Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
Motor Compensation Tables and Constants
159
(
)
iv
pv
old
new
K
K
*
30
Ixx
30
Ixx
+
=
The zero and pole terms use the first-order notch filter parameters Ixx36 and Ixx38, respectively. The
second-order parameters Ixx37 and Ixx39 are set to zero if the filter is used only as an integrator.
second-order parameters Ixx37 and Ixx39 are set to zero if the filter is used only as an integrator.
iv
pv
pv
K
K
K
36
Ixx
+
−
=
1
38
Ixx
−
=
Use to Create a Lead-Lag Filter
This filter can be used simply as a lead-lag filter if the roots are real rather than imaginary. A lead-lag
filter is very similar in performance to a PID filter. It is useful when filter settings are determined
analytically rather than experimentally. When a basic lead-lag servo filter is desired, all servo gains
Ixx31 to Ixx35 should be set to zero; Ixx30 is still used as the generalized gain term.
filter is very similar in performance to a PID filter. It is useful when filter settings are determined
analytically rather than experimentally. When a basic lead-lag servo filter is desired, all servo gains
Ixx31 to Ixx35 should be set to zero; Ixx30 is still used as the generalized gain term.
The PMAC Executive program presently does not have any screens to assist in the automatic
specification of a lead-lag filter.
specification of a lead-lag filter.
Manual Specification
The generalized analytical form of a digital lead-lag filter is:
(
)
(
)
(
)
(
)
d
z
c
z
b
z
a
z
K
)
z
(
L
+
+
+
+
=
where the (z+a)/(z+b) term is the lead filter, with a < b, the (z+c)/(z+d) term is the lag filter, with c > d, and
K is the DC gain term. In Turbo PMAC’s real-time implementation, the transfer function of the filter is:
K is the DC gain term. In Turbo PMAC’s real-time implementation, the transfer function of the filter is:
2
z
2
d
1
bdz
1
2
z
2
c
1
acz
1
K
)
z
(
L
−
+
−
+
−
+
−
+
=
Turbo PMAC term Ixx30 is set to K; Ixx36 is set to ac; Ixx37 is set to c
2
; Ixx38 is set to bd; and Ixx39 is
set to d
2
.
Servo-Loop Modifiers
The PID filter has several modifying terms – non-linearities in control terminology – that can be
important to optimize the filter for performance and safety. Each is covered briefly below.
important to optimize the filter for performance and safety. Each is covered briefly below.