Moog Animatics SmartMotor™ Developer's Guide,Rev. L
Page 511 of 909
KV=formula
Constant, Velocity Feed Forward
APPLICATION: Motion control
DESCRIPTION: Velocity feed forward
EXECUTION: Buffered until an F command is issued
CONDITIONAL TO: N/A
LIMITATIONS: Must be positive
READ/REPORT: RKV
WRITE: Read/write
LANGUAGE ACCESS: Assignment, formulas and conditional testing
UNITS: N/A
RANGE OF VALUES: 0 to 65535
TYPICAL VALUES: 0 to 10000
DEFAULT VALUE: Motor-size dependent
FIRMWARE VERSION: 5.x and later
COMBITRONIC: KV:3=1234
where ":3" is the motor address — use the actual address or a
variable
DETAILED DESCRIPTION:
KV sets the gain for the velocity feed-forward element of the extended PID filter.
NOTE: The motion or servo modifications from this command must be applied by
the F function. For details, see F on page 446.
The velocity feed-forward element can be thought of as a force that the PID outputs based on
the expected speed from the trajectory calculation. This reduces the lag time of the PID
waiting for position feedback. The KV term begins the PID response as soon as the trajectory
calls for more speed. KP and KI are still required, but the KV term will help improve
responsiveness.
If you put the SmartMotor™ into a high-velocity move with KI=0 and monitor the position
error with the Motor View tool's Status tab in the SMI software, then you will see a constant
position error. To reduce the error to zero, issue a series of successively larger KV
parameters followed by F commands.
Acceptable values range from 0 to 65535. Typically, useful values range from 0 to 2000.
Current values can be reported with RKV.
EXAMPLE:
KV=1000 'Set buffered velocity feed forward
F 'Update PID filter
RELATED COMMANDS:
R
KA=formula Constant, Acceleration Feed Forward (see page 495)
Part 2: Commands: KV=formula
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