| Kp |
Proportional Gain.
Increasing proportional gain will decrease position error. Excessive amount of proportional gain will cause middle frequency oscillations (~10 - 100 Hz).
(DAC counts / error counts) |
| Ki |
Integral Gain.
Closes steady state position errors. Excessive amount of integral
gain will cause large, slow (~ <10 Hz) oscillations.
(DAC counts / (error counts * sample period)) |
| Kd |
Derivative Gain.
Damps out low frequency oscillations. Excessive derivative gain will cause high frequency squealing, screeching, or high frequency (~ > 100 Hz) oscillations.
(DAC counts / (error counts / sample period)) |
| Kpff |
Position Feed
Forward Gain.
Compensates for position-based effects in a system. Its effect is
similar to having a spring attached to the stage.
(DAC counts / position counts) |
| Kvff |
Velocity Feed Forward Gain.
Compensates for velocity-based friction or similar effects in a system.
(DAC counts * (commanded position counts / sample period)) |
| Kaff |
Acceleration Feed Forward
Gain.
Compensates for mass in a system.
(DAC counts / (commanded position counts / sample period2 )) |
| Kfff |
Friction Feed Forward Gain.
Compensates for Friction in a stage.
(DAC counts) |
| IMaxMoving |
Integral Limit During Motion.
The integral is clipped to this value while the motion is taking place.
The motion is determined in motion that's based on commanded velocity.
If this is set to zero, the integral is effectively turned off during
motion. A common way to enhance stability is to set ImaxMoving to
half of the Output Limit (if it is used). Setting ImaxMoving to zero
can reduce settling time in non-ideal systems.
(DAC counts) |
| IMaxRest |
Integral Limit During Rest.
The integral is clipped to this value while the motion is idle. The
motion is determined in motion that's based on commanded velocity.
If this is set to zero, the integral is effectively turned off when
there is no motion. A common way to enhance stability is to set ImaxRest
to half of the Output Limit (if it is used).
(DAC counts) |
| DRate |
Derivative Sub
Sampling.
The parameter causes the derivative term to be evaluated every DRate
+ 1 samples. This parameter is normally zero. If an encoder has very
low resolution, DRate can have a smoothing effect, as if a higher
resolution encoder is being used.
(sample periods - 1) |
| Output
Limit |
Control Loop Output Limit.
The absolute value of the control output will never exceed this value.
This is commonly used to limit current that's going to a motor. The
more negative value contained between Output Limit and Output Limit
High will take precedence. The more positive
value contained between Output Limit and Output Limit Low will take
precedence.
(DAC counts) |
| Output
Limit High |
Control Loop Output Positive
Limit.
The control output will never exceed this value in the positive sense.
The smaller (more negative) value contained between Output Limit and
Output Limit High will take precedence.
(DAC counts) |
| Output
Limit Low |
Control Loop Output Negative
Limit.
The control output will never exceed this value in the negative sense.
The smaller (more positive) value contained between Output Limit and
Output Limit Low will take precedence.
(DAC counts) |
| Output
Offset |
Control Loop Offset.
Creates an offset to the control output. This is useful for counter
acting gravity on vertical stages. The Output Offset is not removed
from the DAC in an Abort condition.
(DAC counts) |
| Ka0 |
Used only for noise injection
during testing. |
| Ka1 |
Currently not used. |
| Ka2 |
Currently not used. |
