Too bad that thread is locked, because that is interesting.
It looks like he used servos from a Lego Robotics Kit.
That project would have cost millions of dollars at NASA if you called it a Mars rover.
I did a yahoo search for "raspberry pi tutorial for servos" and got a bunch of results including video tutorials on youtube.
You might want to check those out.
I would rather use
servos and pi for a glider that uses a weather balloon to launch, and GPS for homing guidance system.
Now that I look at the prices of new servos, I am steering towards salvaging them from discarded broken RC toys.

Coding things my way since 1981 -- Currently using AppGameKit V2 Tier 1