Design, Fabrication and Characterization of a Novel Variable Stiffness Structure for Soft Continuum Robotics

Soft Robotics made of soft and compliant materials ensure systems with high inherent safety for a safe human-robot collaboration. Thereby current soft robots mostly lack the required stiffness to apply sufficient loads. To ensure inherent safety and at the same time a greater load capacity, structures with adjustable stiffness are required. In this paper, possible approaches for the realization of a switchable stiffness are analyzed and evaluated against the application background of human-oriented soft robotics, which focus mainly on high switching dynamics and high stiffness ratios. A concept for variable stiffness robotic segments based on particle and layer jamming for planar motion is shown, enabling highly dynamic switching between stiff and soft with a bending stiffness ratio K > 100. For this variable stiffness structural component, both the development steps and the characterization methodology are explained. Finally, an outlook on the design of a soft continuum robotic manipulator using three of these variable stiff segments and two tendons for an underactuated motion control of the whole structure is given.