The XMP has 2D compensation capabilities. The user-supplied compensation table is downloaded into XMP memory. The XMP automatically applies this compensation information to optimize motion profiles in real time.
To compensate a Z (vertical) axis for X-Y surface irregularities, first define the X-Y area to be compensated (Xmin to Xmax, Ymin to Ymax). Then define the spacing of the measuring points for the X and Y axes to determine the compensation table size. Next, aquire high precision distance mesurements (via interferometer, etc.) to the surface at each of the X-Y locations in the compensation area, and store the X and Y offset positions.
These positions will be loaded into one of the XMP’s compensation tables. Once the compensation positions are loaded and the XMP’s compensator is enabled (via MPI software), the compensation will be applied to the Z-axis’ position feedback loop every servo cycle. The applied compensation will be interpolated between X-Y data points in two dimensions. This resulting compensation for the data points in the example can be seen in the graph below:
2D Compensation enables you to get high precision compensation from only a small number of measurements.
