The step position error is the difference between the theoretical stop position and the actual stop position of the motor, and is a measure of the stepping motor stop accuracy. The predetermined initial position of the rotor is used as a reference point, then the actual position is measured while moving step by step through a full revolution. The amount of deviation between the actual position and theoretical position at each step when one rotation (360°) is made from the initial position is recorded as a “±” value. The amount of deviation at each step is related to the manufacturing accuracy of the stator and rotor, as well as the variation in the input current. The step position error of MinebeaMitsumi's stepping motor is ±5% (max). Therefore, a motor with a 1.8° step angle will have a step position error within ±0.09° (max), and a motor with a 0.9° step angle will have a step position error within 0.045° (max).
Find out more accurate stepping motors : Hybrid stepping motors Resolver (Angle sensor) type