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If you speak two languages, you're bilingual.
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Final-ish design of this year's robot. Everything above the turret is assembled off-board but has been tested, everything below is built and assembled, still need to run wiring up top and attach the side panels with sponsor logos. 10 Motors (ugh): 4 CIMS on AndyMark SuperShifters (with pneumatics), 2 FP's with AM planetaries up top, Van Door motor (welcome back) on the paddle, windows on the turret & elevation drives, PG-71 on the conveyor, and a gazillion feedback sensors. Can't believe it's under weight with margin to spare and the CG is 15 inches off the floor.
Discussion
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09-02-2012 15:53
Bill_B
Re: pic: Mad Rockers FRC Team 2973 2012 Robot
Jury is still out on the use of two team numbers on the same side. BUT decidedly illegal is having four balls aboard. You don't want to give opponents points for pickup an extra ball.
09-02-2012 16:16
~Cory~
Re: pic: Mad Rockers FRC Team 2973 2012 Robot
I think the fourth ball is for illustrative purposes...
How much compression did you guys decide on for each ball?
09-02-2012 17:18
Gary Dillard
Re: pic: Mad Rockers FRC Team 2973 2012 Robot
The ball at the shooter is just to get the vertical spacing right; we've cut the numbers but haven't put them on the bumpers yet - still not sure which way we'll go, but for the image we put them both sides on front.
We've found that these balls are fairly insensitive to the compression as far as either slipping or binding - the 6" 2009 wheels are 3.375 on center (2" spacer at the hubs) we have about 8.5 inches from the plate to the axis of the wheels on the conveyor and close to 10 inches (barely touching) on the shooter. I'm sure there's some optimum spacing but we just picked one on each of the prototypes and they worked well so we stuck with them and designed around them.
09-02-2012 17:22
Madison
Re: pic: Mad Rockers FRC Team 2973 2012 Robot
Gary,
I'm interested in learning more about the wheel on the forked arm at the intake. It looks like the idea there is that the wheel and forked up ride up over an incoming ball such that the wheel finds itself in the center of the quarter-round ramp? So, essentially, the ball and wheel are each rotating about one another in space?
If so, that looks like a pretty cool idea and nothing I've seen on an FRC robot before. I'd love to see some video of it in action.
09-02-2012 17:37
Gary Dillard
Re: pic: Mad Rockers FRC Team 2973 2012 Robot
Madison - good catch. We had 2 smaller wheels there in the original design, then we went to 1 larger one this week but haven't tried it out yet. The forked paddle was always multi-functional - push down the bridge, push in balls and lift them to the conveyor. The design thought behind adding the wheel was first that we might put it on the barrier and lift the front of the chassis up to drive over it. Then we decided it would be a good idea to have a rolling interface at the bridge. The balls were an afterthought, figuring we would just slide them rather than roll them - the small wheels were too low touch the balls, and this one is marginal. We may put the smaller ones back on in addition, closer to the ball centerline.
10-02-2012 07:42
Warren Boudreau
Re: pic: Mad Rockers FRC Team 2973 2012 Robot
It looks like a good design.
And no PVC.
My have times changed.
NOTE: Inside joke between Dillard and me.
10-02-2012 10:11
Gary Dillard
Re: pic: Mad Rockers FRC Team 2973 2012 Robot
cpvc spacers on the wheel shafts. It just feels empty without some PVC somewhere, doesn't it?
10-02-2012 10:50
Taylor
Re: pic: Mad Rockers FRC Team 2973 2012 Robot
That is eerily similar to our design. I hope you do well 
24-02-2012 13:28
Gary Dillard
Re: pic: Mad Rockers FRC Team 2973 2012 Robot
So, the wheel and paddle works great if the ball is close to the center of the ramp, not so good if it's to the side - it tends to bind up. We added additional wheels to either side (total of 3) and moved the ball sensor farther inboard (which actuates the paddle), and so far that seems to resolve the problem. Actually broke the joint at the top of the paddle a few times coming up with a fix - that van door motor has tons of torque - but we just kept drilling and replacing rivets until we had a fix, then we bolted it together.
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