I'm curious about your dropped centre wheel 6WD; would you happen to have a picture of it? I ask because that is a very unusual problem to have. In the last two years, my team has done two 6WDs with a dropped centre wheel; instead of having turning be too difficult, we sometimes have issues with turning that is
too easy.
Another PowerPoint that might be handy is the one in my team's site's whitepapers
section.
EDIT:
Quote:
Originally Posted by Dasistmeinmoped
1) 6 WD - saw design with all traction wheels all wheel contacts coplaner
2) 6 WD - Drop center, all traction we prototyped this and found it near impossible to turn while stationary. The center axle was dropped 3 washers (french national measurment, its real look it up..) which was about 3/16" i believe
3) 8 WD with some funky mechanism that lifts the front, and rear wheels off of the ground as to shorten the wheel base.
4) 6 Wheel swerve where the front and rear wheels move up to 80 deg. (view mars rover)
5) 6 WD coplaner- middle and rear traction, front omnis <-(prbly will proto type this withing the weekend)
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(numbering added by me to make this easier to respond to)
1) What is a saw design? Assuming this is just a coplanar 6WD, here are my thoughts: If #2 is giving you turning trouble this definitely will. Of course, this depends on how fast you choose to drive, but with all traction wheels you are looking at a lot of scrub. 25 does quite well with this design, but they mess with their wheels a lot and their turning still is not the smoothest I have seen.
2) Dropped 6WD is probably my favorite drive design. 61% of world championship finalists since 2005 have run a 6wd. Of those, I believe that only team 25 doesn't lower their centre wheel. Turning is usually very good, traction is very good, weight is okay, and they handle uneven terrain quite well.
3) Can you elaborate more on this design, I'm not sure what you mean.
4) This would be very complicated and probably have minimal improvement over the 6WDs. If you are going to make four swerve modules, I'd just make a swerve drive. With this design you are getting the worst characteristic of swerve designs--complexity--without gaining the ability to drive sideways.
5) This should work well. I'm a strong believer in the capability of the lowered centre wheel 6WD, so I personally probably wouldn't go this route. That isn't to say it is a poor choice, most people who go this route probably find the lowered centre 6WD's rock problematic. I don't have a problem with a little rock, so I choose not to do it. If you do end up prototyping this, would you be willing to try putting the two omni wheels at opposite corners (ie front left and right rear)? I have always been curious how such a drive would perform; it seems like it would be handle very nicely, but, as far as I know, nobody has done it.