pic: 1675's REAL IRI Upgrade

[Lil' Lavery]

Open-field movement is not the reason to pick a mecanum, or just about any, omni-directional drive. The notable advantage is analagous to how these drive systems are used in the real world. The ability to translate in multiple axes without rotating the entire robot. This is particular useful in small, tightly packed spaces.

Think of how you parallel park in a car. Or, perhaps more of a direct analogy, moving from one normal parking space to the one next to it. That's not a very efficient or easy to execute series of actions in a FRC match. Strafing saves maneuvers like that in tight spaces.

Whether or not this is enough of an advantage to avoid the numerous drawbacks of mecanum systems is up to each particular team. I know that I won't support the selection of a mecanum system for teams that I'm associated with if FRC games continue to have a similar field lay-out and style of play. On the other hand, I probably carry a bias since an alliance partners' mecanum drive was a significant factor in ending my senior season in the Galileo semi-finals in 2007.

Originally Posted by Kevin Kolodziej

Found the video I was looking for. Its not exactly driving circles around the defender, but its certainly a maneuver that would not have been possible without mecanum wheels: http://youtu.be/PDsq1sEVVKs?t=2m28s

Sure it would have. "Bumper-locked spins" happen in FRC all the time. The real key to that maneuver was the open space where it was happening allowing for ~270deg of rotation. This type of maneuver is easily possible with a tank drive in a "side-impact" scenario like that. This isn't a perfect example, but it's one that was readily available and show the same principle being executed by a 6WD being defended by an excellent defensive machine who was on their way to Einstein.
http://www.youtube.com/watch?v=Bzpo3vVeGEY#t=3m45s
e; Another example in the same video.
http://www.youtube.com/watch?v=Bzpo3vVeGEY#t=4m48s

Originally Posted by Ryan Dognaux

After watching the clip about 5 times in a row, I disagree with this statement. 1675's only goal at that point was to get on the other side of the defender and get to the scoring rack. During the two-robot spinning motion, 1675 was on the opposite side and there was really nothing to stop them from translating away from 2761, as shown below -



I think what contributed to this motion was the mecanum wheel rollers being pushed from the side by 2761. The real trick would have been timing the translation correctly.

Notice how they escape from the spin move at the end, they don't translate directly away. They "spin off" the block, similar to how a tank drive would. Everything in that maneuver could have been executed by a tank drive, and similar situations frequently happen.