Fast Trajectory Tracking of a Flexure-Based, Multiaxis Nanopositioner With 50-mm Travel

The precise, high-speed control of nanopositioning stages is critical for many microscale additive manufacturing systems, such as microscale selective laser sintering (μ-SLS), where high throughput is needed. In μ-SLS, the positioning stage requires achieving 10 Hz steps with sub-100 nm accuracy and a travel range of 50 mm. The open-loop resolution and settling time of the flexure stage presented in the study are found to be 63 nm and 1.27 s, respectively. This settling time is too large for its application in high-throughput μ-SLS. To improve the tracking performance of the stage for fast varying signals up to 10 Hz and achieve better resolution, this paper presents the design of a finite horizon linear quadratic regulator controller for the XY stage. Owing to the good damping properties of the controller, the resolution is improved to 8 nm and input signals with 10-Hz frequency are effectively tracked. With the addition of a resonant shifting control, the tracking bandwidth is improved to 23 Hz. The paper presents a unique combination of low cost, large travel, sub-10 nm resolution and high-bandwidth XY positioning system, which is not to be found in either off-the-shelf nanopositioning stages or in research laboratories.