Winning Drive Train

[Jon Jack]

Originally Posted by squirrel

Thanks!

We have a not very old tradition of sharing most of this type of data during build season....and we haven't found any down side to it yet....

I didn't mean of us not sharing it period, but of breaking tradition in this thread in actually using test data instead of saying 'well I saw team XXXX push every robot collectively at the ABCDE Regional' or 'Team XXX was better than Team YYY because a friend of a friend's girlfriend's sister's brother's nephew said so...'

Not that I'm advocating that we had the best drivetrain, because I don't think we did... To be honest the best drivetrain was different from team to team because each team played this game their own way....

[Akash Rastogi]

Adam, on Raptor's DT, did you have the two rear sets of wheels closer to each other than the front set? I saw this on a lot of the 6wd set ups and was wondering if you could evaluate and explain the advantage of the set up as a posed to a 6wd with equally spaced wheels.

O-O---O

Was this basically creating the effect of a 6wd with a drop center for turning purposes?

[SamC]

Originally Posted by AdamHeard

3who?

you know... those beach city robot kids... haha

[MrForbes]

4 rear wheels close to rear of robot, with weight over them most of the time, makes for very easy steering with the trailer.

[AdamHeard]

Originally Posted by Akash Rastogi

Adam, on Raptor's DT, did you have the two rear sets of wheels closer to each other than the front set? I saw this on a lot of the 6wd set ups and was wondering if you could evaluate and explain the advantage of the set up as a posed to a 6wd with equally spaced wheels.

O-O---O

Was this basically creating the effect of a 6wd with a drop center for turning purposes?

squirrel nailed it.

We ended up with a wheelbase about 36" wide and 9" long. Mathematically this turned better, but we did no testing to confirm such results.

We did however try removing the center wheel, which the driver complained was too slow at turning.

[Brad Voracek]

We did no testing, no precision drilling, just 2 holes on the ends of 2 pieces of box tubing, stuck an axle through them, wide drive base, the widest footprint and longest footprint we could give ourselves.

And it worked awesome.

Lol.

[Akash Rastogi]

I know its probably highly unlikely, but did anyone get to measure pushing/pulling forces on new FRP materials like on Einstein and compare the numbers to heavily worn FRP? It would be interesting to see how much the results differed from FRP dust and lots of other factors. Significant addition in traction? No effect at all?

[martin417]

Originally Posted by Jon Jack

I didn't mean of us not sharing it period, but of breaking tradition in this thread in actually using test data instead of saying 'well I saw team XXXX push every robot collectively at the ABCDE Regional' or 'Team XXX was better than Team YYY because a friend of a friend's girlfriend's sister's brother's nephew said so...'

You will note that on page 2 of this 5 page thread, at least one team did exactly that, post actual test methodology, along with resulting data.

[Lowfategg]

Did anyone run these tests on FRP on top of carpet like the real field is (at full robot weight)?

[sdcantrell56]

Our tests were run with the complete robot on frp over carpet so they were identical conditions to the field.

[notsteve]

to me it seemed like without traction control then nobody had much advantage with drivetrains, except the swerve drive's were pretty slick.

i also saw some of the most creative and out there ones seemed to be less effective, vs regular tank drive.

[Daniel_LaFleur]

Originally Posted by notsteve

to me it seemed like without traction control then nobody had much advantage with drivetrains, except the swerve drive's were pretty slick.

i also saw some of the most creative and out there ones seemed to be less effective, vs regular tank drive.

For all it's simplicity, regular tank drive is efficient and effective.

[Rob]

Well I could go on for a few pages on this one...but I will spare you all.

It seems to me in the few years I have been doing this that what works for each team is different. In general, if you do the simplest thing you feel you can get away with you can spend your time working on the details that make it work really well rather than just making it work at all.

For some teams this means building different things. To us, it meant using kitbot and kit transmissions and then spending our effort on follower wheels and traction control.

To an amazing team like 111, their incredible swerve drive is a given, and they still can spend their effort on just making it work well.

My hat is off to the teams that figured out the drive challenge this year. There were many paths to success, and you can find inspiration in looking at how some of the incredible teams in first got there.

Just remember that you can get just as much inspiration from making a simple system's details work really well as you can from just making a complex system work...

[Jared Russell]

Originally Posted by Akash Rastogi

I know its probably highly unlikely, but did anyone get to measure pushing/pulling forces on new FRP materials like on Einstein and compare the numbers to heavily worn FRP? It would be interesting to see how much the results differed from FRP dust and lots of other factors. Significant addition in traction? No effect at all?

I talked to people on 1218 and their driver commented that the unworn Regolith behaved completely differently than on the Archimedes field.

[Al Skierkiewicz]

Originally Posted by Akash Rastogi

I know its probably highly unlikely, but did anyone get to measure pushing/pulling forces on new FRP materials like on Einstein and compare the numbers to heavily worn FRP? It would be interesting to see how much the results differed from FRP dust and lots of other factors. Significant addition in traction? No effect at all?

Akash,
After several months of practice and several events, I have come to the conclusion that the point of contact with the floor of any wheel is so small that other factors seem to have little effect. I have seen small spots on the floor worn through the surface or have the high spots removed by repeated slipping in one spot. However, the chance of that small spot and your wheel meeting for increased friction is very small and only lasts a fraction of a second. In practice (at our shop) our wheels were picking up all kinds of debris from the floor including what appeared to be wax, to the point they were completely coated. At events, the field people were cleaning the floor at regular intervals to keep the grit to a minimum and clear the floor of the normal hardware, wire ties and insulation from wire. I examined several of these pads after a cleaning and found that same waxy type of coating and extreme amounts of dirt and dust. Anyone who was near the field knows that they were breathing this fine dust and it covered my laptop at the regionals where I inspected everyday. The good news is that every robot that practiced or played one match came off the field with significantly cleaner wheels than when they started. As inspectors we feared we would be making teams sand or clean wheels on a regular basis. That fear was unfounded during the first week regionals. I have a bag of sand paper and sanding blocks at home that went unused.
When we tested pulling force on our field there was no perceptible change from the first day to ship. And the same was true at several places on the floor. I would suspected that humidity might have made a difference but it turns out that the surface is sealed with an overcoat of resin.