Relevance of Series-Elastic actuation in rehabilitation and assistance robotic: Two cases of study

Abstract

This paper presents two cases of exoskeletal platform, embedding a properly-designed element working both as power-transmission and torque-sensing unit. This element belongs to the Series-Elastic-Actuator (SEA) category, as it provides a mechanical stiffness in-series with the active motor, and provides measurement of the torque by means of its deflection. This allows presented exoskeletons to realize an intrinsically safe (as for the compliance) and controllable (both in position and torque) interaction with the user. The two cases respectively deal with upper-limb post-stroke rehabilitation and powered assistance for the lower-limbs. The former exoskeleton - namely NEUROExos - was used by therapists to record experimental torque-angle profiles from desired rehabilitative sessions on the subject's impaired limb, in order to assess quantitatively the current joint resistance and evaluate patient's progression. The latter exoskeleton - namely APO - allowed the implementation of a torque control for gait assistance. Both systems, despite being rather powerful and in close contact with the human body, embeds safety checks and features, which allow them to safely operate in physical contact with the user, without the risk to harm him/her.