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

6.3

Torque Feedforward Function

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

6.3.1 Relationship between the Host Controller and SERVOPACK

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

6.3 Torque Feedforward Function

Servomotor
Current
Power
control
M
-
amplifier
section
Current feedback
ENC
Servomotor
Current
+
Power
control
- amplifier
section
Current feedback
M
6
ENC
6-7