1. Department of Electrical Engineering; UFRGS; Av. Osvaldo Aranha 103 90035-190 Porto Alegre-RS Brazil
2. University of Caxias do Sul - UCS; Rua Francisco Getulio Vargas 1131 95050-560 Caxias do Sul-RS Brazil
3. Department of Automation and Systems; UFSC; PO Box 476 88040-900 Florianópolis-SC Brazil
4. CNRS, LAAS; 7 avenue du colonel Roche F-31400 Toulouse France
5. Univ de Toulouse, LAAS; F-31400 Toulouse France