Quote Originally Posted by CescoAiel View Post
True, but you'd still need to keep in mind the number of rollers squeezing the pump-tube and their relative position to the end of the housing (ie where it stops pinching and allows the tube to return to normal diameter)
Right; the motor controller would just keep the pump stopping point from drifting or dithering. The pump would always turn an integer multiple of 1/n for n lobes. My idea of sensing the pump lobe position optically would allow too much slice-to-slice variation. If the armature modulation counter goes over the number of armature bars, the controller could report an error or even correct an error if somehow the motor revolution counter lost count.