Nonlinear modeling and experimental evaluation of fluid-filled soft pads for robotic hands

After a brief reminder about previous work, this paper addresses the dynamic characterization of fluid-filled soft pads for robotic hands. The adopted pad specimens are constituted by a single hyper-elastic material having hardness similar to that of the human thumb. The overall pad thickness is then divided into a continuous skin layer and an internal layer having communicating voids which are hermetically sealed and filled with a viscous fluid. Despite a more complicated design, it has been proven [1-3] that the pads present enhanced compliance and damping properties, a lower thickness and a higher surface hardness when compared to previously published solutions. In addition, a quasi-linear model, frequently used to describe the behavior of soft biological tissues can be applied in order to predict and control the pad interaction with the environment during grasping and manipulation tasks. In particular, the experimental tests necessary to evaluate the parameters which determine the pad dynamic response are described and discussed in detail.