YesAX V3.1.2 - Software User Manual.pdf - 第263页
Calibration and Verification 25 -3 25.8 Self Test The software provides a comprehensive set of self-testing features that automatically verify all the essential calibration parameters. The self-test determines the curren…
25-2 Calibration and Verification
25.4 Calibrate Stage Linear Comp
The YesAX software compensates for mechanical imperfections of the XY camera transport
mechanism. The software employs three scaling factors for compensation: X, Y, and Skew. The
X factor compensates for any linear error on the X axis that may be caused by inaccuracies of the
X lead screw. The Y factor compensates for linear error on the Y axis and the skew factor
compensates for imperfect XY orthogonality. The Calibrate Stage Linear Comp feature
calibrates these 3 compensation factors.
25.5 Error Map XY Stage
To compensate for non-linear distortion of the XY stage, the Error Map XY Stage feature
extends the error compensation features to include error mapping. The linear error compensation
mentioned earlier uses 3 scale factors to compensate for linear errors commonly found on an XY
stage. Error mapping compensates for all remaining errors by mapping it. Typically, error
mapping, when performed correctly, can increase stage accuracy by a factor of three.
Error mapping employs a grid (for example 27 x 24) of error correction factors. It maps the
distortion of the positioning system. The error correction of any given point is determined by
using a linear formula with the data from the 3 closest correction factors.
25.6 Calibrate Camera Angle
This Calibrate Camera Angle feature calibrates the angle of the top camera to have it aligned
with the X axis. During the procedure, the stage moves left and right to have the target cross on
the calibration board appear on the left and then right side of the field of view. If the camera
angle is correct, the video cross hair should align with the target cross in both positions. To
adjust camera angle, loosen the three small mounting screws (5/64 button head) that hold the
camera PCB to the mounting bar and rotate the camera PCB.
25.7 Calibrate Camera Pixel Size
This Calibrate Camera Pixel Size feature calibrates the pixel size of the top camera. The XY
stage encoder is used as a ruler. The pixel size is determined using the following formula:
Stage movement delta in um
Pixel Size in um = -----------------------------------
Pixel delta in count
To adjust the camera pixel size, raise or lower the camera by putting washers in the camera
mount. Raising the camera increases the pixel size.
Calibration and Verification 25-3
25.8 Self Test
The software provides a comprehensive set of self-testing features that automatically verify all
the essential calibration parameters. The self-test determines the current values of the calibration
items and then compares them with the corresponding specification values in the SysSpec.dat
file to generate a Pass or Fail status for each of the items. The Self Test feature takes the
guesswork out of the calibration.
The self-test requires the specialized calibration board (P/N 10876) in the system. The board
must be properly aligned before any test can be preformed. The first item on the Self-Test dialog
“Set XY Skew” tests the alignment of the calibration board. The rest of the tests will be enabled
only if this test passes.
All the calibration procedures outlined in the previous section are performed in the factory as
part of the quality assurance program. It is unlikely for a machine to get out of calibration so bad
that it would require a complete re-calibration. The self test procedures that verify and correct the
system parameters are much more likely to be used by users or a field service engineer to bring a
machine back into specification.
The Self Test dialog lists a total of 9 tests. On the left is the action button for each individual test.
Clicking it starts the automated test procedure. The middle fields show the status of the tests. It
can be UNTEST, PASS or FAIL. The right buttons launch detailed dialogs that list the test
results. In many cases they also provide a means for the user to tweak the parameters to bring
them back into specification.
The Test All button runs all tests in sequence. The Write Log File button creates a log of the
current calibration session results.
25-4 Calibration and Verification
25.9 Calibrate X-ray
The X2/X3 AXI system has separate calibration and verification functions to calibrate and verify
the functionalities of the X-ray imaging system. An additional calibration board is needed to
complete the tasks.
25.9.1 Align Source to II
This step aligns the X-ray source mount on the Z-axis with the X-ray Image Sensor (For X2, it is
Image Intensifier (II). For X3, it is a flat panel detector). It ensures the center of the view does
not shift when the X-ray source moves up and down on the Z axis while doing a zooming
operation.
The alignment procedure is guided step by step by message prompt dialogs. The Z axis is
mounted with 3 points in contact with the base. There are push-pull mechanisms on the two front
screws; adjusting them can achieve proper alignment.
25.9.2 Calibrate Offset
This step calibrates the offset from the vision camera to the X-ray camera. Because the offset
could be slightly different at different Z levels, this step only serves to achieve a rough offset. To
use the Self-Test fine adjust feature, go to the Details page for each test on the Self-Test X-ray
dialog and select the Adjust button to finish the calibration of the offset.
25.9.3 Calibrate Uniformity
Since X-ray is a point source, the image intensity may not be even across the entire field of view.
This step tries to calibrate out those variations.
25.9.4 Run Self-Test X-ray
This is the same as the vision calibration. In X-ray calibration the software provides a
comprehensive set of self-testing features that automatically verify all essential calibration
parameters.