Here is a short paper that discusses the design considerations for prosthetic hands in a manner that is easy to understand and follow because of clear diagrams.

Intelligent Robotic Hand Design
Project Number: ME-YMM-1236
DESIGN AND ANALYSIS OF A ROBOTIC HAND FOR USE AS A PROSTHETIC DEVICE
A Major Qualifying Project Report Submitted to the Faculty of the
WORCESTER POLYTECHNIC INSTITUTE
in partial fulfillment of the requirements for the Degree of Bachelor of Science in Mechanical Engineering
by Matthew J. Rowell and Douglas D. Whitcomb
Date: April 27, 2006
https://pdfs.semanticscholar.org/1834/e3de7bd2dd70eee678ff7043ec9fad7905...