Biomedical Engineering Reference
In-Depth Information
FIGURE 4-47
Response to a step
input for an integral
controller of the
motor position.
FIGURE 4-48
Classic
configuration of a
proportional plus
integral controller.
This can be rewritten as
K
p
+
G
p
(
s
)
K
i
s
G
o
(
s
)
=
sK
p
+
Ki
s
=
G
p
(
s
)
K
p
s
+
K
i
/
K
p
s
=
G
p
(
s
)
K
p
(
s
+
/τ
i
)
1
=
G
p
(
s
)
s
where
K
p
/
K
i
=
τ
i
is the integral time constant.
It is obvious that a zero at
−
1
/τ
i
and a pole at the origin have been added to the system.
This maintains the same difference in the number of poles and zeros as the plant had and
increases the system order. This serves to maintain the improvement in steady-state error
as well as to improve the relative stability somewhat.
