Compensation for the effect of cylinder friction in the pressure feedback control of the nip load on a paper center winder

This paper describes the development of a control method for paper center winder. The control method includes pressure feedback control of the nip load between the paper roll and the backing roll based on an electrohydraulic servo system. In pressure feedback control of the nip load, the set points for pressure are calculated using a continuous function which is fitted between the target points calculated in the definition of the winding cycle. The cylinder friction is compensated for by a function which takes into account the effects of viscous friction, static friction, Coulomb´s friction and cylinder load pressure on the frictional force. The functioning of the control method has been verified experimentally using equipment containing the functions of a paper center winder