PI M-403 2S Series, Руководство пользователя

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Stepper Motor
An electric motor providing motion in discrete angular steps, without the need
of position sensor or servo-loop. Compared to closed-loop DC motors of the
same size, stepper motors provide poorer dynamic performance and
dissipate more heat, especially in steady state operation. Their advantages
lie in long lifetime and simple control electronics. Most common are 2- and
4-phase designs, which are very inexpensive; 3- and 5-phase motors offer
better performance in terms of dynamics, torque, stiffness, resolution and
noise generation, but their manufacture is more complicated.
Unidirectional Repeatability
The accuracy of returning to a given position from the same direction.
Because unidirectional repeatability is almost unaffected by backlash and
hysteresis, it is often considerably better than bidirectional repeatability.