SpineMan: Design of a soft robotic spine-like manipulator for safe human-robot interaction

Robots made from soft materials have recently captured the interest of researchers from a range of fields including engineers, material scientists, and chemists, biologists, and computer scientists. This new paradigm of soft robotics aims to develop more adaptable, more capable and safer robots that can interact with unstructured environments or permit close cooperation with humans. Current, commercially-available solutions in industrial robotics tend to take a software-centered approach to safe human-robot interaction or focus on the design of lightweight structures consisting of conventional rigid materials. Even though these solutions provide a higher safety level than traditional industrial robots, robots that comprise a sufficiently large amount of soft structures will bring about a certain degree of inherent safety. One of the major challenges in today's soft robotics research is to design robots that are inherently safe and adaptable but are also capable of bearing limited loads. Nature has solved this predicament in larger animals by incorporating stiff endoskeletons, which support the weight of the otherwise predominantly soft bodies. This insight has led to the development of a novel spine-like manipulator (SpineMan) comprised of rigid elements made from polypropylene and soft elements consisting of polyvinyl alcohol (PVA) borax hydrogels that are enveloped in a silicone skin. The initial design, material selection, synthesis, and characterization of this robot are presented in this article.