Date & Venue
Tuesday, 04 February 2020, 04:00pm
The Atomic Force Microscope (AFM) has emerged as an indispensable research tool in the development of nanoscience and nanotechnology. Piezoelectrically actuated nanopositioning stages are widely employed in AFMs to realize accurate the positioning of the sample-to-be-scanned, due to several performance advantages such as fine resolution, repeatability, controllability, fast response, etc. Triangular trajectories, whose high-frequency components tend to excite the lightly damped resonance of the employed nanopositioner and introduce positioning errors, are extensively used to create the popular raster scanning pattern. Scanning errors are further introduced by the rate-dependent hysteresis inherent to the piezoelectric actuators employed in the nanopositioners and the coupling effect to another lateral scanning axis. Here, the repetitive control (novel type) is incorporated to improve the tracking performance of both the lateral scanning axes, providing the fundaments for high-speed scanning of AFM, in which the tracking frequency up to 1587.3 Hz (triangular trajectory) and the scanning rate of 1000 Hz (raster scanning) are achieved with e_rms≈0.5%.
Linlin Li is working toward the Ph.D. degree in mechanical engineering at Shanghai Jiao Tong University, Shanghai, China, since 2016. She visited the University of Aberdeen for 6 months from 1st May to 1st Nov. 2019. She is currently a visiting Ph.D. student at the University of Newcastle. Her research interests include modeling and control of high-bandwidth nanopositioning stages and its applications to atomic force microscopes.