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XPS-Q8 Controller
XPSDocumentation V1.4.x (EDH0301En1060 — 10/17)
The sketch below illustrates this process:
2
Pos = 0
1) Search home of the Secondary positioner. The primary positioner follows
2) Search home of the Primary positioner. The secondary positioner follows.
3) If the distance of the secondary positioner's position to the "End referencing
position" is greater than the value for the "End referencing tolerance", homing is
aborted. If not, the Secondary positioner moves to the "End referencing position"
while the primary positioner stays at its home position.
The index difference refers to the difference of the secondary positioner's position when
the primary positioner is at its home position to the home position of the secondary
positioner. The value for the Index difference can be queried by the function
PositionersEncoderIndexDifferenceGet().
When no other metrology tools are available, the following method can be used to
determine a value for the "End referencing position" of an assembled gantry:
Set the value for "End referencing position" and "End referencing tolerance" to 0.
Complete the configuration of your system. After reboot, initialize and home the gantry
group. With high probability, the homing will fail with error -85 due to the zero value
for the "End referencing tolerance". Query the index difference with the function
PositionersEncoderIndexDifferenceGet(). Repeat the initialization, homing and
querying of the index difference several times and build the average and the standard
deviation from all values. Now, configure a new system with the same gantry. For "End
referencing position", apply the average value of the index difference. For "End
referencing tolerance", apply a value that is approximately equal to 6 times of the
standard deviation of the index difference. Complete your configuration and reboot your
system. Initialize and home the gantry group several times to confirm the gantry is
working properly.
4.9.2
Gantries with linear motors
The parameter "Offset after initialization" defines the offset of magnetic tracks of the
linear motors between the primary and the secondary positioners. This parameter is
important to optimize the performance of a gantry with linear motors. It ensures the
correct sinusoidal commutation of the two motor signals. An accurate measurement of
the offset can be done only with dedicated metrology tools.
For gantries NOT driven in acceleration mode, e.g. gantries with NO linear motors, this
value is set to 0.
Also, for stages driven in acceleration mode and are configured for gantries, it is
recommended to "force the initialization position" using the LMI mode (Large Move
Initialization). To do so, append LMI to the line
MotorDriverInterface=AnalogSinXAccelerationLMI (X = 60, 90 or 120) and add a line
InitializationCycleDuration=5 at the end of the section with driver command interface
parameters in the stages.ini. Example:
Primary
Secondary
1
46
Software Tools
Pos = 0
Pos = End referencing Position
3
Pos = Index difference
Initial position
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