A self-deployable origami structure with locking mechanism induced by buckling effect

Abstract

One of the major problems in utilizing origami structures is ensuring variable stiffness; a deployable structure needs to become stiff or flexible according to the requirements of its use in an application. In this study, we present a self-deploying tubular origami mechanism that switches between two distinctive states: small and flexible at its normal state and rigid and stiffened at a locked state. By embedding compact torsional SMA actuators into the mechanism in a novel way through stitching, the process of deploying from the normal to the locked state proceeds in a simple and low-profile manner. With global heating, the torsional SMA wires activate a buckling effect that draws a radical change of folding line from one diagonal to another in every unit tile of the tube, creating axial stiffness. The activated structure, which weighs only 2.9 g, can endure a load of 2.7 kg or more. Additionally, since it does not require bulky actuators, this origami structure can be highly mobile and small in size. This novel origami mechanism is expected to be useful in a wide variety of applications, such as aerospace equipment, mobile architecture, and medical devices, especially those used in minimally invasive surgery (MIS).

A Review of SMA-Based Actuators for Bidirectional Rotational Motion: Application to Origami Robots

“…Consequently, the fabrication and assembly process can be simplified. Different designs of elementary torsional actuators can be found in literature, rotary actuation capability are experimentally proven using torsional strips (Tobushi et al, 2008;Tobushi et al, 2010;Tobushi et al, 2013), torsional bands (Shim et al, 2015), torsional wires (Kim J. et al, 2015) and torsional tubes (Benafan et al, 2019). Besides the shear-strain-drivenactuators, investigations on torsional coil spring (Salerno et al, 2013;Sheng and Desai, 2015;Sheng et al, 2017) that convert the local normal strain to global shear strain are carried out and results show an improvement of motion range and reduction of output torque compared to the wire form torsional actuator.…”

“…Besides the shear-strain-drivenactuators, investigations on torsional coil spring (Salerno et al, 2013;Sheng and Desai, 2015;Sheng et al, 2017) that convert the local normal strain to global shear strain are carried out and results show an improvement of motion range and reduction of output torque compared to the wire form torsional actuator. It is worth reminding the works introduced by Kim J. et al (2015) and by Wood et al (2016), that presented the origami-based self-deployable structure coupled with torsional wire elements. The former was based on a "Kresling" pattern, and the latter was based on a "Waterbomb" pattern.…”

“…(D) A self-deployable lifting structure (Wood et al, 2016). (E) A "shape switching" module with controllable stiffness (Kim J. et al, 2015). (F) A "2D → 3D" shape-morphing system (Hawkes et al, 2010).…”

An origami-inspired, self-locking robotic arm that can be folded flat

“…Ensuring adequate structural stiffness without losing the inherent advantages of simple and lightweight origami structure is a challenging problem. Bistable origami patterns (26,27), shape memory polymer (SMP) stiffening (25), layer jamming (28,29), and chemical stiffening methods (7) have been suggested for stiffening mechanism for origami structures.…”

An Origami-Inspired Reconfigurable Suction Gripper for Picking Objects With Variable Shape and Size

“…One prominent solution to the problem of reconfiguration and compliance lies in suction gripper morphology; multiple shapes of cross-sectional areas could effectively conform to object geometry and also create various stiffnesses associated with structural density [14]. Such metastructural and metamaterial behavior is the nature of robotic origami design [15,16], where rigid facets connected with flexible hinges generate desired 3-D shape configurations [17]- [19] by self-folding, and different stiffness modes by collapsing the structure [20], locking some of the hinges [21], or by means of variable stiffness material joints [10], theoretically with infinite degrees of freedom (DoF) [22].…”