[Jimmy Cao]

I may be wrong, but i'm betting it's crab/swerve. It's clear that all 4 wheels are steerable (look at the wires sticking up).

After zooming in on the pic, you can see the chains linking the two front and two back wheels. I'm betting it's front and back linked crab. (And, is that an MA3 encoder? It looks like one =D)