Globe gear box

[Joe Johnson]

Originally Posted by Karthik

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I'd be very interested to hear your reasoning on reverting back to simpler drive trains. Is it just that the advantages gained are too small to warrant the effort and complexity, or are there other reasons as well?
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I am a recovering complex-drivetrain-aholic.

We were one of the first teams to really push the limits on what we call "swerve" (steerable drives).

• 1998: 2 wheel drive with 1 motor parallel steering (a.k.a. "2 by 1 Swerve")
• 1999: 4 wheel drive with 1 motor parallel steering (a.k.a. "4 by 1 Swerve")
• 2000: 2 wheel drive with 2 independent steering motors (a.k.a. "2 by 2 Swerve")
• 2001: 4 wheel drive with 4 independent steering motors (a.k.a. "4 by 4 Swerve")
• 2002: 4 wheel drive with 2 independent steering motors (a.k.a. "4 by 2 Swerve")*
  

But, in 2003, the "K-3 Rule" more or less caused us to hit rock bottom. We just could not make the complex drives and meet the $3500 limit on material and labor (at the time we had no mill or lathe at our school and we had limited access to our internal shops, forcing us to farm out our manufacturing).

So... ... we decided to go back to basics. For the last 2 years we have had more or less pretty straightforward 6 wheel drive systems (lowered middle wheels of course) with servos shifting drill tranmissions.

I can honestly say that I don't miss the more complex drives a bit. In fact, quite the opposite. I feel we have had robust drive systems that have gotten the job done when we needed it.

Swerve is a real resource hog. We used 8 motors just for our drive system when we had 4 by 4 Swerve!!! It also requires feedback on the steering angles so that the control system can contain the beast. Plus it uses up extra programming time to make it work. Plus it drives complexity into the operator interface. Plus it uses up valuable drive time for your drivers to make it look easy to drive. Etc. etc. etc....

Will Chief Delphi EVER go back to swerve? Never say never, but I, for one, will be fighting hard for the simplest drive system that gets the job done. If that is a swerve drive, fine, but if a 2 wheel drive system can do the job, that is what we are going for.



Simple, robust drivetrains let you spend your resources on other important tasks, like climbing stairs, sucking up and spitting out small balls, capping goals and hanging from bars.

That is were we came down this year anyway...

Joe J.

*By my naming convention this year, WildStang 2004 had "2 by 1 plus 2 Swerve" I think they had 2 wheels in "front" that steered but always in parallel with eachother plus 2 driven omni wheels that did not steer at all. I believe their 2003 machine had "4 by 2 Swerve" 4 drive wheels that turned but only 2 independent steering motors (the left drive wheels stayed parallel to eachother as did the right drive wheels).

If we ever build my dream of 4 wheel drive, 4 wheel independent steer, with 3 gears on each drive wheel, I will call it "4 by 4 by 3 Swerve." Yes, we can do it, even with the K-3 Rule (did I mention Chief Delphi bought an old Bridgeport and a WWI vintage lathe?), but so far the game has not needed it...

...maybe next year...
...did I tell you I also have ideas on how to give it 4 wheel independent suspension? -- I haven't thought of a good naming convention for that yet...
...also, I THINK I can make it climb stairs too (even better than Wildstang's 2004 cool drive system)...

...Man! That would be cool!...

...no no no... ...stop me before I design again!....

...I am a recovering complex-drivetrain-aholic...
.................I am a RECOVERING complex-drivetrain-aholic...
...............................I am a RECOVERING complex-drivetrain-aholic...
................................................I am a RECOVERING complex-drivetrain-aholic...