The present paper proposes an algorithm for finding the stability margins and cross over frequencies for an uncertain fractional-order system using the interval constraint propagation technique. It is first shown that the problem of finding the stability margins and crossover frequencies can be formulated as an interval constraint satisfaction problem and then solved using the branch and prune algorithm. The algorithm guarantees that the stability margins and the crossover frequencies are computed to the prescribed accuracy. The proposed algorithm is demonstrated on a noninductive cable system and also on a practical application of a gas turbine plant.

1.
Horowitz
,
I. M.
, 1993,
Quantitative Feedback Theory (QFT)
,
QFT
,
Boulder, CO
.
2.
Keel
,
L. H.
, and
Bhattacharyya
,
S. P.
, 1994, “
Robust Parametric Classical Control Design
,”
IEEE Trans. Autom. Control
0018-9286,
39
(
7
), pp.
1524
1530
.
3.
Bhattacharyya
,
S. P.
,
Chapellat
,
H.
, and
Keel
,
L. H.
, 1995,
Robust Control—The Parametric Approach
,
Prentice-Hall
,
New York
.
4.
Wilson
,
B. H.
,
Eriylmaz
,
B.
, and
Shafai
,
B.
, 1997, “
Improving Control Design for Nonlinear Parametric Uncertainty
,”
IEEE Trans. Autom. Control
0018-9286,
66
(
6
), pp.
863
883
.
5.
Barve
,
J. J.
, 2003, “
Interval Methods for Analysis of Linear and Nonlinear Control Systems
,” Ph.D. thesis, Indian Institute of Technology Bombay, Mumbai, India.
6.
Nataraj
,
P. S. V.
, and
Deshpande
,
M.
, 2004, “
An Interval Method to Compute Stability Margins for Fractional Order Systems
,”
Proceedings of the First IFAC Workshop on Fractional Differentiation and Its Applications, (FDA‘04)
, Bordeaux, France, pp.
174
179
.
7.
Chen
,
Y. Q.
, and
Moore
,
K. L.
, 2002, “
Analytical Stability Bound for a Class of Delayed Fractional-Order Dynamic Systems
,”
Nonlinear Dyn.
0924-090X,
29
, pp.
191
200
.
8.
Petras
,
I.
,
Chen
,
Y. Q.
, and
Vinagre
,
B. M.
, 2004, “
Robust Stability Test for Interval Fractional Order Linear Systems
,”
Unsolved Problems in the Mathematics of Systems and Control
,
V. D.
Blondel
and
A.
Megretski
, eds.,
Princeton University Press
,
Princeton, NJ
, pp.
208
211
.
9.
Petras
,
I.
,
Chen
,
Y. Q.
,
Vinagre
,
B. M.
, and
Podlubny
,
I.
, 2004, “
Stability of Linear Time Invariant Systems With Interval Fractional Orders and Interval Coefficients
,”
Proceedings of the Second IEEE International Conference on Computational Cybernetics
, Vienna, Austria, pp.
341
346
.
10.
Chen
,
Y. Q.
,
Ahn
,
H. S.
, and
Podlubny
,
I.
, 2006, “
Robust Stability Check of Fractional Order Linear Time Invariant Systems With Interval Uncertainties
,”
Signal Processing
,
86
(
10
), pp.
2611
2618
. 0165-1684
11.
Chen
,
Y. Q.
,
Ahn
,
H. S.
, and
Podlubny
,
I.
, 2006, “
Robust Controllability of Interval Fractional Order Linear Time Invariant Systems
,”
Signal Process.
0165-1684,
86
(
10
), pp.
2794
2802
.
12.
Ahn
,
H. S.
,
Chen
,
Y. Q.
, and
Podlubny
,
I.
, 2007, “
Robust Stability Test of a Class of Linear Time-Invariant Interval Fractional-Order System Using Lyapunov Inequality
,”
Appl. Math. Comput.
0096-3003,
187
(
1
), pp.
27
34
.
13.
Ahn
,
H. S.
, and
Chen
,
Y. Q.
, 2008, “
Necessary and Sufficient Stability Condition of Fractional-Order Interval Linear Systems
,”
Automatica
0005-1098,
44
(
11
), pp.
2985
2988
.
14.
Tan
,
N.
,
Ozguven
,
O. F.
, and
Ozyetkin
,
M. M.
, 2009, “
Robust Stability Analysis of Fractional Order Interval Polynomials
,”
ISA Trans.
0019-0578,
48
, pp.
166
172
.
15.
Podlubny
,
I.
, 1998,
Fractional Differential Equations
,
Academic
,
New York
.
16.
Wang
,
J. C.
, 1987, “
Realization of Generalised Warburg Impedance With RC Ladder and Transmission Lines
,”
J. Electrochem. Soc.
0013-4651,
134
, pp.
1915
1940
.
17.
Mandelbrot
,
B.
, 1967, “
Some Noises With I/f Spectrum, a Bridge Between Direct Current and White Noise
,”
IEEE Trans. Inf. Theory
0018-9448,
IT-13
(
2
), pp.
289
298
.
18.
Petras
,
I.
, 1999, “
The Fractional-Order Controllers: Methods for Their Synthesis and Application
,”
J. Electr. Eng.
,
50
(
9–10
), pp.
284
288
.
19.
Moore
,
R. E.
, 1979,
Methods and Applications of Interval Analysis
,
Society for Industrial and Applied Mathematics
,
Philadelphia, PA
.
20.
Moore
,
R. E.
,
Kearfott
,
R. B.
, and
Cloud
,
M. J.
, 2009,
Introduction to Interval Analysis
,
Society for Industrial and Applied Mathematics
,
Philadelphia, PA
.
21.
Hyvonen
,
E.
, 1992, “
Constraint Reasoning Based on Interval Arithmetic: The Tolerance Propagation Approach
,”
Artif. Intell.
0004-3702,
58
, pp.
71
112
.
22.
Benhamou
,
F.
,
Goualard
,
F.
, and
Granvilliers
,
L.
, 1999, “
Revising Hull and Box Consistency
,”
Proceedings of the ICLP‘99
,
MIT
,
Cambridge, MA
, pp.
230
244
.
23.
Lhomme
,
O.
, 1993, “
Consistency Techniques for Numeric CSPs
,”
Proceedings of the 13th IJCAI
,
IEEE Computer Society
, pp.
232
238
.
24.
Hansen
,
E.
, and
Walster
,
G.
, 2005,
Global Optimization Using Interval Analysis
, 2nd ed.,
Marcel Dekker
,
New York
.
25.
Granvilliers
,
L.
, and
Benhamou
,
F.
, 2006, “
Realpaver: An Interval Solver Using Constraint Satisfaction Techniques
,”
ACM Trans. Math. Softw.
0098-3500,
32
(
1
), pp.
138
156
.
26.
Bonnet
,
C.
, and
Jonathan
,
R. P.
, 2000, “
Coprime Factorizations and Stability of Fractional Differential Systems
,”
Syst. Control Lett.
0167-6911,
41
, pp.
167
174
.
27.
Ljung
,
L.
, 1999,
System Identification: Theory for the User
,
Prentice-Hall
,
Englewood Cliffs, NJ
.
28.
Deshpande
,
M. K.
, 2006, “
Interval Methods for Analysis and Synthesis of Linear and Nonlinear Uncertain Fractional Order Systems
,” Ph.D. thesis, Indian Institute of Technology Bombay, Mumbai, India.
You do not currently have access to this content.