Nonlinear modeling and experimental identification of hemispherical soft pads for robotic manipulators

In this work the dynamic contact of hemispherical indenter covered by a thick viscoelastic layer and pressed against a flat rigid surface is modelled. The goal is to investigate the dynamic behavior of robotic fingertips composed by an inner rigid structure covered by a soft layer, mimicking the human biological model. A quasi-linear model, frequently used to describe the behavior of soft and pulpy biological tissues, is adopted in order to achieve a compromise between the simplicity of classical linear models and the difficulty of nonlinear approaches. Two different materials (a polyurethane gel and a silicon rubber) have been experimentally tested in order to find the parameters of the model and to validate it. Finally, the advantage of the use of digital filters method in identification process is exploited, so that the identification becomes suitable for online process. Copyright © 2005 by ASME.