A study of two-degree-of-freedom control of rotating speed in an automatictransmission, considering modeling errors of a hydraulic system

A proportional reducing valve is applied here to an automotive automatic tr ansmission system to control shift operation. Its control system must be de signed as a robust control system that considers modeling errors caused by changes in the characteristics of the valve. In this study, a braking mecha nism of an automotive automatic transmission system is considered. Two-degr ee-of-freedom control of the rotating speed is studied, in which modeling e rrors due to changes in the characteristics of a proportional reducing valv e are taken into account. A feedback controller is designed, based on mu sy nthesis, in which both changes in the characteristics of the valve and vari ations of a frictional coefficient are considered as uncertainties of a nom inal model. Introducing a feedforward controller, a two-degree-of-freedom c ontrol system is constructed. The control system is examined through experi ments using a commercial proportional reducing valve. The shift operation i s precisely controlled by the control system under these fluctuating factor s. (C) 1998 Elsevier Science Ltd. All rights reserved.