  Existing prosthetic/orthotic designs are rarely based on kinetostatics of a
biological finger, especially its tendon-pulley system (TPS) which helps render
a set of extraordinary functionalities. Studies on computational models or
cadaver experiments do exist. However, they provide little information on TPS
configurations that lead to lower tendon tension, bowstringing, and pulley
stresses, all of which a biological finger may be employing after all. A priori
knowledge of such configurations and associated trade-offs is helpful not only
from the design viewpoint of, say, an exoskeleton but also for surgical
reconstruction procedures. We present a parametric study to determine optimal
TPS configurations for the flexor mechanism. A compliant, flexure-based
computational model is developed and simulated using the pseudo rigid body
method, with various combinations of pulley/tendon attachment point locations,
pulley heights, and widths. Deductions are drawn from the data collected to
recommend the most suitable configuration. Many aspects of the biological TPS
configuration are explained through the presented analysis. We reckon that the
analytical approach herein will be useful in arriving at customized (optimized)
hand exoskeletal designs.
