An Adaptive Arm-Weight Support Platform for 3D Upper Limb Robot-Aided Neuro-Rehabilitation

Arm-weight support has proved to be a key component in robot-aided neuro-rehabilitation in order to permit a wide range of motion for patients with severe disabilities. In this work, a novel motorized platform for sustaining the upper limb of patients during 3D robot-aided rehabilitation and its control architecture are presented. The proposed system is able to support patient's limb in the 3D space through upper limb kinematic reconstruction during the execution of reaching movements. The platform and the adopted control strategy have been tested on 8 healthy subjects performing point-to-point 3D movements. The trajectory executed by the forearm support has been monitored to assess the performance of the chosen control approach. Moreover, a questionnaire based on the Likert rating scale has been submitted to the subjects to evaluate the overall platform. Preliminary results showed that the proposed control algorithm allowed to follow the arm movement in $\pmb{3}\mathbf{D}$ space with a reduced position error $(0.002\pm 0.012$ rad $)$ , Moreover the subjects felt their arm completely supported, free to move in any direction of the space and judged the platform easy to use.