Microstepping Precision

[Brenck]

Hi all,

Does any one have a good reading about microstepping accuracy? I mean if you use lets say 1/8 microstepping is it more precise then if you use 1/64? I'm speaking about the degree positioning accuracy, all stepper motors have like 5% step accuracy, is that for full step? What that actually means?

I've read threads that people say that stepper has better repeatability then servos due to the fact that the magnets actually always lock up in the ''same'' place, but still servos make a more precise movement due to the fact of closed loop and it can catch up if something goes wrong. Is that considering a stepper running on fullstep or it doesnt matter how many steps?

Thank you,

Gustavo

[packrat]

You can put encoders on stepper motors also, to run closed loop.

cary

[irving2008]

Originally Posted by Brenck Hi all, Does any one have a good reading about microstepping accuracy? I mean if you use lets say 1/8 microstepping is it more precise then if you use 1/64? I'm speaking about the degree positioning accuracy, all stepper motors have like 5% step accuracy, is that for full step? What that actually means? I've read threads that people say that stepper has better repeatability then servos due to the fact that the magnets actually always lock up in the ''same'' place, but still servos make a more precise movement due to the fact of closed loop and it can catch up if something goes wrong. Is that considering a stepper running on fullstep or it doesnt matter how many steps? Thank you, Gustavo

Only full (or arguably 1/2) step is accurate to the positioning accuracy quoted - for a 200step motor thats 1.8deg +/-5% i.e. the angular change per step could vary by as much as +/-0.1degree but over a full revolution it evens out.

Microsteps are achieved by balancing the current in the phase coils to hold the rotor partway between step positions. At best this is an approximation and should not be relied on for accuracy - it is severely affected by the torque load on the motor. Microstepping is there for smoothness of movement not to enhance resolution. If you want improved resolution, more than achieved by 1/2 stepping, use a finer pitch screw or gear the motor down.