Mixed stepping/scanning mode control of stick-slip SEM-integrated nano-robotic systems

Abstract

The ability to do dexterous automated and semi-automated tasks at the micro-and nano-meter scales inside a Scanning Electron Microscope (SEM) is a critical issue for nanotechnologies. SEM-integrated nano-robotic systems with several Degrees Of Freedom (DOF) and one or several end-effectors have therefore widely emerged in research laboratories and industry. The Piezoelectric Stick-Slip (PSS) is one of the best actuation principle for SEM-integrated nano-robotic systems as it has two operating modes, namely a coarse positioning mode with long travel range, and a fine positioning mode with a resolution of the order of the nanometer. The main contribution of this paper is the design of a switch control strategy to deal efficiently and in a transparent way from the user's point of view, with the transition between the coarse and the fine operating modes of PSS actuators. The aim is to be able to perform positioning tasks with a millimeter displacement range and a nanometer resolution without worrying about the mode of operation of the actuator. The coarse mode and the fine mode are respectively controlled with a frequency/voltage proportional control and a H ∞ control. The switch control is based on an internal model of the actuator. Experimental results show the effectiveness of the new mixed coarse/fine mode control strategy to satisfy closed-loop stability and bumpless specifications at the switching time. For the best knowledge of the authors, this result is the first demonstration of such a control capability for PSS actuators.

Robust Hybrid Control of an Atomic Force Microscope for the Characterization of Interaction Force Regions at the Nanoscale

“…This is the main difference with traditional robust and conservative controllers that often lead to unnecessary very high order controllers because the control design itself does not consider only the specifications given by the user but many others that are not mastered. This is typically the case with the H ∞ control design [31]. In this article, we show a new potential of robustness in AFM with a robust method, where the control constraints are really mastered by a wise choice of the pole assignment and the choice of the worst case models.…”

“…It is the relation between the displacement of the slider and the input voltage of the piezoelectric element. In a previous work [31], the hysteresis of the three actuators has been modeled through a multilinear approximation and identified experimentally. It consists of an approximation of the static hysteresis by several straight lines around operating points.…”

“…The actuator dynamics and the static hysteresis have been modeled and identified in a previous work [31]. The results are shown in Table I.…”

Non-Collocated Displacement Sensing by Semiconductor Strain Gauges in Differentially Piezo-Driven Nanopositioners

“…The external dimensions of the nanopositioner had to meet stringent limitations, especially in the vertical direction. The limitations are mainly due to restricted space available on a 6-DoF positioning platform in a SEM (Scanning Electron Microscope) reported in [24]- [27], where the proposed nanopositioner is to be installed. The nanopositioner after installation of all piezo stacks is shown in Fig.…”

Model Predictive Control With Obstacle Avoidance for Inertia Actuated AFM Probes Inside a Scanning Electron Microscope

“…If the actuator is controlled at a higher speed, by increasing the frequency of the sawtooth voltage, the motion of the PIA will be smoother and therefore the mean error of the path following will be reduced. The reader can refer to our previous work [23] related to the dynamic control of PIAs.…”