[de_]

Hi Everyone.

It sounds like I should provide some more details. For the past 4 years, our spread sheet pretty accurately predicted robot speed if we designed an end to end gear train ratio (factoring in wheel circumference of course) and specified an expected CIM RPM (RPS). This worked acceptably for our needs for our typical 2 cim motors per per two speed transmissions each driving 3 wheels with #35 chain. Of course the higher speed required more energy so the RPM would drop somewhat compared to the low speed. This year we used a new transmission and the calculations were 25% slower than expected.

I just recently created new spreadsheet from scratch based on published ratios guessing I must have made some dumb mistake in the original spreadsheet but again I got the same results. My next step is to take the transmission apart and count teeth (not easy on our robot). Maybe I misread the specs.

Our simple model was that 4 cims at full power would run at ~5100 RPM to drive the robot at the low speed of ~4.5 ft/sec and that that 4 cims at full power at 4800 RPM would would drive the high speed of 10-11 ft/s. (all say -/+ 10%). This year it was slower by 25%.

So I was hoping someone else had done the calculations from actual robots (ie measured the robot speed, know the overall ratio and hence know the CIM RPM).