| CPC A61F 2/583 (2013.01) [A61F 2/586 (2013.01); A61F 2/72 (2013.01); A61F 2002/587 (2013.01); A61F 2002/6836 (2013.01); A61F 2002/701 (2013.01); A61F 2002/704 (2013.01); A61F 2002/762 (2013.01); A61F 2002/763 (2013.01); A61F 2002/764 (2013.01)] | 13 Claims |
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1. A prosthetic hand structure, comprising:
at least one mechanical finger having a metacarpal support, a proximal stiff link connected to the metacarpal support by a proximal cylindrical joint, the proximal stiff link arranged for carrying out a rotation of the proximal stiff link of a first predetermined amplitude with respect to the metacarpal support about an axis of the proximal cylindrical joint, said at least one mechanical finger including a distal stiff link connected to the proximal stiff link by a distal cylindrical joint, the distal stiff link being arranged for carrying out a rotation of the distal stiff link of a second predetermined amplitude with respect to the proximal stiff link about an axis of the distal cylindrical joint;
a transmission member connected to the proximal stiff link, the transmission member arranged to actuate the proximal stiff link in order to cause the rotation of the proximal stiff link of the first predetermined amplitude, the transmission member comprising a worm screw having a threaded profile, the worm screw being integral with the proximal stiff link and arranged for carrying out a rotation of the worm screw about a longitudinal axis of the worm screw, the transmission member further comprising a flexible rack having a first end portion pivotally connected to the metacarpal support and a second end portion arranged to engage with a thread of the worm screw at an engagement zone of the flexible rack, wherein the flexible rack is configured to buckle such that compressive loads are not transferred integrally to the metacarpal support, and wherein the second end portion of the flexible rack is configured to translate along a direction substantially parallel to an axis of the worm screw, as the transmission member actuates the proximal stiff link, wherein in distancing the engagement zone away from the first end portion, the second end portion extends into the distal stiff link;
an actuator mounted to said at least one mechanical finger, the actuator arranged to actuate the worm screw of the transmission member to obtain the rotation of the worm screw about the longitudinal axis of the worm screw, in such a way that, when the actuator actuates the worm screw, there is a moving-away movement of the engagement zone from the first end portion, se wherein the second end portion of the flexible rack extends into the distal stiff link, or an approaching movement of the engagement zone to the first end portion, causing the rotation of the proximal stiff link of the first predetermined amplitude, in a direction of rotation, or in an opposite direction of rotation, of the proximal stiff link about the axis of the proximal cylindrical joint, the rotation of the proximal stiff link of the first predetermined amplitude corresponding to an extension or flexion movement of said at least one mechanical finger;
at least one feedback position sensor associated with said at least one mechanical finger, said at least one feedback position sensor being configured to measure a position of the proximal stiff link with respect to the metacarpal support for determining in real time an amplitude of rotation of the proximal stiff link, the feedback position sensor being configured to generate a corresponding feedback signal; and
a control unit connected to the feedback position sensor to receive the feedback signal, the control unit being configured to analyze the feedback signal and to operate the actuator to actuate the worm screw until the amplitude determined in real time meets the first predetermined amplitude.
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