1. Department of Electrical Engineering, Ravensburg-Weingarten University (RWU), 88250 Weingarten, Germany
2. School of Engineering and Computer Science, Bern University of Applied Sciences, 2500 Biel-Bienne, Switzerland
3. Department of Mechanical Engineering, Ravensburg-Weingarten University (RWU), 88250 Weingarten, Germany
4. School of Engineering and Design, Technical University of Munich (TUM), 80333 München, Germany