Velocity feedback controller for piezoelectric tube scanner: A “mixed” negative-imaginary and small-gain approach

This paper presents the design and implementation of a velocity feedback controller for the piezoelectric tube scanner (PTS) of an atomic force microscope (AFM) to damp its first resonant mode. The dynamics of the PTS is identified by using the measured data and the “mixed” negative-imaginary and small-gain approach is used to establish the internal stability of the interconnected systems. The experimental results demonstrate the performance improvement achieved by the proposed controller.