Development of Elastic Robot Finger having Rides which can Detect a Distribution of Contact Condition

An elastic robot finger has been developed for controlling grasping force when weight and frictional coefficient of grasped object are unknown. First, geometry of the finger is designed. The elastic finger has ridges at the surface to divide the contact area. Geometry of the ridges is trapezoid like human ridges. It also has a pair of tactile sensors embedded per one ridge similar to human fingertips. The surface of the whole finger is curved so that normal reaction force distributes unequally. A Finite Element (FE) model of the elastic finger was made to conduct a dynamic contact analysis using a FE method in order to design the elastic finger in detail. Then the elastic finger was made to confirm the results of FE analyses. At a result, it was confirmed by calculation and experiment that the elastic finger can detect the incipient slippage of the ridge that occurs near the edge of contact area and can deduce the stick area ratio. This result in useful for controlling grasping force when the weight and friction coefficient between the elastic finger and grasping object are unknown.