  Able to grasp objects of any shape and size, universal grippers using
variable stiffness phenomenon such as granular jamming have been developed for
disaster robotics application. However, as their contact interface is mainly
composed of unrigid and burnable silicone rubber, conventional soft grippers
are not applicable to objects with sharp sections such as broken valves and
glass fragments, especially on fire. In this research, the authors proposed a
new method of variable stiffness mechanism using a string of beads that can be
composed of cut-resistant and incombustible metals, arrange the mechanism to
form a torus gripper, and conducted experiments to show its effectiveness.
