Digital Morphing Wing: Active Wing Shaping Concept Using Composite Lattice-Based Cellular Structures

Abstract

We describe an approach for the discrete and reversible assembly of tunable and actively deformable structures using modular building block parts for robotic applications. The primary technical challenge addressed by this work is the use of this method to design and fabricate low density, highly compliant robotic structures with spatially tuned stiffness. This approach offers a number of potential advantages over more conventional methods for constructing compliant robots. The discrete assembly reduces manufacturing complexity, as relatively simple parts can be batch-produced and joined to make complex structures. Global mechanical properties can be tuned based on sub-part ordering and geometry, because local stiffness and density can be independently set to a wide range of values and varied spatially. The structure's intrinsic modularity can significantly simplify analysis and simulation. Simple analytical models for the behavior of each building block type can be calibrated with empirical testing and synthesized into a highly accurate and computationally efficient model of the full compliant system. As a case study, we describe a modular and reversibly assembled wing that performs continuous span-wise twist deformation. It exhibits high performance aerodynamic characteristics, is lightweight and simple to fabricate and repair. The wing is constructed from discrete lattice elements, wherein the geometric and mechanical attributes of the building blocks determine the global mechanical properties of the wing. We describe the mechanical design and structural performance of the digital morphing wing, including their relationship to wind tunnel tests that suggest the ability to increase roll efficiency compared to a conventional rigid aileron system. We focus here on describing the approach to design, modeling, and construction as a generalizable approach for robotics that require very lightweight, tunable, and actively deformable structures.

Design and Take-Off Flight of a Samara-Inspired Revolving-Wing Robot

“…To date, nature has provided us solutions for recreation of flight with man-made machines. Bird-like morphing wings manifest high performance aerodynamic surfaces [2]. Taking after insects and hummingbirds, millimeter-scale flying robots leverage unsteady force production and leadingedge vortices as a lift enhancement mechanism through the flapping-wing motion [1], [3].…”

Investigation of a Morphing Wing Capable of Airfoil and Span Adjustment Using a Retractable Folding Mechanism

“…Thus, morphing solutions that excludes the need for smart material may be simpler. Jenett et al [15] described a novel structural approach that turns the entire wing into a morphing mechanism and offers span-wise twist of the wing. The concept relies on a wing structure comprised of cellular solids, which is a structure that is composed of a lattice of interconnected identical building blocks.…”

“…Reduction in β diminishes the leading edge distance to the symmetry plane until y LE = 0, meaning that the gap is eliminated. The correlation between the two is presented in Equation (15).…”

Modeling of Tunable Elastic Ultralight Aircraft

“…The proposed lattice structures that are being used for the substructure have been shown to be ultra-light [13] and previous works have shown that these class of materials inhabit a region of material stiffness that is typically associated with elastomer [15]. The combination of its ultra-light nature and low stiffness means that when it is used to design an aircraft it inherently becomes a flexible aeroelastic system and requires multiple integration modeling techniques.…”