Design
This design overview gives examples of fiber-embedded robotic structures from our work. One set of structures is made by inserting fibers into thin parts or textiles, and another is about incorporating fibers into thicker 3D printed and machined parts.
See details about fibers installed in a sheet or within a 3D printed part in the subsequent pages.
Fibers Installed in a Sheet
Fibers can be used for articulation, sensing, and actuation in thin robotic parts (<1mm thick).
For example, we used conductive threads to add soft electromechanical switches to a bendable, laser cut polymer sheet using an embroidery machine.
Here is a hinged-plate structure with threads as hinges produced by our aligned embroidery method. The magenta threads are hinges that hold it together, while the white threads heat-shrink to lock in the folded shape. These fibers were installed in pre-cut planar pieces using water-soluble materials to hold the parts in place during sewing.
Aligned embroidery can also install functional fibers into soft materials such as elastomers and textiles. In this tutorial we show how to align an optical fiber along a path in a soft material.
Fibers Installed in a 3D Print
Fibers can also be installed in thin 3D printed parts using aligned embroidery. Here an array of thin squares was hinged together with embroidered threads, then 3D printed pyramids were added on top. The resulting part is more flexible than an all 3D printed part would be.
But how can we integrate an embroidered fiber layer into a thicker part? At a height greater than the embroidery machine can accommodate (~5mm)? This tutorial demonstrates how to laser-cut holes in a water soluble stabilizer to allow upper layers of a print to fuse with parts below the fiber layer. In these test structures, a fishing line (4 lb tensile strength) goes around and through holes in printed features. At some locations, the fishing line is deliberately trapped between the print layers, creating an anchor point. These test structures contain the basic ingredients for a robotic structure such as a 3D printed grasshopper leg with tendons and a hinge.
In the above figure: Workflow for inserting a fiber layer in a 3D printed mechanical part. Different fiber paths pass through, around and within 3D printed features. a) The needle locates alignment marks on a laser-cut water soluble sheet, and an aligned embroidery pattern (inset) is generated. b) The pattern is embroidered and c) inserted at a pause point in a 3D print file (inset). d) Before and e) after dissolving the water soluble sheet and freeing the hinged 3D printed features.