Design and Fabrication of Origami Elements for use in a Folding Robot Structure

The aim of the research is to investigate the methodology of the design and fabrication of folding robots that depend on the origami structures. The use of origami structures as a foundation to build reconfigurable and morphing robots that could assist in search and rescue (SAR) tasks are investigated. The design of the origami folding structures divided into three stages: consideration of the geometry of the origami structure, the hinge design, and the actuation system. The result of investigating three origami structures shows the ability to use the unit cell of the origami ball structure as a self-folding element. Furthermore, the novel type of origami structure for manipulation was created according to this result. This novel structure was designed to be a soft manipulation robot arm. Two approaches are used to design and fabricate flexure hinge. The first is by using a 3D printed multi-material technique. By this technique, the hinge printed using soft and solid material at the same time, which is Tango plus flx930 for soft material and Vero for solid material. The soft material act as a flexure hinge. Therefore, three tests were operated for it to calculate the tensile force, fatigue limit, and the required bend force. The second approach is by using acrylic and Kapton materials. Two types of actuation systems were studied: the external actuation system and embedded actuation system. The external actuation system was used for the Origami structure for manipulation, while the embedded actuation system was used for the self-folding structure. The shape memory alloy wires in torsion (TSW) and bending (BSW) was used in an embedded actuation system. A unit cell of origami ball was fabricated as a self-folding element by using three approaches: manually, acrylic, and Kapton and 3D printing. It is actuated by using shape memory alloy wire. Furthermore, an origami structure for manipulation was fabricated and actuated using an external actuation system. This novel type of origami structure provided an excellent bend motion ability

An Untethered Miniature Origami Robot that Self-folds, Walks, Swims, and Degrades

A miniature robotic device that can fold-up on the spot, accomplish tasks, and disappear by degradation into the environment promises a range of medical applications but has so far been a challenge in engineering. This work presents a sheet that can self-fold into a functional 3D robot, actuate immediately for untethered walking and swimming, and subsequently dissolve in liquid. The developed sheet weighs 0.31g, spans 1.7cm square in size, features a cubic neodymium magnet, and can be thermally activated to self-fold. Since the robot has asymmetric body balance along the sagittal axis, the robot can walk at a speed of 3.8 body-length/s being remotely controlled by an alternating external magnetic field. We further show that the robot is capable of conducting basic tasks and behaviors, including swimming, delivering/carrying blocks, climbing a slope, and digging. The developed models include an acetone-degradable version, which allows the entire robot’s body to vanish in a liquid. We thus experimentally demonstrate the complete life cycle of our robot: self-folding, actuation, and degrading.National Science Foundation (U.S.) (Grant 1240383)National Science Foundation (U.S.) (Grant 1138967)American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowshi

Patterning nonisometric origami in nematic elastomer sheets

Nematic elastomers dramatically change their shape in response to diverse stimuli including light and heat. In this paper, we provide a systematic framework for the design of complex three dimensional shapes through the actuation of heterogeneously patterned nematic elastomer sheets. These sheets are composed of \textit{nonisometric origami} building blocks which, when appropriately linked together, can actuate into a diverse array of three dimensional faceted shapes. We demonstrate both theoretically and experimentally that: 1) the nonisometric origami building blocks actuate in the predicted manner, 2) the integration of multiple building blocks leads to complex multi-stable, yet predictable, shapes, 3) we can bias the actuation experimentally to obtain a desired complex shape amongst the multi-stable shapes. We then show that this experimentally realized functionality enables a rich possible design landscape for actuation using nematic elastomers. We highlight this landscape through theoretical examples, which utilize large arrays of these building blocks to realize a desired three dimensional origami shape. In combination, these results amount to an engineering design principle, which we hope will provide a template for the application of nematic elastomers to emerging technologies

An end-to-end approach to self-folding origami structures

This paper presents an end-to-end approach to automate the design and fabrication process for self-folding origami structures. Self-folding origami structures are robotic sheets composed of rigid tiles and joint actuators. When they are exposed to heat, each joint folds into a preprogrammed angle. Those folding motions transform themselves into a structure, which can be used as body of 3-D origami robots, including walkers, analog circuits, rotational actuators, and microcell grippers. Given a 3-D model, the design algorithm automatically generates a layout printing design of the sheet form of the structure. The geometric information, such as the fold angles and the folding sequences, is embedded in the sheet design. When the sheet is printed and baked in an oven, the sheet self-folds into the given 3-D model. We discuss, first, the design algorithm generating multiple-step self-folding sheet designs, second, verification of the algorithm running in O(n 2 ) time, where n is the number of the vertices, third, implementation of the algorithm, and finally, experimental results, several self-folded 3-D structures with up to 55 faces and two sequential folding steps

Solvent-assisted programming of flat polymer sheets into reconfigurable and self-healing 3D structures.

It is extremely challenging, yet critically desirable to convert 2D plastic films into 3D structures without any assisting equipment. Taking the advantage of solvent-induced bond-exchange reaction and elastic-plastic transition, shape programming of flat vitrimer polymer sheets offers a new way to obtain 3D structures or topologies, which are hard for traditional molding to achieve. Here we show that such programming can be achieved with a pipette, a hair dryer, and a bottle of solvent. The polymer used here is very similar to the commercial epoxy, except that a small percentage of a specific catalyst is involved to facilitate the bond-exchange reaction. The programmed 3D structures can later be erased, reprogrammed, welded with others, and healed again and again, using the same solvent-assisted technique. The 3D structures can also be recycled by hot-pressing into new sheets, which can still be repeatedly programmed

Multiwavelength observations of the black hole transient Swift J1745-26 during the outburst decay

We characterized the broad-band X-ray spectra of Swift J1745-26 during the decay of the 2013 outburst using INTEGRAL ISGRI, JEM-X and Swift XRT. The X-ray evolution is compared to the evolution in optical and radio. We fit the X- ray spectra with phenomenological and Comptonization models. We discuss possible scenarios for the physical origin of a ~50 day flare observed both in optical and X- rays ~170 days after the peak of the outburst. We conclude that it is a result of enhanced mass accretion in response to an earlier heating event. We characterized the evolution in the hard X-ray band and showed that for the joint ISGRI-XRT fits, the e-folding energy decreased from 350 keV to 130 keV, while the energy where the exponential cut-off starts increased from 75 keV to 112 keV as the decay progressed.We investigated the claim that high energy cut-offs disappear with the compact jet turning on during outburst decays, and showed that spectra taken with HEXTE on RXTE provide insufficient quality to characterize cut-offs during the decay for typical hard X-ray fluxes. Long INTEGRAL monitoring observations are required to understand the relation between the compact jet formation and hard X-ray behavior. We found that for the entire decay (including the flare), the X-ray spectra are consistent with thermal Comptonization, but a jet synchrotron origin cannot be ruled out.Comment: Accepted for publication by MNRA