A comparison of control architectures for atomic force microscopes

We evaluate the performance of two control architectures applied to atomic force microscopes (AFM). Feedback‐only control is a natural solution and has been applied widely. Expanding on that, combining feedback controllers with plant‐injection feedforward filters has been shown to greatly improve tracking performance in AFMs. Alternatively, performance can also be improved by the use of a closed‐loop‐injection feedforward filter applied to the reference input before it enters the feedback loop. In this paper, we compare the plant‐injection architecture with the closed‐loop‐injection architecture when used in controlling AFMs. In particular, we provide experimental results demonstrating the closed‐loop‐injection architecture yields better tracking performance of a raster scan. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society