Delta RMC151 - Manual (Page 977)

9 Register Reference
with a deadband, this avoids ratcheting the axis back and forth around the deadband.
See the Output Deadband topic for more details.
• Within one-half count of Command Position
When the axis is within one-half count of the Command Position, the Integral Gain is
only allowed to decrease the Integral Output Term. This is similar to the deadband
case. Except in the rare case when the axis is scaled such that the transducer
feedback counts match up exactly with the position units, there will always be a small
difference between the Command Position and the nearest feedback count. Normally,
this would cause the axis to "hunt" for the command position. Constraining the
Integral Output Term to only decrease prevents the axis from "hunting".
Mathematical Definition
PID and I-PD
The Integral Output Term is calculated from the Integral Gain as follows:
I
n
= (e
n
x K
i
x T) + I
n-1
where
I
n
= Integral Term [% of maximum Control Output]
e
n
= Position Error at sample n [cu]
K
i
= Integral Gain [% / (cu x sec)]
T = Time period of control loop [sec]
cu = control unit (position-unit or velocity-unit)
The Integral Gain units are: percent of the maximum Control Output per unit of control
(position, velocity, pressure, force etc) of Position Error times time. The maximum
Control Output is 10V, but can be changed using the Output Scale parameter.
9.2.2.4.8. Differential Gain
Type: Axis Parameter Register
RMC70 Address: Gain Set #1: %MDn.63
Gain Set #2: %MDn.130
where n = 12 + the axis number
RMC150 Address: Gain Set #1: %MDn.63
Gain Set #2: %MDn.130
where n = 24 + the axis number
System Tag: Gain Set #1: _Axis[n].DiffGain
Gain Set #2: _Axis[n].DiffGain_2
where n is the axis number
How to Find: Axes Parameters Pane, Tune tab: Position/Velocity Gains
Data Type: REAL
Units: Position Control: %/(pu/sec)
Velocity control: %/(pu/sec 2)
% = percent of maximum Control Output (default is 10V)
Range: ≥ 0
Default Value: 0
Description
The Differential Gain may greatly enhance performance on many motion systems. On
velocity drives or hydraulic systems, Differential Gain will tend to dampen out oscillations
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