Jody A. Saglia, Nikos G. Tsagarakis, Jian S. Dai and Darwin G. Caldwell,, "Attuatore Lineare e Dispositivo di Riabilitazione Incorporante Tale Attuatore (Linear actuator and rehabilitation device which incorporates such actuator)",  Patent Number: I0134434.

Description
This patent describes a new highly efficient cable-driven, yet compact, linear actuator that combines high force capacity with low friction and high back-drivability. The system makes use of a capstan mechanism to convert the rotatory motion of a brushed DC electric motor to the linear motion of the actuator piston. The linear actuator is designed to be integrated in a platform type robot meant to serve as an ankle rehabilitation tool. The rehabilitation device is composed of three linear actuators connected to a fixed base and a moving platform which is linked to a rigid strut by means of a universal joint. The redundant actuation allows to control orientation and stiffness of the moving platform, at the same time.

Project Page
Redundantly Actuated Parallel Mechanism of Ankle Rehabilitation