Diseño y construcción de un prototipo de prótesis funcional de dos grados de libertad accionado por cables para amputación transradial.

Abstract

The objective of this project was to design and build a functional prosthesis prototype with two degrees of freedom actuated by cables for a trans radial amputation. To define the main design parameters, after collecting the information, the QFD matrix was applied. In the conceptual design, the corrected ordinal method of weighted criteria was applied to determine the alternative solution with the highest priority to be developed for each module in which the modular structure was divided, a prototype suspended from the patient's torso was obtained with a support of shoulder and fastened with velcro, the flexible socket made of TPU and the prosthetic hand with two mobile phalanges for each finger made of PLA. The patient by himself actuates the prosthesis through two body movements: flexion of the elbow and ante pulsion of the shoulder, through the cable system he produces closure of the hand and flexion of the thumb, respectively. The modeling was carried out in the Solidworks software for its subsequent dynamic validation in the Adams View software and its structural validation in Ansys. A test prototype was built in PETG through additive manufacturing, to be used on a person without disabilities. In the velocity and acceleration curves of the phalanges, obtained in Adams, a sudden increase in its magnitude can be seen at the beginning of the movement as an effect of the tension of the cables. Through structural validation, a minimum safety factor of 2.9 was obtained. Satisfactory results were obtained in the functional tests of the prosthesis for holding light and moldable objects. This demonstrates that the designed prosthesis is functional but is susceptible to improvements that increase its efficiency in handling small objects.