successfully landed lunar and Martian mobile exploration robots, as well as the majority of those being developed, have adopted a conventional wheeled rover platform with a variety of architectures. [5,7] This is not surprising because one of the highest priority considerations for space applications is to maximize mechanical reliability, where wheeled platforms have excelled. [2,3,7,8] These missions have been hugely successful, often exceeding mission design lifetime and traverse distance. The 6-wheel Mars Exploration Rover Opportunity currently holds the planetary rover distance record, driving over 45 km across Meridiani Planum. [9] Similarly, the Soviet Union's 8-wheel Lunokhod 2 rover traversed 39 km across the surface of the Moon in 1973. [10] The recent 6-wheel Chinese Yutu and Yutu-2 lunar rovers have travelled hundreds of meters on the surface of the Moon. [11] Although these rovers have had an impressive track record exploring both the Moon and Mars, their missions have revealed significant limitations faced by wheel-based mobility systems, which hinder scientific exploration. For example, the Spirit Mars Exploration Rover ultimately reached the end of its mission due to a low power state after becoming embedded in a patch of loose soil at a location known as "Troy." The ferric sulfate dominated soil at this site had very low cohesion, thus being mechanically weak, and extended to a depth comparable to the wheel radius. [12] Unfortunately, this deposit was hidden beneath a weakly indurated soil crust, rendering the hazard hidden until the rover was already embedded. [9] The challenge of extricating Spirit was made more difficult due to the failure of one of its six wheels earlier in the mission, requiring modified driving strategies. [12] The Opportunity rover had similar challenges navigating ubiquitous large aeolian ripples in Meridiani Planum. In particular, it was stuck for an extended time embedded in the loose sand of the "Purgatory" ripple [13] (Figure 1A).More recently, the Curiosity Mars rover has incurred significant wheel damage along its traverse due to angular rocks protruding from the surface, which punctured the thin aluminum

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Mitigating memory effects during undulatory locomotion on hysteretic materials

Cited by 30 publications

References 55 publications

Surprising simplicity in the modeling of dynamic granular intrusion

Surprising simplicity in the modeling of dynamic granular intrusion

Friction modulation in limbless, three-dimensional gaits and heterogeneous terrains

The Need for and Feasibility of Alternative Ground Robots to Traverse Sandy and Rocky Extraterrestrial Terrain

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