2.0 KiB
+++ title = "Stepper Motor" author = ["Dehaeze Thomas"] draft = false category = "equipment" +++
Tags :
Errors between steps (micro-stepping)
For a two phase stepper motor, there are (typically) 200 steps per revolution (i.e. 1.8% per step).
Between each step, even when using some micro-stepping, there are some position errors that are due to non-perfect magnetic and electromagnetic fields.
The period of this error is corresponding to 200 period/revolution.
Then scanning, this can lead to high frequency vibrations.
This is what is typically limiting the accuracy of the stepper motor (usually specified in between 3% and 5% of the step increment). This is approximately corresponding to 1mrad.
Consider a stepper motor with 200 steps by turn attached to a ball-screw with a pitch of 1mm per turn. A rotation of 1 turn per second will induce vibrations at 200Hz with an amplitude of \(1\,\mu m\).
Note that this error is not a pure sine, it also has some harmonics with corresponding periods of 1/100 revolution and 1/50 revolution.
This error should repeat every turn and can be calibrated provided it is repeatable over time.
One way to reduce these errors is to use a ball-screw mechanism with a smaller pitch. The price to pay is smaller velocity.
Manufacturers
| Manufacturers | Country |
|---|---|
| AML | United Kingdom |
| Sanyo |
2 phase VS 5 phase stepper motor
https://www.orientalmotor.com/stepper-motors/technology/2-phase-vs-5-phase-stepper-motors.html