Self-Learning Compensation of Hysteretic and Creep Nonlinearities in Piezoelectric Actuators

Abstract: Solid-state actuators based on active materials allow high operating frequencies with nearly unlimited displacement resolution. This predestines them, for example, for application in highly precise positioning systems. However, the nonlinear behaviour in such systems is mainly attributed to actuator transfer characteristics as a result of driving with high amplitudes. In this paper a novel self-learning compensation method based on the socalled modified Prandtl-Ishlinskii approach is presented, which allows extensive compensation of the complex solid-state actuator hysteretic and creep nonlinearities during operation. Finally, it is shown in an example involving a two-axis piezoelectric parallel-kinematic positioning system that this compensation substantially decreases the deviations of the actual output displacements from the desired displacements of the controlled system

Plasmabehandlung von Polymeren für biologische und medizinische Anwendungen

The paper describes the possibilities of a low pressure plasma treatment of polymer surfaces to adapt the surface properties to the demands in biology and medical engineering. After a summary of these demands and a description of the plasma process we show examples of sterilization by plasma, controlling of the protein adsorption by plasma coating and the improvement of cell growth on the polymer by a plasma treatment