Design and analysis of a rope-driven elbow-wrist rehabilitation mechanism with joint dislocation compensation

ObjectiveThe rehabilitation training is the key to rehabilitation after fracture surgery. However, the existing rehabilitation robots have insufficient human-machine compatibility due to configuration limitations, and the rehabilitation effect is not ideal. Based on the anatomical structure of human elbows and wrist joints, considering that the dislocation of the human-machine axis was easy to cause the secondary injury to patients, a new elbow and wrist rehabilitation mechanism that conforms to the motion characteristics of elbows and wrist joints and adapts to its rehabilitation needs was proposed according to the rehabilitation medical theory.MethodsAccording to the motion characteristics of the elbow and wrist joints, a rope-driven wrist parallel mechanism and a joint dislocation compensation mechanism were designed to ensure the comfort and safety of the patient’s rehabilitation. The inverse kinematics of the wrist parallel mechanism was solved, and the relation between the wrist joint angle and the length of each driving rope was derived. The workspace of the wrist parallel mechanism was drawn to verify that the mechanism could meet the range of motion of the wrist joint rehabilitation, and the stiffness of the compression spring was determined by combining the motion and static analysis of the wrist parallel mechanism.ResultsThe analysis results indicate that the designed mechanism is capable of meeting the kinematic and mechanical requirements for elbow and wrist rehabilitation exercises, providing fundamental parameter reference for the prototype fabrication.