Design and realization of a flexible finger actuated by shape memory alloy (SMA) wires

A flexible finger for robotic application composed by a variable number of autonomous modules was designed and realized. The motion of a single module is performed by SMA wires, capable of changes in their own length and causing the bending of the module. The heating of the wire, e.g. by means of Joule effect, causes the shortening of the wire itself, whereas the cooling, while a bias force is applied, causes the stretching of the wire to the original shape. The combination of different modules actuation could cause a complex deformation of the finger itself. A finite element model was studied and implemented in order to properly design the device. The preliminary tests on a first prototype demonstrate a good behaviour of the device.