Developing Observer of Electric Drive State for Rolling Mill Stand Based on Augmented Kalman Filter

The use of Kalman filters (KFs) is promising for the development of the systems of on-line monitoring over the technical state of industrial facilities. The observers of state (or coordinates) are used in the devices limiting dynamic loads in electromechanical systems. They are necessary to suppress torsional vibrations in a two-mass electric drive system. At the same time, well-known KF-based observers have not been widely used in rolling production. This is due to the fact that they do not provide a high accuracy of coordinate control in nonlinear systems with a shock load change. For the electric drives of rolling mill stands, the nonlinear properties are due to the presence of angular gaps in the spindle joints and the controller limits while shock load is applied when the piece is captured by the rolls. These features limit the use of the conventional KF designed for two-mass systems. The research contribution consists in the substantiation and development of an observer for the elastic moment of the extended shaft (spindle) and the moment of the second mass (roll) for the KF-based rolling stand with an augmented state vector (Augmented Kalman Filter – AKF). The difference is the addition of the 2nd mass of the two-mass system to the load moment state vector. This allows taking into account the actual filling rate of the deformation region during the capture and the setting of the control system of the electric drive. The AKF matrix equation is presented, the model of the electric drive of the 5000 plate mill stand and the AKF connection diagram in Matlab Simulink are provided. The authors conduct the analysis of the roll speed oscillograms reconstructed by the observer, and the elastic moments on the spindles of the rolling stand in the piece capture mode. The technical effectiveness of using an AKF-based observer has been confirmed. Recommendations on its implementation in the electrical engineering systems of industrial facilities are given.