1. Department of Electrical and Computer Engineering Concordia University 1515 St. Catherine Street Montréal Quebec H3G 2W1 Canada
2. CNRS LAAS 7 avenue du colonel Roche 31400 Toulouse France
3. Univ. de Toulouse, LAAS 31400 Toulouse France
4. Faculty of Electrical Engineering Czech Technical University in Prague Czech Republic
5. Department of Aeronautics and Astronautics Stanford University Durand Building, 496 Lomita Mall Stanford CA 94305‐4035 USA