Roll Eccentricity Control Based on Recursive Estimation Technique

Abstract

This paper discusses a new roll eccentricity control method which has the following features ; the roll eccentricity is modeled by a sine wave equation for each roll and the eccentricity parameters, such as amplitude and initial phase angle are estimated using the recursive estimation technique. In this method, a square root filter is used to prevent the parameters from diverging. In addition, Kalman filter and exponentially weighted least square estimation are applied to decrease the estimation error due to the variance of observation noise and the gradual variation in force offset respectively. Furthermore, the convergence of parameters is automatically checked observing the trace of error convariance matrix. This control method is aplied to the first stand of tandem cold mill as a roll eccentricity control system. The convergence of recursive computation is confirmed and both the force and thickness deviation due to roll eccentricity have been reduced to less than half.