Structural design and active disturbance rejection control of rigid-flexible coupling motion stage for nanopositioning

Abstract

Mechanical-bearing-guided motion stage is widely used in electronic manufacturing equipment for its excellent high-acceleration performance and low cost, but its positioning precision is limited by the friction of mechanical bearing. To this end, a rigid-flexible coupling motion stage (RFCMS) with compound flexure hinges (CFHs) and a single drive is designed to simultaneously achieve large stroke and nanoscale precision in this work. The friction dead zone is isolated by utilizing the bending deflection of CFHs. To suppress the resonance of CFHs and deal with nonlinear disturbances and uncertainties, a model-based active disturbance rejection control (model-based ADRC) is adopted based on the bending stiffness modeling of CFHs, which can improve the tracking accuracy for the position profile and reduce the estimating error of the extended state observer for the total disturbance. Despite the uncertain control input gain and the nonlinear coupling of the working stage and the rigid frame, the tracking and estimating errors of closed-loop system are theoretically investigated. Experimental results show that RFCMS with model-based ADRC strategy can achieve positioning accuracy within 100 nm in point-to-point motion and has strong robustness to load mass changes.