  Stability and reliable operation under a spectrum of environmental conditions
is still an open challenge for soft and continuum style manipulators. The
inability to carry sufficient load and effectively reject external disturbances
are two drawbacks which limit the scale of continuum designs, preventing
widespread adoption of this technology. To tackle these problems, this work
details the design and experimental testing of a modular, tendon driven
bead-style continuum manipulator with tunable stiffness. By embedding the
ability to independently control the stiffness of distinct sections of the
structure, the manipulator can regulate it's posture under greater loads of up
to 1kg at the end-effector, with reference to the flexible state. Likewise, an
internal routing scheme vastly improves the stability of the proximal segment
when operating the distal segment, reducing deviations by at least 70.11%.
Operation is validated when gravity is both tangential and perpendicular to the
manipulator backbone, a feature uncommon in previous designs. The findings
presented in this work are key to the development of larger scale continuum
designs, demonstrating that flexibility and tip stability under loading can
co-exist without compromise.
