Tunneling current analysis over an experimental platform with H_∞ control

摘要

Many new problems have emerged working at nanometer scale. The precision of measured signal at such a scale is one of the pivotal requirements in many applications of nanotechnology, and it is highly sensitive to the external disturbances. Tunneling current is a quantum mechanical phenomenon which is of order of nano-amperes and appears when an extremely sharp metallic electrically charged tip is approached at the vicinity of a conductive sample surface (distance between tip apex and sample surface must be less than 1 nm). In this paper, a modern H_∞ controller design is analyzed in order to achieve better performances in terms of measurement precision, robustness and disturbance rejection for the considered system of tunneling current and a comparison is performed with conventionally used classical PI control technique. The resulting control scheme is validated over an experimental setup (working at ambient atmosphere), developed in GIPSA-Lab (Grenoble Image Parole Signal Automatique) research center. The corresponding simulation and experimental results with the proposed H_∞ control design show improved performances with respect to those obtained with the more conventional PI control technique.