Rockwell Automation 1784-PM16SE SoftLogix Motion Card Setup and Configuration Manual - Manual (Page 408)

Publication 1784-UM003A-EN-P – June 2003
400 Motion Object Attributes
Advanced Drive Limits The advanced attributes map directly to SERCOS IDNs. Thus, for a detailed
description of these attributes refer to the corresponding IDN descriptions
found in the SERCOS Interface standard. Since these attributes are
automatically configured to reasonable default values, manual configuration by
the user is not required unless motivated by a specific application requirement.
Drive Offsets This section covers the various drive attributes that provide offsets to real-time
servo drive loop operation.
Friction Compensation It is not unusual for an axis to have enough static friction, so called “sticktion”,
that even with a significant position error, refuses to budge. Of course, integral
gain can be used to generate enough output to the drive to correct the error,
but this approach may not be responsive enough for the application. An
alternative is to use Friction Compensation to break sticktion in the presence
of a non-zero position error. This is done by adding, or subtracting, a fixed
output level, called Friction Compensation, to the Servo Output value based
on its current sign.
The Friction Compensation value should be just under the value that would
break the sticktion. A larger value will result in the Axis to “dither”, a
phenomena describing a rapid back and forth motion of the axis centered on
the commanded position.
GSV/SSV
Access Attribute Name Data Type Values
SSV/GSV Velocity Limit (Bipolar) REAL Position Units / sec.
SSV/GSV Acceleration Limit (Bipolar) REAL
Position Units / sec.
2
SSV/GSV Torque Limit (Bipolar) REAL %Rated
SSV/GSV Velocity Limit (Positive) REAL Position Units / sec.
SSV/GSV Velocity Limit (Negative) REAL Position Units / sec.
SSV/GSV Velocity Threshold REAL Position Units / sec.
SSV/GSV Velocity Window REAL Position Units / sec.
SSV/GSV Velocity Standstill Window REAL Position Units / sec.
SSV/GSV Acceleration Limit (Pos.) REAL
Position Units / sec.
2
SSV/GSV Acceleration Limit (Neg.) REAL
Position Units / sec.
2
SSV/GSV Torque Limit (Positive) REAL %Rated
SSV/GSV Torque Limit (Negative) REAL %Rated
SSV/GSV Torque Threshold REAL %Rated
GSV/SSV Access Attribute Name Data Type Values
SSV/GSV Friction Compensation REAL % Rated