22-03-2014, 02:55 PM
Design of a Data-Driven PID Controller
Abstract
Since most processes have nonlinearities, controller
design schemes to deal with such systems are required. On
the other hand, proportional-integral-derivative (PID) controllers
have been widely used for process systems. Therefore, in this paper,
a new design scheme of PID controllers based on a data-driven
(DD) technique is proposed for nonlinear systems. According to
the DD technique, a suitable set of PID parameters is automati-
cally generated based on input/output data pairs of the controlled
object stored in the database. This scheme can adjust the PID
parameters in an online manner even if the system has nonlinear
properties and/or time-variant system parameters. Finally, the
effectiveness of the newly proposed control scheme is evaluated on
some simulation examples, and a pilot-scale temperature control
system.
INTRODUCTION
IN RECENT years, many complicated control algorithms
such as adaptive control theory and/or robust control theory
have been proposed and implemented for real systems. Even
though these complicated and subtle control algorithms exist,
less sophisticated proportional-integral-derivative (PID) con-
trollers continue to be widely employed in process industries.
The reasons for the continued popularity of PID controllers are
summarized as follows: 1) the control structure is quite simple;
2) the physical meaning of control parameters is clear; and 3)
the operators’ know-how can be easily utilized in designing
controllers.
Given these reasons, it is still attractive to design PID con-
trollers, but they do have their drawbacks. Since most process
systems have nonlinearities, it is difficult to obtain good control
performances for such systems simply using the fixed PID pa-
rameters. The adaptive or self-tuning PID control schemes [1],
[2] have been frequently employed for systems with weak non-
linearity. However, since these methods have been mainly re-
searched and discussed for use with linear systems.
SIMULATION EXAMPLES
In order to evaluate the effectiveness of the newly proposed
scheme, some simulation examples for nonlinear systems are
considered. These include a Hammerstein model and a system
with a hysteresis. They are discussed below.
CONCLUSION
In this paper, a new design scheme of PID controllers using
the DB modeling method has been proposed. To date, many PID
controller design schemes using NNs and GAs have been pro-
posed for nonlinear systems. In employing these schemes for
real systems, however, the considerably large learning cost be-
comes a serious problem. This problem can be avoided by using
the proposed method because such computational burdens can
be effectively reduced by using the algorithm for removing the
redundant data. In addition, the effectiveness of the proposed
method has been verified by some numerical simulation exam-
ples. Given the success of this newly proposed DD technique
for PID controller