To automate the knives positioning there are several options:
Have one single servomotor with a clamp that takes every knife individually and positions it to the programmed measure. This system offers high precision, but to do a 20 knives complete positioning may take up to 1,5 minutes.
The other option is a servomotor per each knife; which allows moving all of them at the same time. This system offers the same precision and additionally great positioning speed, as it does a complete 20 knives positioning within 2 or 3 seconds.