Thanks for the kind words everyone, it really means a lot to us.
Craig, The module is 1.9 pounds as is. A 1" wheel significantly reduces the weight on top of that. The module was originally 1.1 pounds, but switching to 1.5" wheels, larger bevel gears and increasing the sideplates material all boosted it up a lot. I'm not sure, but between replacing the steel sprocket and turning down the bevel gears (they have BEEFY hubs) we can save a good deal there. The wheel could also be made a bit lighter, as it is currently .43 lbs for a 1.5".
The top of the 1x1 is 7.7ish inches, the entire frame is 6" tall (4" between levels) and we have 1.7ish inches of ground clearance. The frame itself could probably be made lighter, as it is all 1x1x1/8" except for the 4 inner cross members on the top (and the 4 short pieces of 2x1) and weighs 15.3 lbs + welds. It's currently not amazing at climbing ramps, but we drew some varied lower levels that should allow it to climb great. The nice part about this style module design is almost the entire front and rear face of the wheel is open assuming there is no frame blocking it.
I didn't mention before, but with the standard #10 pattern and the fact that the distance between inner and outer frame members is a constant 5", not only can gearboxes be slid up and down a side like I said before, but we can swap the locations of drive and steering gearboxes.
sdcantrell56, I'll tell you we used 12DP miter gears, but won't tell what tooth count or part number. I'm not trying to be secretive, but everyone I talked to about them warned me how important it is to make sure they are strong enough. We did a lot of calculations for it (only possible with the help of some great people) and still aren't sure they're strong enough, as we haven't started full speed, full weight, robot to robot interaction. As you know, the wheel size, tread, gearing, robot weight, etc. all effect the load on it, so you can't really say "it worked for 973.... it'll work for YYY".
What kind of views would you like of the module? The posted pic shows pretty much all it's features.
Quote:
Originally Posted by Qbranch
Neato Design. I've always been fascinated by oddball drive systems like crab... looks like a very slick implementation. 
But... am I just crazy, or is there no way for this drivetrain to spin in place without skid-steering?
-q |
The way "opposite" pairs are steered/driven it is only skid steer.
However, A difference in drive speed also causes the robot to spin unless the wheels are exactly aligned at 0 or 180 degrees (which is 90 degrees off from our skid-steer zone)
We have ideas that make this not really an issue, one is to implement "drift" buttons that slow or kill one pair of drive motors on a curve to cause the robot to spin on center while driving (credit to 1625). We imagine most rotating will be done by this, or by a 2nd stick at the point of scoring. We're working on implementing anglular presets with a gyro as well. I imagine we may try some gyro based turning while driving based on differing drive speeds.
Eh, didn't entirely answer your question, but that's our current gameplan for rotation.