Quote:
Originally Posted by Dale
One of the cool things about this kind of drive, if it has the right configuration, is you get suspension for your Mecannum wheels for free. This insures all four wheels are in contact with the ground at all times. This makes a difference when strafing. I'd suggest flipping your design around so it pivots on the solid wheel. You'll find the Mecannum wheels will work better if you do.
We used this kind of drive this year and in Bunnybots so got to measure this first-hand.
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If you change the design to articulate the Mecanum wheels, you shall be intentionally and regularly creating forces along the axes on a cantilever mounted on another cantilever whenever you're in Mecanum mode. Either you would have to "enclose" the module so that it's mounted on both sides, or beef up both cantilevers beyond what you'd need for the current design.
Mecanum without suspension is OK if the field is fairly flat and the chassis is slightly flexible (e.g. aluminum C-channel or square tubing). If you have a good bit of driver practice, the drivers can even get used to significantly uneven loading. Woody, our practice 'bot for 2014 Aerial Assist had only 13# on one corner wheel and about 50# on the opposite corner. We practiced with it on a patch of parking lot behind the stadium's concession stand; it was less than impeccably level. After a few hours driving, the operators had internalized the compensations. It did take a couple of practice matches indoors with "Buzz", the competition 'bot, to unlearn those compensations. (Yes, Woody actually had a 2-by-4 wooden chassis and kicker and 2-by-2 pickup arms - video of driver practice
here. We decided that the practice 'bot would be different than the prototype(s) and much more like the competition 'bot in 2015.)