THORLABS LNR502E, User Manual

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Page 24 ETN053047-D02
LNR502E Encoded Long Travel, Linear Stage with Stepper Motor Actuator
6.2.3 Position Correction Mode
In addition to the calibration table, the APT software can be set to invoke further positioning correction at the end of an encoded
move. This can sometimes be required when there has been thermal drift in the mechanics since the time the calibration table
was acquired. There are two position correction modes available, 'Position (& Correct)' and 'Position (Stop Short & Correct)'
selected using the 'Position Correct Mode' drop down list.
Position (& Correct)
In 'Position (& Correct)' mode, the system first attempts to move to the required encoder based position (with or without
calibration table support), and then adjusts the motor position, using a series of very small correction steps, until the required
encoder position is achieved.
The various correction stepping parameters that affect this operation are found on the 'Encoder' tab of the settings tabbed
dialog accessed using the 'Settings' button on the main graphical panel.
Note that depending on the nature of the lead screw, the stage/actuator may end up either side of the required position. The
correction moves will be applied in both forward or reverse directions as required in order to achieve the required encoder
position.
In some applications it is desirable to always 'reach' the required final position from the same direction (conventionally using
positive moves on Our stages). To support this, the second 'Position (Stop Short & Correct)' correction mode is available.
Position (Stop Short & Correct)
When this mode is selected the system stops short of the intended position by a user specified distance and then issues small
position correction steps to achieve the required final encoder position. Again the user adjustable parameters associated with
this operation are found on the 'Encoder' tab of the settings tabbed dialog, accessed using the 'Settings' button on the main
graphical panel.
There are various user settings which relate to the position correction modes discussed above.
Note
For best performance, the backlash correction distance should be set to zero (either
by calling the SetBLashDist method, or via the Settings panel Move/Jogs tab.