Abstract: A prosthetic wrist unit includes a drive motor, to be interposed between the distal end of an arm prosthesis and a prosthetic terminal device for positioning the terminal device at desired orientations. A reduction mechanism includes first and second cycloidal reduction stages, connected to each other, the first stage having a central wheel connected to the motor shaft, one or more satellite wheels rotatably placed on a planet carrier, and a fixed outer ring gear, the satellite wheels being in peripheral contact with the central wheel and the outer ring gear, the planet carrier being connected to the second stage. The central wheel, the satellite wheels and the outer ring gear have smooth mutually engaging surfaces, causing a rolling of the satellite wheels on the outer ring gear by friction forces generated by radial interference between the central wheel, the satellite wheels and the outer ring gear.

Abstract: An actuation device (1) comprising a threaded shaft (2) connected at one end to driving means adapted to allow the threaded shaft (2) to rotate about its longitudinal axis (a). A movable element (3) is provided with a cylindrical cavity (30) adapted to receive the threaded shaft (2), and configured so that a rotation of the threaded shaft (2) corresponds to a translation the movable element (3) along the longitudinal axis (a). The device (1) has two guiding rods (4,4?) coupled to the movable element (3) and adapted to constrain the translation of the latter along a direction parallel to the longitudinal axis (a). Element (3) comprises a first (31) and a second (32) element constrained to each other, wherein the first element (31) is coupled to the threaded shaft (2) and the second element (32) is coupled to the two guiding rods (4,4?).

Abstract: The present invention relates to an actuation device (1) comprising a threaded shaft (2) connected at one end to driving means adapted to allow the threaded shaft (2) to rotate about its longitudinal axis (?). The device further comprises a movable element (3) provided with a cylindrical cavity (30) adapted to receive the threaded shaft (2), and configured in such a way that a rotation of the threaded shaft (2) corresponds to a translation the movable element (3) along the longitudinal axis (?). The device (1) further comprises two guiding rods (4,4?) coupled to the movable element (3) and adapted to constrain the translation of the latter along a direction parallel to the longitudinal axis (?). The movable element (3) comprises a first (31) and a second (32) element constrained to each other, wherein the first element (31) is coupled to the threaded shaft (2) and the second element (32) is coupled to the two guiding rods (4,4?).