Development of a system for mapping of thrust ripple induced by PMLSM drives in a single-deck, dual-axis precision stage

Permanent magnet linear synchronous motors (PMLSMs) are becoming increasingly popular for implementation in industrial precision stages. While PMLSMs minimize friction and other undesirable effects in the stages, they induce thrust ripple, which significantly affects control of the devices and has recently been the subject of concentrated research. This paper presents the design and implementation of an innovative mechanism for measuring thrust ripple in two dimensions over the plane of motion of a PMLSM-driven precision planar stage that is currently in development. The device restricts motion in one direction and uses a load cell to measure stage thrust force in the perpendicular direction at intervals across the device´s operating range. The variation of thrust force in relation to position as well as q-axis input current magnitude was measured. Results support the assumption of wavelike, position-dependent PMLSM-induced thrust ripple in the direction of stage motion and have implications in the development of control systems for such devices.