Cable-Driven 4-DOF Upper Limb Rehabilitation Robot

This paper developed a 4-degree-of-freedom cable-driven upper limb rehabilitation robot and proposed a control algorithm of the passive training for this robot. Comparing with the conventional cable-driven rehabilitation robot, the workspace of this robot is increased by optimizing the distribution of the cable attachment points and by improving the mechanical design. The rotation structure of the upper arm module can change the distribution of the attachment points as needed, by which the cable tension planner can be satisfied in almost all cases. At the meantime, the internal/external rotation of shoulder joint can be achieved without the change of the cables configuration, which is also important for increasing the workspace and comfortability of utilization. The activities of daily living (ADLs) training can be achieved well without any manual adjustment. The related controller for passive training is designed, which includes a higher controller for trajectory tracking and a lower controller for keeping cable tension as the output of the tension planner in real-time. The passive training experiments are conducted on five healthy subjects of different body size. The results demonstrated that the passive training can be achieved well on different subjects and the cable tension controller is also working effectively.