Design and Development of a 2 Degree of Freedom 3D Printed Myoelectric Prosthetic Arm to Sustain High Load for Amputees

Abstract

In our fast-moving world, the advancement in 3D printed myoelectric prosthetic arm has been
growing rapidly in the field of rehabilitation engineering. Prosthetic wrist needs to be small and
compact minimizing the space taken. There are few designs developed by other developers around
the globe; however, the designs have issues such as its degree of freedom and ability to handle
high load without failing. Available 3D printed prosthetic hand wrist can rotate the hand along xaxis, however movement of up and down along the y-axis has not been practically researched and
developed thoroughly. The main objective of this work was to design and develop a 3D printed 2
degree of freedom wrist joint for a 3D printed myoelectric prosthetic hand which can handle load
of up to 10kg. The wrist joint design was done in AutoCAD where it will be made available to
public for their development of 3D printed prosthetic hand and modifications. The design connects
the palm and the forearm of the 3D printed myoelectric prosthetic arm. This wrist has 2 servos
where one rotates about the x-axis and another rotates about the z-axis. Furthermore, the tendons
that move the fingers was carefully designed to minimize the tension when the wrist moves along
the x-axis and y-axis rotation. This design was developed to be made reliable and easy to assemble.
The lifting capability was tested and compared with the available 3D printed prosthetic designs.
The prosthetic hand was successfully developed with the new wrist design that can handle load up
to 98.1N. As the fingers could not handle load higher than 800g each, the weight was lifted at its
palm section connecting to the new wrist design.