Modular Morphing Lattices for Large-Scale Underwater Continuum Robotic Structures

Abstract

In this study, we present a method to construct meter-scale deformable structures for underwater robotic applications by discretely assembling mechanical metamaterials. We address the challenge of scaling up nature-like deformable structures while remaining structurally efficient by combining rigid and compliant facets to form custom unit cells that assemble into lattices. The unit cells generate controlled local anisotropies that architect the global deformation of the robotic structure. The resulting flexibility allows better unsteady flow control that enables highly efficient propulsion and optimized force profile manipulations. We demonstrate the utility of this approach in two models. The first is a morphing beam snake-like robot that can generate thrust at specific anguilliform swimming parameters. The second is a morphing surface hydrofoil that, when compared with a rigid wing at the same angles of attack (AoAs), can increase the lift coefficient up to 0.6. In addition, in lower AoAs, the ratio improves by 5 times, whereas in higher angles it improves by 1.25 times. The resulting hydrodynamic performance demonstrates the potential to achieve accessible, scalable, and simple to design and assemble morphing structures for more efficient and effective future ocean exploration and exploitation.

Nodes for modes: Nodal honeycomb metamaterial enables a soft robot with multimodal locomotion

“…For example, in our previous study, we reported an analytical model for nodal honeycomb lattice, characterizing Poisson's ratio and Young's modulus parameters, and demonstrated a mathematical procedure providing its physical and mechanical integration with auxetic anti-tetrachiral lattice to create custom, shape morphing, soft-bodied robots. With this and similar studies, lattice structures have reached the highest maturity level in the field [35]; however, they are underutilized in soft robotics-with a notable exception being hydrosnake [27], of which sections was injection molded and 'discretely assembled' [46] with rivet connections. Utilization of 3D printing would be more convenient than molding for quick development, and may result in a robust multi-functional platform.…”

“…Fortunately, robotic electronic components have decreased in size in recent years such that they are small enough to be embedded in soft robots. Servomotors are typically the most robust and the easiest-to-use actuators in terms of cost, reliability, and physical simplicity and were utilized in previous studies [22,[25][26][27]. Servomotor control is possible using small sized microcontrollers and portable batteries that can be accommodated on board the robot [22].…”

The CLaP System: Chain-based Lattice Printing for Efficient Robotically-Assembled Structures

“…toy building bricks), a number of research efforts related to our work stand out. Gershenfeld's group at MIT has produced works related to fabricating efficient lattice structures utilizing identical material base units, including "cuboct" lattices of octahedra from 'x'-shaped planar units assembled at vertices by externally-placed clips (37), lattice cell utilizing planar triangular units (38), which are also designed with robotic assembly in mind (39), and voxels with tunable mechanical properties (40), which can be selectively incorporated into the inner components of large-scale underwater robotic structures (41).…”