pic: Frop Drives

[joeweber]

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[joeweber]

The Tittle should have been "DROP DRIVES" Wrong key pushed.
I wish we would have had the worm drives from Andymark available when we designed it, it would have saved us a lot of trouble. Anybody ever try to find and purchase beveled gears, the affordable ones have too small of teeth and larger teeth are unaffordable. If we added a small Andymark motor to each of the drives it would have been just enough for high speed across the field and more power when pushing. We thought this was our perfect drive system but did not want to go with eight motor drives so we give up and will go to the supper shifters and call it a day. Toooooo much prototyping this last build. Not again.

[Joey Milia]

Interesting set up, they look pretty cool! I like the sheet metal construction.

Just a few questions about them
What bevel gears did you end up using?
looks like there's a lot of space between the cim and the rollers, is that for a pneumatic to lower then on the ground?
Did you ever have any problems with the timing belt skiping when using the rollers, it doesn't look like you have very much wrap on the pulleys?

sweet wheels
thanks

[joeweber]

We ended up using bevel gears that were made for us. The problem was that they could not make them with a larger DP so we had trouble with them slipping at our first competition. We turned the motors at a right angle for our next competiton to get rid of the beveled gears and that worked much better but with all the friction from all the pully's the CIM's did not have the powere needed for high speed. Below is close to what we actually came up with.


http://www.team1322.org/ideas.htm

[joeweber]

Heres a picture of the bevel gears

[CENTURION]

Was that block machined with a hacksaw and files? Looks like a pretty solid design.

[joeweber]

Band saw, we try to do what we can in house. It seems when you send it out it becomes a low prioity.

[Joe G.]

Very cool! I love how compact the bevel gear makes the system. I've always admired your team and your somewhat unconventional creations, even if they don't always work out quite right. Your 2010 drive comes to mind as well.

What was the rationale behind the multiple rollers rather than a single traction wheel? It looks like it may have compromised your belt tension through inadequate wrap, and as you said, the friction from all the idlers wasn't doing you any favors.

How high were the traction rollers actuated off the ground when in mecanum mode? On similar systems, I've seen teams underestimate how high the traction wheels need to be raised to get them out of the carpet, which causes drag and slows the mecanums down. Plenty of teams manage very fast mecanum drives on four CIMs, so I feel like something else may have been in play.

[pfreivald]

It's very neat, but seems to be a lot of complexity for what amounts to an octocanum drive.

Here's a pretty good closeup of ours: http://www.chiefdelphi.com/forums/sh...d.php?t=111839

It was rugged, reliable, and did almost everything we wanted it to -- almost all COTS, too.

[joeweber]

Originally Posted by Joe G.

What was the rationale behind the multiple rollers rather than a single traction wheel? It looks like it may have compromised your belt tension through inadequate wrap, and as you said, the friction from all the idlers wasn't doing you any favors.

How high were the traction rollers actuated off the ground when in mecanum mode? On similar systems, I've seen teams underestimate how high the traction wheels need to be raised to get them out of the carpet, which causes drag and slows the mecanums down. Plenty of teams manage very fast mecanum drives on four CIMs, so I feel like something else may have been in play.

In 2011 We used belts to drive our Mecanums, they worked great. We were thinking that if we just drop the belt to the ground we could get the traction and power that we needed by just droping it with penumatics. During design we found that it was't much more work to add rubber to our idler pully's that were on the ground. The 2011 bot moved quickly so we thought that this drive would move quickly also, like you say we under estimated the drag on the belt system. We adjusted the lift off the ground enough to just clear it. Durring our last competion we started to remove pulley's and gained speed each time but we could never reach the full speed until we removed all of them.
It's been fun trying to come up with designs different from main stream and has paid off with some awards but we usually work on them for a couple of years befor we put them on a robot, but this year we didn't wait and we should have. We have more Ideas but we are at a point were we want to start wining and are changing how we do things. Watch out the upcomming years we will rock.

[rwkling1]

Originally Posted by joeweber

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Impressive, very impressive.

[DonRotolo]

The title made me laugh.

Many (many) years ago, in university, I had a professor with a speech impediment. He called them "Frip-Frops". (This was when a TTL Flip-Flop IC was relatively new).

[joeweber]

Just because we build robots don't mean we can spell em.

[joeweber]

Here is a picture of the robot the drives were on, 2013 Frisbee game.

[asid61]

I think that is the coolest 2013 robot I have ever seen. The tilted drive wheels and the loop for the frisbess... my god.