Abstract

Adaptive estimation of time-varying parameters in linearly parametrized systems is considered. The estimation time is divided into small intervals; in each interval the time-varying parameter is approximated by a time polynomial with unknown coefficients. A condition for resetting of the parameter estimate at the beginning of each interval is derived; the condition guarantees that the estimate of the time-varying parameter is continuous and also allows for the coefficients of the polynomial to be different in various time intervals. A modified version of the least-squares algorithm is provided to estimate the time-varying parameters. Stability of the proposed algorithm is shown and discussed. Simulation results on an example are given to validate the proposed method.

1.
Narendra
,
K. S.
, and
Annaswamy
,
A. M.
, 1989,
Stable Adaptive Systems
,
Prentice–Hall
,
Englewood Cliffs, NJ
.
2.
Ioannou
,
P. A.
, and
Sun
,
J.
, 1995,
Robust Adaptive Control
,
Prentice–Hall
,
Upper Saddle River, NJ
.
3.
Kreisselmeier
,
G.
, 1986, “
Adaptive Control of a Class of Slowly Time-Varying Plants
,”
Syst. Control Lett.
0167-6911,
8
, pp.
97
103
.
4.
Middleton
,
R. H.
, and
Goodwin
,
G. C.
, 1988, “
Adaptive Control of Time-Varying Linear Systems
,”
IEEE Trans. Autom. Control
0018-9286,
33
, pp.
150
155
.
5.
Tsakalis
,
K. S.
, and
Ioannou
,
P. A.
, 1987, “
Adaptive Control of Linear Time-Varying Plants
,”
Automatica
0005-1098,
23
, pp.
459
468
.
6.
Tsakalis
,
K. S.
, and
Ioannou
,
P. A.
, 1993,
Linear Time-Varying Systems: Control and Adaptation
,
Prentice–Hall
,
Englewood Cliffs, NJ
.
7.
Mathelin
,
M. D.
, and
Lozano
,
R.
, 1999, “
Robust Adaptive Identification of Slowly Time-Varying Parameters With Bounded Disturbances
,”
Automatica
0005-1098,
35
, pp.
1291
1305
.
8.
Joensen
,
A.
,
Madsen
,
H.
,
Nielsen
,
H. A.
, and
Nielsen
,
T. S.
, 2000, “
Tracking Time-Varying Parameters With Local Regression
,”
Automatica
0005-1098,
36
, pp.
1199
1204
.
9.
Xianya
,
X.
, and
Evans
,
R. J.
, 1984, “
Adaptive Control of Discrete-Time Time-Varying Systems With Unknown Deterministic Disturbances
,”
IEE Proc.-D: Control Theory Appl.
0143-7054,
131
, pp.
81
84
.
10.
Zheng
,
L.
, 1988, “
Discrete-Time Adaptive Control For Time-Varying Systems Subject to Unknown Fast Time-Varying Deterministic Disturbances
,”
IEE Proc.-D: Control Theory Appl.
0143-7054,
135
, pp.
445
450
.
11.
Fan
,
J.
, and
Gijbels
,
I.
, 1996,
Local Polynomial Modelling and its Applications
,
Chapman & Hall
,
London
.
12.
Pagilla
,
P. R.
,
Yu
,
B.
, and
Pau
,
K. L.
, 2000, “
Adaptive Control of Time-Varying Mechanical Systems: Analysis and Experiments
,”
IEEE/ASME Trans. Mechatron.
1083-4435,
5
, pp.
410
418
.
13.
Pagilla
,
P. R.
, and
Zhu
,
Y.
, 2004, “
Adaptive Control of Mechanical Systems With Time-Varying Parameters and Disturbances
,”
ASME J. Dyn. Syst., Meas., Control
0022-0434,
126
, pp.
520
530
.
14.
Dieudonné
,
J.
, 1960,
Foundations of Modern Analysis
,
Academic
,
London
.
You do not currently have access to this content.