A low cost continuous passive motion (CPM) machine, the Gannon Exoskeleton for Arm Rehabilitation (GEAR), was designed. The focus of the machine is on the rehabilitation of primary functional movements of the arm. The device developed integrates two mechanisms consisting of a four-bar linkage and a sliding rod prismatic joint mechanism that can be mounted to a normal chair. When seated, the patient is connected to the device via a padded cuff strapped on the elbow. A set of springs have been used to maintain the system stability and help the lifting of the arm.
In this work a multi-body simulation was performed with the software SimWise 4D by Design Simulation Technologies (DST). The simulation was used to determine the stiffness of the springs in the mechanism to provide assistance to raising of the patient’s arm. Furthermore, the software can provide a finite element analysis of the stress induced by the springs on the mechanism and the external load of the arm. Finally, a physical prototype of the mechanism was fabricated using PVC pipes and commercial metal springs. Due to the low cost of fabrication, simplicity, and ease of adjustability, it is believed that the GEAR has the potential to provide effective passive movement to individuals who otherwise would not have access to post-operative or post-stroke rehabilitation therapy.