ElmoMC SimplIQ Command Reference - Manual (Page 65)

FF[N] - Feed Forward
Purpose:
Defines how much of the position reference derivative is fed as a reference to the speed
controller.
ƒ
For most UM=5 applications, FF[2]=1.
ƒ 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.
The FF[1] parameter defines the factor with which the second derivative of the position
reference is injected to the torque controller as a direct torque command.
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
Examples:
Suppose that a gear motor with a reduction ratio of 5 drives a 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
Reference chapter in the SimplIQ Software Manual:
Chapter 11, ”Unit Modes”
SimplIQ Command Reference Manual Alphabetical Listing
MAN-SIMCR (Ver. 4.5)
3-52