Wrist Exoskeleton Actuated by a 2-RRU-U Parallel Manipulator

This article has as the main subject the exoskeleton devices used in rehabilitation applications of the wrist joint for patients who are in the recovery period after suffering a stroke. Exoskeleton devices have some advantages compared to classic therapies, such as the possibility of performing rehabilitation exercises from the comfort of your own home. Therefore, in this article, a short state of the art with the main devices developed at the present time was carried out. By developing a structural analysis, it was shown that the parallel manipulator structures used for the development of the exoskeleton have 2 DoF, and they can contain RRU, RTU, or TRU connection legs. Next, the kinematic analysis of the structure with RRU connection legs is presented, from which the transmission function for the four-bar linkages was extracted. The study continues with the optimization of the synthesis in order to achieve a higher value for the minimum input transmission angle and a lower value for the total size area. Using the optimized results, a 3D prototype and the performance analysis were developed. The main conclusion of this article is that the presented 2-RRU-U parallel manipulator can be a suitable proposal for a rehabilitation exoskeleton-type device due to the optimization of the total size area and the higher value of the minimum input transmission angle.