AbstractsBiology & Animal Science

Replacement of load cells in the Rheo Knee. The possibility of replacing load cells in a prosthetic knee manufactured by Össur using a new sensing technology

by Guðmundur Þórir Ellertsson 1987

Institution: University of Iceland
Year: 2015
Keywords: Mekatróník hátæknifræði
Record ID: 1222041
Full text PDF: http://hdl.handle.net/1946/21587


Össur is an Icelandic prosthesis development and manufacturing company. One of their main products is a variable damping, electronically controlled prosthetic knee used by transfemoral amputees, called the Rheo Knee. In order for the controller to be able to simulate the human gait, it must collect information about the knee’s status within its environment. This is achieved through a set of sensors positioned throughout the prosthetic. Two of these sensors are load cells who measure the load the leg is bearing. The load cells utilized within the knee´s design are becoming obsolete. This is due to the evolution in electronic hardware, making them smaller and cheaper. The load cells takes up to much space and are time consuming and uneconomical to produce. The aim of this project was to find a viable replacement solution for the load cells, something smaller and easier to manufacture. The possibility of replacing the functionality of the load cells with a carbon fibre blade was investigated. This blade was incorporated into the knee´s structural design in a way that it’s flexural displacement could measured by a proximity sensor during the gait cycle. The properties of several components were researched and their behaviour under a range of gait condition were examined. This was accomplished by conducting a walking test on a prototype that incorporated the carbon fibre blade system. The results contain some promising aspects. The signal generated by the proximity sensor matched a derived signal from the load cell.