[1] Univ Nova Lisboa, Fac Ciencias & Tecnol, P-1000029 Lisbon, Portugal
[2] Russian Acad Sci, Inst Informat & Automat, St Petersburg, Russia
[3] Univ Tecn Lisboa, INESC, ID IST, P-1000029 Lisbon, Portugal
[4] Univ Bochum, Dept Elect Engn & Informat Sci, Control Engn Lab, D-44780 Bochum, Germany