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Ironspork
09-20-2007, 03:01 PM
I'm a member of a High School robotics team that competes in the FIRST competition each year, and this is my latest achievement in drive technology:

It is a 6 wheel, tank style drive base, with two speed pneumatically shifted gearboxes. The base frame is made up of welded aluminum box extrusion, and the components of milled aluminum of stock steel gears. Due to the presence of chain in the system, and innovative tensioning method was thought up and designed into place on this system. In order to tighten a chain, we simply tighten a single bolt, which pulls tensions one quarter of the drive train. This makes the system durable, and easy to maintain. As well as the easy tensioning system, I also designed and built a two speed shifting gearbox. This allows the robot to travel at 5 fps in slow speed, and 15 fps in its sprint speed. That way the bot will be competitive in any aspect of the game. The drive base rides on 6 custom designed and CNC'd aluminum wheels, 4 inches in diameter. In total, the system weighs about 34 pounds.

Attached are some photos of the CAD, and the full system.

Dave
09-21-2007, 11:30 AM
That's some nice work. The chain tensioning system sounds cool.

[edit:] Thanks for submitting your project! It's entered in this month's contest.

kdwyer
10-24-2007, 08:18 AM
34 POUNDS!!!
What're you using to power this MacroBot? A small nuclear reactor?
Seriously, that is REAL heavy. Not too familiar with FIRST, does size/weight help or hinder in competition?
The total drive system sounds cool. Me, I'm lazy and prefer not to re-invent a wheel if there's already a usable alternative. Your use of a shiftable transmission is something else too! (Pneumatic???)
I must admit, some of it sounds more complex than it needs to be, but I'm sure you have reasons.
And who am I to complain about complexity for its own sake anyway? LOL

Ironspork
10-25-2007, 04:39 PM
34 POUNDS!!!
What're you using to power this MacroBot? A small nuclear reactor?
Seriously, that is REAL heavy. Not too familiar with FIRST, does size/weight help or hinder in competition?
The total drive system sounds cool. Me, I'm lazy and prefer not to re-invent a wheel if there's already a usable alternative. Your use of a shiftable transmission is something else too! (Pneumatic???)
I must admit, some of it sounds more complex than it needs to be, but I'm sure you have reasons.
And who am I to complain about complexity for its own sake anyway? LOL

Actually, 34 pounds for a drive base with 2 speed capability for a FIRST bot is really light. The base of the bot is 36" by 26". It's powered by two 2.5" CIM motors. Each are around 250W, and came out of electric jackhammers.

The pneumatic shifter is basically a dog style shifter, actuated by a fairly small pneumatic cylinder.

Alex
10-29-2007, 10:56 AM
I thought that 34lbs sounded pretty light for a FIRST robot.

kdwyer, if you haven't already, I'd check out some of your local regional FIRST competitions. They're a load of fun, and really cool to see how brilliant these young people are:)


http://www.usfirst.org/

kdwyer
11-09-2007, 03:58 PM
LOL Being a relative fossil myself (I remember the '60s, OK?) I think any 'checking out the young people' MIGHT be taken the wrong way... besides, I have no need to be reminded how old and stupid and un-cool I am, especially compared to a 'bot. Also, I'm in a relatively rural area of PA, with more cows 'n trees than people. The only tech-minded people I have access to are some scientists at HP and a few IBM retirees. I've checked the local university and find there's not much of a robotics community there. So, I'm stuck raiding the local Radio Shack, and getting most of my parts online. Most of my good info also is online - at least I have a fast connection!
Seriously, there are quite a few good mechanically-minded folks about, but not much electronics or programming people. I'm a computer specialist, but not a 'real' programmer, so I'm reduced to banging my head against my 'bot until inspiration hits me (or I raise a large lump.).
My preference for not re-inventing the wheel is both practical and necessary. I'd love to have others to bounce ideas off, but high-school competitions are mostly out of the question. I floated an idea for a robotics group around the local college but got no nibbles. Too busy chasing grades and skirts, I suppose LOL.
Such is life in rural Pennsylvania - and I still haven't found any of those darn pencils!
OK, so 35 pounds is light - what do I know?

Alex
11-12-2007, 11:45 AM
too funny kdwyer! Reminds me of my hometown, haha:D