Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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cable-driven mechanismLocking mechanismMechanical-differentialProsthesis


The invention relates to a compact, low weight, active locking mechanism, which can be integrated in a poly-articulated under-actuated hand that utilizes a mechanical-differential, cable-driven mechanism, with the goal of increasing the number of grasp functionalities of the hand itself.

Technical features

The current mechanism allows the main mechatronics of the Hannes system to remain the same, thanks to the compact size and integration of the locking mechanism within the differential mechanics but obtaining additional grasp mode (tri-digital) . Therefore, the high grasp speed and high grasp force typical of underactuated robotic prosthetic hands are preserved. When the mechanism in disabled and hence all the fingers are recruited during grasp tasks it is possible to obtain pinch, power and lateral grasp with all the fingers fully extended ore flexed according to the patient’s intention. On the other hand, when the mechanism is enabled, ring and little finger are locked obtaining a pinch, lateral or power grasp with ring and little fully extended.

Possible Applications

  • Prosthetics;
  • Robotics.


  • Only one secondary motor used for different grasp types;
  • Compact size to reduce space and weight.