1. Department of Research & Development, RAFI GmbH Co. KG, Ravensburger Straße, 128–134, D-88276 Berg/Ravensburg, Germany
2. Institute of Control and Computation Engineering, University of Zielona Góra, ul. prof. Z. Szafrana 2, 65-516 Zielona Góra, Poland
3. Faculty of Mechanical Engineering, University of Applied Sciences Ravensburg–Weingarten, Building D., Doggenriedstraße, Weingarten, Germany