Showing papers by "Sumeet S. Aphale published in 2018"

High-precision Control of a Piezo-driven Nanopositioner Using Fuzzy Logic Controllers

Abstract: This paper presents single- and dual-loop fuzzy control schemes to precisely control the piezo-driven nanopositioner in the x- and y-axis directions. Various issues are associated with this control problem, such as low stability margin due to the sharp resonant peak, nonlinear dynamics, parameter uncertainty, etc. As such, damping controllers are often utilised to damp the mechanical resonance of the nanopositioners. The Integral Resonant Controller (IRC) is used in this paper as a damping controller to damp the mechanical resonance. A further inherent problem is the hysteresis phenomenon (disturbance), which leads to degrading the positioning performance (accuracy) of the piezo-driven stage. The common approach to treat this disturbance is to invoke tracking controllers in a closed-loop feedback scheme in conjunction with the damping controllers. The traditional approach uses the Integral Controller (I) or Proportional Integral (PI) as a tracking controller, whereas this paper introduces the Proportional and Integral (PI)-like Fuzzy Logic Controller (FLC) as a tracking controller. The effectiveness of the proposed control schemes over conventional schemes is confirmed through comparative simulation studies, and results are presented. The stability boundaries of the proposed control schemes are determined in the same way as with a conventional controller. Robustness against variations in the resonant frequency of the proposed control schemes is verified.

A Surface Plasmon Resonance Based Photonic Quasi-Crystal Fibre Biosensor with Fan-Shaped Analyte Channel for High Refractive Index Analytes

Abstract: We propose a surface plasmon resonance biosensor using a photonic quasi-crystal fibre with a fan-shaped channel for liquids of high refractive index (from 1.46 to 1.52) and it exhibits a maximum sensitivity of 6100 nm/RIU.

Resonance-shifting Integral Resonant Control for High-speed Nanopositioning

Abstract: The first resonance mode of mechanical systems is a significant limit to the achievable positioning bandwidth This resonance is dependent on the physical, material and geometric properties of the system Significant effort is typically required to increase the resonance frequency by increasing stiffness or reducing mass In this article, a modified IRC scheme is presented that effectively shifts the first resonance mode to a higher frequency, thereby enabling a substantially higher positioning bandwidth A 70% increase in positioning bandwidth is demonstrated