Analytical Study of the Distribution of Grip Forces Dependence on the Coefficient of Friction for a Hand Prosthesis

Data on the distribution of forces acting on the phalanges in individual hand grips are sparse and are usually based on expensive human experiments or time-consuming computer calculations. However, they are essential for the proper design of prosthetic hands. Our goal was to create a simplified model to determine the dependence of these forces on the static coefficient of friction between the cylindrical cylinder held by the hand model, replicating the edgewise objects of everyday use, and the inner surface of the prosthetic phalanges. We created a CAD model of human hand kinematics based on literature data. The cylindrical grip was tested for a 70 mm diameter cylinder mimicking a 1 L bottle. The results showed that the relationship between the tested static friction coefficient and finger-cylinder forces is nonlinear. In the next stages, we plan to validate the obtained force results and use the data in the mechanical design of the prosthesis.