Using 6 motors in a drive system?

[Tristan Lall]

Originally Posted by Joe Ross

With those two pieces of information, I have no doubt that it is possible to completely drain the battery in 2 minutes and 15 seconds without tripping the main 120 amp circuit breaker.

I've personally verified this through calculations and empirical observation; Woburn Robotics has used variations of 6-motor drivetrains for the last three years, with occasionally stunning results.

In 2002, the 60 A circuit breaker was a major liability; we removed the two drill motors at our second event (and used the CIMs and Johnson F-Ps), after several breaker-throwing episodes. (Incidentally, we needed a 2-speed, badly, that year.)

In 2003 with a single-speed transmission, all but the most hard-fought matches were handled easily, with no breaker issues (on the more rugged 120 A main breaker); however, matches with more than a minute of consistent pushing would reduce the robot to 6 or 7 V under load, and disable the robot controller. We once managed to push one reasonably powerful opponent up and over the ramp, from our end zone to theirs, before running out of juice, and ourselves getting pushed most of the way back. (Consider that my only driving mistake.... ) The breaker never tripped. For high-speed driving (and the robot was geared rather high), it was very driveable, and extremely responsive.

In 2004, the robot was given a 2-speed gearbox, and though (in hindsight), the gear ratios were too far apart, it demonstrated superb speed and pushing power, while never encountering a power consumption issue. (Batteries were, however, religiously changed after every match; there was no desire to find ourselves short on power.)

The bottom line: it's never been easier to do it, because of the four CIMs, and, if you don't want to put those motors elsewhere, it's a nice place to make use of them. Remember, if you have trouble, you can always remove the offending motors!