The Design of a Hybrid Exoskeleton for Distal Arm Rehabilitation

Abstract

An electrical actuated exoskeleton based on a hybrid mechanism is presented for the rehabilitation of elbow, forearm and wrist after fracture or contusion. It is comprised of a parallel 2-URR/RRU mechanism for elbow and wrist and a revolute joint for forearm. Based on screw theory the mobility of 2-URR/RRU is analyzed. The output revolute axes of 2-URR/RRU are perpendicular to each other and the distance between them is adjustable which makes it suitable for different arm length. The inverse kinematics of 2-URR/RRU mechanism are derived for position control. In the aspect of mechanical design, it is actuated by DC steering engines and a three dimensional force sensor is used to regulate the contact forces between patient and robot. Its height and angle are both adjustable by hand to enable the patient have a comfortable posture during the rehabilitation sessions. It can realize rehabilitation exercise for each joint and the ranges of motion meet the rehabilitation demands of daily living.