Gearmotor mechanism with two alternatively selectable outputs for the movement of the fingers and for the opposition (abduction / adduction) of the thumb of a prosthetic hand consisting of a single power actuator and a miniaturized actuator for selection with a simplified control system.

Patent Status


Priority Number

IT102019000016631/ WO2021053539A1

Priority Date





The advanced prosthetics was valued as $1.42 billion in FY 2018 and is forecasted to grow with a CAGR of 10.31% in the period of 2019-2024 and is estimated to be valued $2.55 billion in FY 2024.


Guaranteeing the patient who has lost the limb the possibility of recovering most of the functions of a hand, while at the same time using an immediately learning, highly effective and non-invasive human machine interface (HMI), is nowadays the strongest need. in the field of prostheses.

The technical problem consists in the realization of a complete hand prosthesis, which uses a single power motor to actuate both all the fingers in flexion / extension and the opposition (abduction / adduction) of the thumb, inside a hand shape. with anthropomorphic features and anthropometric dimensions. Everything has been created in order to maintain the high standards of compactness required, and at the same time guaranteeing the performance of a human hand with an activated thumb, silent in operation and irreversible with the engine off.

Current Technology Limits

At present there are no robotic actuation systems which allow to obtain from a single actuator two different outputs having different reduction ratios.

This solution can be applied to add a further degree of freedom to the thumb (ab-adduction) to the Hannes prosthetic hand (IT102018000005213) without altering and distorting as much as possible the original routing led to the definition of a new reduction system that had two shafts. selectable output.

Killer Application

Any application in which, due to space constraints (dimensions) and / or energy consumption and / or the need to displace more than one movement mechanism with respect to the real axis of rotation, a power actuator is required, as e.g. robotics. This invention allows to have two outputs possibly having different reduction using a single power actuator. By means of a secondary actuator (of much smaller dimensions than the one previously mentioned) it will therefore be possible to select which of the two outputs to actuate in a completely independent and selective manner.

Our Technology and Solution

Electric actuator typically for robotic and / or prosthetic applications able to offer a double output with different reduction ratio and, consequently, able to implement two different degrees of freedom in a completely selective and mutually exclusive way where required and / or necessary while keeping the overall dimensions almost unchanged compared to a gearmotor of equal performance which, however, is able to carry out only one output at a time.

In the context of the Hannes prosthetic hand (IT102018000005213), the need for this actuator / mechanism was fundamental to allow the implementation of two different joints (opening and closing of the hand and movement of the thumb) in a completely selective and mutually exclusive way while lying at the same time. dimensions of a gearmotor of equal performances.


  • Use of a single power gearmotor, which usually represents the heaviest part of the systems, to obtain a gear train that offers two outputs with different reduction
  • Possibility of using a smaller size selection actuator than the one for moving the joint
  • Ability to remotely drive the joint of interest using flexible or other transmissions
  • The remote control of the motor, where there is greater availability of space, also allows the use of actuator cuts more suitable for the application which could instead be considered bulky and heavy to be used directly on the joint itself
  • Operation in both directions of rotation for both outputs
  • The use of the cyclo stage, being irreversible, allows to simplify the selection system, which otherwise would need three operating states (first shaft locking, second shaft locking, both shafts locking) instead of two.
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