1. ESTIG - Polytechnic Institute of Bragança Campus de Sta. Apolónia, Apartado 1134, 5301-857 Bragança, Portugal
2. IDMEC/IST - Technical University of Lisbon Av. Rovisco Pais, 1049-001 Lisbon, Portugal,
3. IDMEC/IST - Technical University of Lisbon Av. Rovisco Pais, 1049-001 Lisbon, Portugal