Re: Picking up from both sides
 

Here's how our team is thinking of building a chassis that can do it. Still tweaking a lot, of course.

http://teamwork.saintsrobotics.com/a...nt.php?aid=671

Re: Picking up from both sides
 

Cost benefit analysis... That is all.

The thinking is: Why build a heavier, more complicated robot (though marginally) robot when all you need to do is rotate 180º? Of course, the perceived values of each are up for debate - some may think it is worth the time/driver effort to have that extra intake - I don't. But we're hardly shying away from complexity. We're just trying to win.

As an aside, the complexity is beyond just designing it. You need to have an effective way to queue the balls coming in from both sides without jams or other issues, and perhaps take extra measures to keep a 4th ball out. Maybe you write some fancy code to do all this for you and keep matches running smoothly, but you had to write that code. So the question is always, is it worth it? Maybe having to change robot orientation will be a frequent necessity and thus a hindrance if you have only one intake. I am under the impression it will not be.

I should say that our team has made no official decision regarding this (as far as I know). I'm leaning towards a single intake, but the team may feel otherwise, based on predictions of game mechanics, etc.

Re: Picking up from both sides
 

It turns out that our double intake is the least of our worries, heh. What goes on top of it (after we've staged 2 balls vertically in it) is on iteration #4. That's three full conveyor/shooter systems I've CAD'ed in the wee hours that won't be used.

I think the fourth one's a keeper though. It's simple enough that there wasn't a single objection or criticism to the ball pathing sketch, and the part count is down by about half from the first conveyor, heh. It even looks like our electronic worries will become irrelevant and our secret for success is ... more flexible ... muahahahaha. (Car Nack here we come!)

Even with all the work, it feels like we're so far behind. The lower frame comes back from welding just tomorrow.

Re: Picking up from both sides
 

cannot reach this link without a login. Saints? or sinners? ;)

Re: Picking up from both sides
 

The thing about rotating 180 degrees is that it sounds simple, but there are more complications to the rotating than there are to the translating to get to the ball. Other robots for one, rotating into the path of one in the wrong place could score for the other side. Also rotating and touching the ball before you're ready to pick it up will send it off in some other unreachable direction that is not likely to be part of your planned 180 degrees. Seeing a ball on my left side, I want to reach for it with my left hand instead of wheeling about to get the right hand into position.

Re: Picking up from both sides
 

Oh yeah sorry. I posted a pic up on pinypic now:

EDIT oops too big xD here we go


To make big: http://oi44.tinypic.com/2vrvltw.jpg

Re: Picking up from both sides
 

What's going on with all those belts near the wheels?

Re: Picking up from both sides
 

Nothing... =p

That's just the drivetrain. 1: 49 reduction from CIM to wheel. The other sprocket on the outside of the mechanum wheels is a secret, though =p

Re: Picking up from both sides
 

It is a good idea but it is not really necessary because this year you can only hold up to three balls at once

Re: Picking up from both sides
 

We plan on using systems of poly cord and as thay approach the center of the robot from all for sides turn to 4 vertical poly cord systems that will lead the balls to our shooter.

Re: Picking up from both sides
 

You may want to rethink having a reduction that high. At that reduction your top speed will end up at something like 3 ft/s (assuming 8 inch wheels) and actually less because they are mecanum (2ish maybe?). Something like 16:1 or less would be much more appropriate.

And I'm going to hazard a guess that you're planning on running a belt between the mecanums (mecana...? :P ) and riding over the bump like that? Unless it's a hefty belt I don't know if I would trust it with my robot's weight.

Re: Picking up from both sides
 

Thanks for pointing that out. 7" pulleys are waaaay too big. We will shrink them.

The belt between the mechanums will be supported by a rail. Of the two pulleys that this belt will ride on, one will be fixed to the axle, the other will be free spinning, so as to not force the belt to skip when the mechanums are spinning in opposite directions.

Re: Picking up from both sides
 

Looks beautiful! Those wheels down there look amazing!

And as for the OP, picking up from more than one side can result in accidental pickup of more balls than intended, leading to a foul (although by now you probably already decided on your pickup mechanism, just my two bits worth :p ).