Nanoforce estimation with Kalman filtering applied to a force sensor based on diamagnetic levitation.

International audienceNano force sensors based on passive diamagnetic levitation with a macroscopic seismic mass are a possible alternative to classical Atomic Force Microscopes when the force bandwidth to be measured is limited to a few Hertz. When an external unknown force is applied to the levitating seismic mass, this one acts as a transducer that converts this unknown input into a displacement that is the measured output signal. Because the little damped and long transient response of this kind of macroscopic transducer can not be neglected, it is then necessary to deconvolve the output to correctly estimate the unknown input force. The deconvolution approach proposed in this article is based on a Kalman filter that use an uncertain a priori model to represent the unknown nanoforce to be estimated. The main advantage of this approach is that the end-user can directly control the unavoidable trade-off that exists between the wished resolution on the estimatedforce and the response time of the estimation

Nanoforce estimation based on Kalman filtering and applied to a force sensor using diamagnetic levitation

International audienceNanoforce sensors based on passive diamagnetic levitation with a macroscopic seismic mass are a possible alternative to classical Atomic Force Microscopes when the force bandwidth to be measured is limited to a few Hertz. When an external unknown force is applied to the levitating seismic mass, this one acts as a transducer that converts this unknown input into a displacement that is the measured output signal. Because the under-damped and long transient response of this kind of macroscopic transducer cannot be neglected for time-varying force measurement, it is then necessary to deconvolve the output to correctly estimate the unknown input force. The deconvolution approach proposed in this paper is based on a Kalman filter that use an uncertain a priori model to represent the unknown nanoforce to be estimated. The main advantage of this approach is that the end-user can directly control the unavoidable trade-off that exists between the wished resolution on the estimated force and the response time of the estimation

H∞-based Position Control of a 2DOF Piezocantilever Using Magnetic Sensors.

International audienceThe article addresses the position control problem of a 2 degrees of freedom (DOF) piezoelectric cantilever by means of an embedded magnetic-based position sensor. The active part of the piezocantilever used in the experimental setup is similar to cantilevers previously developed and already used for low-frequency micro-actuators in microrobotics devices. The contribution relies on the estimation of the biaxial displacement of the piezocantilever via conventional Hall-effect (HE) sensors, reducing the mechanical complexity and cost aspects.The actual sensing approach is validated via the implementation of a real-time position control based on the H1 scheme. In comparison with high resolution sensors, as laser or confocal chromatic (high-cost) or capacitive displacement (bulky), the actual sensor-control system is provides a satisfactory performance to cope with traditional micro-positioning tasks requiring a micrometer resolution. The performanceof the embedded magnetic-based position sensor is evaluated, in open- and closed-loop, with respect the measurements provided by a Keyence laser sensors