3D‐Architected Soft Machines with Topologically Encoded Motion

Abstract

The limited range of mechanical responses achievable by materials compatible with additive manufacturing hinders the 3D printing of continuum soft robots with programmed motion. This paper describes the rapid design and fabrication of low-density, 3D-architected soft machines (ASMs) by combining Voronoi tessellation and additive manufacturing. On tendon-based actuation, ASMs deform according to the topologically encoded buckling of their structure to produce a wide range of motions (contraction, twisting, bending, and cyclic motion). ASMs exhibiting densities as low as 0.094 g cm −3 (≈8% of bulk polymer) can be rapidly built by the stereolithographic 3D printing of flexible photopolymers or the injection molding of elastomers. The buckling of ASMs can be programmed by inducing gradients in the thickness of their flexible beams or by the localized enlargement of the Voronoi cells to generate complex motions such as multi-finger gripping or quadrupedal locomotion. The topological architecture of these low-density soft robots confers them with the stiffness necessary to recover their original shape even after ultrahigh compression (400%) and extension (500%). ASMs expand the range of mechanical properties currently achievable by 3D printed or molded materials to enable the fabrication of soft machines with auxetic mechanical metamaterial properties.

Exploiting Mechanical Instabilities in Soft Robotics: Control, Sensing, and Actuation

“…Our group introduced an algorithmic design strategy based on Voronoi tessellation to create architected soft machines (ASMs) with programmable motion. [31] ASMs deform according to the topologically encoded buckling of their structure to produce a wide range of motions such as contraction, twisting, bending, and cyclic motion. As an example, Figure 4B shows the programmable twisting response of frustum-shaped ASMs, which exhibit either a unidirectional or bidirectional twisting regime depending on their curve angle α.…”

“…Soft robots often benefit from the integration of pneumatic or hydraulic valves, [1,[27][28][29] or small motors for tendon-driven systems, [30,31] and the distribution of arrays of sensors across their bodies [32,33] to facilitate the control of their complex motion and to the monitor their interactions with the environment. Unfortunately, these rigid valves, sensors, and their corresponding wiring often compromise the flexibility of soft machines, reducing their degrees of freedom and limiting their maneuverability and dexterity.…”

Development of the Ultralight Hybrid Pneumatic Artificial Muscle: Modelling and optimization

“…Moreover, direct 3D printing of PAMs (similarly to other soft actuators) is becoming a feasible option, when carefully tuning the printing parameters for soft materials [14]. Indeed, such 3D printing technology enables programmable multidimensional actuations that feature complex architectures and tunable stiffness by using multi-materials [15][16][17]. Nevertheless, main challenges are still to be met, such as large pulling force, deformation, and fast response [18,19].…”

Programmable Hierarchical Kirigami

“…The ability to program the mechanical response of materials and structures is enabling a wide set of innovative applications ranging from stretchable electronics and wearable devices [1,2] to soft robots [3][4][5][6][7] and drug delivery systems. [8,9] Recently, kirigami-the Japanese art of paper cutting-has been identified as a powerful tool to realize programmable mechanical metamaterials.…”