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Chapter 6
Stepper Motor Operation - Background
D.3
Error Correction
D.3.1
Backlash correction
The term backlash refers to the tendency of the stage to reach a different position
depending on the direction of approach.
Backlash can be overcome by always making the last portion of a move in the same
direction, conventionally the positive direction. Consider the situation in Fig. 4.1, a
positive move, from 10 to 20 mm, is carried out as one simple move, whereas a
negative move, from 20 to 10 mm, first causes the stage to overshoot the target
position and then move positively through a small amount.
Fig. 4.1 Backlash correction
The controller has this type of ‘backlash correction’ enabled as its default mode of
operation, but it can be overridden if the overshoot part of the move is unacceptable
for a particular application.
See Chapter 5 (Local Mode) and Chapter 6 (Remote Mode) for details on setting the
backlash correction.
negat ive move
positive move
10mm
20mm
position
