Beginning to design – Casey

This week was an exciting beginning to our process of 3D modeling. Using Rhino, I created a structure that will be used to mount other finger models to for testing and evaluating their designs. I plan to print it this week and begin refining my process for the evaluation of printed models.


Here’s the rendered image of what I designed.  The base is 3″x3″ and it’s 2.5″ tall.

The qualities that will be measured are pretty much set in stone. The activation energy of a prosthetic device is very important to its usability, so minimizing this will be one of the highest priorities. Next on the list is the efficiency of the prosthetic, in other words how much energy one has to put in to get a standardized amount of force out. The hardest to quantify is how well a prosthetic grips something, which cannot be measured by individual fingers alone. A combination of the friction of the contacting surfaces, the efficiency of its application of force, and how much of the prosthetic is able to make contact. This will have to be measured for objects of different sizes and shapes, such as rods and relatively flat boxes, but also includes the test of a pinch, which the prosthetics should be able to perform.

We will perform most of these tests by using a standardized force on the strings of the prosthetic, then adding weight to an object until the prosthetic can no longer hold it. This week we hope to find a solution to measure the force that a finger can produce to calculate the efficiency, so I’ll have to design some sort of rig that will incorporate a pressure plate.

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