The solution of a new inferential 3 1/2-degree-of-freedom stochastic optimal control problem is discussed which may be either H2 or H optimal. The system includes a 2 1/2-degree-of-freedom inferential tracking controller and a feedforward control action. The feedback controller must be robust and is therefore normally designed to minimize an H, criterion. However, the solution obtained is sufficiently general that the feedback, tracking or feedforward control functions can be chosen to minimize either an H2 or a H criterion. The inferential control problem considered was motivated by a problem in the control of metal strip rolling mills. The design study presented considers the control of strip thickness given stand force measurements, and the use of feedforward signal from an upstream stand.

1.
Grimble, M. J., 1986, “Feedback and Feedforward LQG Controller Design,” American Control Conference, Seattle.
2.
Hunt
K. J.
,
1988
, “
General Polynomial Solution to the Optimal Feedback/Feedforward Stochastic Tracking Problem
,”
Int. J. Control
, Vol.
48
, No.
3
, pp.
1057
1073
.
3.
Bongiorno, J. J., and Lee, Hai-Ping, 1991, “On the Design of Optimal Decoupled Multivariable Feedback Control Systems,” ACC Boston, MA, pp. 3040–3041.
4.
Lee
Hai-Ping
, and
Bongiorno
J. J.
,
1993
, “
Wiener-Hoff Design of Optimal Decoupled Multivariable Feedback Control Systems
,”
IEEE Trans. on Auto. Contr.
, Vol.
38
, No.
12
, pp.
1838
1843
.
5.
Grimble
M. J.
,
1992
, “
Youla Parameterized 2 1/2 Degree of Freedom LQG Controller and Robustness Improvement Cost Weighting
,”
IEE Proceedings, Part D
, Vol.
139
, No.
2
, pp.
147
160
.
6.
Grimble
M. J.
,
1994
, “
Two and a Half Degrees of Freedom LQG Controller and Application to Wind Turbines
,”
IEEE Tram. AC
, Vol.
39
, No.
1
, pp.
122
127
.
7.
Grimble, M. L., 1994, Robust Industrial Control, Prentice Hall, Hemel Hempstead.
8.
Kucˇera, V., 1979, Discrete Linear Control, Wiley, Chichester.
9.
Grimble, M. J., 1995, “Feedforward/feedback Control of Inferred Variables for Hot and Cold Strip Mills,” Research Report, Industrial Control Centre, ICC/100.
10.
Mosca
E.
, and
Giarre
L.
,
1992
, “
A Polynomial Approach to the MIMO LQ Servo and Disturbance Rejection Problems
,”
Automatica
, Vol.
28
, No.
1
, pp.
209
213
.
11.
Kwakernaak
H.
,
1986
, “
A Polynomial Approach to Minimax Frequency Domain Optimisation of Multivariable Feedback Systems
,”
Int. J. Control
,
44
, No.
1
, pp.
117
156
.
12.
Grimble, M. J., and Johnson, M. A., 1988, Optimal Multivariable Control and Estimation: Theory and Applications: Vol. II and II, Wiley.
13.
Grimble
M. J.
,
1995
, “
Polynomial Solution of the Standard H2 Optimal Control Problem for Machine Control System Applications (LQG Gauge Control Problem Design)
,”
Optimal Control Applications and Methods
, Vol.
16
, pp.
77
104
.
14.
Grimble
M. J.
,
1995
, “
Polynomial Solution of the Standard H2 Control Problem for Strip Mill Gauge Control
,”
IEE Proceedings on Control Theory and Applications
, Vol.
142
, No.
5
, pp.
515
525
.
15.
Odonde, J. S. O., 1988, “Industrial Application of Kalman Filtering and Optimal Control Techniques,” PhD Thesis, Industrial Control Centre, University of Strathclyde.
16.
Choi
S. G.
,
Johnson
M. A.
, and
Grimble
M. J.
,
1994
, “
Polynomial LQG Control of Back-Up-Roll Eccentricity Gauge Variations in Cold Rolling Mills
,”
Automatica
, Vol.
30
, No.
6
, pp.
975
992
.
17.
Grimble
M. J.
,
1988
, “
Two-Degrees of Freedom Feedback and Feedforward Optimal Control of Multivariable Stochastic Systems
,”
Automatica
, Vol.
24
, No.
6
, pp.
809
817
.
18.
Sternad Mikael, 1985, “Feedforward Control of Non-Minimum Phase Systems,” Institute of Technology, Uppsala University.
19.
Grimble
M. J.
,
1986
, “
Optimal H Robustness and the Relationship to LQG Design Problems
,”
IJC
, Vol.
43
, No.
2
, pp.
351
372
.
20.
Bryant, G. P., “Automation of Tandem Mills,” Iron and Steel Institute, 1973.
21.
Hearns, O., and Grimble, M. J., 1998, “Robust Hot Strip Mill Thickness Control,” IFAC Symposium on Automation in Mining, Minerals and Metals Processing, Germany.
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