Research ArticleSOFT ROBOTS

Bioinspired dual-stiffness origami

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Science Robotics  25 Jul 2018:
Vol. 3, Issue 20, eaau0275
DOI: 10.1126/scirobotics.aau0275
  • Fig. 1 Bioinspired dual-stiffness origami.

    (A) Pictures of a Brachythemis contaminata and of its hindwing nodus. Blue, green, and red indicate the presence of resilin, less-sclerotized cuticle, and highly sclerotized cuticle, respectively [images adapted from (29)]. (B) Structure of the bioinspired dual-stiffness origami consisting of prestretched elastomeric membranes, akin to resilin joints of insect wings, sandwiched between rigid tiles, akin to cuticles of insect wings. (C) Young’s moduli of the elastomeric membrane and the rigid tiles are the same as those of resilin and cuticle. (D) The rigid plate and the adhesive foil are bonded together into a single composite structure. (E) The composite is laser-machined to engrave the folding pattern (here, two transversal folds) and to remove the adhesive foil along the folding pattern. (F) Two composite structures are bonded on a prestretched elastomer membrane.

  • Fig. 2 Mechanical behavior.

    (A) The compliant origami consists of three layers: a prestretched elastomer membrane bonded between two outer tiles of rigid material. L is the length of the membrane around the fold that is not bonded to the rigid plate and, hence, is free to deform when the origami is stretched. (B) Under axial load F, the fold stretches only when the load exceeds a threshold indicated by the horizontal dashed line. (C) When folded with the bending angle β, the origami undergoes deflection upon exceeding the threshold of the moment M indicated by the horizontal dashed line. (D) The model predicts an increase in the transition threshold when the prestretch of the silicone membrane is increased. (E) The model predicts a decrease in the stiffness of the origami structure when the length L is increased.

  • Fig. 3 Quadcopter equipped with dual-stiffness origami arms.

    (A) Three-dimensional model of the robot with a partial section highlighting the magnets that constrain the apex angle of the arm. The robot weighs 30 g and has a size of 160 mm by 160 mm by 30 mm when deployed and a size of 60 mm by 60 mm by 30 mm when folded. (B) The three phases of the arm behavior under flexural load. (C) Bending force F, (D) opening moment Mα, and (E) maximum stress σ in the silicone membrane as a function of the bending angle β. (F) Experimental data related to arm fatigue, force F2 corresponding to a 2° deflection of the arm as a function of the number of cycles. The data summarize the results of fatigue tests on three arm samples. Error bars indicate SD.

  • Fig. 4 Collision resilience and foldability of the origami drone.

    (A) Snapshots of a collision: The arms buckle and then go back to the initial flight configuration. (B) Snapshots of the deployment process: Initially, the arms are wrapped around the main frame and then self-deploy in the air using the energy stored in the elastomeric joints.

  • Fig. 5 Dual-stiffness origami gripper.

    (A) The original Oriceps (18) crease pattern was modified with two additional folds indicated by the red dashed lines. (B) The grasping motion of the compliant origami gripper (i.e., the bending angle β) is activated by folding the two input tiles highlighted in green with the angle α. (C) Experimental measurement of the grasping force F as a function of the input angle α. When the origami gripper grasps an object, the grasping force rapidly grows until a threshold is reached, as indicated by the horizontal dashed line, when the structure undergoes buckling along the compliant fold, hence avoiding overload of the grasped object. (D) The origami gripper in the rigid configuration firmly holding an object. (E) The origami gripper in the soft configuration holding an object without overloading it.

Supplementary Materials

  • robotics.sciencemag.org/cgi/content/full/3/20/eaau0275/DC1

    Supplementary Text

    Fig. S1. Folding behavior of the dual-stiffness origami.

    Fig. S2. Bending behavior of the dual-stiffness origami arm.

    Table S1. Design parameters of the experimental sample.

    Movie S1. Manufacturing process.

    Movie S2. Crash-resilient and self-deployable quadcopter.

    Movie S3. Compliant origami gripper.

    References (41, 42)

  • Supplementary Materials

    The PDF file includes:

    • Supplementary Text
    • Fig. S1. Folding behavior of the dual-stiffness origami.
    • Fig. S2. Bending behavior of the dual-stiffness origami arm.
    • Table S1. Design parameters of the experimental sample.
    • References (41, 42)

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Manufacturing process.
    • Movie S2 (.mp4 format). Crash-resilient and self-deployable quadcopter.
    • Movie S3 (.mp4 format). Compliant origami gripper.

    Files in this Data Supplement:

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