This paper presents the mechatronic analysis and performance estimation of a pulse-width modulated permanent magnet synchronous motor (PMSM), which is part of a direct-drive rotational servo system. Physical modeling together with dynamic error budgeting are applied to identify the minimal required switching frequency that maximizes the energy efficiency of the system while maintaining the required precision. The analysis is carried out for a wide velocity range and considers various friction phenomena. The disturbances induced by the switched amplifier are also considered and compared to a linear amplifier. The accuracy of the derived model and analysis is experimentally verified over the entire velocity range as well as for the considered range of switching frequencies.@en

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

Robust feedback control with large parameter uncertainties in a high precision stage with large sample mass variation is presented. Instead of expressing the nominal plant and its uncertainty by parametric models, they are expressed using the identified frequency response data. The open loop transfer function is mapped onto a Nyquist plot, to assess robust stability. Next, the complementary sensitivity function is derived from this data to describe tracking performance, which is verified by experiments. The advantage is that the parameter estimation step is omitted, without compromising robust stability and performance.@en

Correct tuning of feedback gains is important for AFMs to cope with uncertainties of the system dynamics coming from a large range of different samples, cantilevers and scan parameters. For state of the art AFMs gains have to be adjusted manually by the operator. The typical operator such as biologist, physicist or material scientist may not have detailed knowledge about control engineering. In order to increase usability and acceptance an easy and intuitive approach is needed. The method presented in this paper is based on the commonly applied manual tuning strategy for AFM-imaging and copies the behavior of an experienced user. By spectral analysis ringing of the feedback loop is detected when feedback gains are increased beyond the stability margins. Increasing gains is stopped when an 1/f stop criteria is reached. The algorithm is successfully tested in simulation and practical AFM topography measurements with different cantilever - sample combinations, demonstrating that auto-tuning can be applied to achieve imaging performance close to ideal settings.@en