ElmoMC SimplIQ Digital Servo Drives-Bell Command Reference - Manual (Page 212)

1. Has any new BG command been accepted by the software or hardware? If yes,
update the speed target to the value of JV, and also update the permitted
acceleration and deceleration to the values of AC and DC.
2. If the speed target and speed command are positive, and the speed target is greater
than the speed command, select AC for the acceleration limit. If the speed target and
speed command are negative, and the speed target is less than the speed command,
also select AC. Otherwise, select DC for the acceleration limit.
3. Converge the speed command towards the speed target as fast as
acceleration/deceleration limits permit. If the speed command already equals the
speed target, do nothing.
The SF (Smooth Factor) determines the time required to build the full acceleration.
Example 1:
Let:
MO=1; JV=4000; AC=100,000; DC=200,000; SD=1e6; PM=1; RM=0; SF=0; BG;
The following figure depicts how the speed command to the controller (
DV[2]
) tracks the
target speed specified by changing the
JV
parameter, followed by a
BG
.
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
-1000
-500
0
500
1000
JV
DV[2]
AC
DC
AC
Figure 3-3: Speed Profiling Using JV, AC and DC
The speed reference to the controller may be changed at any time, regardless of the
state of the profiler. In the previous figure, the required speed was changed at time
0.065, from -1000 to 0, before reaching the speed command of -1000.
Example 2:
This example demonstrates the smoothing filter and the smoothing factor SF:
MO=1; JV=4000; AC=100,000; DC=100,000; SD=1000000; PM=1; RM=0;BG
SF has three different values:
The SF=0 graph displays sharp corners (discontinuous acceleration), because
there is no smoothing.
The SF=10 graph takes 10 milliseconds more to stabilize the speed software
command; however, the speed reference profile is much smoother.
SimplIQ for Steppers Application Note Unit Modes
MAN-STECR (Ver. 1.1)
13