International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 09 | Sep 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 609
Analysis of Fractional PID Controller Parameters on Time Domain
Specifications using Nelder-Mead Algorithm & Interior Point Algorithm
D. Shanmukha Chandra Kumar
1
, B.T.Krishna
2
1
Student, Dept. of ECE, UCEK, JNTU Kakinada, AP, India
2
Professor, Dept. of ECE, UCEK, JNTU Kakinada, AP, India
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Abstract - Fractional PID controller is an extension of
classical order PID controller having five parameters rather
than three guidelines for the effect of classical PID controller
parameters on the time domain analysis are available but for
fractional order PID controller there is no guidelines
available particularly for the order of integration and order
of differentiation. To assist fine tuning ,the effect of the order
of differentiation and integration parameters on the time
domain specification on various order plants are
investigated using nelder mead algorithm and interior point
algorithm. The relation between parameters (integration
and differentiation) and time domain parameters (rise time,
peak time, overshoot, settling time) are observed using
nelder mead algorithm and interior point algorithm. The
design and simulation is done by using MATLAB and
fractional order modeling and control tool box. In general
classical PID controller is a kind of feedback control loop
mechanism that is widely used in control systems. PID has
good stability, In order to improve its stability in control
systems several attempts to enhance the classical PID
controller, one of them is Fractional order PID controller.
Key Words: fractional order PID controller, fractional order
calculus, effect of parameters
1. INTRODUCTION
In general for classical PID controller guidelines are
available for the effect of classical controller parameters on
the time domain specifications. However, no guidelines are
available for fractional PID controllers, particularly for the
order of differentiation (µ) and integration (λ). To assist with
fine tuning, the effect of the order of differentiation and
integration parameters on the time domain specifications for
various plants are investigated.
Fractional calculus provides an excellent instrument for
the description of memory and hereditary properties of
various materials and processes. This is the primary
advantage of fractional derivatives in comparison to classical
integer order models, where such dynamics not taken into
account. The advantages of fractional derivatives become
more appealing in the modeling of mechanical, electrical and
electro-mechanical properties of real materials, as well as in
the description of rheological properties of rocks, and in
many other fields. Recent times have wide application of field
fractional integrals and derivatives also in the theory of
control of dynamical systems, where the controlled system
or/and the controller is described by a set of fractional
differential equations
2. FRACTIONAL PID CONTROLLER
A. FRACTIONAL CALCULUS:
The mathematical modeling and simulation of systems
and processes, based on the description of their properties in
terms of fractional derivatives, naturally leads to differential
equations of fractional order the necessity to solve such
equations to obtain the response for a particular input.
Thought in existence for more than 300 years, the idea of
fractional derivatives and integrals has remained quite a
strange topic, very hard to explain, due to absence of a
specific tool for the solution of fractional order differential
equations. Fractional order calculus has gained acceptance in
last couple of decades. J.Liouville made the first major study
of fractional calculus in 1832. In 1867, A.K.Grunwald worked
on the fractional operations. G. F. B. Riemann developed the
theory of fractional integration in 1892. Fractional order
mathematical phenomena allow us to describe and model a
real object more accurately than the classical “integer”
methods. Earlier due to lack of available methods, a fractional
order system was used to be approximated as an integer
order model. But at the present time, there are many
available numerical techniques which are used to
approximate the fractional order derivatives and integrals.
In fractional calculus, the differentiation integration
operator, is defined as follows
Here α >0 it becomes differentiation if α<0 it becomes
integration.
B. DEFINITIONS:
(Caputo’sdefinition of Fractional Order differentiation).
Caputo’s definition is given by