Researchers Use 3D Printed End Plates and Paper Origami Mechanisms to Create Flexible, Inching Robots

A team of students and professors from the University of Illinois at Urbana-Champaign have been working on innovative research that illustrates how they used bio-inspired design and origami structures to make small, crawling robots. The research team is with the university’s Department of Mechanical Science and Engineering (MechSE). We’ve seen origami, 3D printing, and robotics combined before, but the MechSE team’s robots are much smaller, and inspired by a common theme in creatures with flexible bodies, like Venus Flytraps, earthworms, and uni-flagellated bacteria that swim through liquid, that rapidly snap their bodies to move, which saves energy while also allowing them to move quickly.

Assistant professors Aimy Wissa and Sameh Tawfick led the team, together with graduate student Alexander Pagano and undergraduates Tongxi Yan and Brian Chien. They built and actuated mechanisms and machines, using the principles of origami folding, that could potentially be integrated with inexpensive, small robots or “deployable adaptive structures.”

The team published its research in an invited paper, titled “A crawling robot driven by multi-stable origami,” in Smart Materials and Structures.

Wissa explained, “This paper presents the design of a bio-inspired crawling robot. The robot uses origami building blocks to mimic the gait and metameric properties of earthworms and directional material design to mimic the function of the setae on earthworms that prevents backward slipping.”

The team created two origami-inspired robots: the 51 mm wide Poly, and the untethered Peri, 106 mm wide and powered by batteries. They used a laser cutter to cut paper for the folding origami mechanisms that allow the robots to inch along, and 3D printed the small, clear faceplates for the ends of the two robots. While we have seen 3D printing and origami combined in order to make self-folding implants, the researchers have to fold the origami for this project by hand.

For the project, the researchers investigated the Kresling crease origami pattern. This pattern has a polygonal base and a chiral tower, and, similar to how a screw works, combines its contraction and expansion with both rotational and longitudinal motion.

The abstract explains, “We design the origami to have multi-stable structural equilibria which can be tuned by changing the folding CP. Kinematic analysis of these structures based on rigid-plates and hinges at fold lines precludes the shape transformation associated with the bistability of the physical models. To capture the kinematics of the bi-stable origami, the panels’ deformation behavior is modeled utilizing principles of virtual folds. Virtual folds approximate material bending by hinged, rigid panels, which facilitates the development of a kinematic solution via rigid-plate rotation analysis. As such, the kinetics and stability of folded structures are investigated by assigning suitable torsional spring constants to the fold lines. The results presented demonstrate the effect of fold-pattern geometries on the snapping behavior of the bi-stable origami structure based on the Kresling pattern. The crawling robot is presented as a case study for the use of this origami structure to mimic crawling locomotion.”

Buckling instabilities were utilized to get the robots to achieve a large-stroke snapping motion. Two of the buckling origami towers, placed inside a bellow made out of paper, made up the skeleton of the robot, and the 3D printed end plates connected everything together. The researchers used DC motors to actuate the robots’ movement in quick expansions and contractions; this allowed the robots to inch forward in a “crawling gait,” and also turn in either direction.

The team wrote in the paper, “The ability to produce a functional and geometrically complex 3D mechanical system from a flat sheet introduces exciting opportunities in the field of robotics for remote, autonomously deployable systems or low cost integrated locomotion.”

According to MechSE, the research team’s mathematical analysis could be the very first to make use of virtual folds to analyze panel bending in Kresling origami towers that snap.

“The work presented in this paper leverages the team’s expertise in the design of architectured materials and bio-inspired robotics. We plan to continue to build on our findings to design, model, and test bio-inspired modular robots capable of multiple modes of locomotion,” said Wissa.

The innovative design could also potentially be used in active structures, booms, and manipulations. Discuss in the Origami Robot forum at 3DPB.com.

[Images: MechSE]