Special Issue: Fabrication of Fully Integrated Robotic Mechanisms

摘要

The past two decades have seen immense strides being made in novel fabrication techniques, particularly in additive manufacturing (AM) technologies, also known as “rapid prototyping” and “3D printing,” as well as in novel subtractive techniques such as laser-cutting and waterjet-cutting. The most popular practical technologies, such as fused-deposition modeling (FDM), stereolithography, selective-laser-sintering, and laser-cutting, are currently used worldwide and are rapidly becoming even more widespread and inexpensive. While all these processes enable rapid and easy fabrication of parts with complex geometries, they are limited in a number of ways, including a small number of available materials, low strength of fabricated parts, and are generally only capable of producing monolithic components.Fabricating robotic mechanisms—which generally consist of many moving parts, complicated kinematics, and require the incorporation of actuators, sensors, power sources, interconnects, and power and control electronics—prompts the need for novel manufacturing processes in order to move past the heterogeneity of current approaches, in which many subcomponents are fabricated separately and then assembled together with fasteners to produce the full system. As a result, traditionally fabricated systems are generally more expensive, heavy, inefficient, and/or less durable than is desirable. In order to be able to produce fully integrated robotic mechanisms that significantly extend the capabilities of current techniques, novel approaches to fabricating multipart and multimaterial systems that combine previously disjoint components and/or enable completely new functionality must be developed. Ongoing efforts with processes such as shape deposition manufacturing and origami-inspired folding processes are charting a course in this general direction, but much work remains to be done.This special issue represents a collection of 15 papers from researchers in seven countries on three continents. The papers generally address new methods and techniques for fabricating robotic mechanisms or subsystems, or methodologies and designs for the effective utilization of emerging fabrication techniques. We organize the papers into three main topic areas: novel AM techniques (four papers); soft robotics and structures (four papers); and folding-based approaches (seven papers).On the first topic, related to novel approaches for AM techniques, the first two papers focus on the mechanical structure of fabricated components. The first, by Tanner et al., describes a technique by which photolithographic patterning and infiltrating carbon nanotubes with a variety of bulk materials to produce stacked layered parts with submillimeter resolution. Next, Ma et al. describe a technique to utilize traditional FDM in a new way, to print both mechanical structures and sacrificial molds that are then filled with other resins to create multimaterial components. The second two papers describe approaches to enable the printing of electrically conductive components, both using FDM as a basis. The first, by Kim et al., implements a method of laying down conductive wires or meshes via a second extrusion head to embed them within the AM printed part. The second, by Swensen et al., introduces a technique in which parts are printed with hollow traces that are then filled with a low-melting temperature metal in order to produce AM parts with integrated electrical traces and components.The second major topic area, consisting of four papers, concerns the production and design of “soft” structures and robotics. The first three papers in this group concern the development of soft, compliant grippers, or hands built from multimaterial processes and with integrated electrical and transmission components. Suresh et al. describe a novel membrane-based gripper and a related fabrication technique for the purposes of grasping curved surfaces. Gafford et al. describe a miniature adaptive surgica