There is no apparent speed control, very much a forward/stop/backward for each side. Except it doesn't even allow one side to stop while other moves, to get an additional degree of turning ratio. Stop is synchronized. This would allow the sides to always be in sync as far as 2 outers on one side working with mid of other.
So really, the only motion it is capable of is forward, backward, turn left, turn right, and stop.
The turns will always be the sides running opposite, never a one-side-stop situation.