Pitch analysis and control design for the linear motor of a railway carriage

At the University of Paderborn a mechatronic railway system (NBP-Neue Bahntechnik Paderborn) is designed and developed, which is guided by ordinary wheels and rails and is driven via a doubly fed linear motor. The concept is based on the operation of small shuttle units. The drive modules are designed as single axle units. As a result of thrust and normal forces the secondaries can pitch up and down because of the rising torque around the axle. So the pitching angle of the secondary remains in an unstable state. Each of them includes two independently fed secondaries, one axle and the respective primary element. This motion should be controlled to ensure a constant airgap between primaries and secondaries. In this paper the modelling of the system and a method for pitch control with state feedback and output integration for flexible mounted linear drives is described. A Kalman filter is used for estimation of the state variables. Finally the simulation and experimental results of pitch control for two secondaries are presented.