pic: The Beginning (GM Milford Proving Grounds Team 548 2011 Robot)



This is where it all began. At the end of week two, our design, build, and prototype divisions delivered this drivetrain to electrical and programing. This is what it looked like prior to putting the arm, manipulator, and minibot on. They had code ready to go, and at the end of the day it was running. We were very happy with the drivetrain, and have only had a few minor difficulties with it. This drivetrain was designed to give us the lowest c of g possible, with the highest reliability possible. Even after putting the rest of our components on the bot, over 70% of our weight lies in the bottom 8 inches of the robot. The drivetrain was designed to be extremely reliable and is a 6 wheel design.
Stats:
(4) Sims
(2) 12:1 Banebots P80 Transmissions
(2) 6"x2" IFI center wheels
(4) 4"x1.5" IFI outer wheels
Live center hex axle with dead axles on outside wheels.
(The goal is that even if this drivetrain throws all 4 chain runs, it will still opperate like normal.)
#25 chain
The drivetrains highest point is 5" off of the ground, with the exception of the center wheel which is 1" taller.

Let us know what you think!

Its so elegant, no joke. I really like how every thing is so low to the ground, and you are only using 8 “major” pieces of metal.

How much does it weight w/o battery? How fast does it go? and How are the 2 different diameter wheels working out for y’all, did you have any problems with the 2 different wheel sizes?

I really like this, so elegant…

I don’t have experience with the Banebots P80 transmissions, how do you like them so far? Are they robust, unlike most other BB products? Looks good. Those large pockets in the material could easily be split into two smaller pockets each.

Did you have any issues press fitting your roller bearings into those water jetted side plates? or was there a secondary operation before pressing?

Looks very nice! It’s extremely similar to the drive design we have used the past 5 years on 125.

-Brando

how thick are those waterjet cut side plates? 1/8" 1/4"?

looks very nice btw.

We used the P80s in 09 and I can’t speak for this team but we hated them. They actually broke the night before ship and we had to come close to take apart our robot to swap them out. We stayed late that night to say the least.

Looks nice. What was the reasoning for using different sized wheels as well as not just using a spur gear transmission with gears from Andymark or other stock gears?

CIM --> 12:1 --> 6" wheel gives a speed of ~11 fps (theoretical) with direct drive. My guess is they wanted 6" wheels for the speed, yet also wanted the lower weight of 4" wheels (since there are 4 of them, that weight savings adds up). Since the outer wheels are driven via sprockets, this seems like a very logical setup for the drive train.

No troubles turning with the 1.5" wide wheels on the corners?

You’ve got it! Yeah, we have never had a problem with the P80’s, and we have put them through some serious wear and tear. They are great little transmissions, but I agree they are very fragile. The main problem that we had was the set screw holding the key in on one of the motors came loose and the key fell down the shaft, but again, that plays into the reliability thing, one of the motors failed, and the drive train could still function. We tested both the 4" x 1.5" IFI wheels and the 4" x 1" IFI wheels and they both had the same turning chop at high speeds, but with the weight as low as it is, we really had no issues turning. Also, the side plates are cut out of 3/16", and the cross members are 1/8" 1"x1" with 3/4" plugs in the end drilled and tapped. The entire robot, with the tower, arm, manipulator, and mini-bot deployment weighs in at 107 lbs. Thanks guys for all of the great comments, mainly we built this to be simple, reliable, lightweight, and robust.

I’d hate to bring back an old thread, but, how would one go about attaching bumpers to this type of drivetrain?

I’ll look at the next meeting and see if we have the bumpers still. If I recall correctly the bumpers had threaded studs sticking out the back, which went through holes in the plates, with wing nuts to secured them. 4 separate parts I think.

Hey, this was my year, guess I could shed some light on it. Here’s probably the best pic that exists of the bumpers. Basically move the front and back lateral 1x1’s to the ends of the frame to define the frame perimeter. Then we used 4 bumper sections with 2 1/4-20 studs each and wing nuts to hold them in. It definitely wasn’t the best system, and 548 has used one piece bumpers instead since then.