Reconfigurable laminates enable multifunctional robotic building blocks

Abstract

Folding and assembling of two-dimensional laminated materials have greatly facilitated robot fabrication by creating robots with lightweight body frames, articulated joints, and embedded actuators and sensors. The combinations of rigid laminates bridged by thin-film flexures, often called rigid-flex linkages, have been extensively used in micro- and macro-scale robots to achieve complex joint motions with simplified kinematic and dynamic properties. Much like traditional robots these rigid-flex laminate robots are designed with a fixed body-plan, and thus may face challenges when environments require mechanical reconfiguration such as stiffening joints for load support or changing appendage morphologies for navigating confined spaces. Recent advances in adaptive materials and smart actuators have highlighted the features that robots with morphable geometries and tunable mechanical properties can provide, such as self-folding joints and variable stiffness and damping mechanisms. However, incorporation of these reconfigurable elements into laminate robots has been limited. In this paper, we present a new method for creating quasi two-dimensional structures for robotics, called reconfigurable laminates, that use geometric reconfiguration of laminate layers to alter passive mechanical properties and actuate joints. Unlike traditional rigid-flex linkages with single-layered flexures, here we create laminate joints with dual-layered soft hinges and rigid channels allowing a multitude of reconfiguration opportunities including: sliding-layer laminates for passive stiffness control, snapping-hinge locks for reconfigurable joints, and buckle-bend joints for bending actuation. Through experimental characterization we demonstrate the capabilities of these multifunctional robotic building blocks.