The traumatic loss of a hand is usually followed by significant psychological, functional and rehabilitation challenges. Even though much progress has been reached in the past decades, the prosthetic challenge of restoring the human hand functionality is still far from being achieved. Autonomous prosthetic hands showed promising results and wide potential benefit, a benefit that must be still explored and deployed. Here, we hypothesized that a combination of a radar sensor and a low-resolution time-offlight camera can be sufficient for object recognition in both static and dynamic scenarios. To test this hypothesis, we analyzed via deep learning algorithms HANDdata, a human-object interaction dataset with particular focus on reach-to-grasp actions. Inference testing was also performed on unseen data purposely acquired. The analyses reported here, broken down to gradually increasing levels of complexity, showed a great potential of using such proximity sensors as alternative or complementary solution to standard camera-based systems. In particular, integrated and low-power radar can be a potential key technology for next generation intelligent and autonomous prostheses.@en

To design an underactuated wrist prosthesis, a preliminary study has been conducted to identify the relationship between the Degrees of Freedom (DoFs) of the wrist during the execution of tasks of daily living. After the identification of the principal orientations of the wrist describing the tasks, polynomial functions were used to define a synergetic relationship between the DoFs. The latter can be implemented in a prosthetic wrist featuring one actuator to obtain motion along three DoFs, with the purpose of reducing compensatory movements.

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State of art upper limb prostheses lack several degrees of freedom (DoF) and force the individuals to compensate for them by changing the motions of their arms and body. Such movements often yield to articulation injuries, nonetheless these could be prevented by adding DoFs, for instance, an articulated passive wrist. Available stiff or compliant wrists with passive flexion/extension and/or
radial/ulnar deviation are sub-optimal solutions. Indeed, stiff wrists induce the individuals wearing them to perform exaggerated compensatory movements during the reaching phase while compliant wrists proved to be unpractical while
manipulating heavy objects. Here we present a wrist capable of combining the benefits of stiff and compliant wrists. It is provided with two switchable levels of passive compliance that are automatically selected. The prototype was integrated in a body-powered hydraulic hand prosthesis and actuated using the same hydraulic circuit of the hand. Detailed analysis of the parameters that affect the compliance, the critical load and the performance of the prosthesis are presented.
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