Development of an Active Fault-Tolerant Speed Control System for a Hot Rolling Mill using a Bank of Filter-Observers
Résumé
Sensor or actuator failures, equipment fouling, feedstock variations, product changes and seasonal influences may affect the controller's performance and as many as 60% of industrial controllers problems. The objective of an Active Fault Tolerant Control System (AFTCS) is to maintain its current performance close the desired one and preserve its stability conditions in the presence of component and/or instrument faults; in some circumstances a reduced performances may be accepted as a trade-off leading to a sub-optimal outcome. An Active Fault Tolerant Control System dedicated to the speed control of a hot roughing rolling mill under disturbances is designed. Actuator and/or sensors faults are considered to occur simultaneously on the hot roughing rolling mill which is used to carry out multi-pass forward-forward or forward-reverse rolling. The main contribution of this current study concerns the design of an accurate bank of filter-observers tandem able to isolate and estimate both the sensor and the actuator faults while preserving the system's integrity in terms of structure and performance. The effectiveness and performance of the method are illustrated over a practical experiment using the Sheffield Hille-Mill as well as via a wide range of pertinent simulations.