Ayo call me Teo…

…the way my hand got ice on its wrist. Ok, ok ok, new intro style, but today’s session was about the wrist and a couple other things. First off, I realized that to express every character in the sign language alphabet you only need two degrees of freedom, so i worked on a differential wrist design to save space. Basically the wrist is just two stepper motors, with cycloidal gear ratio, that drives a belt to actuate the different axes.

Buttt, this was only the first half of this work session session. Off camera I printed the finger to test, and I realized a couple of problems and good things. First, the finger works how i intend it to, mostly. The major limiting factor is friction. On my design friction is both needed and should be avoided, so finding a balance is tricky.

On one hand friction between gears, allows the finger to hold position when oriented a certain way, which is good because it means the motor doesn’t experience any holding torque. On the other hand, too much friction stalls the motor out, which could lead to it dying. Basically, im using cheap ahh motors that are NOT designed for anything torque related, so I’m copping out and finding ways to make it work.

I plan to add bearing and limit range of motion through stoppers next session, so that’s all for now folks…