Modelling and control of 3D STM-like scanning device with application to surface reconstruction

This paper presents the modelling of the 3D motion of a piezo-actuated tunneling tip in an STM-like (Scanning Tunneling Microscope) micromechanical system, with the aim of summarizing challenging control problems in such a nanoscale device and developing a control strategy accordingly. Those control problems are settled with a purpose of surface reconstruction. To do so, various adverse phenomena like tunneling nonlinearity, actuator hysteresis, creep, vibrations and cross-couplings are compensated. A multivariable Linear Quadratic Integral (LQI) control is proposed, together with a Kalman observer for surface reconstruction, which are shown to provide improved performances in comparison with a more classical Single-Input Single-Output (SISO) control approach.