pic: 172 almost done-ish!

[K.Porter]

haha, not solid bar on the uprights, it's box tubing. As you see the robot there, it weighed 110 pounds. We've currenty cheese-holed the box tubing, and the holes you see on the back were prototype for a second ball manipulation system we've added.
A pair of 3/4" 12 inch stroke pistons are stacked vertically on the back, mounted to a plate and sensor. In Hybrid mode, we plan to extend one cylinder so that the plate will be within reach of the bottom of the ball, then command the robot to drive to the ball position, and then deploy the second piston to throw the ball straight up when it senses the ball over it. (all added up, we're ~118 pounds now, with a CG that isn't bad actually)

The steering system (mostly made of 1/4" flat bar...that's where the weight is) isn't an ackerman system, it's what we have dubbed a "red wagon drive." Both wheels and transmissions are attatched on a "yoke" that can pivot freely around a center pin. When one wheel is commanded faster than the other, the yoke pivots up to about 30 degrees in the direction of the turn, and pulls the rest of the chassis around in a smooth turn without having to slow down.

As for the pneumatics, the 2" cylinder does draw a lot of air, so it can be slow if we've been squandering our air fumbling with the ball or something like that. We don't anticipate any problems though. We used the same type cylinder on our tetra robot and didn't have any problems, and this year's game requires less arm actuation than that game did. To release the ball over the overpass, we can either bounce over, or toss over with forward momentum. Both work well so far.

Hope this answered your questions, I look forward to seeing you at Manchester!