Nanoforce Estimation using Interval Observer: Application to Force Sensor based on Diamagnetic Levitation

This paper presents a new design to measure slowly time-varying vertical nanoforces. The proposed sensor is based on diamagnetic levitation. It uses auto-stabilized magnetic springs and relies on a macroscopic seismic mass: a capillary tube used in a vertical configuration. When a vertical external force is applied to it, the capillary tube acts as a transducer that converts this unknown input force into a vertical displacement that is measured. Relying on this measurement, a Generic Linear Extended State Observer based on an interval approach is proposed to reconstruct this unknown input force and the state of the considered system. This is achieved without any a priori knowledge on the vertical force, i.e. magnitude and bounds. The efficiency of the proposed interval observer is illustrated by experimental results. Copyright (C) 2020 The Authors.