Redesign of the Shoulder Elbow Perturbator

The Shoulder Elbow Perturbator (SEP) is an apparatus used to measure the force resistance against sudden stretching of the elbow by stroke patients, while simultaneously modulating shoulder abduction and adduction effort. The SEP is in development by the company Hankamp Rehab. A first prototype was produced but it contains a number of problems. During execution of the internship solution are proposed for the several problems and a redesign of the SEP was performed. The stiffness of the construction and especially the arm holder in the design was a problem. By making a third Sarrus linkage in the design the stiffness improved theoretically with 53.7% in the most unfavorable orientation of the arm holder. A gravity compensation system enhanced in the design was improved by reducing the number of pulleys and changing the selection of bearings used for the rotation of those pulleys. The number of pulleys was reduced by 1 by rotating the entire setup of this gravity compensation system, including the Sarrus linkages, toward the axis of ration of the arm holder. Safety end stops in the design of the SEP were difficult to change in position. A new setup for those end stops was designed where the position of those end stops could be fixed with a pin-hole connection present at the edge of the frame supporting the SEP. Besides this, a housing was designed to protect user from the moving parts. Also some minor issue in the design which could relative easily be resolved were addressed. As a result the proposed improvements to the design were incorporated in a new SolidWorks file, which makes it possible to view the features of the improvements/new design in a 3D-environment.