Characterization of a Class of Soft Bending Arms

Abstract

Bending permits soft arms to access a workspace that is not colinear with the initial arm axis; the size and shape of this space depends on the characteristics of the soft arm. Soft bending actuators and arms have developed for specific applications, but not characterized for the general relationship between design variables and performance. This paper defines a class of soft bending arms based on its design, considering the arm as a system constructed from many contracting actuators organized into segments. A modular segment design is presented, and seven variants of this design were constructed and tested for bend radius, bend direction, lateral stiffness and contraction. The variants isolate system parameters, in this case, arm radius and number of actuators within a given segment, to quantify how these parameters affect performance. A trade-off was found between lateral stiffness and bend radius, which can be controlled by altering the arm radius or the number of actuators. Bend direction was found to be coupled to both bend radius and arm load. Finally, a three-segment arm following a bio-inspired design is presented to demonstrate how the experimental results apply to soft robot system design.