Feedback scheme based on fuzzy control at nanometer scale

Abstract

Fuzzy control is a practical alternative for a variety of challenging control applications, since it provides a convenient method for constructing nonlinear controllers via the use of heuristicinformation. In this work, it is proposed a control system based on fuzzy logicto control the tip-sample distance in a scanning near field optical microscope (SNOM) using fuzzy control. The fuzzy controller design assumes only one input signal defined as the difference of the sampled signal (tuning fork-tip) and the reference signal, which are compared through designedsoftware. This signal is used as the rule-base of the fuzzy logic controller. It wasusedLabView 8.2 to develop the set of rules on how to control the process. A basic data acquisition is used as interface to manipulate the fuzzy controller as feedback scheme in the positioning system (piezoelectric bimorph) for the shear force control. The approach curve of the shear-force measurement of the piezoelectric bimorph was obtained using this scheme. In conclusion, this approach can be viewed as simple and reliable as feedback scheme based on fuzzy control for shear force control in a SNOM. However, in many cases, the fuzzy control can be used to improve existing traditional controller systems by adding an extra layer of intelligence to the current control method.