Active probe control of a metrological Atomic Force Microscopy

This article considers the force control of an active probe for Atomic Force Microscopy (AFM). Firstly, the structure of this active probe is described. For designing the force controller, the model of this active probe was identified. Based on the measured frequency response, two notch filters were used to remove the resonant peak in open-loop frequency response. Then, a PI controller was designed to regulate the force of the probe. This controller was then implemented in a Digital Signal Processor (DSP). Experimental results were given to compare the actual performance of this controller with the conventional PI controller. It is shown that the controller with notch filters reduces the control error considerably and enables faster scan speed at weaker tip-sample interaction forces. ? 2011 IFAC.