Motor Calculations

[John Gutmann]

I was just looking at some things for the small CIMs and felt like doing a few calculations.

I wanted a output speed of 10 fps on a 6 inch wheel.

So the circumfrence of the wheel is about 1.57 feet this means it needs to rotate 6.36 times. This comes to 381.60 rpms.

I then looked at that data sheet and found the most efficient load and speed. which is 45.00 oz-in and 4614.00 rpms.

Ok so now you have to gear it down from the 4614 rpms to 381.6 rpms. this means you need a gear ratio of 12.09. So now I multiplied 45 oz-in of torque by the ratio, which gives me 544.05 oz-in of torque.

544.05 oz-in = 34 lb-in = 11.3 lbs is the max weight of this robot

This doesn't make much sense to me seeing as how teams use 2 CIMs the go faster then 10 fps and carry way more weight. this means from what I got to beable to carry the 133 pounds the max speed would be 10 in/sec.

From this I am thinking I went terribly wrong somewhere, If somebody could help me out with this it would be great.