6 CIM Drivetrains... What's Your Experience?

[Jonathan Norris]

Originally Posted by Nathan Streeter

So far, I only know of 254 using 6 CIMs in 2013 with their 2-speed+PTO gearbox and of 610 using them this year in their 1-speed+PTO gearbox. I heard though that when 610 set aside their climber mechanism they also removed the 2 "extra" CIMs... according to their website they designed for a top speed of about 9fps.

Any recommendations, cautions, or further information?

I wasn't directly involved in designing the drivetrain last year, but the whole thinking around the drive system was to minimize the time it took to get from the loading station to the pyramid. Surprisingly when you crunch the numbers it doesn't mean building a 2-speed gearbox with a 22ft/s high gear, actually a single speed drive system with 6 CIMs geared at ~10-11ft/s is the fastest way to get from the loading station to the pyramid.

The main reason for this is acceleration, having 6 CIMs geared at a 'slower' top speed gave us incredible acceleration, actually allowing us to reach that top speed quickly. It also allowed our driver to be more creative and precise trying to get around defence, our drive team figured out quickly that we could accelerate away from anyone. So when teams tried to play D on us, it would almost seem like they just bounced off us, because when we got into a collision we could spin our robot around them and get away quickly. I believe the drive system was one of our keys to success last year.

I highly recommend teams analyze the game and use that analysis to figure out your optimal drive system. 610 has been doing this analysis for years, there is no 'perfect' drive system that works every year, the best drive system is the one thats optimized for your team's game strategy.

(pro-hint: the acceleration difference between a 6 CIM and 4 CIM drive geared at 10ft/s isn't that much different. Start thinking more about acceleration/agility/control vs. top speed, its a real tradeoff, you need an amazing driver to control a robot above ~15ft/s)