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Originally Posted by Lireal
What were the issues that you had?
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The major problem was that when you impart a force to make the balls turn you're also giving a force that wants to make some of the balls come out. So you couldn't immediately go full power without risking unseating some of the balls. You could just go partial throttle to start though and you'd be ok, but that basically meant that you wouldn't want to ever get in a pushing match either.
These balls are larger and heavier than the ones that I used while having an identical amount of power so it's possible it might not be quite so bad. Another difference is that in this system the spring is the balls. I don't know if that's good or bad though. I don't know that this system is radically better as far as keeping the balls in.
To me it's almost uncanny how similar it looks: We used a 1x1 tube frame with two different levels that was mostly 90 degrees except for the pieces at 45 degrees over the top of the ball. Also, this doesn't matter functionally, but seeing this image really surprised me because one of the types of balls we tested was bright yellow. We also ran with 4 CIMs, one per side, but we used belts and pulleys rather than large wheels to distribute the power.
The second issue that we had was that it wasn't super controllable. There are plenty of robots that don't like to drive quite straight - most of them will just sort of wander off into a big cicrle though. This one liked to be going straight and then it would decide that one of the sides was going to just start going slower at unpredictable times. So you could be walking down a hallway with it and things are going smoothely and then the robot decides that it's going 30 degrees to the left of where it had been a second ago. I'd be interested to know if that was due to a flaw in our robot or if that's sort of inherent to this type of drive.
The third issue was how it stacked up to the alternatives for that year's game. It used four CIMs, which was as many as were allowed, but 2005 was also the first year with the AndyMark C-base drive chassis and gearboxes that could take all four of those CIMs. It wasn't the first year with powerful tank drives, but it was the year that it became easy and common. And this was before mandatory bumpers and for a game that was played in a largely open field. The name of the game was go someplace fast don't be movable once you're there - exactly the opposite of what this kind of drive gives you.