[ErvinI]

The way I've seen it called usually is if the attacking robot "follows through" the tip. In other words, after the charging robot unbalances the second robot, if they back off and the other robot still tips over, I typically don't see refs calling it. If, on the other hand, the tipping robot already has a few wheels elevated but the attacking robot is still pushing them and this causes them to be knocked over, then the foul is usually called.

That being said, I have seen some pretty nasty tips that are not called, so it really depends on the ref. I have yet to see a team get a foul after they backed off, however.