  Soft robots have the ability to adapt to their environment, which makes them
suitable for use in disaster areas and agricultural fields, where their
mobility is constrained by complex terrain. One of the main challenges in
developing soft terrestrial robots is that the robot must be soft enough to
adapt to its environment, but also rigid enough to exert the required force on
the ground to locomote. In this paper, we report a pneumatically driven, soft
modular appendage made of silicone for a terrestrial robot capable of
generating specific mechanical movement to locomote and transport loads in the
desired direction. This two-segmented soft appendage uses actuation in between
the joint and the lower segment of the appendage to ensure adequate rigidity to
exert the required force to locomote. A prototype of a soft-rigid-bodied
tethered physical robot was developed and two sets of experiments were carried
out in both air and underwater environments to assess its performance. The
experimental results address the effectiveness of the soft appendage to
generate adequate force to navigate through various environments and our design
method offers a simple, low-cost, and efficient way to develop terradynamically
capable soft appendages that can be used in a variety of locomotion
applications.
