On line detection of faults in a rolling mill process a method for detecting faults in a rolling mill process using multivariate SPC and system identification

A method for detecting on line a fault and his nature in a rolling mill process controlled by SPC (Statistical Process Control) is presented. The method uses the integration of multivariate SPC, traditional APC (Automatic Process Control) and a System Identification technique based on the shape factor of the system´s step response. The normal behaviour of the automation system is controlled on line computing the shape factor of several step responses registered during the process cycle. The faults due to a change of the automation system and the faults due to a change in the process are then separated. The results of an implementation in a real plant are presented.