RTC6 boards
Doc. Rev. 1.0.21 en-US
8 Advanced Functions for Scan Head Control and Laser Control
228
8.3 Online Positioning
The preceding Chapter 8.2 ”Coordinate
Transformations”, page 224 details how to precisely
align a scan system relative to the Image Field, see
also Section ”Coordinate Transformations in the
Virtual Image Field”, page 169.
The user program can, for example, determine the
required transformation values by automatic position
analysis for a workpiece on a conveyor belt and then
execute the associated transformations.
However, it is not easy to achieve well-controlled
timing (referenced to the 10 µs clock of the
RTC6 PCIe Board) while positioning a workpiece and
aligning the scan system by the control commands
described in Chapter 8.2 ”Coordinate
Transformations”, page 224. For applications in
which such timing is important, commands for so-
called Online Positioning are available. Here, data for
an offset and/or rotation coordinate transformation
or a general matrix operation can be inputted by the
McBSP interface.
The following variants are provided for different use
cases:
• The previous “Local Online Positioning“ concerns
the scan system-specific coordinate
transformations in the real Image Field analogous
to set_offset, set_angle and set_matrix with
parameter
HeadNo
= 1 or 2 according to 5 and 6
in Chapter 7.3.6 ”Output Values to the Scan
System”, page 181. It is described in
Chapter 8.3.1 ”“Local Online Positioning“”,
page 228.
• The “Global Online Positioning“ concerns global
coordinate transformations in the virtual Image
Field analogous to set_offset, set_angle and
set_matrix each with
HeadNo
= 4 according to 3
in Chapter 7.3.6 ”Output Values to the Scan
System”, page 181. It is described in
Chapter 8.3.2 ”“Global Online Positioning“”,
page 231.
Online Positioning cannot be combined with
Processing-on-the-fly applications with position
information, but it can be combined with encoder-
based Processing-on-the-fly applications.
Notes
• Since coordinate transformations 5 and 6 are
calculated after the Processing-on-the-fly
correction 4, larger Image Field rotations are not
well compatible with linear Processing-on-the-fly
corrections. In such cases,
“Global Online Positioning“ is preferable.
8.3.1 “Local Online Positioning“
Reading in data for “Local Online Positioning“ via the
McBSP interface needs to be configured by
set_mcbsp_x, set_mcbsp_y and/or set_mcbsp_rot
or set_mcbsp_matrix (or by the equivalent
list commands).
With apply_mcbsp or apply_mcbsp_list, you can
acquire the most recent fully transferred values and
define the required coordinate transformations (as
with set_offset and/or set_angle or se
t_matrix or
the
equivalent list commands). Here, as with the
commands described in Chapter 8.2 ”Coordinate
Transformations”, page 224 an
at_once
parameter
can be used to specify when the newly defined (total)
transformation should take effect.
For precise timing, execution of the list command
that triggers the transformation (depending on the
at_once
parameter, this would be apply_mcbsp_list
or jump_abs or jump_rel or any other list command)
can be made dependent on the input of an external
control signal (for conditional command execution,
see Chapter 9.3.2 ”Conditional Command
Execution”, page 295).
The McBSP interface is described in Chapter 4.6.6
”McBSP/ANALOG Socket Connector”, page 84.
To Next Page
Loading...