In a web tension control system, where feed forward is to be used. A tension set point is desired lets say 20lbs, and a load cell system provides feed back. There will be dead weight on the load cell as the material with no pull sits on top of the load cell system. [Obviously I will need to compensate for that too]. The take-up reel diameter and speed are known values at all times of rotation - driven by a motor via a gearbox where both motor Hz / RPM and GB Ratio (25:1) are known values. For the moment assume constant speed 1750 RPM @ 60hz , diameter = 1 foot The formula Torque = Tension (foot lbs) x Radius (in feet) I have 20lbs on the load cell (don't know if I can call that foot lbs ) a roller with load cells under each side of the roller. 20 x .5 = Torque = 10'lbs should I then Divide that by 25 (gearbox ratio) = .4 How can I calculate the additional RPM required to achieve the tension set point ? Keep in mind there will also be a material on top of the load cell so dead weight would be a dead band and I will obviously need to offset by the dead weight ..