The first thought in my after watching the videos was electromagnets, but now i am pretty certain its not the best way to go. Mainly because it will draw too much current and drain lots of power (snatching it from the motors), the electronic noise it will create has to be monitored using some H-bridges or something similar to save the motors, because it will hurt that for sure, thus increasing needless complexity. Also the magnetic grip wont be as powerful as you want it to be.
It would be pretty cool if some teams could actually use it effectively, so good luck to them.
Vivek.
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