A3-phase stepping motor is to be used to drive a linear axis for a robot. the motor output shaft will be connected to a screw thread with a screw pitch of 1 mm. we want to be able to have a spatial control of at least 0.05 mm. a)how many poles should the motor have?

The  number of poles is 12.

Explanation:

The step angle is given by

Where

is the step angle

To Find the Step angle of the Stator

Where

 is the step angle

is the number of poles or teeth on stator

To Find the Step angle of the Rotor

where

 is the step angle

is the number of poles or teeth on rotor

In the question it is stated that

Selecting = 12 and = 8  

=  

=

the answer is true.