Visco-elastic contact interfaces can be found invarious robotic components covered with a compliant surface(pad) such as anthropomorphic hands, bio-mimetic haptic/tactilesensors, prostheses and orthoses. In all these cases, it is desirableto obtain thin and resistant pads with predetermined complianceand damping properties (e.g. mimicking the human skin andpulpy tissues).In order to overcome the limits of homogeneous layers of softvisco-elastic material, commonly used in the aforementioneddevices, this paper suggests the adoption of soft pads composedof a continuous external layer (skin) coupled with an internallayer having fluid-filled voids. The process of designing thepad starts with the selection of a hyper-elastic medium withproper tribological features, whose constitutive parameters aredetermined by numerically fitting nonlinear stress-strain curvesunder pure homogenous deformations. The optimization of theinternal layer morphology is then achieved through nonlinearfinite element analysis which provides an estimate of hardnessand friction influence on the pad static compliance. At last,the pad is filled with a viscous fluid chosen so as to modifytime-dependent phenomena and to increase damping effects.The effectiveness of the procedure is proven by designing andmodeling better-behaved artificial pads which mimic the humanfinger dynamic properties.
Engineering design of fluid-filled soft covers for robotic contact interfaces: Guidelines, nonlinear modelling, and experimental validation / Berselli, Giovanni; M., Piccinini; G., Palli; G., Vassura. - In: IEEE TRANSACTIONS ON ROBOTICS. - ISSN 1552-3098. - STAMPA. - 27:(2011), pp. 436-449. [10.1109/TRO.2011.2132970]