1. Department of Electrical, Electronic Telecommunications Engineering and Naval Architecture, University of Genoa, Genoa, Italy
2. IMT School for Advanced Studies Lucca, Lucca, Italy
3. Department of Mechanical Engineering, Control Systems Technology Section, Technische Universiteit Eindhoven, MB Eindhoven, The Netherlands
4. Department of Electrical and Electronic Engineering, Department of Aeronautics, Imperial College London, London, U.K