XPS-Q8 Controller Motion Tutorial
14.3.3.2 Basics
The PIDDualFFVoltage corrector can be seen as a mix between the PIDFFVelocity and
PIDFFAcceleration correctors. It is difficult to give a precise picture of this behavior
which depends a lot on the response of the stage (speed and acceleration versus motor
voltage).
14.3.3.3 Methodology of Tuning PID's for PIDDualFF Corrector (DC motors with
tachometers)
1. Adjust KFeedForwardVelocityOpenLoop to optimize the fidelity of the speed at
high speed.
2. Close the loop using the same value for KFeedForwardVelocity, set Kp, increase it
to minimize following errors until oscillations/vibrations appears during motion,
decrease Kp to eliminate oscillations.
3. Set Kd, increase until oscillations/vibrations appear during motion, and decrease it
to eliminate oscillations.
4. Increase Ki to cancel static error and minimize settling time until appearance of
overshoot/oscillations.
14.3.4 Corrector = PIPosition
PIPosition corrector can be used with AnalogStepperPosition or AnalogPosition
interface.
The AnalogPosition interface is to be used with a driver having a position input
(example = piezo driver).
The AnalogStepperPosition interface is to be used with a driver having two sine and
cosine current inputs (constant voltage gives constant currents in motor windings so
position is constant).
Figure 58: Corrector = PIPosition.
14.3.4.1 Parameters
FeedForward:
• One feed forward in position. No adjustable gain.
• When the system is used in open loop, the PI output is cut and the feed forward in
position is applied.
PI corrector:
• Output of the PI is a position.
Kp has no units.
Ki is given in 1/s.
183 XPSDocumentation V1.4.x (EDH0301En1060 — 10/17)
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