Newport XPS-D - Definition of the Positions Available for each Positioner

XPS Unified Programmer’s Manual
5.2.2 Definition of the Positions Available for Each Positioner
For each positioner, three different positions can be called:
1. The SetpointPosition is the profiler position. This is the position where the
positioner should be according to the ideal theoretical motion profile.
2. The CurrentPosition is the encoder position of the stage after mapping corrections
are applied. This is the actual position of the positioner at this moment of the query.
3. The TargetPosition is the final target position commanded by the user.
The difference between the SetpointPosition and the CurrentPosition is called the
following error.
For example, during a motion from the position 0 (units) to 100 (units), a query in the
middle of the motion could have the following result:
SetpointPosition = 50
CurrentPosition = 49.998 (FollowingError = 50 – 49.998 = 0.002 unit)
TargetPosition = 100.
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