Precision machine tool X-Y stage utilizing a planar air bearing arrangement

This paper presents a new X-Y stage concept for precision machine tools. A large work area (300 mm × 300 mm) is achieved using a T-type gantry arrangement, which locates the work table supported on a vacuum preloaded air bearing on top of a reference granite surface. Actuation is provided with direct drives that fulfil the functions of motion controls, stiffness enhancement, and vibration damping. Thermal deformations are mitigated by designing internally cooled motor couplings. The error budget for the stage, as well as multivariable control law design and stability analysis, and metrology results are discussed in the paper.