Rockwell Automation 1756-HYD02 ControlLogix Hydraulic Servo Module - Manual (Page 72)

72 Publication 1756-UM525A-EN-P - June 2003
Chapter 4 Using the 1756-HYD02 Module Features
Offset Tab
Use the Offset tab to make offline adjustments to the following values:
• Deadband Compensation
• Velocity Offset
• Output Offset
The parameters on this tab can be edited in two ways:
• Type parameter changes in the fields available on this tab and use the
OK or Apply buttons to save your edits.
• Edit in the Manual Adjust dialog. To do so:
a. Click on the Manual Tune button.
b. Use the spin controls to edit parameter settings.
Your changes are saved the moment a spin control changes any
parameter value.
The parameters on this tab become read-only when the controller is online if
the controller is set to Hard Run mode, or if a Feedback On condition exists.
When RSLogix 5000 is offline, the following parameters can be edited and the
program saved to disk using either the Save command or by clicking on the
Apply button. You must download the edited program to the controller before
it can be run.
Table lists the configurable features available on the Offset tab.
Feature: Definition:
Friction/Deadband
Compensation: Friction
Compensation The percentage of output level added to the current positive value, or subtracted from the current negative
value, for the purpose of moving an axis that is stuck in place due to static friction. The default value of this
parameter is 0%.
It is not unusual for an axis to have enough static friction–called "sticktion"–that, even with a significant
position error, the axis refuses to budge. Friction Compensation is used to break "sticktion" in the presence
of a non-zero position error.
The Friction Compensation value should be slightly less than the value that would break the "sticktion". A
larger value will cause the axis to "dither" (i.e. move rapidly back and forth about the commanded position).
This value is not applicable for Ultra3000 drives.
Friction/Deadband
Compensation: Window This window is defined as: command position - window attribute to command position + window attribute
While the command velocity is zero and the actual position is within this window, the Friction Compensation
(or Deadband Compensation, for Hydraulics) is applied proportionally to the position error. While the
command velocity is non-zero, the full Friction Compensation is applied.