# How do I calculate rotation from rpm?

I was trying to program an system to rotate a robot a certain amount in a given time and I was wondering if I have two sides of a drive train and 1 side is going let’s say 130rpm and the other side is going 180rpm how would I calculate the angle it turned? (assuming the wheels are parallel to each other)

You can find the the angle of the robot by using the formula:

(L-R) / (sL+sR) (This gives an answer in radians which you’ll have to convert to degrees)

sL+sR being the distance (in inches) between the center of your robot to the left and right wheels respectively

L and R are the distances the wheels travel (also in inches), to get the distance with rpm you can use the formula:

D × pi × rpm × T

D being wheel diameter (in inches) and T being the amount of minutes spent at that rpm

If you are trying to get rotation with RPM I would highly suggest using degrees of encoders instead (built in to the motors or external) and using a slightly different formula to find L and R