Rockwell Automation 2092-DAx Ultra1500 User Manual - Manual (Page 116)

Publication 2092-UM001D-EN-P — July 2005
5-36 Ultra1500 Application Examples
the Kff term is increased, it affects the response more. When Kff = 50, the
system response is good, with the quickest rise time and no overshoot. When
Kff = 100 the response is faster, but has some overshoot (that could be
reduced by increasing the Integrator Time setting of the velocity loop).
Figure 5.16
Position Regulator Step Response with Varied Kff
Figure 5.17 illustrates the effect of the Kff gain on the follower response or
position error for a typical motion profile. The steady state error is reduced as
the Kff term is increased. When Kff is 100, the steady state error is almost
zero, but there is some error during the acceleration and deceleration portions
of the profile. The velocity loop tuning can determine the effectiveness of the
position loop feedforward term.
Position
Command
Kff= 0
Kff= 50
Kff= 100 Kff = 0
Kff = 100
Time (msec)
0 5 10 15 25
0
2000
4000
14000
12000
10000
8000
6000
Follower Position (counts)
20