Positionercorrectorautotuning - Newport XPS Programmer's Manual

XPS Unified
EDH0373En1023 — 01/18
7.2.1.205

PositionerCorrectorAutoTuning

Name
PositionerCorrectorAutoTuning – Executes auto-tuning process for determining
position control loop PID values.
Input tests
- Refer to section 7.1: "Input Tests Common to all XPS Functions".
- Checks group type: (-8)
- Positioner must not be a "Secondary Positioner": (-8)
- Checks positioner name: (-18)
- Group status must be "READY": (-22)
- Control loop type must be "PIDFFVelocity", "PIDDualFFVoltage" or
"PIDFFAcceleration": (-24)
Description
The function executes an auto-tuning process and returns the calculated PID settings
(KP, KI and KD values). The selected group must be in "READY" state, else (-22) error
is returned.
This function works only if the positioner control loop type is "PIDFFVelocity"
(velocity control), "PIDDualFFVoltage" (voltage control) or "PIDFFAcceleration"
(acceleration control), else it returns (-24) error.
If the function is called when the positioner is not in READY state, (-22) error will be
returned.
The "Mode" input value indicates the control mode of the position loop (Short Settle or
High Robustness).
In the Short Settle mode, the PID values are adjusted to have high motion performance
(short settling time, less following errors).
The High Robustness mode is used for a relatively good performance in motion, but
guarantees the robustness (stability) for all stage situations (positions, velocities,
accelerations).
If auto-tuning initialization fails (-104) error is returned, or if the motion becomes
disabled then (-26) error is returned.
The auto-tuning process is executed in 5 periods. At the end of each period, the auto-
tuning process estimates the auto-tuning quality by calculating the noise/signal ratio. If
the noise/signal ratio is very close to zero (it means no oscillation), an (-101) error is
returned. Else if the noise ratio >MaximumNoiseRatio (normally between 0.1 and 0.2,
exact value defined in system.ref) then (-102) error is returned.
If the number of acquired data points (minimum = 9) or the number of acquired signal
periods (minimum = 5) is not enough for a good estimate then (-103) error is returned.
At end of this function, the new PID setting is returned and the group status becomes
"READY" once again.
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