Comparative study on control concepts of a robot manipulator with multiple-link/joint flexibilities

If one is dealing with active vibration suppression on a highly nonlinear flexible system, various techniques are needed. On the one hand a suitable dynamic model of the system is required. And on the other hand intelligent model based control concepts are necessary for active vibration damping. We deal with a basic model, where the flexibilities are approximated with linear springs and dampers, a so called lumped element model (LEM). For the control design we propose a control structure with two degrees of freedom (2DoF) for solving the tracking problem, based on the LEM. Such an approach allows designing the feedforward part independently of the feedback part. Hereby the feedforward control is based on the flatness approach, while for the feedback control several strategies are studied using acceleration- and gyrosensor-measurements. The contribution is completed with a validation by measurements from a very fast trajectory on an articulated robot with two flexible links and three elastic joints. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

SIMS investigations of titanium profiles in LiNbO3 produced by ion beam mixing and diffusion

Summary In order to increase the refractive indices of LiNbO₃ just beneath the surface, i.e. to produce waveguides, titanium was incorporated into y-cut substrates by two different methods: Evaporated Ti layers were either diffused at 1000°C or mixed into the substrate with a 3 MeV Ti⁺ beam. Radiation damage caused by ion beam mixing was removed by epitaxial regrowth. The resulting Ti concentration profiles were investigated by means of secondary ion mass spectrometry. The diffused profiles could be fitted by half Gaussians with a diffusion constant ofD = 5.25 × 10^–17 m²/s at 1000°C. The ion beam mixed and annealed profiles show a non-zero slope at the surface and differ significantly from Gaussians.

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SIMS-Untersuchung von Titanprofilen in LiNbO₃ hergestellt durch Ionenstrahl-Mischung und Diffusion

     

Ueber Wasseruntersuchungen

Ohne Zusammenfassung     

A study of photographic paper by secondary-ion-mass-spectrometry

Summary Constant quality of photographic paper is significantly depending on constant composition of the pulp. While this can be supervised by chemical investigations, secondary ion mass spectrometry (SIMS) is the method of choice for detection of composition changes in the final product. Several samples of photographic paper were analyzed using 6 keV Ar⁺.

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Untersuchung von photographischem Papier durch Sekundärionen-Massenspektrometrie