ElmoMC SimplIQ Digital Servo Drives-Bell Command Reference - Manual (Page 71)

FF[N] - Feed Forward
Purpose:
Defines the feed forward control effort.
FF[1] defines the ratio between the acceleration reference and the direct current
command.
FF[2] defines the ratio between the speed reference and direct commanding of the
speed controller.
Attributes: Type: Parameter, Real
Source: Program, RS-232, CANopen
Restrictions: None
Default values:
FF[1]=0 (RS), Non-volatile
FF[2]=1 (RS), Non-volatile
Range: [0.0…32000.00]
Index range: [1,
2]
Unit modes: UM=4, 5
Activation: Immediate
SimplIQ: Slightly
modified
Notes:
For UM=3 (open loop stepping), the HT[2] command defines the ratio between
acceleration and drive.
For most UM=5 applications, FF[2]=1.
For most UM=4 applications, FF[2] is the number of counts traveled by the main
(speed) feedback, while the position (auxiliary) feedback travels one count.
Examples:
Suppose that a gear motor with a reduction ratio of 5 drives per load. The motor has
an encoder with 1000 lines. The motor speed is used for the inner feedback loop. The
load position, measured by an encoder with 2000 lines, is used as feedback for the
outer loop. To prevent a steady-state error at constant speed,
set: 5 . 2
2000
5 1000
] 2 [
=
∗
=
FF .
See also:
UM
Application notes:
Unit Modes
The Position Controller
The Speed Controller
SimplIQ for Steppers Command Reference Manual Alphabetical Listing
MAN-STECR (Ver. 1.1)
63