Abstract:
Soft robotics is a major disruptive technology that
is rapidly revolutionizing the world of robotics. As the design
optimization of these soft robotic structures are still in its infancy,
their designers have to resort to prototype testing. This paper
describes how a novel casting method based on a 2D layered
approach and thermal programming of pneumatic tubing can
be used to simplify soft structure prototyping. The proposed
casting method is based on the sequential stacking of laser-cut
pre-fabricated plates, i.e. PMMA (acrylic) sheets, to create a 3D
mold, instead of the traditional methods of fabricating 3D molds,
such as CNC machining or 3D printing. Contemporary soft
robotic applications are more interested in pneumatic actuation
and thus require pneumatic channels embedded within their
structure. Creation of channels is a critical factor that limit the
fabrication scope of most such soft structures. A simple solution
is using Polyurethane (PU) tubing to create channels within soft
structures. A limitation of PU tubes is that, they cannot be
directly embedded as any twist added to obtain the required path
of the tube adds a strain on the soft structure from within, which
can affect the desired operation. Hence, the authors propose
removing the strain on the PU tubes by thermally programming
the required shape onto the PU tube. PU tubes reinforced with
copper cores are bent in to the desired shape and are heat treated
to program the desired shape. After placing the programmed
tubes within the mold, silicon rubber can be simply poured into
the mold; and the finished structure can be taken out of the mold
once cured. Main purpose of this paper is to present these two
novel fabrication methods to simplify soft robotic prototyping,
without the need for advanced, costly, complex equipment.
