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XPS-Q8 Controller
XPSDocumentation V1.4.x (EDH0301En1060 — 10/17)
results in a much smoother motion. The jerk time defines the time needed to reach the
necessary acceleration. One feature of the XPS controller is that it automatically adapts
the jerk time to the step width by defining a minimum and a maximum jerk time. This
auto-adaptation of the jerk time allows a perfect adjustment of the system's behavior
with different motion step sizes.
Because of jerk-controlled acceleration, any move has a duration of at least four
times the jerk time.
For the XPS controller, the following parameters need to be configured for the SGamma
profile:
• MaximumVelocity (units/s)
• MaximumAcceleration (units/s
• EmergencyDecelerationMultiplier
• MinimumJerkTime (s)
• MaximumJerkTime (s)
The above parameters are set in the stages.ini file for a positioner. When using the XPS
controller with Newport stages, these parameters are automatically set during the
configuration of the system.
The velocity, acceleration and jerk time parameters is modified by the function
PositionerSGammaParametersSet().
Example
PositionerSGammaParametersSet (MyGroup.MyStage, 10, 80, 0.02, 0.02)
This function sets the positioner "MyStage" velocity to 10 units/s, acceleration to 80
units/s
2
and minimum and maximum jerk time to 0.02 seconds. The set velocity and
acceleration must be less than the maximum values set in the stages.ini file. These
parameters are not saved if the controller is shut down. After a re-boot of the controller,
the parameters will retain the values set in the stages.ini file.
In actual use, the XPS places a priority on the displacement position value over the
velocity value. To reach the exact position, the speed of the positioner may vary slightly
from the value set in the stages.ini file or by the PositionerSGammaParametersSet
function. So the drawback of the SGamma profile is that the velocity used during the
move can be a little bit different from the velocity defined in the parameters. For
example, the exact velocity will change when the move distance is changed, move
100mm, then 100.001 mm then 100.011 mm. There will be some changes to the
commanded velocity. This change can be ignored for many applications except where
an accurate time synchronization during the motion is required.
The function, PositionerSGammaExactVelocityAdjustedDisplacementGet(), can be
used as described below to achieve the exact desired speed in applications that require
an accurate value of the velocity during a move. In this case, the velocity value is
adhered to, but the target position may be slightly different from the one required. In
other words, according to the application requirements, the user can choose between
very accurate positions or very accurate velocities.
Example
PositionerSGammaExactVelocityAdjustedDisplacementGet
(MyGroup.MyStage, 50.55, ExactDisplacement)
This function returns the exact displacement for that move with the exact
constant velocity set shown in the example above (10 mm/s). The result is
stored in the variable ExactDisplacement, for instance 50.552.
GroupMoveAbsolute (MyGroup.MyStage, 50.552)
74
NOTE
2
)
(Applies to Emergency Stop)
Motion Tutorial
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