I'm in the process of designing a simple 2 link robotic arm, akin pretty much identical to what is shown in the Robotic Arm Designer excel sheet. While I'm always for finding fun and easy systems which will do calculations for me, I decided to check what I was getting from the sheet, and I found something which doesn't make sense. The equation used to determine the torque requirements consists of the two general parts:
Eq 1) mass * Radius <- Makes sense, it's the moment generated by the various elements when you consider the mass is in lbm, which numerically converts directly to lbf.
Eq 2) mass * radius * radius * angular velocity <- kinda lost on this one.
The units should end up as Force * distance , however for the second equation, the units end up as Kg * m* m / s, which is not quite Force * distance, which would be (kg * m / s^2) * m. So, if the angular velocity term were squared, this would work, all else being the same. Basically, that equation 2 should be:
mass * (radius * angular velocity)^2
Did I miss something in the units, or am I on to something here?
P.S. I love this site
On closer inspection, I found the part of the site referring to a "Robot Motor Factor," and realized that this is what the calculation is referencing. Thinking some more about this, it looks to be an approximation for (Moment of Inertia * angular acceleration), though I wonder about how accurate it is. Either way, I'm still curious about what others think of this.