Delta RMC151 - Manual (Page 1002)

RMC70/150 and RMCTools User Manual
Description
Note:
The Directional Gain Ratio has been removed in RMC70 firmware versions 1.50 and greater
because it proved to be confusing. It has been replaced by the Symmetrical/Ratioed
parameter and the Velocity Feed Forward (Positive) and Velocity Feed Forward (Negative).
The Directional Gain Ratio is not used in any versions of the RMC150.
The Directional Gain Ratio is used in closed-loop control to ratio the Control Output
depending on the direction of travel. This accounts for system dynamics that change with
the direction of travel, as occurs with single-rod hydraulic cylinders. If you are not using a
single-rod hydraulic cylinder, you should probably leave this parameter at its default
value of 1.
Note:
The Directional Gain Ratio will not affect open-loop motion.
The Directional Gain Ratio will never increase the Control Output. It will only decrease the
output in one direction. If the ratio is greater than one, it will decrease the Control Output
in the negative direction. If the ratio is less than one, it will decrease the Control Output
in the positive direction. The default value of 1 uses the same Control Output in both
directions.
The Control Output will be multiplied by the Directional Gain Ratio depending on whether
the Control Output is positive or negative.
Directional Gain
Ratio
Multiplier with Positive
Control Output
Multiplier with Negative
Control Output
1 1 1
> 1 1 1 / Directional Gain Ratio
< 1 Directional Gain Ratio 1
Determining the Directional Gain Ratio
In the tuning process, the Directional Gain should be set before adjusting any gains.
Follow these steps to set the Directional Gain Ratio:
• Use the Open Loop Rate (10) command to move the axis in the positive direction. Use
a value of Requested Output, for example 1.0 V, that will move the axis at a
reasonable speed. Make sure the cylinder reaches a constant speed. Be prepared to
stop the axis with a Requested Output of 0 to keep it from slamming into the end of
the cylinder. Record the constant Actual Velocity that the cylinder reached.
• Repeat the previous step for the opposite direction (the Requested Output will be
negative).
• The Directional Gain Ratio parameter should be: (Velocity in Negative Direction) /
(Velocity in Positive Direction)
A single-rod hydraulic cylinder typically requires a Directional Gain Ratio less than 1 (if
the positive direction is the extend direction).
9.2.2.6.3. Invert Output Polarity
Type: Axis Parameter Register
RMC70 Address: %MDn.34/0, where n = 12 + the axis number
RMC150 Address: %MDn.34/0, where n = 24 + the axis number
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