Non-Linear Error Compensation - HEIDENHAIN POSITIP 880 User Manual

Non-Linear Error Compensation

Non-linear error compensation should be applied, if the results of the
comparison with a reference standard show an alternating or
oscillating deviation. The required correction values are calculated and
entered in a table. POSITIP 880 supports up to 128 points per axis. The
error value between two entered adjacent correction points is
calculated with linear interpolation.
Non-linear error compensation is only available on scales
with reference marks. If non-linear error compensation
has been defined, no error compensation will be applied
until the reference marks have been crossed.
Select NON-LINEAR and press EDIT TABLE.
The encoder's error compensation table and a graph showing the
error are displayed in the left two-thirds of the display screen.
The error compensation table shows the table entry, the scale's
measured value, and the amount of error at the measured value.
Reading the graph
The graph shows a plot of a translation error (reference - measured)
vs. measured value. The graph has a fixed scale. As the cursor is
moved through the form, the location of the point on the graph is
indicated with a blue vertical line. See Fig. II.13.
Starting a Non-linear Error Compensation Table
To start a new error compensation table, first press the CLEAR TABLE
soft key. This key will only be present if a table containing data
already exists.
The error compensation measured values are relative to the table
datum location. When the error compensation table is cleared, the
POSITIP 880 resets the table datum to the location, of the scale's
reference point.
The table datum may be set to another location. Move to the
location from which the table values to be measured and press the
SET TABLE DATUM soft key. The table datum must be set before
adding entries to the table.
Configuring the Compensation Table
Error compensation information is added to the table by pressing
the ADD NEW POINT soft key.
There are two possible ways to enter information to the table; Direct
Entry or Auto Calculation.
POSITIP 880
Fig. II.13 Non-linear error compensation form
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