A monolithic linear motion platform driven by a piezoelectric and fluidic pressure-fed dual mechanism

This paper presents a novel dual-mode motion mechanism capable of achieving nanopositioning on a monolithic linear motion platform. Unlike conventional dual-mode stages that use piezoelectric (PZT)- and electromagnetic-combined or similar actuation mechanisms comprising two separate motion axes, the dual-mode actuation was developed by combining a PZT for a coarse motion and a fluidic pressure-fed mechanism (FPFM) for a fine motion and was implemented in a monolithic flexure stage fabricated by metal additive manufacturing. The FPFM actuates the flexure stage by pressuring the media in the fluidic channels created inside the flexure spring structures. Experimental tests were performed to investigate the performance of the dual-mode linear motion platform. The stiffness, damping, and frequency response functions of the dual-mode stage were experimentally characterized. The proportional-integral-differential control combined with dual-mode control was employed to control the position of the flexure stage while bidirectionally controlling the flow of compressed air for a fine motion. The FPFM motion showed a good response to 1 nm stepwise input (every 10 psi), and it was implemented to provide up to ∼10 nm fine motion along with the PZT coarse motion (1 µm). The hysteresis characteristics of the FPFM were also characterized and compensated to track the positioning error.