Robust speed control of rolling mill drive systems using the loop transfer recovery design methodology

The authors describe the control problems associated with rolling mill drive systems and propose a robust speed controller for the suppression of the torsional vibrations. The undesirable mechanical vibrations inherent in a rolling mill drive system impose severe limitations on the dynamic performance of the speed control loop. Plant parameter variations uncertain dynamics, and load torque disturbances are among the major factors which must be addressed to guarantee the system stability and the high-performance operation of the system. To solve these problems, a robust speed controller based on a state feedback control structure is developed. The control law is derived using the loop transfer recovery design methodology, where plant and disturbance uncertainties are incorporated in the design to achieve a robust speed control loop. The design steps of the state controller and the state observer are described, and the constraints imposed on the system are discussed. Analysis and simulation results of the total speed drive system are presented