Research ArticleUNDERSEA ROBOTICS

Rotary-actuated folding polyhedrons for midwater investigation of delicate marine organisms

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Science Robotics  18 Jul 2018:
Vol. 3, Issue 20, eaat5276
DOI: 10.1126/scirobotics.aat5276
  • Fig. 1 State-of-the-art midwater sampling tools.

    (A) ROV Ventana outfitted with a rack of D samplers and a suction sampler; the ROV thrusters are used to maneuver D samplers into position. (B and C) Close-up views of the suction sampler and D sampler. (D) RAD sampler mounted on the ROV Ventana via a robotic arm. (E) Magnified schematic view of the RAD sampler in its unfolded configuration. Scale bars, 0.1 m.

  • Fig. 2 RAD sampler design.

    (A) One arm of the RAD sampler with revolute joints shown as dotted lines. A fold is initiated by rotating the central fold link with respect to the central assembly link. (B) Axisymmetric dodecahedron net. Each arm is made by connecting a folding unit with its rotated chiral counterpart. (C) Folding sequence when encapsulating a marine organism.

  • Fig. 3 Details of seal design.

    (A) RAD sampler (left), with close-up view (right) indicating the soft edges that form the light seal. (B) Cross-sectional shape of the gasket with curved cantilever design used to minimize deflection forces and accommodate alignment variance. (C) Inner and outer faces of one of three gasket shapes made (with the same cross section) to cover the RAD sampler panel edges. Scale bars, 15 mm.

  • Fig. 4 Capture sequences of a RAD-equipped deep-sea vehicle operating in the Monterey Bay Canyon.

    (A to D) The RAD enclosing an Oegopsina sp. deep-sea squid at 563-m depth. (E to H) RAD sampler encompassing the scyphomedusa Stellamedusa ventana at 644 m. (I to L) RAD interacting with a Stigmatoteuthis sp. deep-sea squid at 645-m depth (video of various collections is provided in the Supplementary Materials). Scale bars, 0.05 m.

  • Fig. 5 Folding unit based on the plane symmetric Bricard linkage.

    (A) Six links are connected to each other by revolute joints. The linkage is separated into two layers: a folding linkage layer and an assembly linkage layer. The folding linkage layer consists of link 1 and link 6. The assembly linkage layer is on top of the folding linkage layer and comprises the remaining four links. (B) As link 6 rotates about link 5, the assembly layer folds link 1 with respect to link 6. (C) By joining a folding unit with its chiral (prime symbol denotes links of the chiral folding unit) by connecting link 1 to link 6′ and link 2 to link 5′, rotation of link 1 about link 6 propagates down the chain.

  • Fig. 6 Kinematic and mechanical advantage trade-off study.

    As initial offset angle (θs) of the folding unit increased, bidirectional folding became more symmetric. When normalized distance between the assembly linkage layer and the folding linkage layer (Embedded Image) increased, the corresponding minimum mechanical advantage increased.

Supplementary Materials

  • robotics.sciencemag.org/cgi/content/full/3/20/eaat5276/DC1

    Fig. S1. Modified Denavit-Hartenberg convention.

    Fig. S2. Visual description of plane symmetric Bricard linkage Denavit-Hartenberg parameters in table S1.

    Fig. S3. Comparison of measured folding angle θ1 with theory.

    Table S1. Modified Denavit-Hartenberg parameters of folding unit.

    Table S2. RAD morphological parameters.

    Movie S1. RAD sampler capture sequences.

    Movie S2. Folding dodecahedron at the mesoscale.

    Motion capture data: Dataset_Segmented_fold.mat

    Code: compare_device_to_theory.py and calculate_qF1.py

    Estimate of hydrodynamic drag and buoyancy forces: force_estimate.xlsx

    Reference (47)

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. Modified Denavit-Hartenberg convention.
    • Fig. S2. Visual description of plane symmetric Bricard linkage Denavit-Hartenberg parameters in table S1.
    • Fig. S3. Comparison of measured folding angle θ1 with theory.
    • Table S1. Modified Denavit-Hartenberg parameters of folding unit.
    • Table S2. RAD morphological parameters.
    • Legends for movies S1 and S2
    • Legend for motion capture data
    • Legend for code
    • Legend for estimate of hydrodynamic drag and buoyancy forces
    • Reference (47)

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    Other Supplementary Material for this manuscript includes the following:

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