Precision motion control based on a periodic adaptive disturbance observer

This paper proposes a periodic adaptive disturbance observer (PADOB) for a precision position control of a PMLSM (Permanent Magnet Linear Synchronous Motor), which is based on a periodic adaptive learning control(PALC). It updates the output of a classical linear DOB to compensate modeling errors between a nominal plant and actual plant and external disturbance forces such as the friction and detent force. Therefore, it can improve problems occured by inaccurate parameters of the nominal plant and the instability problem occurred by updating parameters of nominal model in the DOB directly. Also, the complicated procedures to design the initial conditions in PALC are not needed. Through simulation test and experiments of the PMLSM, the validity of PADOB is illustrated.