Journal of Control Engineering and Technology (JCET)
JCET Vol. 2 Iss. 4 October 2012 PP. 168-176 www.ijcet.org
○
C World Academic Publishing
PID Controller Tuning Techniques: A Review
Hari Om Bansal, Rajamayyoor Sharma, P. R. Shreeraman
Electrical and Electronics Engineering Department, Birla Institute of Technology and Science
Pilani, India
hobansal@gmail.com
Abstract- This paper presents a review of the current as well as
classical techniques used for PID tuning. PID controllers have
been used for industrial processes for long, and PID tuning has
been a field of active research for a long time. The techniques
reviewed are classified into classical techniques developed for
PID tuning and optimization techniques applied for tuning
purposes. A comparison between some of the techniques has
also been provided. The main goal of this paper is to provide a
comprehensive reference source for people working in PID
controllers.
Keywords- PID Controllers; Tuning; Classical Techniques;
Intelligent Computational Techniques
I. INTRODUCTION
Proportional Integral and Derivative (PID) controllers
have been used in industrial control applications for a long
time. PID controllers date to 1890s governor design
[1]-[2]
.
Despite having been around for a long time, majority of
industrial applications still use PID controllers. According
to a survey in 1989, 90% of process industries use them
[3]
.
This widespread use of PID in industry can be attributed to
their simplicity and ease of re-tuning on-line
[4]
.
The PID controller is so named because its output sum
of three terms, proportional, integral and derivative term.
Each of these terms is dependent on the error value e
between the input and the output,
output =
dt
de
d
K
t
0
dte(t)
i
Ke(t)
p
K ×+
∫
×+×
(1)
where K
p
, K
i
and K
d
are the P, I and D parameters
respectively. K
i
and K
d
can also be written as,
(2)
where T
i
and T
d
are reset time and derivative time
respectively. These terms determine the type of system
response. The properties of P, I and D are discussed briefly
here.
Proportional term: This term speeds up the response as
the closed loop time constant decreases with the
proportional term but does not change the order of the
system as the output is just proportional to the input. The
proportional term minimizes but does not eliminate the
steady state error, or offset.
Integral term: This term eliminates the offset as it
increases the type and order of the system by 1. This term
also increases the system response speed but at the cost of
sustained oscillations.
Derivative term: This term primarily reduces the
oscillatory response of the system. It neither changes the
type and order of the system nor affects the offset.
A change in the proportionality constants of these terms
changes the type of response of the system. That is why PID
tuning, which is the variation of the PID proportionality
constants, is of utmost importance. This paper talks about
the different types of PID tuning techniques implemented
and the comparison between some of them.
There have been various types of techniques applied for
PID tuning, one of the earliest being the Ziegler Nichols
technique. These techniques can be broadly classified as
classical and computational or optimization techniques.
A. Classical Techniques
Classical techniques make certain assumptions about the
plant and the desired output and try to obtain analytically, or
graphically some feature of the process that is then used to
decide the controller settings. These techniques are
computationally very fast and simple to implement, and are
good as a first iteration. But due to the assumptions made,
the controller settings usually do not give the desired results
directly and further tuning is required. A few classical
techniques have been reviewed in this paper.
B. Computational or Optimization Techniques
These are techniques which are usually used for data
modeling and optimization of a cost function, and have been
used in PID tuning. Few examples are neural networks
(computational models to simulate complex systems),
genetic algorithm and differential evolution. The
optimization techniques require a cost function they try to
minimize. There are four types of cost functions used
commonly,
• Integral Absolute Error
IAE=
(3)
• Integral Square error
ISE=
(4)
• Integral Time Absolute Error
ITAE=
(5)
• Integral Time square Error
ITSE=
(6)
Computational models are used for self tuning or auto
tuning of PID controllers. Self tuning of PID controllers
essentially sets the PID parameters and also models the