Drive Train & Control Types '07

[teenmisfit]

Originally Posted by Lil' Lavery

384, 1086, and 540 (the West Henrico Triad) actually used Mecanum, not crab.
With a few exceptions (111 @ MWR, 540 @ VCU, 175 @ BAE, and probably a couple others), the traditional "tank steering" drive has won every event. Although, this may be (at least in part) a bi-product of the vastly higher quantity of these drives.

Becuase now with all the power being put into drivetrains you need a solid way of connecting with the floor... high traction wheels and power will get you far in any years game.

[sdcantrell56]

I must say we are very happy with our 6 wheel drive system using 2" wide colsons and andymark 2 speed transmissions. We haven't been out-pushed yet after 2 regionals. and we haven't had a single problem with it yet.

[AdamHeard]

Originally Posted by Joel J.

I don't think they are using bumpers, and I think they are in the 110 lb weight class. So, they are at about 124lbs, with battery (maximum). I also read something about them weighing about 85lbs, because they were planning on adding ramps. If they didn't add weight to get to 110lbs, then they are really scrawny at 100lbs, with battery. That hurts their pushing power. 100*1.3 is equivalent to 150*.867, about the amount of traction advantage a full-weighted 4ft class robot would have with something even less grippy than the old wheelchair wheels that were in the kit. They have the torque, and they have the treads, but they are lacking the weight.

Do the old wheelchair wheels realyl have that much traction? The new AM wheels are 1.0-1.1 and they seem to have a lot more traction than the skyways...

And to contribute to the post; At LA we ran two small CIMs on each side to 1.2 cof wheels in a 6 wheel drive. We weren't traction limited and had a 9-10 fps top speed. For San Diego, we are probably switching to a small CIM, a large and a FP (modularity and CNCs = awesome) which will give us the same speed, but we will be traction limited so we we'll be able to push a lot better.

[ScoutingNerd175]

Originally Posted by teenmisfit

Personally i find 175 drivetrain to be wonderful. It isnt new but every year it helps them do wonderful. They use 2 drivetrains. One is the normal bot 6 wheel 4cim drivetrain and then they have another drivetrain mounted sideways underneath the chassis on pneumatic pistons. When this drive train pops down it enables them to physically move sideways.

Buzz's lateral drive is actually new this year. We have used the 6 wheel drive before (more than once), but not the lateral.

I hadn't seen any regionals in person this year, and it is very different watching the video feed where you cannot see the whole match. But I was at UTC this weekend, and I certainly came away with the impression that a strong drive train is very important this year. (last year as well, of course) It has certainly been important in other years, but this year there are many many ramp bots who don't score until the end of the match, and they play very strong defense during the rest of the match. I've seen really good and innovative scorers be shut down by great defensive bots. The scorers with stronger drives (and good drivers) are scoring.

[JSand]

Originally Posted by Adamskiy

There was one crab drive (1057), and one robot had mecanum wheels (I forget the number) with independent suspension.

I forget the team number as well but I saw the mecanum/suspension set up in their pits and it was impressive looking.

[RobJ]

Originally Posted by AdamHeard

Lack of pushing power? I think they would be upset if they heard that...

They have a 5fps/16fps (or 6/15 I forget...). The high gear is very fast, and the low gear is putting out a significant amount of torque, probably just around traction limited knowing them (which is a lot, using gum rubber roughtop tread... which is about the highest coefficient of friction you can legally get for wheels). So, I'd say they can push if they need to; They're just too busy scoring.

It is 5 in low and 15 to 16 in high. The first statement was true about us not having much pushing power as we weighed in at about 90 pounds at each event since we did not have ramps.

[Jeff Pahl]

Originally Posted by JSand

I forget the team number as well but I saw the mecanum/suspension set up in their pits and it was impressive looking.

That was ours, team 1379. It works great, you can drive over a 1x4 with it! Perfect for driving over field debris.

I will ask Matt to post some pictures of it when we get the robot back this week.

[Carpe_Noctem]

Our crab drive made getting aligned to ramps alot easier...
a lot of robots had to get running starts to make it up some ramps.

[cbale2000]

Team 703 took a deviation from our normal tank drive system and came up with a new powerhouse drivetrain....


14 WHEEL TANK DRIVE!!!!!



No joke either,

For more info, see This link, and This other link

[Otaku]

At the Silicon Valley Regional, I saw a few teams with omnidrive wheels (two, three teams maybe), only noticed one team with Mecanums, and a lot of 4 or 6-wheel tank drive systems. A few rocker chassis, too. I know teams 100 and 254 were running rocker chassis setups.

675 ran a 4-wheel tank drive setup with one CIM+Gearbox per motor.

We also saw one or two teams with authentic tank tread setups, I know 670 (Homestead Robotics, HRT) ran tank treads.

I forget the number of the team, but I saw a mecanum-bot going sideways at the practice area at San Jose and it was really cool looking -- now I want to build a bot with Mecanums.

[Jared Russell]

We (341) used four AM Plastic Omniwheels this year. At Jersey, they were arranged in a diamond (kiwi style). However, we had bad slippage and controllability issues with this configuration.

For Chesapeake and Philly, we re-oriented the wheels a bit. The front left and rear right wheels go forwards/backwards, and the other two go left/right. This allows for:

1. Stability from all four corners of the robot.
2. Higher straight line speed in the principal axes than either kiwi or mecanum drives of the same gearing.
3. Mechanically straight driving. Try getting a kiwi bot driving straight without slippage or sluggish response, even with encoders and gyros! (We did, we failed, and then we changed it).

The drive is still holonomic, but way easier to control and operate in this configuration.

I also believe that this makes 341 (and I could be wrong about this) the only regional winner with a true holonomic drivetrain.

[EricH]

Originally Posted by Otaku

I forget the number of the team, but I saw a mecanum-bot going sideways at the practice area at San Jose and it was really cool looking -- now I want to build a bot with Mecanums.

I suspect you mean 1072, Harker Robotics. Unless 1138 was up there. (The two most likely that I can think of, and I know that 1072 was up there.)

[Jeff K.]

Originally Posted by EricH

I suspect you mean 1072, Harker Robotics. Unless 1138 was up there. (The two most likely that I can think of, and I know that 1072 was up there.)

We didn't go up to San Jose, so it was probably 1072. I remember seeing a mecanum bot at LA that didn't use the AM wheels. It caught my eye because they used a record as their rotation control. Was that 1072?

We went with the AM wheels. Got the job done, and we had a decent amount of pushing power and controllability.

[AndyB]

We, for the first time ever, used a "Sworm" drive. It is, to the best of our knowledge, the first application of a worm gearbox crossed with a crab drive. It has 180* rotation and our driver has done well with it.

I have noticed this year a few crab drives (1 at St Louis, 2 at GTR). There were a few teams using traditional omni-wheels with a diagonal setup (854) and a good number of teams trying out mecanums.

[JohnMorenski]

we've got 2 speed pneumatic AM shifters with custom made direct drive shafts connected to a wheel then the direct wheel has a chain going to another wheel on each side we have a small drive wheelbase in the back with omni wheels in the front for stability
we also had 4 custom 3"wide wheels with an 8" diameter