Speed Feedforward Function; Relationship Between The Host Controller And Servopack - YASKAWA S-7 Series Command Manual

6.4

Speed Feedforward Function

The speed feedforward function applies feedforward compensation to position control to
shorten the positioning time. The speed feedforward reference is created from the differential of
the position reference at the host controller. Speed feedforward is specified with VFF (speed
feedforward) in the position control command.
You can specify speed feedforward for the INTERPOLATE command.
6.4.1 Relationship between the Host Controller and SERVO-
PACK
The following figure illustrates specifying speed feedforward in a command from the host con-
troller when the SERVOPACK is performing speed control.
Host controller
K FF
Differential Differential
K FF
Differential
TPOS
Position
reference
Encoder divided
pulse output
K FF : Feedforward gain
SERVOPACK (when INTERPOLATE command is used)
Pn426
TFF
Torque feedforward
average movement time
Pn30C
VFF
Speed feedforward
average movement time
Electronic
+
Smoothing
gear
-
B
A
Pn20E Pn811
Pn210 Pn812
Position
feedback
Divider
Pn212

6.4.1 Relationship between the Host Controller and SERVOPACK

Speed
+ +
Deviation
control
-
counter
Posi t i o n
section
control secti o n
Pn522
Positioning
Speed
completed
conversion
width
Speed
feedback
PSET

6.4 Speed Feedforward Function

Servomotor
Current
+
Power
control
M
- amplifier
section
Current feedback
ENC
6
6-9