Identifying Position-Dependent Mechanical Systems: A Modal Approach Applied to a Flexible Wafer Stage

Increasingly stringent performance requirements for motion control necessitate the use of increasingly detailed models of the system behavior. Motion systems inherently move, therefore, spatiotemporal models of the flexible dynamics that are essential. In this article, a two-step approach for the identification of the spatiotemporal behavior of mechanical systems is developed and applied to a lightweight prototype industrial wafer stage. The proposed approach exploits a modal modeling framework and combines recently developed powerful linear-time-invariant (LTI) identification tools with a spline-based mode-shape interpolation approach to estimate the spatial system behavior. The experimental results for the wafer-stage application confirm the suitability of the proposed approach for the identification of complex position-dependent mechanical systems and its potential for motion control performance improvements