Stopping a Triple Balance

[dellagd]

UNLESS your mecanum-drive robot has (1) "super-creep" (low geared, high torque - I think that's what they call it, I'm not a mechanical type) mode where it just crawls right up there, alone OR pushing another bot, and (2) "e-brake" gyro-based software which enables it to hold its position on the bridge using micro-adjustments (that's in lay terms and I might not be getting it right, but it's the general idea).

I dont believe torque is the problem with mecanum wheels. The problem is that mecanum wheels just arnt designed to go up a ramp. I believe that when going up, the rollers on mecanum wheels (those that are the whole reason the function to strafe) just act like casters and you slide down the bridge. This is what we saw in very early testing anyway. In a way, this can be looked at as having "very low traction" on the bridge.

Anyone else see the same thing?

[Squillo]

Well, all I know is that our (mecanum) wheels have absolutely no trouble going up the bridge (which is built as best as we could to spec, with the proper surface covering). Or stopping on the bridge while it is fully tilted. I guess I will leave it to the techies (I'm just the rulesmeister) to explain why (except I don't think any of them are on here).

And of course I'll eat my words if it doesn't work that way on the competition bridge. I love words, they're so tasty, I eat them all the time. (now what smiley would you put here? wink? embarrassed? ???)

[pfreivald]

Originally Posted by Squillo

Well, all I know is that our (mecanum) wheels have absolutely no trouble going up the bridge (which is built as best as we could to spec, with the proper surface covering). Or stopping on the bridge while it is fully tilted. I guess I will leave it to the techies (I'm just the rulesmeister) to explain why (except I don't think any of them are on here).

And of course I'll eat my words if it doesn't work that way on the competition bridge. I love words, they're so tasty, I eat them all the time. (now what smiley would you put here? wink? embarrassed? ???)

We can drive up the bridge and balance with just our mecanum wheels, too -- though balancing is even easier and more consistent with the traction wheels down. Where the traction wheels shine over the mecanum wheels is not moving nearly as much when bumped by a clumsy or over-exhuberant balancing partner.

[Djur]

Originally Posted by Zoughtbaj

Likewise. At the Oregon Regional, just about every Mecanum I saw not only could not easily balance on the bridge, but had trouble even getting over the bridge. Interestingly, it would seem that CG would have a lot to do with that, but after what I saw, all the tipping and violence in the balancing process would simply cause the Mecanum wheels to slip. Traction wheels are definitely nescessary for a tripple balance.

We have mecanums and were very good at balancing in the Boston regional -- the robot never slid, nor did it take us more than 10 seconds to double balance. We also did a triple balance with 246 and 3958 on the practice field without traction problems.

EDIT:

Originally Posted by pfreivald

I think part of the issue is that some teams have their mecanums geared way, way too high for easy bridge-climbing or balancing... Though from what I've seen this isn't just a mecanum problem.

We're using 1:16 worm drive and gearing was a non-issue.

[pfreivald]

I think part of the issue is that some teams have their mecanums geared way, way too high for easy bridge-climbing or balancing... Though from what I've seen this isn't just a mecanum problem.

[Siri]

Originally Posted by pfreivald

I think part of the issue is that some teams have their mecanums geared way, way too high for easy bridge-climbing or balancing... Though from what I've seen this isn't just a mecanum problem.

I have to agree. I've had many a team tell me simply, "we can't climb the bridge; see, we have mecanums". They don't seem to realize that this is largely meaningless without specifying gearing, but I'd believe some of their ignorance may be spreading to some other teams.

[Djur]

Originally Posted by Siri

I have to agree. I've had many a team tell me simply, "we can't climb the bridge; see, we have mecanums". They don't seem to realize that this is largely meaningless without specifying gearing, but I'd believe some of their ignorance may be spreading to some other teams.

Again, mecanums are not unable to climb the bridges as demonstrated here and here (with lower weight and gearing). I'm not sure why people think that mecanums can't do this.

[PAR_WIG1350]

Originally Posted by Djur

Again, mecanums are not unable to climb the bridges as demonstrated here and here (with lower weight and gearing). I'm not sure why people think that mecanums can't do this.

Because they weren't here for the 45 degrees carpet in 2010?

[stingray27]

Just throwing this out there that 3572 did an excellent job playing defense and stopping 2054 from balancing in the semifinals of Niles FiM tournament. Great job guys! Thanks to 2834 as well for your shooting. Might want to get the topic back on to stopping triple balancing though.

[Squillo]

Well, we did actually have a LITTLE more trouble on the competition bridge, but it wasn't due to the mecanums. It was because our CG was too high. Midway through the competition we adjusted our weight distribution, and after that, we not only climbed the bridge, but balanced it successfully (alone and with a partner) several times.

The only sad thing was that we had a great strategy for achieving a triple balance with another very narrow bot (we tested it on the practice field, the two of us could actually climb the bridge side by side!) and any third bot, but neither of us were captains, and we got picked by the 6th alliance, and then the 7th picked them, splitting us up. So we never got to do it - and there was no triple balance at the Hawaii regional .

But overall it was a fantastic competition (the field system problems aside, that's another issue and we know they're working on it), our first elimination victory (we went down 2-1, but at least we won one! Last time we made it to quarters we lost 2-0), and it was great to see our bot dunking balls consistently in hybrid, picking them up, scoring, and balancing. Really rewarding to see all that hard work pay off.

So for us, next year starts tomorrow.

[Hawiian Cadder]

In the elimination round at Denver we successfully defended against a triple balance team, in the second match we were unsuccessful because they prevented us from crossing the field until the end of the match. I think that an alliance geared towards a triple balance should take a hard look at playing anti defense until 2 robots are on the bridge by preventing defenders from crossing the field or interfereing. Once we figured out that they would block the cooperation bridge and switched to our alliance bridge for crossing, they were unable to complete the triple balance.