Civil Engineering Reference
In-Depth Information
Fig. 5.3
MPC strategy
•
It is a totally open methodology based on certain basic principles which will permit
future extensions.
However, the major drawback of MPC strategies is based on the need of a model
which properly reflects the dynamic behaviour of the process.
The principal framework of MPC strategies is composed of four elements which
are shared by all of them, see Fig.
5.3
. Therefore, the main differences among these
versions are both the selected strategy and the subjacent philosophy of how each one
of these elements is implemented. These elements are:
•
Reference or setpoint specification
. This element consists of the definition of
the desired trajectory or reference which must be followed by the output of the
controlled process,
w
=[
w
(
k
+
1
),
w
(
k
+
2
),...
]
, where
k
stands for discrete time
sampling.
•
Prediction of the output of the controlled process
. As was mentioned previously,
MPC algorithms make use of an appropriate model of the process to predict its
future outputs,
y
ˆ
=[ˆ
y
(
k
+
1
|
k
),
ˆ
y
(
k
+
2
|
k
), ...,
ˆ
y
(
k
+
N
|
k
)
]
, along a prediction
horizon
N
defined in the absence of control actions.
