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Unread 15-12-2014, 00:44
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Re: pic: REV 2 of GBX-116, Drill press swerve drive

Quote:
Originally Posted by GeeTwo View Post
It's wonderful to see that someone's going after this idea! Given that bevel gears are essential to this working, my thoughts on this line were to go OTS on this, using something similar to one of AndyMark's LJ bevel boxes (am-2796 or am-2622), each of which already include a 2:1 reduction. I'd love to see my vision of a "dizzybot" become reality using something like this. The "dizzybot" would have the full capability of a "unicorn swerve" that is software-constrained to prevent slipping wheels, but with only three control pins needed from the 'RIO:
Control #1 - steer all the wheels relative to the base frame (all of them always point the same direction)
Control #2 - spin the wheels against the floor (all at the same speed, always)
Control #3 - spin the superstructure relative to the base frame (since the base frame ideally never rotates)

The simplest implementation I can imagine would be to put all of the electrical system on the "superstructure", and extend three shafts and sprockets (or gears) down to the base structure.
I considered using the LJ bevelbox, but I decided against it due to the $130 price tag. For that much, you could just buy a $50 cross slide table from HF or Grizzly and use that to position the bevel gear holes.

That sounds like an interesting swerve design. I don't think it would work perfectly though, as the individual wheels spin and rotate at different speeds for different maneuvers. So either you have to use a microcontroller between the cRio (or rRio) and the swerve modules, or you have to sacrifice the pins.
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