Velocity error, Velocity integrator error, Velocity command – Rockwell Automation 1784-PM16SE SoftLogix Motion Card Setup and Configuration Manual User Manual
Page 359: Velocity feedback
Publication 1784-UM003A-EN-P – June 2003
Motion Object Attributes 351
Velocity Error
Velocity Error is the difference, in configured axis Position Units per Second,
between the commanded and actual velocity of a drive axis. For an axis with an
active velocity servo loop, velocity error is used, along with other error terms,
to drive the motor to the condition where the velocity feedback is equal to the
velocity command.
Velocity Integrator Error
Velocity Integrator Error is the running sum of the Velocity Error, in the
configured axis Position Units per Second, for the specified axis. For an axis
with an active velocity servo loop, the velocity integrator error is used, along
with other error terms, to drive the motor to the condition where the velocity
feedback is equal to the velocity command.
Velocity Command
Velocity Command is the current velocity reference to the velocity servo loop,
in the configured axis Position Units per Second, for the specified axis. The
Velocity Command value, hence, represents the output of the outer position
control loop. Velocity Command is not to be confused with Command
Velocity which represents the rate of change of Command Position input to
the position servo loop.
Velocity Feedback
Velocity Feedback is the actual velocity of the axis as estimated by the
SERCOS module, in the configured axis Position Units per second. The
estimated velocity is generated by applying a 1 KHz low-pass filter to the
change in actual position over the servo update interval. Velocity Feedback is a
signed value—the sign (+ or -) depends on which direction the axis is currently
moving.
GSV/SSV Access
Attribute Name
Data Type
Values
GSV
Velocity Error
REAL
Position Units / Sec
GSV/SSV Access
Attribute Name
Data Type
Values
GSV
Velocity Integrator Error
REAL
Position Units – mSec / Sec
GSV/SSV Access
Attribute Name
Data Type
Values
GSV
Velocity Command
REAL
Position Units / Sec
GSV/SSV Access
Attribute Name
Data Type
Values
GSV
Velocity Feedback
REAL
Position Units / Sec