A control performance index which relates actual output variance to minimal achievable variance was first presented by Harris (1989). In the present paper, a modification of that index is applied. Instead of comparing to minimum variance control-which corresponds to placing all closed-loop poles in the origin-one pole is placed using either control design guidelines or additionally available process knowledge. Some possible choices of the free closed-loop pole are discussed. Based on this modified closed-loop system, a performance index can be calculated which relates actual output variance to the minimum achievable variance using the modified closed-loop system. It is shown that for the calculation of this index no other information apart from the measured process output and the time-delay is necessary. The original Harris index and the proposed modified index are computed using data from industrial processes.
[1]
Tore Hägglund.
Automatic Monitoring of Control Loop Performance
,
1994
.
[2]
Matthew L. Tyler,et al.
Performance Assessment for Unstable and Nonminimum-Phase Systems
,
1995
.
[3]
Sirish L. Shah,et al.
Practical Issues in Multivariable Feedback Control Performance Assessment
,
1997
.
[4]
C. T. Seppala,et al.
A Review of Performance Assessment and Process Monitoring Techniques for Univariate and Multivariate Control Systems
,
1997
.
[5]
P.-G. Eriksson,et al.
Some aspects of control loop performance monitoring
,
1994,
1994 Proceedings of IEEE International Conference on Control and Applications.
[6]
Karl Johan Åström,et al.
Computer-Controlled Systems: Theory and Design
,
1984
.
[7]
T. Harris.
Assessment of Control Loop Performance
,
1989
.