Exploring the inner workings of the clove hitch knot

Sano, Tomohiko G.; Johanns, Paul; Grandgeorge, Paul; Baek, Changyeob; Reis, Pedro

doi:10.1016/j.eml.2022.101788

Cited by 7 publications

(5 citation statements)

References 18 publications

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“…For example, untangling with small R requires forming small, energetically costly loops. Similarly, untangling by means of the linear trajectories corresponding to large R gaits requires braids to be unraveled by pulling rather than unweaving, a motion associated with a higher friction penalty (7,23). Furthermore, blackworm dynamics are necessarily multifunctional, and topological requirements must be balanced with the need to support efficient, biologically feasible locomotion (14,32,35).…”

Section: Discussionmentioning

confidence: 99%

“…Knots determine the robustness and function of filamentous matter across a wide range of scales, from the intertwined yarns in ropes and fabrics ( 1 ) to the tangled polymers in rubbers ( 2 , 3 ) and gels ( 4 ). The extraordinary stability of knotted materials arises from the intricate interplay of mutual mechanical obstruction ( 5 ) and contact friction ( 6 ) between adjacent filaments ( 7 , 8 ). As any fisherman or long-haired creature can confirm, creating knotty structures ( 9 ) is not difficult: When soft elastic fibers are randomly mixed together ( 10 ), they naturally tend to form a highly disordered tangled state ( 11 , 12 ).…”

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confidence: 99%

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Ultrafast reversible self-assembly of living tangled matter

Patil

Tuazon

Kaufman

et al. 2023

Science

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Tangled active filaments are ubiquitous in nature, from chromosomal DNA and cilia carpets to root networks and worm collectives. How activity and elasticity facilitate collective topological transformations in living tangled matter is not well understood. We studied California blackworms ( Lumbriculus variegatus ), which slowly form tangles in minutes but can untangle in milliseconds. Combining ultrasound imaging, theoretical analysis, and simulations, we developed and validated a mechanistic model that explains how the kinematics of individual active filaments determines their emergent collective topological dynamics. The model reveals that resonantly alternating helical waves enable both tangle formation and ultrafast untangling. By identifying generic dynamical principles of topological self-transformations, our results can provide guidance for designing classes of topologically tunable active materials.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Ultrafast reversible self-assembly of living tangled matter

Patil

Tuazon

Kaufman

et al. 2023

Science

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“…Next, by applying a sequence of prescribed displacements and rotations to control the nodes located at each end and the central coordinate of filament (1), two half-hitches were formed around filament (2), corresponding to the sliding granny knot. A similar tying protocol was introduced in ( 52 ), in the context of the clove hitch knot. Both knots share the same topology but differentiate by their application: A clove hitch knot attaches a rod to a rigid cylinder (typically larger than the rod diameter), whereas the sliding granny knot is a binding knot, connecting two rods (of equal diameters).…”

Section: Methodsmentioning

confidence: 99%

“…Both knots share the same topology but differentiate by their application: A clove hitch knot attaches a rod to a rigid cylinder (typically larger than the rod diameter), whereas the sliding granny knot is a binding knot, connecting two rods (of equal diameters). We made use of the tying algorithm used in ( 52 ), with minor adaptations to tie the S || S knots.…”

Section: Methodsmentioning

confidence: 99%

The strength of surgical knots involves a critical interplay between friction and elastoplasticity

Johanns,

Baek,

Grandgeorge

et al. 2023

Sci. Adv.

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Knots are the weakest link in surgical sutures, serving as mechanical ligatures between filaments. Exceeding their safe operational limits can cause fatal complications. The empirical nature of present guidelines calls for a predictive understanding of the mechanisms underlying knot strength. We identify the primary ingredients dictating the mechanics of surgical sliding knots, highlighting the previously overlooked but critical effect of plasticity and its interplay with friction. The characterization of surgeon-tied knots reveals the relevant ranges of tightness and geometric features. Using model experiments coupled with finite element simulations, we uncover a robust master curve for the target knot strength versus the tying pre-tension, number of throws, and frictional properties. These findings could find applications in the training of surgeons and robotic-assisted surgical devices.

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“…However, because of their flexibility, DLOs are often prone to complex tangling, which complicates manipulation. In addition, the complicated structures made by DLOs usually have unique topology-induced mechanical properties [9]- [13] and are, therefore, used to tie knots for sailing, fishing, climbing, and various other engineering applications. Given all of the above, a robust, efficient, and accurate perception algorithm for DLOs is crucial to both deformable material manipulation and soft robotics.…”

Section: Introductionmentioning

confidence: 99%

mBEST: Realtime Deformable Linear Object Detection Through Minimal Bending Energy Skeleton Pixel Traversals

Choi¹,

Tong²,

Park³

et al. 2023

Preprint

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Robotic manipulation of deformable materials is a challenging task that often requires realtime visual feedback. This is especially true for deformable linear objects (DLOs) or "rods", whose slender and flexible structures make proper tracking and detection nontrivial. To address this challenge, we present mBEST, a robust algorithm for the realtime detection of DLOs that is capable of producing an ordered pixel sequence of each DLO's centerline along with segmentation masks. Our algorithm obtains a binary mask of the DLOs and then thins it to produce a skeleton pixel representation. After refining the skeleton to ensure topological correctness, the pixels are traversed to generate paths along each unique DLO. At the core of our algorithm, we postulate that intersections can be robustly handled by choosing the combination of paths that minimizes the cumulative bending energy of the DLO(s). We show that this simple and intuitive formulation outperforms the state-of-theart methods for detecting DLOs with large numbers of sporadic crossings and curvatures with high variance. Furthermore, our method achieves a significant performance improvement of approximately 40 FPS compared to the 15 FPS of prior algorithms, which enables realtime applications.

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Exploring the inner workings of the clove hitch knot

Cited by 7 publications

References 18 publications

Ultrafast reversible self-assembly of living tangled matter

Ultrafast reversible self-assembly of living tangled matter

The strength of surgical knots involves a critical interplay between friction and elastoplasticity

mBEST: Realtime Deformable Linear Object Detection Through Minimal Bending Energy Skeleton Pixel Traversals

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