17-02-2008 01:36

Ian Curtis

Re: pic: 172 almost done-ish!

Where are you guys hiding the depleted uranium, doesn't look like 120 lbs to me.

Is that an Ackerman steering system I see?

Nice use of the 2" bore 24" throw cylinder, we've always wanted to use it just for kicks. Do you have any problems with air?

To score, do you simply release it and it bounces over, or do you drop it while moving towards the overpass?

Is there some unseen part that utilizes the holes on your uprights, or are those remnants of parts unused?

Looks good guys!

Wait a sec, are you uprights solid 1/2" flat bar?! If so, I guess that's where you're hiding the weight. Any particular reason for that choice? Also, anticipate any problems with center of gravity and tipping?

17-02-2008 11:29

K.Porter

Re: pic: 172 almost done-ish!

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!

17-02-2008 12:23

Jethr0

Re: pic: 172 almost done-ish!

how long does it take you to hurdle, and how many fps can you go? we've seen that it takes about 10-20 seconds to hurdle, and the average fps is about 11 or so.





p.s. GO MAINE!

19-02-2008 16:58

Ian Curtis

Re: pic: 172 almost done-ish!

Quote:

Originally Posted by K.Porter 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.