Data-based double-feedforward controller design for a coupled parallel piezo nanopositioning stage

Vibrations as well as cross-coupling effects severely hinder fast and accurate tracking for coupled parallel piezo nanopositioning stages. In this article, a data-based double-feedforward controller is proposed to reduce individual-axis repetitive errors and cross-coupling-caused errors simultaneously. The proposed approach utilizes modeling-free inversion-based iterative control to compensate repetitive errors and data-based feedforward decoupling controller to eliminate cross-coupling effect, which has the advantages of no need for accurate identified process and alleviating the difficulty in inversion of non-minimum phase systems. Comparative experiments were performed on a piezo parallel nanopositioning stage to validate the effectiveness of the proposed controller. Experimental results indicate that the cross-coupling errors are compensated significantly and the fast and accurate tracking can be achieved via implementing the proposed controller on planar raster scanning and XY star trajectory with different tracking periods.