Utilizing Systematic Design and Shape Memory Alloys to Enhance Actuation of Modular High-Frequency Origami Robots

Shape memory alloys (SMAs) describe a group of smart metallic materials that can be deformed by external magnetic, thermal, or mechanical influence and then returned to a predetermined shape through the cycling of temperature or stress. They have several advantages, such as having excellent mechanical properties, being low cost, and being easily manufactured, while also providing a compact size, completely silent operation, high work density, and requiring less maintenance over time. SMAs can undergo sold-to-solid phase transformations, and it is because of these phase transformations that they can experience shape memory effect (SME); or the ability to recover from a deformed shape to an initially determined shape through the cycling of temperature. However, since SME requires the cycling of temperature to actuate SMAs, the actuation frequency of these materials has been slow for small-scale applications, as actuation speed is limited by the time it takes to transition from a higher temperature (actuated, pre-determined state) to a lower temperature (flexible, reconfigurable state). While SMAs are known to be highly advantageous, their main drawback is that they are one of the slowest actuation methods in the field of origami robotics. SMAs cannot actuate quickly enough cyclically due to the long cooling times required to get from their austenite (higher temperature, actuated, pre-determined state) phase to their martensite (lower temperature, flexible, reconfigurable state) phase. Researchers have attempted to achieve a higher actuation speed in previous projects by using active cooling agents. However, this study investigated the use of SMAs to initiate high-frequency cyclic movement through a small-scale origami fold without an active cooling source. This study used a combination of different system design parameters to mechanically hasten the actuation speed of a folding hinge with no cooling component present. Through only design and a complete understanding of the SMAs, this study achieved consistent and relatively high results (\u3e1.5 Hz) of an actuation speed for a system of this size. This study discovered knowledge regarding the composition, material properties, and actuation limits of SMAs, and a new systematic design method was proposed for creating origami robots

Universal computing by DNA origami robots in a living animal

Biological systems are collections of discrete molecular objects that move around and collide with each other. Cells carry out elaborate processes by precisely controlling these collisions, but developing artificial machines that can interface with and control such interactions remains a significant challenge. DNA is a natural substrate for computing and has been used to implement a diverse set of mathematical problems1-3, logic circuits4-6 and robotics7-9. The molecule also naturally interfaces with living systems, and different forms of DNA-based biocomputing have previously been demonstrated10-13. Here we show that DNA origami14-16 can be used to fabricate nanoscale robots that are capable of dynamically interacting with each other17-18 in a living animal. The interactions generate logical outputs, which are relayed to switch molecular payloads on or off. As a proof-of-principle, we use the system to create architectures that emulate various logic gates (AND, OR, XOR, NAND, NOT, CNOT, and a half adder). Following an ex vivo prototyping phase, we successfully employed the DNA origami robots in living cockroaches (Blaberus discoidalis) to control a molecule that targets the cells of the animal

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

Ingestible, controllable, and degradable origami robot for patching stomach wounds

© 2016 IEEE.Developing miniature robots that can carry out versatile clinical procedures inside the body under the remote instructions of medical professionals has been a long time challenge. In this paper, we present origami-based robots that can be ingested into the stomach, locomote to a desired location, patch a wound, remove a foreign body, deliver drugs, and biodegrade. We designed and fabricated composite material sheets for a biocompatible and biodegradable robot that can be encapsulated in ice for delivery through the esophagus, embed a drug layer that is passively released to a wounded area, and be remotely controlled to carry out underwater maneuvers specific to the tasks using magnetic fields. The performances of the robots are demonstrated in a simulated physical environment consisting of an esophagus and stomach with properties similar to the biological organs

Generalized modeling of origami folding joints

Origami robots self-reconfigure from a quasi two-dimensional manufactured state to three-dimensional mobile robots. By folding, they excel in transforming their initial spatial configuration to expand their functionalities. However, unlike paper-based origamis, where the materials can remain homogeneous, origami robots require varying payloads and controllability of their reconfigurations. Therefore, the mechanisms to achieve automated folding adapt flat thin panels and folding hinges that are often of different materials to achieve the folding. While the fundamental working principle of an origami hinge remains simple, these multi-component, multi-material origami joints can no longer be modeled by beam theory without considering the semi-rigid connections at the material interfaces. Currently, there is no comprehensive model to analyze physical behavior of an actuated folding hinge accurately. In this work, we propose a model based on the plate theory to predict the origami folding joint: we adapt a torsional spring to capture this semi-rigid connection, predict the folding stiffness and bending of origami joints. Herein, the semi-rigid connection is calibrated by quasi-static folding tests on a series of physical origami folding joints, and the accuracy of our model is compared to finite element simulations. With this analytical model, we can accurately simulate the mechanics of physical origami folding joints

Towards printable robotics: Origami-inspired planar fabrication of three-dimensional mechanisms

This work presents a technique which allows the application of 2-D fabrication methods to build 3-D robotic systems. The ability to print robots introduces a fast and low-cost fabrication method to modern, real-world robotic applications. To this end, we employ laser-engraved origami patterns to build a new class of robotic systems for mobility and manipulation. Origami is suitable for printable robotics as it uses only a flat sheet as the base structure for building complicated functional shapes, which can be utilized as robot bodies. An arbitrarily complex folding pattern can be used to yield an array of functionalities, in the form of actuated hinges or active spring elements. For actuation, we use compact NiTi coil actuators placed on the body to move parts of the structure on-demand. We demonstrate, as a proof-of-concept case study, the end-to-end fabrication and assembly of a simple mobile robot that can undergo worm-like peristaltic locomotion.United States. Defense Advanced Research Projects Agency (Grant W911NF-08-C-0060)United States. Defense Advanced Research Projects Agency (Grant W911NF-08-1-0228

Reconfigurable Surfaces Employing Linear-Rotational and Bistable-Translational (LRBT) Joints

Reconfigurable surfaces are useful in many applications. This paper proposes a type of reconfigurable surfaces that consist of rigid elements (tiles) connected by novel compliant joints. Depending on the actuation, these novel connecting joints can either operate as torsional hinges, which create isometric transformation (like origami folding) between connected tiles, or bistable translational springs, which accommodate metric-changing transformation between connected tiles. A specific example of a reconfigurable surface with square tile shape that can morph into flat, cylindrical (in two different directions), and spherical configurations with simple actuation is given