🚀 go-pugleaf

assuming one is using optical encoders (with 2-phase output)
to measure position of a (rotary) robotic joint, what should one use
to then measure velocity??

two possibilities come to mind:

1) use the position encoders with some sort of digital differentiator
   
2) a specialized velocity encoder 

any ideas, suggestions, possibilities, clues as to the feasibility
of the above. in fact any we would welcome any sort of discussion
with regard to obtaining velocity information.

thanks in advance
apollo@ecf.utoronto.ca
.vp