Inherent non-linearity of piezo electric transducers, used in atomic force microscopy limits the position accuracy. In order to improve linearity, the elongation can be estimated by charge measurements. To extend the frequency range to DC, strain gauges are added by means of sensor fusion. This paper addresses the challenge of choosing the filter parameters for a first order complimentary filter used for sensor fusion. After identifying stochastic and systematic errors of charge and strain gauge measurements, the optimal parameters of a first order complimentary filter is computed. Depending on the application different filter parameters are found for the same nano-positioning system, by minimizing either stochastic errors, systematic errors or a combination of both. By this method the positioning uncertainty of charge monitoring (234.1 nm) and strain gauge measurement (347.1 nm) is reduced to 140.6 nm for a commercial tube piezo.

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This paper shows a method to increase the vibrational amplitude range of commercial geophones. One major limitation of geophones is the maximum stroke of the seismic mass at its resonance frequency, which also limits the vibrational amplitude range. Reduction of the stroke is achieved by electrical damping. Via an applied shunt resistor a back electromotive force is introduced, which acts as damping. The maximum electrical damping is limited by the value of the passive resistor. This paper proposes the negative resistance of a negative impedance converter, allowing to overcome this limitation and further increasing the effective damping. It is theoretically derived and experimentally demonstrated that the increased damping reduces the required stroke of the geophones seismic mass. This allows to measure higher vibrational amplitudes or choosing a smaller geophone for the same vibrational amplitude.@en