Every encoder line is interpolated 1,024 times, Greene said. That equals fractions of arc-seconds of tracking error, he explained. The EAD motor had no cogging error, Greene said. The reason, according to EAD, is that the slotless, brushless dc motors have no stator teeth. The rotor has no preferred position, the manufacturer said.
Stators consist of high-density copper windings in toothless, laminated rings.