Dual position locking joint design for a medical walker

Abstract

In this thesis we analyzed a joint created for a medical walker currently in the prototyping stage of development. The walker is designed to help a user stand up from a seated position. The joint holds two legs of the walker together in an 'x' shape. It must be able to lock in two positions and support the full weight of the user while he or she is getting up. We looked at four different locking mechanisms including a spring loaded pull pin, a friction bearing, a clutch, and an electronic solenoid. After weighing the pros and cons of each mechanism we recommend and present a design using the pull pin. In order to determine the strength and deflection of the loaded pin we modeled it both as a cantilevered beam, and a simply supported beam with three points of contact. We compared the hand calculations to FEA of solid models and found that modeling the pin as a simply supported beam is more accurate than the cantilever representation.