What exactly does it mean by BACKLASH.

[abikutn]

hello,

       I want to control a XY stage ( THOR LABS ) using a stepper motor (MYCOM PS464-01A). What exactly does it mean by backlash compensation. Does it have to do with my motor or the stage or both.

Please provide guidance so that I understand this concept very clearly.

Abhi

[DAD]

Look at the Wikipedia entry for "Backlash (engineering)".  Basically it's trying to compensate for the the play between gears in your motion hardware.

[abikutn]

Yeah. Read an article on NEWPORT. So one question I have is. Does this baclash depend on the mechanical error of my stepper motor or on the stage I am using.

[johnsold]

abhi,

Backlash is primarily mechanical.  It is due to the gap between the teeth of two (or more) gears.  When the system is rotating in one direction all the gears are directly in contact and everythign works well.  When the system stops and reverses direction there is a moment when the motor is moving in the opposite direction but the gear teeth have not yet moved to be in contact with the opposite face of the tooth. During this time the output shaft is not turning.  When the teeth make contact, there may be an instant of impact resulting in high acceleration and large forces at the contact points.  There are designs which have essentially no backlash.

So the backlash is primarily in the stage.  The stepper motor may have some hysteresis of position upon reversal, but this is probably small.

Lynn