Quote:
Originally Posted by GeeTwo
I believe he means that he's using these three Banebots as drive motors; no CIM or mini-CIM. They are presumably steering with 3 (or perhaps 1) through Banebots + Versaplanetaries. After gearing them down with the CIMile, it appears that they can get good low-speed torque for a smaller current draw than a CIM. The trade off is loss of peak power in the 30+A part of the curve, where you don't spend much time anyway. It sounds like a good performance trade off, especially for this more deliberate game. It doesn't surprise me that they're blowing motors; smaller means hotter for a given amount of power.
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Ok so here's the deal.
We started with 3 CIMs on our 3 WildSwerve modules*. Then we needed to save weight (big surprise). We noticed that the CIMs were never getting even warm in practice with our wooden "drives like" practice chassis (nick named Trojan -- get it?). So... hey presto, we started using Mini-CIMs and pocketed 0.6lbs per motor (1.8lbs when you're over weight is like manna from heaven).
We are now 1 week to Bag & Tag and we still need to shave some weight (yeah I know another big surprise). Looking at the power, a BB 775 motor has more Peak Power than the Mini-CIM. A
CIM-ile from VexPro makes the BB 775 output shaft and mounting look like a CIM/Mini-CIM. And saves about 0.9lbs OVER A MINI-CIM!!!
The 775 hangs out a bit over the 2.5" Diameter of the CIM so we had to do some grinding on the WildSwerve plates and shift the orientation of the mounting screws, but all in all, not that much work for 2.5lbs very late in the game.
As to overheating, this year's game does not put much stress on the drive motors. The field isn't that big plus acceleration is not the best idea with a 5 stack on our forks...
So now you know.
By the way, it's our steering motors that do the most work and get the hottest (by far -- all the other motors are not doing much work and/or have beautiful counter balance systems).
Dr. Joe J.
*which are working awesome for us -- thanks
221 Robotic Systems/Anthony Lapp for the team sponsorship, but even if I didn't have them as a sponsor, I would say the same.
Side note: If you are a team thinking of doing swerve for the first time, seriously, buy the mechanical bits first, get them mounted to a chassis (including your sensor scheme) and get that chassis in the hands of your coders and then your drivers. SO many teams that try swerve for the first time have such a lousy experience because they take so long getting the mechanical hardware designed and debugged, the coding team barely has time to get anything working yet alone giving drivers stick time -- and time to slap the coders upside the head for the goofy User Interface they've most likely come up with ;-)
Point is that it takes iteration loops to get this right and those take time. Don't be learning lessons during you qualification matches. /end soap box rant/