1. DIFFER-Dutch Institute for Fundamental Energy Research, P.O. Box 6336, 5600HH Eindhoven, The Netherlands
2. Department of Mechanical Engineering, Control Systems Technology, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands
3. Department of Fundamental Electricity and Instrumentation, Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
4. Department of Applied Mathematics, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands
5. Department of Mechanical Engineering, Dynamics and Control, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands